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Title: Elements of the Theory and Practice of Chymistry, 5th ed.

Author: Pierre Joseph Macquer

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*** START OF THE PROJECT GUTENBERG EBOOK ELEMENTS OF
THE THEORY AND PRACTICE OF CHYMISTRY, 5TH ED. ***

ELEMENTS
OF THE

THEORY AND PRACTICE
OF
CHYMISTRY·

Translated from the French of

M. MACQUER,
Member of the Royal Academy of Sciences, and Professor
of Medicine in the University of Paris.

The FIFTH EDITION.
EDINBURGH:
Printed for Alexander Donaldson; and sold at his Shop, No. 48, East
Corner of St. Paul's Church-Yard, London; and at Edinburgh.
M. DCC. LXXVII.

THE
AUTHOR's
PREFACE.

An hundred and fifty years are scarce elapsed since the clouds of prejudice,
which had long overspread the world, began to clear up, and men were
convinced, by cultivating the Sciences, and attending to Nature, that no
fanciful hypotheses would ever lead them to the true causes of those various
phenomena that incessantly and every where meet the observer's eye; but
that the narrow limits of the human understanding confine the course of our
researches to one single path; namely, that of Experiment, or the Use of our
Senses. Yet, in this short period, Natural Philosophy hath risen to a high
pitch of improvement, and may with truth be said to have made much
greater advances towards perfection, since the experimental method was
introduced, than in the many ages before.
This is true with regard to every branch of Natural Philosophy; but more
particularly with regard to Chymistry. Though this Science cannot be said to
have ever existed without experiments, yet it laboured under the same
disadvantages with the rest; because those who studied it made all their
experiments with a view to confirm their own Hypotheses, and in
consequence of principles which had no foundation whatever, but in their
wild imaginations.
Hence arose that enormous heap, that incongruous jumble of facts, which
some time ago constituted all the knowledge of Chymists. Most of them,
and especially those who assumed the pompous title of Alchymists, were
persuaded that all the Metals were no other than Nature's rude unfinished
essays towards making Gold; which, by means of due coction in the bowels
of the earth, advanced gradually towards maturity, till at last they were
perfectly converted into that beautiful and precious Metal.
On this principle, which, if not demonstrably false, is at least utterly
destitute of proof, and unsupported by a single observation, they attempted
to finish what Nature had begun, by procuring to the imperfect Metals this
much desired coction. To attain it they made an infinite number of
experiments and trials; which all conspired to detect the falsity of their

system, and to satisfy men of sense, that the methods they employed were
very far from answering the purpose.
However, as facts always promote the knowledge of Nature, it happened
that those experiments, though quite useless with regard to the end for
which they were originally made, proved the occasion of several curious
discoveries.
These lucky consequences of their mistaken labours raised the courage of
the Chymists, or rather Alchymists, who looked upon every such instance of
success as a new step towards the Grand Work, and greatly increased the
fond opinion they entertained of themselves, and of their Art, which, on that
account, they set up very high above all other Sciences. Nay, they carried
this notion of superiority so far, as to hold the rest of mankind unworthy, or
incapable, of rising to such sublime knowledge. In consequence thereof
Chymistry became an occult and mysterious Science; its expressions were
all tropes and figures, its phrases metaphorical, and its axioms so many
enigmas: in short, an obscure unintelligible jargon is the justest character of
the Alchymistic Language.
Thus, by endeavouring to conceal their secrets, those gentlemen rendered
their Art useless to mankind, and brought it into deserved contempt. But at
length the genius of true philosophy prevailed in Chymistry, as well as in
the other Sciences. Some great men arose, who had generosity enough to
think their knowledge no otherways valuable than as it proved of service to
Society. They did their utmost to introduce both the knowledge and the
practice of many important secrets, till then of no use; they drew aside the
veil which hid the charms of Chymistry; and that Science emerging from
the profound obscurity, in which it had for many ages lain concealed,
gained the admiration of the world as soon as it appeared in open day.
Several societies of ingenious men were formed in the most learned
countries of Europe, who vied with one another in their labours to execute
the noble scheme, and assisted each other by mutually communicating their
discoveries. Chymistry made the most rapid progress, enriching and
perfecting the Arts derived from, or depending on it. In a word, it put on a
new face, and became truly worthy of the title of Science; founding its
principles and its processes on solid experiments, and on just consequences
deduced from them.

Since that time the Art is become so extensive, by the numerous discoveries
which Chymists have already made, and are daily making, that large
volumes are required to contain a complete Treatise on the subject. In short,
Chymistry may now, in some degree, be compared to Geometry: each of
these Sciences takes in a most ample field of inquiry, which every day
enlarges very considerably; from each are derived several Arts, not only
useful but even necessary to Society; each hath its Axioms and its
undeniable principles, either demonstrated from internal evidence, or
founded on constant experience; so that the one, as well as the other, may
be reduced to certain fundamental truths, on which all the rest are built.
These fundamental truths connected together, and laid down with order and
precision, form what we call the Elements of a Science. It is well known
that there are many such works relating to Geometry, but it is not so with
regard to Chymistry; there being very few books which treat of this Science
in an Elementary manner.
Yet it must be owned, that performances of this kind are exceedingly useful.
Many who have a relish for the Sciences, but have not leisure to read
elaborate Works which treat of them minutely, are glad to meet with a book
from which, without sacrificing too much of their time, or neglecting their
ordinary business, they may obtain a taste or just notion of a Science that is
not their principal study. Those who incline to go farther, and learn more,
may, by reading an elementary tract, be enabled to understand Authors,
who, as they commonly write only for proficients in the Art, are obscure
and hardly intelligible to mere beginners. Nay, I presume to say, that an
Elementary Treatise of Chymistry may prove a very useful book, even to
those who have made some progress in the Science: for as it contains only
the fundamental propositions, and indeed is an abstract of the whole Art, it
may help them to recollect the most important parts of what they have read
in many different works, and fix in their memoirs the most essential truths,
which might else be either confounded with others, or entirely forgot. And
these are the motives which determined me to compose the Work which I
now offer to the Public.
The general Plan on which I proceed is to suppose my Reader an absolute
Novice in Chymistry; to lead him from the most simple truths, and such as
imply the lowest degree of knowledge, to such as are more complex, and
require a greater acquaintance with Nature. This order, which I have laid

down for my rule, hath obliged me to begin with examining the most simple
substances that we know, and which we consider as the elements whereof
others are composed; as, by knowing the properties of these elementary
parts, we are naturally led to those of their several combinations; and, on
the other hand, in order to know the properties of compound bodies, it is
necessary we should be first acquainted with the properties of their
principles. The same reason induced me, when enquiring into the properties
of one substance, to take no notice of those which relate to any other
substance not treated of before. For example: as I treat of Acids before
Metals, I say nothing under the head of those Acids concerning their power
of dissolving metals; that I defer till I come to the subject of Metals: and
thus I avoid speaking prematurely of a substance with which I suppose my
Reader wholly unacquainted. And this method I was so much the more
easily induced to follow, that I know of no Chymical book written on the
same Plan.
After discoursing of Elements in general, I treat next of such substances as
are immediately composed of them, and are, next to them, the most simple:
such are all saline substances. This head comprehends mineral Acids, fixed
Alkalis, and their several combinations; the volatile sulphureous spirit,
sulphur, phosphorus, and the Neutral salts which have an earth or fixed
Alkali for their basis: those which have for their basis either a volatile
Alkali, or some metallic substance, are referred, according to my general
Plan, to the heads under which I treat of those substances.
Metallic substances are scarcely more compounded than the saline; which
induces me to consider them next. I begin with those which are the most
simple, or at least seem to be so; because their principles, being very
strongly connected together, are separated with the greatest difficulty: such
are the Metals properly so called; namely, Gold, Silver, Copper, Iron, Tin,
and Lead. After these come the Semi-metals in order; to wit, Regulus of
Antimony, Zinc, Bismuth, and Regulus of Arsenic. Mercury being a
doubtful substance, which some Chymists rank with the Metals, and others
with the Semi-metals, because it actually possesses certain properties in
common with each, I have treated of it in a separate Chapter, which stands
between the Metals and Semi-metals.

I next proceed to examine the several sorts of Oils, whether Vegetable,
which are divided into fat, essential, and empyreumatic; or Animal, and
Mineral Oils.
By examining these substances we obtain ideas of all the principles which
enter into the composition of Vegetable and Animal bodies; that is, of those
substances that are capable of fermentation: this enables me to treat of
fermentation in general; of its three different degrees or kinds, the
spirituous, acetous, and putrid; and of the products of those fermentations,
ardent spirits, acids analogous to those of vegetables and animals, and
volatile alkalis.
The order in which I treat of all those substances being different from that
in which they are obtained from compound bodies, I give, in a distinct
Chapter, a general idea of Chymical Decomposition, with a view to shew
the order in which they are separated, from the several bodies in the
composition whereof they are found. This brings them a second time under
review, and gives me an opportunity of distinguishing those which exist
naturally in compound bodies, from those which are only the result of a
new combination of some of their principles produced by the fire.
The succeeding Chapter explains the late Mr Geoffroy's Table of Affinities;
which I take to be of great use at the end of an Elementary tract like this, as
it collects into one point of view the most essential and fundamental
doctrines which are dispersed through the work.
I conclude with an account of the Construction of such Vessels and
Furnaces as are usually employed in Chymistry.
In this Part I say nothing of any manual operations, or the several ways of
performing Chymical processes; reserving these particulars for my Treatise
of Practical Chymistry, to which this must be considered as an Introduction.

CONTENTS.

Elements of the Theory of Chymistry.

CHAP. I.
Page
Of the Principles of Bodies
1
Sect. 1. Of Air 2
Sect. 2. Of Water 3
Sect. 3. Of Earth 4
Sect. 4. Of Fire 5
Sect. 5. Of the Phlogiston 7
Chap. II. A general View of the Relations or Affinities between
Bodies 9
Chap. III. Of Saline Substances in general 11
Sect. 1. Of Acids 12
Sect. 2. Of Alkalis 14
Sect. 3. Of Neutral Salts 15
Chap. IV. Of the Several Sorts of Saline Substances.
Sect. 1. Of the Universal Acid 18
Sect. 2. Of the Nitrous Acid 22
Sect. 3. Of the Marine Acid 25
Chap. V. Of Lime 29
Chap. VI. Of Metallic Substances in general 34
Chap. VII. Of Metals 37
Sect. 1. Of Gold ib.
Sect. 2. Of Silver 39
Sect. 3. Of Copper 44
Sect. 4. Of Iron 47
Sect. 5. Of Tin 52
Sect. 6. Of Lead 53
Chap. VIII. Of Quick-Silver 58
Chap. IX. Of the Semi-Metals.
Sect. 1. Of Regulus of Antimony 62

Sect. 2. Of Bismuth 69
Sect. 3. Of Zinc 70
Sect. 4. Of Regulus of Arsenic 72
Chap. X. Of Oil in general 76
Sect. 1. Of Charcoal 77
Sect. 2. Of Soap 78
Chap. XI. Of the Several Sorts of Oils.
Sect. 1. Of Mineral Oils 79
Sect. 2. Of Vegetable Oils 80
Sect. 3. Of Animal Oils 82
Chap. XII. Of Fermentation in general 83
Chap. XIII. Of the Spirituous Fermentation 84
Chap. XIV. Of the Acetous Fermentation 90
Sect. 1. Of Vinegar 91
Sect. 2. Of Tartar 93
Chap. XV. Of the Putrid Fermentation, or Putrefaction 96
Chap. XVI. A general View of Chymical Decomposition 101
Sect. 1. The Analysis of Vegetable Substances 102
Emulsions 104
Sect. 2. The Analysis of Animal Substances 106
Sect. 3. The Analysis of Mineral Substances 108
Of the Pyrites 110
Of Ores 112
Chap. XVII. Explanation of the Table of Affinities 119
Chap. XVIII. The Theory of Constructing the Vessels most commonly
used in Chymistry 126
Chap. XIX. The Theory of Constructing the Furnaces most
commonly used in Chymistry 133
Of Lutes 147
Elements of the Practice of Chymistry.
Introduction 153
PART I. Of Minerals.
SECTION I.
Operations performed on Saline Mineral Substances.

Chap. I. Of the Vitriolic Acid.
1. Process. To extract Vitriol from the Pyrites 159
2. To extract Sulphur from the Pyrites, and other Sulphureous
Minerals 162
3. To extract Alum from aluminous Minerals 165
4. To extract the Vitriolic Acid from Copperas or Green Vitriol 170
5. To decompose Sulphur, and extract its Acid, by burning it 174
6. To concentrate the Vitriolic Acid 176
7. To decompound Vitriolated Tartar by means of the
Phlogiston; or to compose Sulphur by combining the Vitriolic
Acid with the Phlogiston 179
Chap. II. Of the Nitrous Acid.
1. Process. To Extract Nitre out of Nitrous Earths and Stones.
The Purification of Salt-Petre. Mother of Nitre. Magnesia 181
2. To decompose Nitre by means of the Phlogiston. Nitre fixed
by Charcoal. Clyssus of Nitre. Sal Polychrestum 186
3. To decompose Nitre by means of the Vitriolic Acid. The
Smoking Spirit of Nitre. Sal de duobus. The Purification of
Spirit of Nitre 191
Chap. III. Of the Marine Acid.
1. Process. To extract Sea-salt from Sea-water, and from Brine-
springs. Epsom Salt 195
2. Experiments concerning the Decomposition of Sea-salt by
means of the Phlogiston. Kunckel's Phosphorus 197
3. To decompose Sea-salt by means of the Vitriolic Acid.
Glauber's Salt. The Purification and Concentration of Spirit
of Salt 211
4. To decompose Sea-salt by means of the Nitrous Acid. Aqua
regis. Quadrangular Nitre 217
Chap. IV. Of Borax. 218
SECTION II.
Of Operations on Minerals.
Chap. I. Of Gold.
1. Process. To separate Gold, by Amalgamation with Mercury,
from the Earths and Stones with which it is found mixed 223

2. To dissolve Gold in Aqua Regis, and by that means separate
it from Silver. Aurum Fulminans. Aurum Fulminans reduced 227
3. To dissolve Gold by Liver of Sulphur 232
4. To separate Gold from all other Metalline substances by
means of Antimony 233
Chap. II. Of Silver.
1. Process. To separate Silver from its Ore, by means of
Scorification with Lead 238
2. The refining of Silver by the Cupel 243
3. To purify Silver by Nitre 248
4. To dissolve Silver in Aqua Fortis, and thereby separate it
from every other Metalline substance. The Purification of
Aqua Fortis. Silver precipitated by Copper 250
5. To separate Silver from the Nitrous Acid by Distillation.
Crystals of Silver. The Infernal Stone 254
6. To separate Silver from the Nitrous Acid by Precipitation.
Luna Cornea. Luna Cornea reduced 256
7. To dissolve Silver, and separate it from Gold, by
Cementation 258
Chap. III. Of Copper.
1. Process. To separate Copper from its Ore 262
2. To purify Black Copper, and render it malleable 264
3. To deprive Copper of its Phlogiston by Calcination 266
4. To resuscitate the Calx of Copper, and reduce it to Metal, by
restoring its Phlogiston 267
5. To dissolve Copper in the Mineral Acids 268
Chap. IV. Of Iron.
1. Process. To separate Iron from its Ore 270
2. To render Pig-iron and brittle Iron malleable 273
3. To convert Iron into Steel 274
4. The Calcination of Iron. Sundry Saffrons of Mars 276
5. Iron dissolved by the mineral Acids 277
Chap. V. Of Tin.
1. Process. To extract Tin from its Ore 279
2. The Calcination of Tin 280

3. The Dissolution of Tin by Acids 284
Chap. VI. Of Lead.
1. Process. To extract Lead from its Ore 286
2. To separate Lead from Copper 289
3. The Calcination of Lead 292
4. To prepare Glass of Lead 293
5. Lead dissolved by the Nitrous Acid 295
Chap. VII. Of Mercury.
1. Process. To extract Mercury from its Ore, or to revivify it
from Cinabar 298
2. To give Mercury, by the action of Fire, the appearance of a
Metalline Calx 301
3. To dissolve Mercury in the Vitriolic Acid. Turbith Mineral 302
4. To combine Mercury with Sulphur. Æthiop's Mineral 304
5. To sublime the Combination of Mercury and Sulphur into
Cinabar 306
6. To dissolve Mercury in the Nitrous Acid. Sundry Mercurial
Precipitates 307
7. To combine Mercury with the Acid of Sea-salt. Corrosive
Sublimate 308
8. Sweet Sublimate 312
9. The Panacea of Mercury 314
SECTION III.
Of Operations on the Semi-Metals.
Chap. I. Of Antimony.
1. Process. To separate Antimony from its Ore 315
2. The common Regulus of Antimony 316
3. Regulus of Antimony precipitated by Metals 318
4. The Calcination of Antimony 321
5. Calx of Antimony reduced to a Regulus 323
6. Antimony calcined with Nitre. Liver of Antimony. Crocus
Metallorum 325
7. Another Calcination of Antimony with Nitre. Diaphoretic
Antimony. Materia Perlata. Clyssus of Antimony 326
8. Calx of Antimony vitrified 330

9. Kermes Mineral 331
10. Regulus of Antimony dissolved in the Mineral Acids 335
11. Regulus of Antimony combined with the Acid of Sea-salt
Butter of Antimony. Cinabar of Antimony 338
12. Butter of Antimony decompounded by means of Water only.
Pulvis Algaroth, or Mercurius Vitæ. The Philosophic Spirit of
Vitriol 342
13. Bezoar Mineral. The Bezoartic Spirit of Nitre 343
14. Flowers of Antimony 347
15. Regulus of Antimony converted into Flowers 348
Chap. II. Of Bismuth.
1. Process. To extract Bismuth from its Ore 350
2. Bismuth dissolved by Acids. Magistery of Bismuth.
Sympathetic Ink 352
Chap. III. Of Zinc.
1. Process. To extract Zinc from its Ore, or Calamine 357
2. To sublime Zinc into Flowers 359
3. To combine Zinc with Copper. Brass. Prince's Metal, &c. 361
4. Zinc dissolved in the Mineral Acids 365
Chap. IV. Of Arsenic.
1. Process. To extract Arsenic from its matrix. Zafre or Smalt 367
2. To separate Arsenic from Sulphur 371
3. To give Arsenic the Metalline Form. Regulus of Arsenic 374
4. To distil the Nitrous Acid by the interposition of Arsenic.
Blue Aqua Fortis. A new Neutral Salt of Arsenic 377
5. To alkalizate Nitre by Arsenic 379
PART II. Of Vegetables.
SECTION I. Operations on unfermented Vegetables.
Chap. I. Of the Substances obtained from Vegetables by Expression
only.
1. Process. To express and depurate the juice of a Plant,
containing its Essential Salt. The crystallization of that Salt 383
2. To draw the Oils out of Kernels, Seeds, and Fruits, by
Expression 386
3. To draw the Essential Oils of certain Fruits by Expression 387

Chap. II. Of the Substances obtained from Vegetables by Triture.
1. Process. To make the Extract of a Plant by Trituration 389
2. To extract from Seeds and Kernels, by Trituration, the matter
of Emulsions 392
Chap. III. Of Operations on Fat Oils.
1. Process. To attenuate Fat Oils, and change their nature, by
exposing them to the action of fire, and distilling them 395
2. To combine Fat Oils with Acids. The decomposition of this
combination 398
3. To combine Fat Oils with Fixed Alkalis. Hard and Soft Soap.
The decomposition of Soap 400
4. To combine Fat Oils with Sulphur 405
5. To combine Fat Oils with Lead, and the Calces of Lead. The
Basis of Plasters. The decomposition of this combination 406
Chap. IV. Of the substances obtained from Vegetables with a degree
of heat not exceeding that of boiling water.
1. Process. To obtain from Plants, by distilling them with the
mean degree of heat between freezing and boiling water, a
liquor impregnated with their Principle of Odour 408
2. To extract the Fat Oils of Plants by Decoction in boiling
water. Cacao-Butter 410
3. To extract the Essential Oils of Plants by Distillation with the
heat of boiling water. Distilled Water 412
4. To extract the Essential Oils of Plants by distillation per
descensum 418
5. Infusions, Decoctions, and Extracts of Plants 419
Chap. V. Of Operations on Essential Oils.
1. Process. The Rectification of Essential Oils 422
2. To fire Oils by combining them with highly concentrated
Acids: instanced in Oil of Turpentine 426
3. To combine Essential Oils with mineral Sulphur. Balsam of
Sulphur. This composition decompounded 434
4. To combine Essential Oils with Fixed Alkalis. Starkey's Soap 438
Chap. VI. Of the Substances obtained from Vegetables by means of a
graduated heat, from that of boiling water, to the strongest

that can be applied to them in close vessels.
1. Process. To analyze vegetable substances that yield neither a
Fat nor an Essential Oil: instanced in Guaiacum-Wood 440
2. To analyze a vegetable substance which yields the same
principles as are obtained from Animal matters: instanced in
Mustard-seed 445
Chap. VII. Of the Substances obtained from Vegetables by
Combustion.
1. Process. To procure a Fixed, Caustic, Alkaline Salt from a
vegetable substance, by burning it in the open air 448
2. To procure the Fixed Salt of a Plant, by burning it after the
manner of Tachenius 453
3. To render Fixed Alkalis very Caustic by means of Lime. The
Caustic Stone 455
4. The Analysis of Soot 457
Chap. VIII. The Analyses of some particular substances belonging to
the Vegetable Kingdom.
1. Process. Analysis of the Native Balsams: instanced in
Turpentine 460
2. The Analysis of Resins: instanced in Benjamin. The Flowers
and Oil of Benjamin 463
Reflections on the Nature and Properties of Camphor 465
3. The Analysis of Bitumens: instanced in Amber. The Volatile
Salt and Oil of Amber 467
4. The Analysis of Bee's Wax, and such Oily Compounds as are
analogous to it 472
5. The Saccharine juices of Plants analyzed: instanced in Honey 474
6. Gummy substances analyzed: instanced in Gum Arabic 476
SECTION II. Of Operations on Fermented Vegetable Substances.
Chap. I. Of the Product of Spirituous Fermentation.
1. Process. To make Wine of Vegetable Substances that are
susceptible of Spirituous Fermentation 478
2. To draw an Ardent Spirit from substances that have
undergone the Spirituous Fermentation. The Analysis of
Wine 482

3. To dephlegmate Spirit of Wine by the means of Fixed
Alkalis. Spirit of Wine analyzed 486
Chap. II. Spirit of Wine combined with different Substances.
1. Process. To combine Spirit of Wine with the Vitriolic Acid.
This combination decompounded. Rabel's Water. Æther.
Sweet Oil of Vitriol. Hoffman's Anodyne Mineral Liquor 492
2. Spirit of Wine combined with Spirit of Nitre. Sweet Spirit of
Nitre 503
3. Spirit of Wine combined with the Acid of Sea-salt. Dulcified
Spirit of Salt 508
4. Oils, or Oily matters, that are soluble in Spirit of Wine,
separated from Vegetables, and dissolved, by means of that
Menstruum. Tinctures; Elixirs; Varnishes. Aromatic Strong
Waters 510
Chap. III. Of Tartar.
1. Process. Tartar analyzed by distillation. The Spirit, Oil, and
Alkaline Salt of Tartar 514
2. The depuration of Tartar. Cream and Crystals of Tartar 517
Chap. IV. Crystal of Tartar combined with several substances.
1. Process. Crystal of Tartar combined with Absorbent Earths.
Soluble Tartars 519
2. Crystal of Tartar combined with Fixed Alkalis. The Vegetable
Salt. Saignette's Salt. The decomposition of Soluble Tartar 524
3. Crystal of Tartar combined with Iron. Chalybeated Tartar.
Tincture of Steel with Tartar. Soluble Chalybeated Tartar 528
4. Crystal of Tartar combined with the reguline part of
Antimony. Stibiated or Emetic Tartar 534
Chap. V. Of the Product of Acetous Fermentation.
1. Process. Substances susceptible of the Acetous Fermentation
turned into Vinegar 536
2. To concentrate Vinegar by Frost 540
3. Vinegar analyzed by distillation 542
Chap. VI. The Acid of Vinegar combined with different Substances.
1. Process. The Acid of Vinegar combined with Alkaline 547
Substances. Foliated Salt of Tartar, or Regenerated Tartar.

Decomposition of that Salt
2. The Acid of Vinegar combined with Copper. Verdegris.
Crystals of Copper. This combination decompounded. Spirit
of Verdegris 550
3. The Acid of Vinegar combined with Lead. Ceruse. Salt or
Sugar of Lead. This combination decompounded 552
Chap. VII. Of the Putrid Fermentation of Vegetable Substances.
1. Process. The Putrefaction of Vegetables 557
2. Putrefied Vegetable substances analyzed 559
PART III. Of Operations on Animal Substances.
CHAP. I. Of Milk.
1. Process. Milk separated into Butter, Curd, and Whey:
instanced in Cow's Milk 562
2. Butter analyzed by distillation 566
3. The Curd of Milk analyzed by distillation 569
4. Whey analyzed 571
Chap. II. Of the Substances which compose an Animal Body.
1. Process. Blood analyzed: instanced in Bullock's Blood 574
2. Flesh analyzed: instanced in Beef 580
3. Bones analyzed: instanced in Ox-bones 583
4. Animal Fat analyzed: instanced in Mutton-Suet 584
5. Eggs analyzed: instanced in Pullet's Eggs 586
Chap. III. Of Animal Excrements.
1. Process. Dung analyzed: instanced in Human Excrement.
Mr. Homberg's Phosphorus 588
2. Human Urine analyzed 596
Chap. IV. Of Volatile Alkalis.
1. Process. Volatile Alkalis rectified and depurated 599
2. Volatile Alkalis combined with Acids. Sundry Ammoniacal
Salts. Sal Ammoniac 602
3. Sal Ammoniac decompounded by Acids 607
4. Sal Ammoniac decompounded by Fixed Alkalis. Volatile
Salt. The Febrifuge of Sylvius 608
5. Sal Ammoniac decompounded by Absorbent Earths and 611
Lime. Volatile Spirit of Sal Ammoniac. Fixed Sal Ammoniac.

Oil of Lime
6. Volatile Alkalis combined with oily matters. A Volatile Oily
Aromatic Salt 616
Illustrations
PLATE FIRST. Alembics. 621
PLATE SECOND. Alembic and other equipment. 622
PLATE THIRD. Reverberating Furnace. 623
PLATE FOURTH. Cupelling Furnace. 624
GEOFFROY'S TABLE of the COMPARATIVE AFFINITIES 625
INDEX 629

ELEMENTS
OF THE
THEORY of CHYMISTRY.

CHAP. I.

Of the Principles of Bodies.
he object and principal end of Chymistry, is to separate the different
T substances that enter into the composition of bodies; to examine each
of them apart; to discover their properties and relations; to decompose,
if possible, those very substances; to compare them together, and combine
them with others; to re-unite them again into one body, so as to reproduce

the original compound with all its properties; or even to produce new
compounds that never existed among the works of nature, from mixtures of
other matters differently combined.
But this Analysis, or Decomposition, of bodies is finite; we being unable to
carry it beyond a certain limit. In whatever way we attempt to go further,
we are always stopped by substances in which we can produce no change,
which will not admit of being resolved into others, and which stand as so
many firm barriers obstructing our progress.
To these substances we may, in my opinion, give the title of Principles or
Elements: at least, with regard to us, they are really such. Of this sort the
principal are Earth, Water, Air, and Fire. For though there is ground to
believe that these are not the primary component parts, or the most simple
elements, of matter; yet, as we know by experience, that our senses cannot
possibly discover the principles of which they are composed, it seems more
reasonable to fix upon them, and consider them as simple homogeneous
bodies, and the principles of the rest, than to fatigue our minds with vain
conjectures about the parts or elements of which they may consist; seeing
there is no criterion by which we can know whether we have hit upon the
truth, or whether the notions we have formed are mere fancies. We shall
therefore consider these four substances as the principles or elements of all
the various compounds which nature presents to our inquiries: because, of
all those we have as yet discovered, they are in fact the most simple; and
because all our decompositions, all our experiments on other bodies, plainly
prove that they are at last resolvable into these primary parts.
These principles do not enter in the same proportion into all bodies: there
are even some mixts in the composition of which this or that particular
principle is not to be found. Thus Air and Water seem to be wholly excluded
from the texture of Metals; at least all the experiments that have hitherto
been made on them seem to confirm this opinion.
The substances composed immediately of these first Elements we shall call
secondary Principles; because in reality their several combinations with
each other, the interchangeable coalitions that take place between them,
constitute the different natures of all other bodies; which, as they result

from the union both of primary and secondary principles, are properly
entitled to the name of Compounds or Mixts.
Before we enter upon the examination of Compound Substances, it is
necessary to consider with some attention the most Simple ones, or our four
first principles, in order to discover their chief properties.

SECTION I.

Of Air.
Air is that Fluid which we constantly breathe, and which surrounds the
whole surface of the terrestrial globe. Being heavy, like all other bodies, it
penetrates into all places that are not either absolutely inaccessible, or filled
with some other body heavier than itself. Its principal property is to be
susceptible of condensation and rarefaction; so that the very same quantity
of Air may occupy a much greater, or a much smaller space, according to
the different state it is in. Heat and cold, or, if you will, the presence and the
absence of the particles of Fire, are the most usual causes, and indeed the
measures, of its condensation and rarefaction: for if a certain quantity of Air
be heated, its bulk enlarges in proportion to the degree of heat applied to it;
the consequence of which is, that the same space now contains fewer
particles of Air than it did before. Cold again produces just the opposite
effect.
On this property which Air has, of being condensed and rarefied by heat, its
elasticity or springiness chiefly depends. For if Air were forced by
condensation into a less compass than it took up before, and then exposed
to a very considerable degree of cold, it would remain quite inactive,
without exerting such an effort as it usually makes against the compressing
body. On the other hand, the elasticity of heated Air arises only from hence,
that being rarefied by the action of Fire, it requires much more space than it
occupied before.
Air enters into the composition of many substances, especially vegetable
and animal bodies: for by analysing most of them such a considerable
quantity thereof is extricated, that some naturalists have suspected it to be
altogether destitute of elasticity when thus combined with the other

principles in the composition of bodies. According to them, the efficacy of
the elastic power of the Air is so prodigious, and its force when compressed
so excessive, that it is not possible the other component parts of bodies
should be able to confine so much of it, in that state of compression which
it must needs undergo, if retaining its elasticity it were pent up among them.
However that be, this elastic property of the Air produces the most singular
and important phenomena, observable in the resolution and composition of
bodies.

SECTION II.

Of Water.
Water is a thing so well known, that it is almost needless to attempt giving a
general idea of it here. Every one knows that it is a transparent, insipid
substance, and usually fluid. I say it is usually so; for being exposed to a
certain degree of cold it becomes solid: solidity therefore seems to be its
most natural state.
Water exposed to the Fire grows hot; but only to a limited degree, beyond
which its heat never rises, be the force of Fire applied to it ever so violent: it
is known to have acquired this degree of heat by its boiling up with great
tumult. Water cannot be made hotter, because it is volatile, and incapable of
enduring the heat, without being evaporated and entirely dissipated.
If such a violent and sudden heat be applied to Water, as will not allow it
time to exhale gently in vapours, as when, for instance, a small quantity
thereof is thrown upon a metal in fusion, it is dissipated at once with vast
impetuosity, producing a most terrible and dangerous explosion. This
surprising effect may be deduced from the instantaneous dilatation of the
parts of the Water itself, or rather of the Air it contains. Moreover, Water
enters into the texture of many bodies, both compounds and secondary
principles; but, like Air, it seems to be excluded from the composition of all
metals and most minerals. For although an immense quantity of Water
exists in the bowels of the Earth, moistening all its contents, it cannot be
thence inferred, that it is one of the principles of minerals. It is only
interposed between their parts; for they may be entirely divested of it,

without any sort of decomposition: indeed it is not capable of an intimate
connection with them.

SECTION III.

Of Earth.
We observed that the two principles above treated of are volatile; that is, the
action of Fire separates them from the bodies they help to compose,
carrying them quite off, and dissipating them. That of which we are now to
speak, namely Earth, is fixed, and, when it is absolutely pure, resists the
utmost force of Fire. So that, whatever remains of a body, after it hath been
exposed to the power of the fiercest Fire, must be considered as containing
nearly all its earthy principle, and consisting chiefly thereof. I qualify my
expression thus for two reasons: the first is, because it often happens, that
this remainder does not actually contain all the Earth which existed
originally in the mixt body decomposed by Fire; since it will afterwards
appear that Earth, though in its own nature fixed, may be rendered volatile
by being intimately united with other substances which are so; and that, in
fact, it is common enough for part of the Earth of a body to be thus
volatilized by its other principles: the second is, that what remains after the
calcination of a body is not generally its earth in perfect purity, but
combined with some of its other principles, which, though volatile in their
own natures, have been fixed by the union contracted between it and them.
We shall, in the sequel, produce some examples to illustrate this theory.
Earth, therefore, properly so called, is a fixed principle, which is permanent
in the Fire. There is reason to think it very difficult, if not impossible, to
obtain the earthy principle entirely free from every other substance: for after
our utmost endeavours to purify them, the Earths we obtain from different
compounds are found to have different properties, according to the different
bodies from which they are procured; or else, if those Earths be pure, we
must allow them to be essentially different, seeing they have different
properties.
Earth, in general, with regard to its properties, may be distributed into
fusible, and unfusible; that is, into Earth that is capable of melting or
becoming fluid in the Fire, and Earth that constantly remains in a solid

form, never melting in the strongest degree of heat to which we can expose
it.
The former is also called vitrifiable, and the second unvitrifiable Earth;
because, when Earth is melted by the force of Fire, it becomes what we call
Glass, which is nothing but the parts of Earth brought into nearer contact,
and more closely united by the means of fusion. Perhaps the Earth, which
we look upon as incapable of vitrification, might be fused if we could apply
to it a sufficient degree of heat. It is at least certain, that some Earths, or
stones, which separately resist the force of Fire, so that they cannot be
melted, become fusible when mixed together. Experience convinced Mr. du
Hamel that lime-stone and slate are of this kind. It is however undoubtedly
true, that one Earth differs from another in its degree of fusibility: and this
gives ground to believe, that there may be a species of Earth absolutely
unvitrifiable in its nature, which, being mixed in different proportions with
fusible Earths, renders them difficult to melt.
Whatever may be in this, as there are Earths which we are absolutely unable
to vitrify, that is a sufficient reason for our division of them. Unvitrifiable
Earths seem to be porous, for they imbibe Water; whence they have also got
the name of Absorbent Earths.

SECTION IV.

Of Fire.
The Matter of the Sun, or of Light, the Phlogiston, Fire, the Sulphureous
Principle, the Inflammable Matter, are all of them names by which the
Element of Fire is usually denoted. But it should seem, that an accurate
distinction hath not yet been made between the different states in which it
exists; that is, between the phenomena of Fire actually existing as a
principle in the composition of bodies, and those which it exhibits when
existing separately and in its natural state: nor have proper distinct
appellations been assigned to it in those different circumstances. In the
latter state we may properly give it the names of Fire, Matter of the Sun, of
Light, and of Heat; and may consider it as a substance composed of
infinitely small particles, continually agitated by a most rapid motion, and,
of consequence, essentially fluid.

This substance, of which the sun may be called the general reservoir, seems
to flow incessantly from that source, diffusing itself over the world, and
through all the bodies we know; but not as a principle, or essential part of
them, since they may be deprived thereof, at least in a great measure,
without suffering any decomposition. The greatest change produced on
them, by its presence or its absence, is the rendering them fluid or solid: so
that all other bodies may be deemed naturally solid; Fire alone essentially
fluid, and the principle of fluidity in others. This being presupposed, Air
itself might become solid, if it could be entirely deprived of the Fire it
contains; as bodies of most difficult fusion become fluid, when penetrated
by a sufficient quantity of the particles of Fire.
One of the chief properties of this pure Fire is to penetrate easily into all
bodies, and to diffuse itself among them with a sort of uniformity and
equality: for if a heated body be contiguous to a cold one, the former
communicates to the latter all its excess of heat, cooling in exact proportion
as the other warms, till both come to have the very same degree of heat.
Heat, however, is naturally communicable soonest to the upper parts of a
body; and consequently, when a body cools, the under parts become soonest
cold. It hath been observed, for instance, that the lower extremity of a
heated body, freely suspended in the air, grows cold sooner than the upper;
and that, when a bar of iron is red-hot at one end, and cold at the other, the
cold end is much sooner heated by placing the bar so that the hot end may
be undermost, than, when that end is turned uppermost. The levity of the
matter of Fire, and the vicinity of the Earth, may possibly be the causes of
this phenomenon.
Another property of Fire is to dilate all bodies into which it penetrates. This
hath already been shewn with regard to Air and Water; and it produces the
same effect on Earth.
Fire is the most powerful agent we can employ to decompose bodies; and
the greatest degree of heat producible by man, is that excited by the rays of
the sun collected in the focus of a large burning-glass.

SECTION V.

Of the Phlogiston.

From what hath been said concerning the nature of Fire, it is evidently
impossible for us to fix and confine it in any body. Yet the phenomena
attending the combustion of inflammable bodies shew, that they really
contain the matter of Fire as a constituent principle. By what mechanism
then is this fluid, which is so subtle, so active, so difficult to confine, so
capable of penetrating into every other substance in nature; how comes it, I
say, to be so fixed as to make a component part of the most solid bodies? It
is no easy matter to give a satisfactory answer to this question. But, without
pretending to guess the cause of the phenomenon, let us rest contented with
the certainty of the fact, the knowledge of which will undoubtedly procure
us considerable advantages. Let us therefore examine the properties of Fire
thus fixed, and become a principle of bodies. To this substance, in order to
distinguish it from pure and unfixed Fire, the Chymists have assigned the
peculiar title of the Phlogiston, which indeed is no other than a Greek word
for the Inflammable Matter; by which latter name, as well as by that of the
Sulphureous Principle, it is also sometimes called. It differs from
elementary Fire in the following particulars. 1. When united to a body, it
communicates to it neither heat nor light. 2. It produces no change in its
state, whether of solidity or fluidity; so that a solid body does not become
fluid by the accession of the Phlogiston, and vice versa; the solid bodies to
which it is joined being only rendered thereby more apt to be fused by the
force of the culinary fire. 3. We can convey it from the body with which it is
joined into another body, so that it shall enter into the composition thereof,
and remain fixed in it.
On this occasion both these bodies, that which is deprived of the Phlogiston
and that which receives it, undergo very considerable alterations; and it is
this last circumstance, in particular, that obliges us to distinguish the
Phlogiston from pure Fire, and to consider it as the element of Fire
combined with some other substance, which serves it as a basis for
constituting a kind of secondary principle. For if there were no difference
between them, we should be able to introduce and fix pure Fire itself,
wherever we can introduce and fix the Phlogiston: yet this is what we can
by no means do, as will appear from experiments to be afterwards
produced.
Hitherto, Chymists have never been able to obtain the Phlogiston quite
pure, and free from every other substance: for there are but two ways of

separating it from a body of which it makes a part; to wit, either by
applying some other body with which it may unite the moment it quits the
former; or else by calcining and burning the compound from which you
desire to sever it. In the former case it is evident that we do not get the
Phlogiston by itself, because it only passes from one combination into
another; and in the latter, it is entirely dissipated in the decomposition, so
that no part of it can possibly be secured.
The inflammability of a body is an infallible sign that it contains a
Phlogiston; but from a body's not being inflammable, it cannot be inferred
that it contains none; for experiments have demonstrated that certain metals
abound with it, which yet are by no means inflammable.
We have now delivered what is most necessary to be known concerning the
principles of bodies in general. They have many other qualities besides
those above-mentioned; but we cannot properly take notice of them here,
because they pre-suppose an acquaintance with some other things relating
to bodies, of which we have hitherto said nothing; intending to treat of them
in the sequel as occasion shall offer. We shall only observe in this place,
that when animal and vegetable matters are burnt, in such a manner as to
hinder them from flaming, some part of the Phlogiston contained in them
unites intimately with their most fixed earthy parts, and with them forms a
compound, that can be consumed only by making it red-hot in the open air,
where it sparkles and wastes away, without emitting any flame. This
compound is called a Coal. We shall inquire into the properties of this Coal
under the head of Oils: at present it suffices that we know in general what it
is, and that it readily communicates to other bodies the Phlogiston it
contains.

CHAP. II.

A general View of the Relations or Affinities between Bodies.
efore we can reduce compound Bodies to the first principles above

B pointed out, we obtain, by analysing them, certain substances which
are indeed more simple than the bodies they helped to compose, yet are
themselves composed of our primary principles. They are therefore at one
and the same time both principles and compounds; for which reason we
shall, as was before said, call them by the name of Secondary Principles.
Saline and oily matters chiefly constitute this class. But before we enter
upon an examination of their properties, it is fit we lay before the reader a
general view of what Chymists understand by the Relations or Affinities of
Bodies; because it is necessary to know these, in order to a distinct
conception of the different combinations we are to treat of.
All the experiments hitherto made concur with daily observation to prove,
that different bodies, whether principles or compounds, have such a mutual
Conformity, Relation, Affinity, or Attraction, if you will call it so, as
disposes some of them to join and unite together, while they are incapable
of contracting any union with others. This effect, whatever be its cause, will
enable us to account for, and connect together, all the phenomena that
Chymistry produces. The nature of this universal affection of matter is
distinctly laid down in the following propositions.
First, If any substance hath any Affinity or conformity with another, the two
will unite together, and form one compound.
Secondly, It may be laid down as a general rule, that all similar substances
have an Affinity with each other, and are consequently disposed to unite; as
water with water, earth with earth, &c.
Thirdly, Substances that unite together lose some of their separate
properties; and the compounds resulting from their union partake of the
properties of those substances which serve as their principles.
Fourthly, The simpler any substances are, the more perceptible and
considerable are their Affinities: whence it follows, that the less bodies are

compounded, the more difficult it is to analyse them; that is, to separate
from each other the principles of which they consist.
Fifthly, If a body consist of two substances, and to this compound be
presented a third substance, that has no Affinity at all with one of the two
primary substances aforesaid, but has a greater Affinity with the other than
those two substances have with each other, there will ensue a
decomposition, and a new union; that is, the third substance will separate
the two compounding substances from each other, coalesce with that which
has an Affinity with it, form therewith a new combination, and disengage
the other, which will then be left at liberty, and such as it was before it had
contracted any union.
Sixthly, It happens sometimes that when a third substance is presented to a
body consisting of two substances, no decomposition follows; but the two
compounding substances, without quitting each other, unite with the
substance presented to them, and form a combination of three principles:
and this comes to pass when that third substance has an equal, or nearly
equal, Affinity with each of the compounding substances. The same thing
may also happen even when the third substance hath no Affinity but with
one of the compounding substances only. To produce such an effect, it is
sufficient that one of the two compounding substances have to the third
body a Relation equal, or nearly equal, to that which it has to the other
compounding substance with which it is already combined. Thence it
follows, that two substances, which, when apart from all others, are
incapable of contracting any union, may be rendered capable of
incorporating together in some measure, and becoming parts of the same
compound, by combining with a third substance with which each of them
has an equal Affinity.
Seventhly, A body, which of itself cannot decompose a compound
consisting of two substances, because, as we just now said, they have a
greater affinity with each other than it has with either of them, becomes
nevertheless capable of separating the two by uniting with one of them,
when it is itself combined with another body, having a degree of Affinity
with that one, sufficient to compensate its own want thereof. In that case
there are two Affinities, and thence ensues a double decomposition and a
double combination.

These fundamental truths, from which we shall deduce an explanation of all
the phenomena in Chymistry, will be confirmed and illustrated by applying
them, as we shall do, to the several cases, of which our design in this
treatise obliges us to give a circumstantial account.

CHAP. III.

Of Saline Substances in general.
f a particle of water be intimately united with a particle of earth, the
I result will be a new compound, which, according to our third proposition
of Affinities, will partake of the properties of earth and of water; and this
combination principally forms what is called a Saline Substance.
Consequently every Saline Substance must have an affinity with earth and
with water, and be capable of uniting with both or either of them, whether
they be separate or mixed together: and accordingly this property
characterizes all Salts, or Saline Substances, in general.
Water being volatile and Earth fixed, Salts in general are less volatile than
the former, and less fixed than the latter; that is, fire, which cannot
volatilize and carry off pure earth, is capable of rarefying and volatilizing a
Saline Substance; but then this requires a greater degree of heat than is
necessary for producing the same effects on pure water.
There are several sorts of Salts, differing from one another, in respect either
of the quantity, or the quality of the earth in their composition; or, lastly,
they differ on account of some additional principles, which not being
combined with them in sufficient quantity to hinder their Saline properties
from appearing, permit them to retain the name of Salts, though they render
them very different from the simplest Saline Substances.
It is easy to infer, from what has been said of Salts in general, that some of
them must be more, some less, fixed or volatile than others, and some more,
some less, disposed to unite with water, with earth, or with particular sorts
of earth, according to the nature or the proportion of their principles.
Before we proceed further, it is proper just to mention the principle reasons,
which induce us to think that every Saline Substance is actually a
combination of earth and water, as we supposed at our entering on this
subject. The first is, the conformity Salts have with earth and water, or the
properties they possess in common with both. Of these properties we shall
treat fully, as occasion offers to consider them, in examining the several
sorts of Salts. The second is, that all Salts may be actually resolved into

earth and water by sundry processes; particularly by repeated dissolution in
water, evaporation, desiccation, and calcination. Indeed the Chymists have
not yet been able to procure a Saline Substance, by combining earth and
water together. This favours a suspicion, that, besides these two, there is
some other principle in the composition of salts, which escapes our
researches, because we cannot preserve it when we decompose them; but it
is sufficient to our purpose, that water and earth are demonstrably amongst
the real principles of Saline Substances, and that no experiment hath ever
shewn us any other.

SECTION I.

Of Acids.
Of all Saline Substances, the simplest is that called an Acid, on account of
its taste; which is like that of verjuice, sorrel, vinegar, and other sour things,
which, for the same reason, are also called Acids. By this peculiar taste are
Acids chiefly known. They have moreover the property of turning all the
blue and violet colours of vegetables red, which distinguishes them from all
other salts.
The form, under which Acids most commonly appear, is that of a
transparent liquor; though solidity is rather their natural state. This is owing
to their affinity with water; which is so great, that, when they contain but
just as much of it as is necessary to constitute them Salts, and consequently
have a solid form, they rapidly unite therewith the moment they come into
contact with it: and as the air is always loaded with moisture and aqueous
vapours, its contact alone is sufficient to liquify them; because they unite
with its humidity, imbibe it greedily, and by that means become fluid. We
therefore say, they attract the moisture of the air. This change of a salt from
a solid to a fluid state, by the sole contact of the air, is also called
Deliquium; so that when a salt changes in this manner from a solid into a
fluid form, it is said to run per deliquium. Acids being the simplest species
of Saline bodies, their affinities with different substances are stronger than
those of any other sort of salt with the same substances; which is agreeable
to our fourth proposition concerning Affinities.

Acids in general have a great affinity with earths: that with which they most
readily unite is the unvitrifiable earth to which we gave the name of
absorbent earth. They seem, not to act at all upon vitrifiable earths, such as
sand; nor yet upon some other kinds of earths, at least while they are in
their natural state. Yet the nature of these earths may be in some measure
changed, by making them red-hot in the fire, and then quenching them
suddenly in cold water: for, by repeating this often, they are brought nearer
to the nature of absorbent earths, and rendered capable of uniting with
Acids.
When an acid liquor is mixed with an absorbent earth, for instance with
chalk, these two substances instantly rush into union, with so much
impetuosity, especially if the acid liquor be as much dephlegmated, or
contain as little water, as may be, that a great ebullition is immediately
produced, attended with considerable hissing, heat, and vapours, which rise
the very instant of their conjunction.
From the combination of an acid with an absorbent earth there arises a new
compound, which some Chymists have called Sal Salsum; because the Acid
by uniting with the earth loses its sour taste, and acquires another not unlike
that of the common sea-salt used in our kitchens; yet varying according to
the different sorts of Acids and earths combined together. The Acid at the
same time loses its property of turning vegetable blues and violet colours
red.
If we inquire what is become of its propensity to unite with water, we shall
find that the earth, which of itself is not soluble in water, hath, by its union
with the Acid, acquired a facility of dissolving therein; so that our Sal
Salsum is soluble in water. But, on the other hand, the Acid hath, by its
union with the earth, lost part of the affinity it had with water; so that if a
Sal Salsum be dried, and freed of all superfluous humidity, it will remain, in
that dry solid form, instead of attracting the moisture of the air, and running
per deliquium, as the Acid would do if it were pure and unmixed with earth.
However, this general rule admits of some exceptions; and we shall have
occasion in another place to take notice of certain combinations of Acids
with earths, which still continue to attract the moisture of the air, though not
so strongly as a pure Acid.

Acids have likewise a great affinity with the Phlogiston. When we come to
treat of each Acid in particular, we shall examine the combinations of each
with the Phlogiston: they differ so widely from one another, and many of
them are so little known, that we cannot at present give any general idea of
them.

SECTION II.

Of Alkalis.
Alkalis are Saline combinations, in which there is a greater proportion of
earth than in Acids. The principal arguments that may be adduced to prove
this fact are these: First; if they be treated in the manner proposed above for
analyzing Saline Substances, we obtain from them a much greater quantity
of earth than we do from Acids. Secondly; by combining certain Acids with
certain earths we can produce Alkalis; or at least such saline compounds as
greatly resemble them. Our third and last argument is drawn from the
properties of those Alkalis which, when pure and unadulterated with any
other principle, have less affinity with water than Acids have, and are also
more fixed, resisting the utmost force of fire. On this account it is that they
have obtained the title of Fixed, as well as to distinguish them from another
species of Alkali, to be considered hereafter, which is impure and volatile.
Though fixed Alkalis, when dry, sustain the utmost violence of fire without
flying off in vapours, it is remarkable that, being boiled with water in an
open vessel, considerable quantities of them rise with the steam: an effect
which must be attributed to the great affinity between these two substances,
by means whereof water communicates some part of its volatility to the
fixed salt.
Alkalis freed of their superfluous humidity by calcination attract the
moisture of the air, but not so strongly as Acids: so that it is easier to
procure and preserve them in a solid form.
They flow in the fire, and are then capable of uniting with vitrifiable earths,
and of forming therewith true glass, which, however, will partake of their
properties, if they be used in sufficient quantity.

As they melt more readily than vitrifiable earth, they facilitate its fusion; so
that a weaker fire will reduce it to glass, when a fixed Alkali is joined with
it, than will melt it without that addition.
Alkalis are known by their taste, which is acrid and fiery; and by the
properties they possess of turning vegetable blues and violet colours green;
particularly syrop of violets.
Their affinity with acids is greater than that of absorbent earths; and hence
it comes to pass, that if an Alkali be presented to a combination of an Acid
with an absorbent earth, the earth will be separated from the Acid by the
Alkali, and a new union between the Acid and the Alkali will take place.
This is both an instance and a proof of our fifth proposition concerning
Affinities.
If a pure Alkali be presented to a pure Acid, they rush together with
violence, and produce the same phenomena as were observed in the union
of an absorbent earth with an Acid; but in a greater and more remarkable
degree.
Fixed Alkalis may in general be divided into two sorts: one of these hath all
the above-recited properties; but the other possesses some that are peculiar
to itself. We shall consider this latter sort more particularly under the head
of Sea-Salt.

SECTION III.

Of Neutral Salts.
The Acid and the Alkali thus uniting mutually rob each other of their
characteristic properties; so that the compound resulting from their union
produces no change in the blue colours of vegetables, and has a taste which
is neither sour nor acrid, but saltish. A saline combination of this kind is for
that reason named Sal Salsum, Sal Medium, of a Neutral Salt. Such
combinations are also called by the plain general name of Salts.
It must be observed that, in order to make these Salts perfectly Neutral, it is
necessary that neither of the two saline principles of which they are
compounded be predominant over the other; for in that case they will have

the properties of the prevailing principle. The reason is this: neither of these
saline substances can unite with the other but in a limited proportion,
beyond which there can be no further coalition between them. The action by
which this perfect union is accomplished is termed Saturation; and the
instant when such proportions of the two saline substances are mixed
together, that the one is incorporated with as much of the other as it can
possibly take up, is called the Point of Saturation. All this is equally
applicable to the combination of an Acid with an absorbent earth.
The combination is known to be perfect, that is, the Point of Saturation is
known to be obtained, when, after repeated affusions of an Acid in small
quantities to an Alkali, or an absorbent earth, we find those phenomena
cease, which in such cases constantly attend the conflict of union, as we
said above, namely, ebullition, hissing, &c. and we may be assured the
Saturation is complete when the new compound hath neither an acid nor an
acrid taste, nor in the least changes the blue colours of vegetables.
Neutral salts have not so great an affinity with water as either Acids or
Alkalis have; because they are more compounded: for we observed before,
that the affinities of the most compounded bodies are generally weaker than
those of the most simple. In consequence hereof few Neutral Salts, when
dried, attract the moisture of the air; and those that do, attract it more
slowly, and in less quantity, than either Acids or Alkalis do.
All Neutral Salts are soluble in water; but more or less readily, and in a
greater or smaller quantity, according to the nature of their component
principles.
Water made boiling hot dissolves a greater quantity of those salts which do
not attract the moisture of the air, than when it is cold; and indeed it must be
boiling hot to take up as much of them as it is capable of dissolving: but as
for those which run in the air, the difference, if there be any, is
imperceptible.
Some Neutral Salts have the property of shooting into crystals, and others
have it not.
The nature of Crystallization is this: Water cannot dissolve, nor keep in
solution, more than a determinate quantity of any particular Salt: when

therefore such a quantity of water is evaporated from the solution of a Salt
capable of crystallization, that the remainder contains just as much Salt as it
can dissolve, then by continuing the evaporation the Salt gradually recovers
its solid form, and concretes into several little transparent masses called
Crystals. These crystals have regular figures, all differing from one another
according to the species of salt of which they are formed. Different methods
of evaporating saline solutions have different effects on the figure and
regularity of the crystals; and each particular sort of salt requires a peculiar
method of evaporation to make its crystals perfectly regular.
A solution of salt designed for crystallization is usually evaporated by
means of fire to a pellicle; that is, till the Salt begin to concrete; which is
perceived by a kind of thin dark skin that gathers on the surface of the
liquor, and is formed of the crystallized particles of Salt. When this pellicle
appears the solution is suffered to cool, and the crystals form therein faster
or slower, according to the sort of salt in hand. If the evaporation be carried
on briskly to perfect dryness, no crystals will be formed, and only an
irregular mass of salt will be obtained.
The reasons why no crystals appear when the evaporation is hastily
performed, and carried on to dryness, are, first, that the particles of salt,
being always in motion while the solution is hot, have not time to exert their
mutual affinities, and to unite together as crystallization requires: Secondly,
that a certain quantity of water enters into the very composition of crystals;
which is therefore absolutely necessary to their formation, and in a greater
or smaller proportion according to the nature of the Salt[1].
If these crystallized salts be exposed to the fire, they first part with that
moisture which is not necessary to a saline concretion, and which they
retained only by means of their crystallization: afterwards they begin to
flow, but with different degrees of fusibility.
It must be observed, that certain salts melt as soon as they are exposed to
the fire; namely, those which retain a great deal of water in crystallizing.
But this fluor which they so readily acquire must be carefully distinguished
from actual fusion: for it is owing only to their superfluous humidity, which
heat renders capable of dissolving and liquifying them; so that when it is

evaporated the Salt ceases to be fluid, and requires a much greater degree of
fire to bring it into real fusion.
The Neutral Salts that do not crystallize may, indeed, be dried by
evaporating the water which keeps them fluid; but by becoming solid they
acquire no regular form; they again attract the moisture of the air, and are
thereby melted into a liquor. These may be called Liquescent Salts.
Most of the Neutral Salts, that consist of an Acid joined with a fixed Alkali,
or with an absorbent earth, are themselves fixed and resist the force of fire;
yet several of them, if they be dissolved in water, and the solution boiled
and evaporated, fly off along with the steams.

CHAP. IV.

Of the several Sorts of Saline Substances.

SECTION I.

Of the Universal Acid.
he Universal Acid is so called, because it is in fact the Acid which is

T most universally diffused through all nature, in waters, in the
atmosphere, and in the bowels of the earth. But it is seldom pure; being
almost always combined with some other substance. That from which we
obtain it with most ease, and in the greatest quantity, is Vitriol, a mineral
which we shall consider afterwards: and this is the reason why it is called
the Vitriolic Acid; the name by which it is best known.
When the Vitriolic Acid contains but little phlegm, yet enough to give it a
fluid form, it is called Oil of Vitriol, on account of a certain unctuosity
belonging to it. In truth this name is very improperly bestowed on it; for we
shall afterwards see that, bating this unctuousness, it has none of the
properties of oils. But this is not the only impropriety in names that we shall
have occasion to censure.
If the Vitriolic Acid contain much water, it is then called Spirit of Vitriol.
When it does not contain enough to render it fluid, and so is in a solid form,
it is named the Icy Oil of Vitriol.
When Oil of Vitriol highly concentrated is mixed with water, they rush into
union with such impetuosity, that, the moment they touch each other, there
arises a hissing noise, like that of red-hot iron plunged in cold water,
together with a very considerable degree of heat, proportioned to the degree
to which the Acid was concentrated.
If, instead of mixing this concentrated Acid with water, you only leave it
exposed to the air for some time, it attracts the moisture thereof, and
imbibes it most greedily. Both its bulk and its weight are increased by this

accession; and if it be under an icy form, that is, if it be concreted, the
phlegm thus acquired will soon resolve it into a fluid.
The addition of water renders the Vitriolic Acid, and indeed all other Acids,
weaker in one sense; which is, that when they are very aqueous they leave
on the tongue a much fainter taste of acidity, and are less active in the
solution of some particular bodies: but that occasions no change in the
strength of their affinities, but in some cases rather enables them to dissolve
several substances, which, when well dephlegmated, they are not capable of
attacking.
The Vitriolic Acid combined to the point of saturation with a particular
absorbent earth, the nature of which is not yet well known, forms a Neutral
Salt that crystallizes. This Salt is called Alum, and the figure of its crystals
is that of an octahedron, or solid of eight sides. These octahedra are
triangular pyramids, the angles of which are so cut off that four of the
surfaces are hexagons, and the other four triangles.
There are several sorts of Alum, which differ according to the earths
combined with the Vitriolic Acid. Alum dissolves easily in water, and in
crystallization retains a considerable quantity of it; which is the reason that
being exposed to the fire it readily melts, swelling and puffing up as its
superfluous moisture exhales. When that is quite evaporated, the remainder
is called Burnt Alum, and is very difficult to fuse. The Acid of the Alum is
partly dissipated by this calcination. Its taste is saltish, with a degree of
roughness and astringency.
The Vitriolic Acid combined with certain earths forms a kind of Neutral Salt
called Selenites, which crystallizes in different forms according to the
nature of its earth. There are numberless springs of water infected with
dissolved Selenites; but when this Salt is once crystallized, it is exceeding
difficult to dissolve it in water a second time. For that purpose a very great
quantity of water is necessary, and moreover it must boil; for as it cools
most of the dissolved Selenites takes a solid form, and falls in a powder to
the bottom of the vessel.
If an Alkali be presented to the Selenites, or to Alum, these Salts, according
to the principles we have laid down, will be thereby decomposed; that is,
the Acid will quit the earths, and join the Alkali, with which it hath a greater

affinity. And from this conjunction of the Vitriolic Acid with a fixed Alkali
there results another sort of Neutral Salt, which is called Arcanum
duplicatum, Sal de duobus, and Vitriolated Tartar, because one of the fixed
Alkalis most in use is called Salt of Tartar.
Vitriolated Tartar is almost as hard to dissolve in water as the Selenites. It
shoots into eight-sided crystals, having the apices of the pyramids pretty
obtuse. Its taste is saltish, inclining to bitter; and it decrepitates on burning
coals. It requires a very great degree of fire to make it flow.
The Vitriolic Acid is capable of uniting with the Phlogiston, or rather it has
a greater affinity with it than with any other body: whence it follows, that
all compounds, of which it makes a part, may be decomposed by means of
the Phlogiston.
From the conjunction of the Vitriolic Acid with the Phlogiston arises a
compound called Mineral Sulphur, because it is found perfectly formed in
the bowels of the earth. It is also called Sulphur vivum, or simply Sulphur.
Sulphur is absolutely insoluble in water, and incapable of contracting any
sort of union with it. It melts with a very moderate degree of heat, and
sublimes in fine light downy tufts called Flowers of Sulphur. By being thus
sublimed, it suffers no decomposition, let the operation be repeated ever so
often; so that Sublimed Sulphur, or Flower of Sulphur, hath exactly the
same properties as Sulphur that has never been sublimed.
If Sulphur be exposed to a brisk heat in the open air, it takes fire, burns, and
is wholly consumed. This deflagration of Sulphur is the only means we
have of decomposing it, in order to obtain its Acid in purity. The Phlogiston
is destroyed by the flame, and the Acid exhales in vapours: these vapours
collected have all the properties of the Vitriolic Acid, and differ from it only
as they still retain some portion of the Phlogiston; which, however, soon
quits them of its own accord, if the free access of the common air be not
precluded.
The portion of Phlogiston retained by the Acid of Sulphur is much more
considerable when that mineral is burnt gradually and slowly: in that case
the vapours which rise from it have such a penetrating odour, that they
instantaneously suffocate any person who draws in a certain quantity of

them with his breath. These vapours constitute what is called the Volatile
Spirit of Sulphur. There is reason to think this portion of Phlogiston which
the Acid retains is combined therewith in a manner different from that in
which these two are united in the Sulphur itself; for, as has just been
observed, nothing but actual burning is capable of separating the Vitriolic
Acid and the Phlogiston, which by their union form Sulphur; whereas in the
Volatile Spirit of Sulphur they separate spontaneously when exposed to the
open air; that is, the Phlogiston flies off and leaves the Acid, which then
becomes in every respect similar to the Vitriolic Acid.
That the Volatile Spirit of Sulphur is a compound, as we have asserted it to
be, appears evidently from hence, that whenever the Vitriolic Acid touches
any substance containing the Phlogiston, provided that Phlogiston be
disengaged or opened to a certain degree, a Volatile Spirit of Sulphur is
infallibly and immediately generated. This Spirit hath all the properties of
Acids, but considerably weakened, and of course less perceptible. It unites
with absorbent earths or fixed Alkalis; and with them forms Neutral Salts;
but when combined therewith it may be separated from them by the
Vitriolic Acid, and indeed by any of the mineral Acids, because its affinities
are weaker. Sulphur hath the property of uniting with absorbent earths, but
not near so intimately as with fixed Alkalis.
If equal parts of Sulphur and an Alkali be melted together, they incorporate
with each other; and from their conjunction proceeds a compound of a most
unpleasant smell, much like that of rotten eggs, and of a red colour nearly
resembling that of an animal liver, which has occasioned it to bear the name
of Hepar Sulphuris, or Liver of Sulphur.
In this composition the fixed Alkali communicates to the Sulphur the
property of dissolving in water: and hence it comes that Liver of Sulphur
may be made as well when the Alkali is dissolved by water into a fluid, as
when it is fused by the action of fire.
Sulphur has less affinity than any Acid with the fixed Alkalis: and therefore
Liver of Sulphur may be decompounded by any Acid whatever; which will
unite with the fixed Alkali, form therewith a Neutral Salt, and separate the
Sulphur.

If Liver of Sulphur be dissolved in water, and an Acid poured thereon, the
liquor, which was transparent before, instantly turns to an opaque white;
because the Sulphur, being forced to quit its union with the Alkali, loses at
the same time the property of dissolving in water, and appears again in its
own opaque form. The liquor thus made white by the Sulphur is called Milk
of Sulphur.
If this liquor be suffered to stand still for some time, the particles of
Sulphur, now most minutely divided, gradually approach each other, unite,
and fall insensibly to the bottom of the vessel; and then the liquor recovers
its transparency. The Sulphur thus deposited on the bottom of the vessel is
called the Magistery or Precipitate of Sulphur. The names of Magistery and
Precipitate are also given to all substances whatever, that are separated from
another by this method; which is the reason that we use the expression of
precipitating one substance by another, to signify the separating one of them
by means of the other.

SECTION II.

Of the Nitrous Acid.
It is not certainly known what constitutes the difference between the
Nitrous Acid and the Vitriolic Acid, with regard to the constituent principles
of each. The most probable opinion is, that the Nitrous Acid is no other than
the Vitriolic Acid combined with a certain quantity of Phlogiston by the
means of putrefaction. If it be so, the Phlogiston must be united with the
Universal Acid in another manner than it is in sulphur, and in its volatile
spirit: for the Nitrous Acid differs from them both in its properties. What
gives ground for this opinion is, that the Nitrous Acid is never found but in
earths and stones which have been impregnated with matters subject to
putrefaction, and which therefore must contain the Phlogiston. For it is
necessary just to observe here, though it be not yet proper to enter
particularly into the subject, that all substances susceptible of putrefaction
really contain the Phlogiston.
The Nitrous Acid combined with certain absorbent earths, such as chalk,
marle, boles, forms Neutral Salts which do not crystallize; and which, after
being dried, run in the air per deliquium.

All those Neutral Salts which consist of the Nitrous Acid joined to an earth,
may be decomposed by a fixed Alkali, with which the Acid unites, and
deserts the earth; and from this union of the Nitrous Acid with a fixed
Alkali results a new Neutral Salt which is called Nitre, or Salt-peter. This
latter name signifies the Salt of Stone; and, in fact, Nitre is extracted from
the stones and plaster, in which it forms, by boiling them in water saturated
with a fixed Alkali.
Nitre shoots in long crystals adhering sideways to each other; it has a saltish
taste, which produces a sensation of cold on the tongue.
This Salt easily dissolves in water; which, when boiling hot, takes up still a
greater quantity thereof.
It flows with a pretty moderate degree of heat, and continues fixed therein;
but being urged by a brisk fire, and in the open air, it lets go some part of its
Acid, and indeed flies off itself in part.
The most remarkable property of Nitre, and that which characterizes it, is
its fulmination or explosion; the nature of which is as follows:
When Nitre touches any substance containing a Phlogiston, and actually
ignited, that is, actually on fire, it bursts out into a flame, burns, and is
decompounded with much noise.
In this deflagration the Acid is dissipated, and totally separated from the
Alkali, which now remains by itself.
Indeed the Acid, at least the greatest part of it, is by this means quite
destroyed. The Alkali which is left when Nitre is decompounded by
deflagration, is called in general Fixed Nitre, and, more particularly, Nitre
fixed by such and such a substance as was used in the operation. But if
Nitre be deflagrated with an inflammable substance containing the vitriolic
Acid, as sulphur, for instance, the fixed Salt produced by the deflagration is
not a pure Alkali, but retains a good deal of the vitriolic Acid, and, by
combining therewith, hath now formed a neutral Salt.
Hitherto Chymists have been at a loss for the reason why Nitre flames, and
is decompounded in the manner above-mentioned, when it comes in contact
with a Phlogiston properly circumstanced. For my part, I conjecture it to be

for the same reason that vitriolated tartar is also decompounded by the
addition of a Phlogiston; viz. the Nitrous Acid, having a greater affinity with
the Phlogiston than with the fixed Alkali, naturally quits the latter to join
with the former, and so produces a kind of sulphur, differing probably from
the common sulphur, formed by the vitriolic Acid, in that it is combustible
to such a degree, as to take fire and be consumed in the very moment of its
production; so that it is impossible to prevent its being thus destroyed, and
consequently impossible to save it. In support of this opinion let it be
considered, that the concurrence of the Phlogiston is absolutely necessary to
produce this deflagration, and that the matter of pure fire is altogether
incapable of effecting it: for though Nitre be exposed to the most violent
degree of fire, even that in the focus of the most powerful burning-glass, it
will not flame; nor will that effect ever happen till the Nitre be brought into
contact with a Phlogiston properly so called, that is, the matter of fire
existing as a principle of some body; and it is moreover necessary that this
Phlogiston be actually on fire, and agitated with the igneous motion, or else
that the Nitre itself be red hot, and so penetrated with fire as to kindle any
inflammable matter that touches it.
This experiment, among others, helps to shew the distinction that ought to
be made between pure elementary fire, and fire become a principle of
bodies, to which we have given the name of Phlogiston.
Before we leave this subject, we shall observe, that Nitre deflagrates only
with such substances as contain the Phlogiston in its simplest and purest
form; such as charcoal, sulphur, and the metalline substances; and that,
though it will not deflagrate without the addition of some combustible
matter, it is nevertheless the only known body that will burn, and make
other combustibles burn with it, in close vessels, without the admission of
fresh air.
The Nitrous Acid hath not so great an affinity with earths and Alkalis as the
vitriolic Acid hath with the same substances; whence it follows that the
vitriolic Acid decomposes all neutral salts arising from a combination of the
Nitrous Acid with an earth or an Alkali. The vitriolic Acids expells the
Nitrous Acid, unites with the substance which served it for a basis, and
therewith forms a neutral salt, which is an Alum, a Selenites, or a vitriolated
Tartar, according to the nature of that basis.

The Nitrous Acid, when thus separated from its basis by the vitriolic Acid,
is named Spirit of Nitre, or Aqua Fortis. If it be dephlegmated, or contain
but little superfluous water, it exhales in reddish vapours; these vapours,
being condensed and collected, form a liquor of a brownish yellow, that
incessantly emits vapours of the same colour, and of a pungent disagreeable
smell. These characters have procured it the names of Smoaking Spirit of
Nitre, and Yellow Aqua Fortis. This property in the Nitrous Acid, of
exhaling in vapours, shews it to be less fixed than the vitriolic Acid; for the
latter, though ever so thoroughly dephlegmated, never yields any vapours,
nor has it any smell.

SECTION III.

Of the Acid of Sea-Salt.
The Acid of Sea-salt is so called because it is in fact obtained from such
Sea-salt as is used in our kitchens. It is not certainly known in what this
Acid differs from the vitriolic and the nitrous, with regard to its constituent
parts. Several of the ablest Chymists, such as Becher and Stahl, are of
opinion that the Marine Acid is no other than the Universal Acid united to a
particular principle which they call a Mercurial Earth. Concerning this earth
we shall have occasion to say more, when we come to treat of metallic
substances: but in the mean time it must be owned, that the truth of this
opinion is so far from being proved by a sufficient number of experiments,
that the very existence of such a mercurial earth is not yet well established;
and therefore, that we may not exceed the bounds of our knowledge, we
shall content ourselves with delivering here the properties which
characterize the Acid in question, and by which it is distinguished from the
two others considered above.
When it is combined with absorbent earths, such as lime and chalk, it forms
a neutral salt that does not crystallize, and, when dried, attracts the moisture
of the air. If the absorbent earth be not fully saturated with the Marine Acid,
the salt thereby formed has the properties of a fixed Alkali: and this is what
made us say, when we were on the subject of those salts, that they might be
imitated by combining an earth with an Acid. The Marine Acid, like the
rest, hath not so great an affinity with earths as with fixed Alkalis.

When it is combined with the latter, it forms a neutral salt which shoots into
cubical crystals. This salt is inclined to grow moist in the air, and is
consequently one of those which water dissolves in equal quantities, at least
as to sense, whether it be boiling hot or quite cold.
The affinity of this Acid with Alkalis and absorbent Earths is not so great as
that of the vitriolic and nitrous Acids with the same substances: whence it
follows, that, when combined therewith, it may be separated from them by
either of those Acids.
The Acid of Sea-salt, thus disengaged from the substance which served it
for a basis, is called Spirit of Salt. When it contains but little phlegm it is of
a lemon colour, and continually emits many white, very dense, and very
elastic vapours; on which account it is named the Smoaking Spirit of Salt.
Its smell is not disagreeable, nor much unlike that of saffron; but extremely
quick and suffocating when it smokes.
The Acid of Sea-salt, like the other two, seems to have a greater affinity
with the Phlogiston, than with fixed Alkalis. We are led to this opinion by a
very curious operation, which gives ground to think that Sea-salt may be
decomposed by the proper application of a substance containing the
Phlogiston.
From the Marine Acid combined with a Phlogiston results a kind of
Sulphur, differing from the common sort in many respects; but particularly
in this property, that it takes fire of itself upon being exposed to the open
air. This combination is called English Phosphorus, Phosphorus of Urine,
because it is generally prepared from urine; or, only Phosphorus.
This combination of the Marine Acid with a Phlogiston is not easily
effected; because it requires a difficult operation in appropriated vessels.
For these reasons it does not always succeed; and Phosphorus is so scarce
and dear, that hitherto Chymists have not been able to make on it the
experiments necessary to discover all its properties. If Phosphorus be
suffered to burn away in the air, a small quantity of an acid liquor may be
obtained from it, which seems to be spirit of salt, but either altered, or
combined with some adventitious matter; for it has several properties that
are not to be found in the pure Marine Acid; such as, leaving a fixed fusible

substance behind it when exposed to a strong fire, and being easily
combined with the Phlogiston so as to reproduce a Phosphorus.
Phosphorus resembles sulphur in several of its properties: it is soluble in
oils; it melts with a gentle heat; it is very combustible; it burns without
producing soot; and its flame is vivid and bluish.
From what has been said of the union of the Acid of Sea-salt with a fixed
Alkali, and of the neutral salt resulting therefrom, it may be concluded that
this neutral salt is no other than the common kitchen-salt. But it must be
observed, that the fixed Alkali, which is the natural basis of the common
salt obtained from sea-water, is of a sort somewhat differing from fixed
Alkalis in general, and hath certain properties peculiar to itself. For,
1. The basis of Sea-salt differs from other fixed Alkalis in this, that it
crystallizes like a neutral salt.
2. It does not grow moist in the air; on the contrary, when exposed to the air,
it loses part of the water that united with it in crystallization, by which
means its crystals lose their transparency, become, as it were, mealy, and
fall into a fine flour.
3. When combined with the vitriolic Acid to the point of saturation, it forms
a neutral salt differing from vitriolated tartar, first, in the figure of its
crystals, which are oblong six-sided solids; secondly, in its quantity of
water, which in crystallization unites therewith in a much greater proportion
than with vitriolated tartar; whence it follows, that this salt dissolves in
water more readily than vitriolated tartar; thirdly, in that it flows with a very
moderate degree of heat, whereas vitriolated tartar requires a very fierce
one.
If the Acid of Sea-salt be separated from its basis by means of the vitriolic
Acid, it is easy to see that, when the operation is finished, the salt we have
been speaking of must be the result. A famous Chymist, named Glauber,
was the first who extracted the Spirit of Salt in this manner, examined the
neutral salt resulting from his process, and, finding it to have some singular
properties, called it his Sal mirabile, or wonderful Salt: on this account it is
still called Glauber's Sal mirabile, or plainly Glauber's Salt.

4. When the basis of Sea-salt is combined with the nitrous Acid to the point
of saturation, there results a neutral salt, or a sort of nitre, differing from the
common nitre, first, in that it attracts the moisture of the air pretty strongly;
and this makes it difficult to crystallize; secondly, in the figure of its
crystals, which are parallelopipeds; and this has procured it the name of
Quadrangular Nitre.
Common salt, or the neutral salt formed by combining the Marine Acid with
this particular sort of fixed Alkali, has a taste well known to every body.
The figure of its crystals is exactly cubical. It grows moist in the air, and,
when exposed to the fire, it bursts, before it melts, into many little
fragments, with a crackling noise; which is called the Decrepitation of Sea-
salt.
That neutral salt mentioned above, which is formed by combining the
Marine Acid with a common fixed Alkali, and called Sal febrifugum Sylvii,
hath also this property.
India furnishes us with a saline substance, known by the name of Borax,
which flows very easily, and then takes the form of glass. It is of great use
in facilitating the fusion of metallic substances. It possesses some of the
properties of fixed Alkalis, which has induced certain Chymists to represent
it, through mistake, as a pure fixed Alkali.
By mixing borax with the vitriolic Acid, Mr. Homberg obtained from it a
salt, which sublimes in a certain degree of heat, whenever such a mixture is
made. This salt has very singular properties; but its nature is not yet
thoroughly understood. It dissolves in water with great difficulty; it is not
volatile, though it rises by sublimation from the borax. According to Mr.
Rouelle's observation, it rises then only by means of the water which carries
it up: for, when once made, it abides the fiercest fire, flows and vitrifies just
as borax does: provided care be taken to free it previously from moisture by
drying it properly. Mr. Homberg called it Sedative Salt, on account of its
medical effects. The sedative salt hath the appearance, and some of the
properties, of a neutral salt; for it shoots into crystals, and does not change
the colour of violets; but it acts the part of an Acid with regard to Alkalis,
uniting with them to the point of saturation, and thereby forming a true
neutral salt. It also acts, like the Acid of vitriol on all neutral salts; that is, it

discharges the Acid of such as have not the vitriolic Acid in their
composition.
Since Mr. Homberg's time it hath been discovered, that a sedative salt may
be made either with the nitrous or with the marine Acid; and that
sublimation is not necessary to extract it from the borax, but that it may be
obtained by crystallization only. For this latter discovery we are indebted to
Mr. Geoffry, as we are to Mr. Lemery for the former.
Since that time M. Baron d'Henouville, an able Chymist, hath shewn that a
sedative salt may be obtained by the means of vegetable Acids; and hath
lately demonstrated, in some excellent papers published in the collection of
Memoirs written by the correspondents of the Academy of Sciences, that
the sedative salt exists actually and perfectly in the borax, and that it is not
produced by mixing Acids with that saline substance, as it seems all the
Chymists before him imagined. This he proves convincingly from his
analysis of borax, (which thereby appears to be nothing else but the sedative
salt united with that fixed Alkali which is the basis of Sea-salt) and from his
regenerating the same borax by uniting together that Alkali and the sedative
salt: a proof the most complete that can possibly be produced in natural
philosophy, and equivalent to demonstration itself.
In order to finish what remains to be said upon the several sorts of saline
substances, we should now speak of the Acids obtained from vegetables and
animals, and also of the volatile Alkalis: but, seeing these saline substances
differ from those of which we have already treated, only as they are
variously altered by the unions they have contracted with certain principles
of vegetables and animals, of which nothing has been yet said, it is proper
to defer being particular concerning them, till we have explained those
principles.

CHAP. V.

Of Lime.
ny substance whatever, that has been roasted a considerable time in a

A strong fire without melting, is commonly called a Calx. Stones and
metals are the principal subjects that have the property of being
converted into Calces. We shall treat of Metalline Calces in a subsequent
chapter, and in this confine ourselves to the Calx of Stone, known by the
name of Lime.
In treating of earths in general we observed that they may be divided into
two principal kinds; one of which actually and properly flows when
exposed to the action of fire, and turns to glass; whence it is called a fusible
or vitrifiable earth; the other resists the utmost force of fire, and is therefore
said to be an unfusible or unvitrifiable earth. The latter is also not
uncommonly called calcinable earth; though sundry sorts of unfusible
earths are incapable of acquiring by the action of fire all the qualities of
calcined earth, or Lime properly so called: such earths are particularly
distinguished by the denomination of refractory earths.
As the different sorts of stones are nothing more than compounds of
different earths, they have the same properties with the earths of which they
are composed, and may, like them, be divided into fusible or vitrifiable, and
unfusible or calcinable. The fusible stones are generally denoted by the
name of Flints; the calcinable stones, again, are the several sorts of marbles,
cretaceous stones, those commonly called free-stones, &c. some of which,
as they make the best Lime, are, by way of eminence, called Lime-stones.
Sea-shells, also, and stones that abound with fossile shells, are capable of
being burnt to Lime.
All these substances, being exposed, for a longer or shorter time, as the
nature of each requires, to the violent action of fire, are said to be calcined.
By calcination they lose a considerable part of their weight, acquire a white
colour, and become friable though ever so solid before; as, for instance, the
very hardest marbles. These substances, when thus calcined, take the name
of Quick Lime.

Water penetrates Quick Lime, and rushes into it with vast activity. If a lump
of newly calcined Lime be thrown into water, it instantly excites almost as
great a noise, ebullition, and smoke, as would be produced by a piece of
red-hot iron; with such a degree of heat too, that, if the Lime be in due
proportion to the water, it will set fire to combustible bodies; as hath
unfortunately happened to vessels laden with Quick Lime, on their
springing a small leak.
As soon as Quick Lime is put into water, it swells, and falls asunder into an
infinite number of minute particles: in a word, it is in a manner dissolved by
the water, which forms therewith a sort of white paste called Slacked Lime.
If the quantity of water be considerable enough for the Lime to form with it
a white liquor, this liquor is called Lac Calcis; which, being left some time
to settle, grows clear and transparent, the Lime which was suspended
therein, and occasioned its opacity, subsiding to the bottom of the vessel.
Then there forms on the surface of the liquor a crystalline pellicle,
somewhat opaque and dark-coloured, which being skimmed off is
reproduced from time to time. This matter is called Cremor Calcis.
Slacked Lime gradually grows dry, and takes the form of a solid body, but
full of cracks and destitute of firmness. The event is different when you mix
it up, while yet a paste, with a certain quantity of uncalcined stony matter,
such as sand, for example: then it takes the name of Mortar, and gradually
acquires, as it grows drier and older, a hardness equal to that of the best
stones. This is a very singular property of Lime, nor is it easy to account for
it: but it is a beneficial one; for every body knows the use of Mortar in
building.
Quick Lime attracts the moisture of the air, in the same manner as
concentrated acids, and dry fixed alkalis; but not in such quantities as to
render it fluid: it only falls into extremely small particles, takes the form of
a fine powder, and the title of Lime slacked in the air.
Lime once slacked, however dry it may afterwards appear, always retains a
large portion of the water it had imbibed; which cannot be separated from it
again but by means of a violent calcination. Being so recalcined it returns to
be Quick Lime, recovering all its properties.

Besides this great affinity of Quick Lime with water, which discovers a
saline character, it has several other saline properties, to be afterwards
examined, much resembling those of fixed alkalis. In Chymistry it acts very
nearly as those salts do, and may be considered as holding the middle rank
between a pure absorbent earth and a fixed alkali: and this hath induced
many Chymists to think that Lime contains a true salt, to which all the
properties it possesses in common with salts may be attributed.
But as the chymical examination of this subject hath long been neglected,
the existence of a saline substance in Lime hath been long doubtful. Mr. du
Fay, author of some excellent chymical experiments, was one of the first
who obtained a salt from Lime, by lixiviating it with a great deal of water,
which he afterwards evaporated. But the quantity of salt he obtained by that
means was very small; nor was it of an alkaline nature, as one would think
it should have been, considering the properties of Lime. Mr. du Fay did not
carry his experiments on this subject any further, probably for want of time;
nor did he determine of what nature the salt was.
Mr. Malouin had the curiosity to examine this salt of Lime, and soon found
that it was nothing else but what was above called Cremor Calcis. He
found, moreover, that, by mixing a fixed alkali with lime-water, a
vitriolated tartar was formed; that, by mixing therewith an alkali like the
basis of sea-salt, a Glauber's salt was produced; and, lastly, by combining
lime with a substance abounding in phlogiston, he obtained a true sulphur.
These very ingenious experiments prove to a demonstration, that the
vitriolic acid constitutes the salt of Lime: for, as hath been shewn, no other
acid is capable of forming such combinations. On the other hand, Mr.
Malouin, having forced the vitriolic acid of this salt to combine with a
phlogiston, found its basis to be earthy, and analogous to that of the
selenites: whence he concluded, that the salt of Lime is a true neutral salt,
of the same kind as the selenites. Mr. Malouin tells us he found several
other salts in Lime. But as none of them was a fixed alkali, and as all the
saline properties of Lime have an affinity with those of that kind of salt,
there is great reason to think that all those salts are foreign to Lime, and that
their union with it is merely accidental.
I myself have made several experiments in order to get some insight into
the saline nature of Lime, and shall here produce the result with all possible

conciseness. I took several stones of different kinds, some of which
produced by calcination a very strong Lime, and others but a very weak
one. These I impregnated with different saline substances, acids, alkalis,
and neutrals, and then exposed them all to the same degree of fire, which
was a pretty strong one, and long enough continued to have made very good
Lime of stones the most difficult to calcine. The consequence was, that, in
the first place, those stones which naturally made but a weak Lime were
not, by this process, converted into a stronger Lime; and, moreover, that
none of these stones, even such as would naturally have produced the most
active Lime, had acquired the properties of Lime. These experiments I
varied many ways, employing different proportions of saline matters, and
almost every possible degree of fire, and constantly observed, after
calcination, that all those stones were so much the farther from the nature of
Lime, as they had been combined with larger doses of salts. Among those
which were impregnated with the greatest proportion of salts, and had
suffered the greatest violence of fire, I observed some that had begun to
flow, and were in a manner vitrified. Now, as the same subject cannot be, at
one and the same time, in the state of glass and of Lime too; as a body
cannot approach to one of these states but in proportion as it recedes from
the other; and as salts in general dispose those bodies to fusion and
vitrification which are in themselves the most averse to either, I concluded
from my experiments, that the saline substances I used, had, by acting as
fluxes upon the stones, prevented their calcination; that consequently we
may suspect there is no saline matter in the composition of Lime, as Lime;
and that Lime does not owe its saline and alkaline properties to any salt; or
at least that, if it does owe those properties to a salt, such salt must be
naturally and originally combined with the matter of the stone in so just a
proportion, that it is impossible to increase the quantity thereof without
prejudicing the Lime, and depriving it in some measure of its virtue. This
theory agrees perfectly with the illustrious Stahl's opinion; for he thinks, as
we observed in discoursing of salts in general, that every saline substance is
but an earth combined in a certain manner with water. This notion he
applies to Lime, and says, that fire only subtilizes and attenuates the earthy
matter, and thereby renders it capable of uniting with water in such a
manner, that the result of their combination shall be a substance having
saline properties; and that Lime accordingly never acquires these properties
till it be combined with water.

I have dwelt longer on the Salt of Lime than I shall on any other particular;
because the subject, though in itself of great importance, has hitherto been
but little attended to, and because the experiments here recited are entirely
new.
Lime unites with all acids, and in conjunction with them exhibits various
phenomena.
The vitriolic acid poured upon Lime dissolves it with effervescence and
heat. From this mixture there exhales a great quantity of vapours, in smell
and colour perfectly like those of sea-salt; from which, however, they are
found to be very different when collected into a liquor. From this
combination of the vitriolic acid with Lime arises a neutral salt, which
shoots into crystals, and is of the same kind with the selenetic salt obtained
from Lime by Mr. Malouin.
The nitrous acid poured upon Lime dissolves it in like manner with
effervescence and heat: but the solution is transparent, and therein differs
from the former, which is opaque. From this mixture there arises a neutral
salt, which does not crystallize, and has withal the very singular property of
being volatile, and rising wholly by distillation in a liquid form. This
phenomenon is so much the more remarkable, as Lime, the basis of this
salt, is one of the most fixed bodies known in Chymistry.
With the acid of sea-salt Lime forms also a singular sort of salt, which
greedily imbibes the moisture of the air. We shall have occasion to take
further notice of it in another place.
These experiments made on Lime with acids are likewise quite new. We are
indebted for them to Mr. Du Hamel of the Academy of Sciences, whose
admirable Memoirs on several subjects shew his extensive knowledge in all
parts of Natural Philosophy.
Lime applied to fixed alkalis adds considerably to their caustic quality, and
makes them more penetrating and active. An alkaline lixivium in which
Lime hath been boiled, being evaporated to dryness, forms a very caustic
substance, which flows in the fire much more easily, attracts and retains
moisture much more strongly, than fixed alkalis that have not been so
treated. An alkali thus acuated by Lime is called the Caustic Stone, or

Potential Cautery; because it is employed by surgeons to produce eschars
on the skin and cauterize it.

CHAP. VI.

Of Metallic Substances in general.
etallic Substances are heavy, glittering, opaque, fusible bodies. They
M consist chiefly of a vitrifiable earth united with the phlogiston.
Several Chymists insist on a third principle in these bodies, and have given
it the name of Mercurial Earth; which, according to Becher and Stahl, is the
very same that being combined with the vitriolic acid forms and
characterizes the acid of sea-salt. The existence of this principle hath not yet
been demonstrated by any decisive experiment; but we shall shew that there
are pretty strong reasons for admitting it.
We shall begin with mentioning the experiments which prove Metallic
Substances to consist of a vitrifiable earth united with the phlogiston. The
first is this: if they be calcined in such a manner as to have no
communication with any inflammable matter, they will be spoiled of all
their properties, and reduced to an earth or calx, that has neither the
splendour nor the ductility of a metal, and in a strong fire turns to an actual
glass, instead of flowing like a metal.
The second is, that the calx or the glass resulting from a metal thus
decomposed, recovers all its metalline properties by being fused in
immediate contact with an inflammable substance, capable of restoring the
phlogiston of which calcination had deprived it.
On this occasion we must observe, that Chymists have not yet been able, by
adding the phlogiston, to give the properties of metals to all sorts of
vitrifiable earths indiscriminately; but to such only as originally made a part
of some metallic body. For example, a compound cannot be made with the
phlogiston and sand that shall have the least resemblance of a metal: and
this is what seems to point out the reality of a third principle, as necessary
to form the metalline combination. This principle may probably remain
united with the vitrifiable earth of a metallic substance, when reduced to a
glass; whence it follows, that such vitrified metals require only the addition
of a phlogiston to enable them to appear again in their pristine form.

It may be inferred from another experiment, that the calx and the glass of a
metal are not its pure vitrifiable earth, properly so called: for by repeated or
long-continued calcinations, such a calx or glass may be rendered incapable
of ever resuming the metalline form, in whatever manner the phlogiston be
afterwards applied to it; so that by this means it is brought into the
condition of a pure vitrifiable earth, absolutely free from any mixture.
Those Chymists who patronize the Mercurial earth, produce many other
proofs of the existence of that principle in Metallic Substances; but they
would be misplaced in an elementary treatise like this.
When by adding the phlogiston to a metallic glass we restore it to the form
of a metal, we are said to reduce, resuscitate, or revivify that metal.
Metallic Substances are of different kinds, and are divided into Metals and
Semi-metals.
Those are called Metals which, besides their metalline splendour and
appearance, are also malleable; that is, have the property of stretching under
the hammer, and by that means of being wrought into different forms
without breaking.
Those which have only the metalline splendour and appearance, without
malleability, are called Semi-metals.
Metals are also further subdivided into two sorts; viz. Perfect and Imperfect
Metals.
The Perfect Metals are those which suffer no damage or change whatever
by the most violent and most lasting action of fire.
The Imperfect Metals are those which by the force of fire, may be deprived
of their phlogiston, and consequently of their metalline form.
When but a moderate degree of fire is employed to deprive a Metal of its
phlogiston, the metal is said to be calcined; and then it appears in the form
of a powdered earth, which is called a Calx: and this metalline calx being
exposed to a more violent degree of fire melts and turns to glass.
Metallic Substances have an affinity with acids: but not equally with all;
that is, every Metallic Substance is not capable of uniting and joining with

every acid.
When an acid unites with a Metallic Substance there commonly arises an
ebullition, attended with a kind of hissing noise and fuming exhalations. By
degrees, as the union becomes more perfect, the particles of the metal
combining with the acid become invisible: this is termed Dissolution; and
when a metalline mass thus appears in an acid, the metal is said to be
dissolved by that acid. It is proper to observe, that acids act upon Metalline
Substances, in one respect, just as they do upon alkalis and absorbent
earths: for an acid cannot take up above such a certain proportion thereof as
is sufficient to saturate it, to destroy several of its properties, and weaken
others. For example, when an acid is combined with a metal to the point of
saturation, it loses its taste, does not turn the blue colour of a vegetable red,
and its affinity with water is considerably impaired. On the other hand,
Metalline Substances, which when pure are incapable of uniting with water,
by being joined with an acid acquire the property of dissolving in water.
These combinations of Metalline Substances with acids form different sorts
of neutral salts; some of which have the property of shooting into crystals,
while others have it not: most of them, when thoroughly dried, attract the
moisture of the air.
The affinity which Metalline Substances have with acids is less than that
which absorbent earths and fixed alkalis have with the same acids; so that
all metalline salts may be decompounded by one of these substances, which
will unite with the acid, and precipitate the metal.
Metalline Substances thus separated from an acid solvent are called
Magisteries and Precipitates of metals. None of these precipitates, except
those of the perfect metals, retain the metalline form: most of their
phlogiston hath been destroyed by the solution and precipitation, and must
be restored before they can recover their properties. In short, they are nearly
in the same state with Metalline Substances deprived of their phlogiston by
calcination; and accordingly such a precipitate is called a Calx.
A metalline calx prepared in this manner loses a greater or a less portion of
its phlogiston, the more or less effectually and thoroughly the Metalline
Substance, of which it made a part, was dissolved by the acid.

Metallic Substances have affinities with each other which differ according
to their different kinds: but this is not universal; for some of them are
incapable of any sort of union with some others.
It must be observed, that Metallic Substances will not unite, except they be
both in a similar state; that is, both in a Metalline form, or both in the form
of a Glass; for a Metalline Substance retaining its phlogiston cannot
contract an union with any metallic glass, even its own.

CHAP. VII.

Of Metals.
here are six Metals, of which two are Perfect and four Imperfect. The

T perfect Metals are Gold and Silver; the others are Copper, Tin, Lead,
and Iron. Some Chymists admit a seventh Metal, to wit, Quick-silver:
but as it is not malleable, it has been generally considered as a metallic
body of a particular kind. We shall soon have occasion to examine it more
minutely.
The ancient Chymists, or rather the Alchymists, who fancied a certain
relation or analogy between Metals and the Heavenly Bodies, bestowed on
the seven Metals, reckoning Quick-silver one of them, the names of the
seven Planets of the Ancients, according to the affinity which they imagined
they observed between those several bodies. Thus Gold was called Sol,
Silver Luna, Copper Venus, Tin Jupiter, Lead Saturn, Iron Mars, and
Quick-silver Mercury. Though these names were assigned for reasons
merely chimerical, yet they still keep their ground; so that it is not
uncommon to find the Metals called by the names, and denoted by the
characters, of the Planets, in the writings even of the best Chymists. Metals
are the heaviest bodies known in nature.

SECTION I.

Of Gold.
Gold is the heaviest of all Metals. The arts of wire-drawing and gold-
beating shew its wonderful ductility. The greatest violence of fire is not able
to produce any alteration in it. Indeed Mr. Homberg, a famous Chymist,
pretended that he had made this metal fume, and even vitrified it, by
exposing it to the focus of one of the best burning-glasses, known by the
name of the Lens of the Palais Royal: but, there are very good reasons for
calling in question the experiments he made on this occasion, or rather for
thinking that he was quite mistaken. For,

1. No man hath since been able to vitrify Gold, though several good
Experimenters have assiduously tried to effect it, by exposing it to the focus
of the same lens, and of other burning-glasses still stronger.
2. It hath been observed, that though Gold, when exposed to the focus of
those glasses, did indeed emit some vapours and decrease in weight; yet,
those vapours being carefully collected on a piece of paper, proved to be
true Gold, in no degree vitrified, and which consequently had suffered no
change but that of being carried away by the violence of the heat, its nature
not being in the least altered.
3. The small portion of vitrified matter, which was formed on the arm that
supported the Gold in Mr. Homberg's experiment, may have come either
from the arm itself, or rather from some heterogeneous particles contained
in the Gold; for it is almost impossible to have it perfectly pure.
4. Neither Mr. Homberg, nor any that have repeated his experiment, ever
reduced this pretended glass of Gold by restoring its Phlogiston, as is done
with other metallic glasses.
5. To render the experiment decisive, the whole mass of Gold employed
ought to have been vitrified; which was not the case.
Nevertheless, I do not pretend that this metal is in its own nature absolutely
indestructible, and unvitrifiable: but there is reason to think that no body
hath hitherto found the means of producing those effects on it, probably for
want of a sufficient degree of fire; at least the point is very doubtful.
Gold cannot be dissolved by any pure acid: but if the acid of nitre be mixed
with the acid of sea-salt, there results a compound acid liquor, with which it
has so great an affinity that it is capable of being perfectly dissolved
thereby. The Chymists have called this solvent Aqua Regis, on account of
its being the only acid that can dissolve Gold, which they consider as the
King of Metals. The solution of gold is of a beautiful orange colour.
If Gold dissolved in aqua regis be precipitated by an alkali or an absorbent
earth, the precipitate gently dried, and then exposed to a certain degree of
heat, is instantly dispersed into the air, with a most violent explosion and
noise: Gold thus precipitated is therefore called Aurum Fulminans. But if
the precipitated Gold be carefully washed in plenty of water, so as to clear it

of all the adhering saline particles, it will not fulminate, but may be melted
in a crucible without any additament, and will then appear in its usual form.
The acid of vitriol being poured on aurum fulminans likewise deprives it of
its fulminating quality.
Gold does not begin to flow till it be red-hot like a live coal. Though it be
the most malleable and most ductile of all metals, it has the singular
property of losing its ductility more easily than any of them: even the fumes
of charcoal are sufficient to deprive it thereof, if they come in contact with
it while it is in fusion.
The malleability of this metal, and indeed of all the rest, is also
considerably diminished by exposing it suddenly to cold when it is red-hot;
for example, by quenching it in water, or even barely exposing it to the cold
air.
The way to restore ductility to gold, when lost by its coming in contact with
the vapour of coals, and in general to any metal rendered less malleable by
being suddenly cooled, is to heat it again, to keep it red hot a considerable
time, and then to let it cool very slowly and gradually; this operation
frequently repeated will by degrees much increase the malleability of a
metal.
Pure sulphur hath no effect on Gold; but being combined with an alkali into
a hepar sulphuris, it unites therewith very readily. Nay, so intimate is their
union, that the Gold, by means thereof, becomes soluble in water; and this
new compound of Gold and liver of sulphur, being dissolved in water, will
pass through the pores of brown paper without suffering any
decomposition; which does not happen, at least in such a manifest degree,
to other metallic substances dissolved by liver of sulphur.
Aurum fulminans, mixed and melted with flower of sulphur, loses its
fulminating quality: which arises from hence, that on this occasion the
sulphur burns, and its acid, which is the same with the vitriolic, being
thereby set at liberty becomes capable of acting upon the Gold as a vitriolic
acid would; which, as was said above, deprives the Gold of its fulminating
quality.

SECTION II.

Of Silver.
Next to Gold, Silver is the most perfect metal. Like Gold it resists the
utmost violence of fire, even that in the focus of a burning-glass. However,
it holds only the second place among metals; because it is lighter than Gold
by almost one half; is also somewhat less ductile; and, lastly, because it is
acted upon by a greater number of solvents.
Yet Silver hath one advantage over gold, namely that of being a little
harder; which makes it also more sonorous.
This metal, like Gold, begins to flow when it is so thoroughly penetrated by
the fire as to appear ignited like a live coal.
While this metal is in fusion, the immediate contact of the vapour of
burning coals deprives it almost entirely of its malleability, in the same
manner as we observed happens to Gold: but both these metals easily
recover that property by being melted with nitre.
The nitrous acid is the true solvent of Silver, and being somewhat
dephlegmated will very readily and easily take up a quantity of Silver equal
in weight to itself.
Silver thus combined with the nitrous acid forms a metallic salt which
shoots into crystals, called by the name of Lunar Crystals, or Crystals of
Silver.
These crystals are most violently caustic: applied to the skin they quickly
affect it much as a live coal would; they produce a blackish eschar,
corroding and entirely destroying the parts they touch. Surgeons use them to
eat away the proud fungous flesh of ulcers. As Silver united with the nitrous
acid hath the property of blackening all animal substances, a solution of this
metallic salt is employed to dye hair, or other animal matters, of a beautiful
and durable black.
These crystals flow with a very moderate heat, and even before they grow
red. Being thus melted they form a blackish mass; and in this form they are
used by Surgeons, under the title of Lapis Infernalis, Infernal Stone, or
Lunar Caustic.

Silver is also dissolved by the vitriolic acid: but then the acid must be
concentrated, and in quantity double the weight of the Silver; nor will the
solution succeed without a considerable degree of heat.
Spirit of salt and aqua regis, as well as the other acids, are incapable of
dissolving this metal; at least in the ordinary way.
Though Silver be not soluble in the acid of sea-salt, nor easily in the acid of
vitriol, as hath just been observed, it doth not follow that it hath but a weak
affinity with the latter, and none at all with the former: on the contrary, it
appears from experiment that it hath with these two acids a much greater
affinity than with the acid of nitre: which is singular enough, considering
the facility with which this last acid dissolves it.
The experiment which proves the fact, is this. To a solution of Silver in the
nitrous acid, add the acid either of vitriol or of sea-salt, and the Silver will
instantly quit its nitrous solvent to join with the superadded acid.
Silver thus united with the vitriolic or the marine acid is less soluble in
water than when combined with the nitrous acid; and for this reason it is,
that when either of these two acids is added to a solution of Silver, the
liquor immediately becomes white, and a precipitate is formed, which is no
other than the Silver united with the precipitating acid. If the precipitation
be effected by the vitriolic acid, the precipitate will disappear upon adding a
sufficient quantity of water, because there will then be water enough to
dissolve it. But the case is not the same when the precipitation is made by
the marine acid; for Silver combined therewith is scarce soluble in water.
This Precipitate of Silver, procured by means of the marine acid, is very
easily fused, and when fused changes to a substance in some measure
transparent and flexible, which hath occasioned it to be called by the name
of Luna Cornea. If it be proposed to decompound this luna cornea, that is,
to separate the marine acid from the Silver with which it is united, the luna
cornea must be melted along with fatty and absorbent matters, with which
the acid will unite, and leave the metal exceeding pure.
It must be observed, that if, instead of the marine acid, sea-salt in substance
be added to a solution of Silver in the nitrous acid, a Precipitate is also
produced, which by fusion appears to be a true luna cornea. The reason is,

that the sea-salt is decomposed by the nitrous acid, which seizes its basis, as
having a greater affinity therewith than its own acid hath; and this acid
being consequently disengaged and set at liberty unites with the Silver,
which, as has been shewn, has a greater affinity with it than with the nitrous
acid. This is an instance of decomposition effected by means of one of those
double affinities mentioned by us in our seventh proposition concerning
Affinities.
From what hath been already said it is clear, that all these combinations of
Silver with acids may be decompounded by absorbent earths and by fixed
alkalis; it being a general law with regard to all metallic substances. We
shall not therefore repeat this observation when we come to treat of the
other metals; unless some particular occasion require it.
With regard to Silver I must take notice that, when separated by these
means from the acids in which it was dissolved, it requires nothing but
simple fusion to restore it to its usual form; because it does not, any more
than Gold, lose its Phlogiston by those solutions and precipitations.
Silver unites with sulphur in fusion. If this metal be only made red-hot in a
crucible, and sulphur be then added, it immediately flows; the sulphur
acting as a flux to it. Silver thus united with sulphur forms a mass that may
be cut, is half malleable, and hath nearly the colour and consistence of
Lead. If this sulphurated Silver be kept a long time in fusion, and in a great
degree of heat, the sulphur flies off and leaves the Silver pure. But if the
sulphur be evaporated by a violent heat, it carries off with it part of the
Silver.
Silver unites and mixes perfectly with Gold in fusion. The two metals thus
mixed form a compound with properties partaking of both.
Metallurgists have hitherto sought in vain for a perfectly good and easy
method of separating these two metals by the dry way only: (this term is
used to signify all operations performed by fusion): but they are
conveniently enough parted by the moist way, that is, by acid solvents. This
method is founded on the above-mentioned properties of Gold and Silver
with respect to acids. It hath been shewn that aqua regis only will dissolve
Gold; that Silver, on the contrary, is not soluble by aqua regis, and that its
proper solvent is the acid of nitre; consequently, when Gold and Silver are

mixed together, if the compound mass be put into aqua fortis, this acid will
take up all the Silver, without dissolving a particle of the Gold, which will
therefore remain pure; and by this means the desired separation is effected.
This method, which is commonly made use of by Goldsmiths, and in Mints,
is called the Parting Assay.
It is plain, that if aqua regis were employed instead of aqua fortis, the
separation would be equally effected; and that the only difference between
this process and the former would consist in this, that now the Gold would
be dissolved, and the Silver remain pure. But the operation by aqua fortis is
preferable; because aqua regis does take up a little Silver, whereas aqua
fortis hath not the least effect on Gold.
It must be observed, that, when Gold and Silver are mixed together in equal
parts, they cannot be parted by the means of aqua fortis. To enable the aqua
fortis to act duly on the Silver, this metal must be, at least, in a triple
proportion to the Gold. If it be in a less proportion, you must either employ
aqua regis to make the separation, or, if you prefer the use of aqua fortis,
melt the metalline mass, and add as much Silver as is necessary to make up
the proportion above-mentioned: and hence this Process is called
Quartation.
This effect, which is pretty singular, probably arises from hence, that when
the Gold exceeds or even equals the Silver in quantity, the parts of both
being intimately united, the former are capable of coating over the latter,
and covering them so as to defend them from the action of the aqua fortis;
which is not the case when there is thrice as much Silver as Gold.
There is one thing more to be taken notice of with regard to this process;
which is, that perfectly pure aqua fortis is rarely to be met with, for two
reasons; first, it is difficult in making it wholly to prevent the rising of the
medium employed to disengage the nitrous acid; that is, a little of the
vitriolic acid will mix with the vapours of the aqua fortis: secondly, unless
the salt-petre be very well purified it will always hold some small portion of
sea-salt, the acid of which, we know, is very readily set loose by the
vitriolic acid, and consequently rises together with the vapours of the aqua
fortis. It is easy to see that aqua fortis mixed either with the one or the other
is not proper for the Parting Process; because, as has just been said, the

vitriolic and the marine acid equally precipitate Silver dissolved in the
nitrous acid; by which means, when they are united with that acid, they
weaken its action upon the Silver, and hinder the dissolution. Add, that
aqua fortis adulterated with a mixture of spirit of salt becomes an aqua
regis, and consequently is rendered capable of dissolving Gold, in
proportion as its action upon Silver is diminished.
In order to remedy this inconvenience, and free aqua fortis from the
vitriolic or marine acid with which it is tainted, Silver must be dissolved
therein: by degrees as the metal dissolves, those heterogeneous acids lay
hold of it, and precipitate with it in the form of a white powder, as we
observed before. This precipitate being wholly fallen, the liquor grows
clear; after which, if it be found capable of dissolving more silver, without
turning milky, it may be depended on as a perfectly pure aqua fortis. Then
filtre it, dissolve more Silver in it, as long as it will take up any, and you
will have a solution of Silver in a very pure aqua fortis. By means of this
solution may other aqua fortis be purified: for pour a few drops thereof into
a very impure aqua fortis, and immediately the vitriolic or marine acid,
with which that aqua fortis is contaminated, will join the Silver and fall
therewith to the bottom. When the solution of Silver, prepared as above,
does not in the least affect the transparency of the aqua fortis, it is then very
pure, and fit for the purposes of Quartation.
This operation of purifying aqua fortis by a solution of Silver is called the
Precipitation of Aqua Fortis, and aqua fortis thus purified is called
Precipitated Aqua Fortis.
When Silver is dissolved in aqua fortis it may be separated therefrom, as
hath been shewn, by absorbent earths and fixed alkalis.
We shall see by and by that there are other means of effecting this: but
whatever way it be separated from its solvent it recovers its metalline form,
as Gold does, by being simply fused without any additament.

SECTION III.

Of Copper.

Of all the imperfect metals Copper comes the nearest to Gold and Silver. Its
natural colour is a deep-red yellow. It resists a very violent degree of fire for
a considerable time; but losing its phlogiston at last, it changes its metalline
form for that of a calx, or a pure reddish earth. This calx is hardly, if at all,
reducible to glass, without the addition of something to promote its fusion;
all that the fiercest heat can do being only to render it soft. Copper, even
while it retains its metalline form, and is very pure, requires a considerable
degree of fire to melt it, and does not begin to flow till long after it is red-
hot. When in fusion, it communicates a greenish colour to the flame of the
coals.
This metal is inferior to Silver in point of gravity; nor is its ductility so
great, though it be pretty considerable: but, on the other hand, it exceeds
that metal in hardness. It unites readily with Gold and Silver; nor does it
greatly lessen their beauty when added to them in a small quantity: nay, it
even procures them some advantages; such as making them harder, and less
subject to lose their ductility, of which those metals are often liable to be
deprived, by the mixture of the smallest heterogeneous particle. This may
probably arise from hence, that the ductility of Copper has the peculiarity of
resisting most of those causes which rob the perfect metals of theirs.
The property, which other metalline substances have in common with
Copper, of losing the phlogiston by calcining and then vitrifying, furnishes
us with a method of separating them from Gold and Silver, when they are
combined therewith. Nothing more is required than to expose the mass
compounded of the perfect metals and other metalline substances to a
degree of heat sufficient to calcine whatever is not either Gold or Silver. It
is evident, that, by this means, these two metals will be obtained as pure as
is possible; for, as hath already been said, no metalline calx or glass is
capable of uniting with metals possessed of their phlogiston. On this
principle is formed the whole business of refining Gold and Silver.
When the perfect metals have no other alloy but Copper, as this metal is not
to be calcined or vitrified without great difficulty, which is increased by its
union with the unvitrifiable metals, it is easy to see that it is almost
impossible to separate them without adding something to facilitate the
vitrification of the Copper. Such metals as have the property of turning
easily to glass are very fit for this purpose; and it is necessary to add a

certain quantity thereof, when Gold or Silver is to be purified from the alloy
of Copper. We shall have occasion to be more particular on this subject
when we come to treat of Lead.
Copper is soluble in all the acids, to which it communicates a green colour,
and sometimes a blue. Even the neutral salts, and water itself, act upon this
metal. With regard to water indeed, as the procuring it absolutely pure and
free from any saline mixture is next to an impossibility, it remains a
question whether the effect it produces on Copper be not owing to certain
saline particles contained in it. It is this great facility of being dissolved that
renders Copper so subject to rust; which is nothing else but some parts of its
surface corroded by saline particles contained in the surrounding air and
water.
The rust of Copper is always green or blue, or of a colour between these
two. Internally used it is very noxious, being a real poison, as are all the
solutions of this metal made by any acid whatever. The blue colour which
Copper constantly assumes, when corroded by any saline substance, is a
sure sign by which it may be discovered wherever it exists, even in a very
small quantity.
Copper dissolved in the vitriolic acid forms a kind of metalline salt, which
shoots into rhomboidal crystals of a most beautiful blue colour. These
crystals are called Blue Vitriol, or Vitriol of Copper. They are sometimes
found ready formed in the bowels of the earth; and may be artificially made
by dissolving Copper in the vitriolic acid; but the solution will not succeed
unless the acid be well dephlegmated. The taste of this vitriol is saltish and
astringent. It retains a considerable quantity of water in crystallizing, on
which account it is easily rendered fluid by fire.
It must be observed, that, when it is exposed to a certain degree of heat, in
order to free it of its humidity, a great part of its acid flies off at the same
time: and hence it is that, after calcination, there remains only a kind of
earth, or metalline calx, of a red colour, which contains but very little acid.
This earth cannot be brought to flow but with the greatest difficulty.
A solution of Copper in the nitrous acid forms a salt which does not
crystallize, but, when dried, powerfully attracts the moisture of the air. The

same thing happens when it is dissolved in the spirit of salt, or in aqua
regis.
If the Copper thus dissolved by any of these acids be precipitated by an
earth or an alkali, it retains nearly the colour it had in the solution: but these
precipitates are scarce any thing more than the earth of Copper, or Copper
deprived of most of its phlogiston; so that if they were exposed to a violent
fire, without any additament, a great part of them would be converted into
an earth that could never be reduced to a metalline form. Therefore, when
we intend to reduce these precipitates to Copper, it is necessary to add a
certain quantity of a substance capable of restoring to them the phlogiston
they have lost.
The substance which hath been found fittest for such reductions is charcoal-
dust; because charcoal is nothing but a phlogiston closely combined with an
earth, which renders it exceedingly fixed, and capable of resisting a violent
force of fire. But as charcoal will not melt, and consequently is capable of
preventing rather than forwarding the flux of a metalline calx or glass,
which nevertheless is essentially necessary to complete the reduction, it
hath been contrived to mix it, or any other substance containing the
phlogiston, with such fixed alkalis as easily flow, and are fit to promote the
flux of other bodies. These mixtures are called Reducing Fluxes; because
the general name of Fluxes is given to all salts or mixtures of salts, which
facilitate fusion.
If Sulphur be applied to Copper made perfectly red-hot, the metal
immediately runs; and these two substances uniting form a new compound
much more fusible than pure Copper.
This compound is destroyed by the sole force of fire, for two reasons: the
first is, that, sulphur being volatile, the fire is capable of subliming a great
part of it, especially when it is in a great proportion to the Copper with
which it is joined; the second is, that the portion of sulphur which remains,
being more intimately united with the Copper, though it be rendered less
combustible by that union, is nevertheless burnt and consumed in time.
Copper being combined with sulphur, and together with it exposed to the
force of fire, is found to be partly changed into a blue vitriol; because the
vitriolic acid, being disengaged by burning the sulphur, is by that means

qualified to dissolve the Copper. The affinity of Copper with sulphur is
greater than that of Silver.
This metal, as well as the other imperfect metals and the semi-metals, being
mingled with nitre and exposed to the fire, is decomposed and calcined
much sooner than by itself; because the phlogiston which it contains
occasions the deflagration of the nitre, and consequently the two substances
mutually decompose each other. There are certain metalline substances
whose phlogiston is so abundant, and so weakly connected with their earth,
that when they are thus treated with nitre, there arises immediately a
detonation, accompanied with flame, and as violent as if sulphur or
charcoal-dust had been employed; so that in a moment the metalline
substance loses its phlogiston, and is calcined. The nitre, after these
detonations, always assumes an alkaline character.

SECTION IV.

Of Iron.
Iron is lighter and less ductile than Copper; but it is much harder, and of
more difficult fusion.
It is the only body that has the property of being attracted by the magnet,
which therefore serves to discover it wherever it is. But it must be observed,
that it hath this property only when in its metalline state, and loses it when
converted to an earth or calx. Hence very few Iron-ores are attracted by the
load-stone: because, for the most part, they are only sorts of earths, which
require a phlogiston to be added before they can be brought to the form of
true Iron.
When Iron hath undergone no other preparation but the fusion which is
necessary to smelt it from its ore, it is usually quite brittle, and flies to
pieces under the hammer: which arises in some measure from its containing
a certain portion of unmetallic earth interposed between its parts. This we
call Pig Iron.
By melting this a second time it is rendered purer, and more free from
heterogeneous matters: but still, as its proper parts are probably not brought

sufficiently near, or closely enough united, till the Iron hath undergone
some further preparation besides that of fusion, it seldom hath any degree of
malleability.
The way to give it this property is to make it just red-hot, and then hammer
it for some time in all directions; to the end that its parts may be properly
united, incorporated, and welded together, and that the heterogeneous
matters which keep them asunder may be separated. Iron made by this
means as malleable as possible we call Bar Iron, or Forged Iron.
Bar Iron is still harder to fuse than Pig Iron: to make it flow requires the
utmost force of fire.
Iron has the property of imbibing a greater quantity of phlogiston than is
necessary to give it the metalline form. It may be made to take in this
superabundant phlogiston two ways: the first is by fusing it again with
matters that contain the phlogiston; the second is, by encompassing it with a
quantity of such matters, charcoal-dust, for instance, and then exposing it so
encompassed, for a certain time, to a degree of fire barely sufficient to keep
it red-hot. This second method, whereby one substance is incorporated with
another by means of fire, but without fusing either of them, is in general
called Cementation.
Iron thus impregnated with an additional quantity of phlogiston is called
Steel. The hardness of Steel may be considerably augmented by tempering
it; that is, by making it red-hot, and suddenly quenching it in some cold
liquor. The hotter the metal, and the colder the liquor in which it is
quenched, the harder will the Steel be. By this means tools are made, such
as files and sheers, capable of cutting and dividing the hardest bodies, as
glass, pebbles, and Iron itself. The colour of Steel is darker than that of Iron,
and the facets which appear on breaking it are smaller. It is also less ductile
and more brittle, especially when tempered.
As Iron may be impregnated with an additional quantity of phlogiston, and
thereby converted into Steel, so may Steel be again deprived of that
superabundant phlogiston, and brought back to the condition of Iron. This is
effected by cementing it with poor earths, such as calcined bones and chalk.
By the same operation Steel may be untempered; nay, it will lose the
hardness it had acquired by tempering, if it be but made red-hot, and left to

cool gradually. As Iron and Steel differ only in the respects we have here
taken notice of, their properties being in all other respects the same, what
follows is equally applicable to both.
Iron being exposed to the action of fire for some time, especially when
divided into small particles, such as filings, is calcined and loses its
phlogiston. By this means it turns to a kind of reddish yellow earth, which,
on account of its colour, is called Crocus Martis, or Saffron of Mars.
This calx of Iron has the singular property of flowing in the fire with
somewhat less difficulty than Iron itself; whereas every other metalline calx
flows with less ease than the metal that produced it. It has moreover the
remarkable property of uniting with the phlogiston, and of being reduced to
Iron without fusion; requiring for that purpose only to be made red-hot.
Iron may be incorporated with Silver, and even with Gold, by means of
certain operations. Under the article of Lead we shall see how it may be
separated from these metals.
The acids produce on it much the same effects as on Copper; every one of
them acts upon it. Certain neutral salts, alkalis, and even water itself, are
capable of dissolving it; and hence it is also very subject to rust. The
vitriolic acid dissolves it with the greater ease: but the circumstances which
attend the solution thereof are different from those with which the same
Acid dissolves Copper: for, 1. whereas the vitriolic acid must be
concentrated to dissolve Copper, it must on the contrary be diluted with
water to dissolve Iron, which it will not touch when well dephlegmated. 2.
The vapours which rise in this dissolution are inflammable; so that if it be
made in a small-necked bottle, and the flame of a candle be applied to the
mouth thereof, the vapours in the bottle take fire with such rapidity as to
produce a considerable explosion.
This solution is of a beautiful green colour; and from this union of the
vitriolic acid with Iron there results a neutral metalline salt, which has the
property of shooting into crystals of a rhomboidal figure, and a green
colour. These crystals are called Green Vitriol, Vitriol of Mars, and
Copperas.

Green Vitriol hath a saltish and astringent taste. As it retains a great deal of
water in crystallizing, it quickly flows by the action of fire: but this fluidity
is owing to its water only, and is not a real fusion; for, as soon as its
moisture is evaporated, it resumes a solid form. Its green transparent colour
is now changed into an opaque white: and, if the calcination be continued,
its acid also exhales and is dissipated in vapours; and as it loses that, it turns
gradually to a yellow colour, which comes so much the nearer to a red the
longer the calcination is continued, or the higher the force of the fire is
raised; which being driven to the utmost, what remains is of a very deep
red. This remainder is nothing but the body of the Iron, which having lost
its phlogiston is now no more than an earth, nearly of the same nature with
that which is left after calcining the metal itself.
Green Vitriol dissolved in water spontaneously lets fall a yellowish earthy
sediment. If this solution be defecated by filtration, it still continues to
deposite some of the same substance, till the vitriol be wholly decomposed.
This sediment is nothing but the earth of Iron, which is then called Ochre.
The nitrous acid dissolves Iron with great ease. This solution is of a yellow
colour, inclining more or less to a russet, or dark-brown, as it is more or less
saturated with Iron. Iron dissolved by this acid, also, falls spontaneously in
a kind of calx, which is incapable of being dissolved a second time; for the
nitrous acid will not act upon Iron that has lost its phlogiston. This solution
does not crystallize, and if evaporated to dryness attracts the moisture of the
air.
Spirit of salt likewise dissolves Iron, and this solution is green. The vapours
which rise during the dissolution are inflammable, like those which ascend
when this metal is attacked by the vitriolic acid. Aqua regis makes a
solution of Iron, which is of a yellow colour.
Iron hath a greater affinity than either Silver or Copper with the nitrous and
vitriolic acids: so that if iron be presented to a solution of either in one of
these two acids, the dissolved metal will be precipitated; because the acid
quits it for the Iron, with which it has a greater affinity.
On this occasion it must be observed, that if a solution of Copper in the
vitriolic acid be precipitated by means of Iron, the precipitate has the form
and splendour of a metal, and does not require the addition of a phlogiston

to reduce it to true Copper; which is not the case, as has been shewn, when
the precipitation is effected by earths or alkaline salts.
The colour of this metalline precipitate hath deceived several persons, who
being unacquainted with such phenomena, and with the nature of blue
vitriol, imagined that Iron was transmuted into Copper, when they saw a bit
of Iron laid in a solution of that vitriol become, in form and external
appearance, exactly like Copper: whereas the surface only of the Iron was
crusted over with the particles of Copper contained in the vitriol, which had
gradually fallen upon and adhered to the Iron, as they were precipitated out
of the solution.
Among the solvents of Iron we mentioned fixed alkalis; and that they have
such a power is proved by the following phenomenon. If a large proportion
of alkaline salts be suddenly mixed with a solution of Iron in an acid, no
precipitation ensues, and the liquor remains clear and pellucid; or if at first
it look a little turbid, that appearance lasts but a moment, and the liquor
presently recovers its transparency. The reason is, that the quantity of alkali
is more than sufficient to saturate all the acid of the solution, and the
superabundant portion thereof, meeting with the Iron already finely divided
by the acid, dissolves it with ease as fast as it falls, and so prevents its
muddying the liquor. To evince that this is so in fact, let the alkali be
applied in a quantity that is not sufficient, or but barely sufficient, to
saturate the acid, and the Iron will then precipitate like any other metal.
Water also acts upon Iron; and therefore Iron exposed to moisture grows
rusty. If iron-filings be exposed to the dew, they turn wholly to a rust, which
is called Crocus Martis Aperiens.
Iron exposed to the fire together with nitre makes it detonate pretty briskly,
sets it in a flame, and decomposes it with rapidity.
This metal hath a greater affinity than any other metalline substance with
sulphur; on which account it is successfully used to precipitate and separate
all metalline substances combined with sulphur.
Sulphur uniting with Iron communicates to it such a degree of fusibility,
that if a mass of this metal heated red-hot be rubbed with a bit of sulphur, it

incessantly runs into as perfect a fusion as a metal exposed to the focus of a
large burning-glass.

SECTION V.

Of Tin.
Tin is the lightest of all metals. Though it yields easily to the impression of
hard bodies, it has but little ductility. Being bent backwards and forwards it
makes a small crackling noise. It flows with a very moderate degree of fire,
and long before it comes to be red-hot. When it is in fusion, its surface soon
grows dusty, and there forms upon it a thin dark-coloured dusty pellicle,
which is no other than a part of the Tin that has lost its phlogiston, or a calx
of Tin. The metal thus calcined easily recovers its metalline form on the
addition of a phlogiston. If the calx of Tin be urged by a strong fire it grows
white, but the greatest violence of heat will not fuse it; which makes some
Chymists consider it as a calcinable or absorbent earth, rather than a
vitrifiable one. Yet it turns to glass, in some sort, when mixed with any
other substance that vitrifies easily. However, it always produces an
imperfect glass only, which is not at all transparent, but of an opaque white.
The calx of Tin thus vitrified is called Enamel. Enamels are made of several
colours by the addition of this or that metalline calx.
Tin unites easily with all the metals; but it destroys the ductility and
malleability of every one of them, Lead excepted. Nay, it possesses this
property of making metals brittle in such an eminent degree, that the very
vapour of it, when in fusion, is capable of producing this effect. Moreover,
which is very singular, the most ductile metals, even Gold and Silver, are
those on which it works this change with the most ease, and in the greatest
degree. It has also the property of making Silver mixed with it flow over a
very small fire.
It adheres to, and in some measure incorporates with, the surface of Copper
and of Iron; whence arose the practice of coating over those metals with
Tin. Tin plates are no other than thin plates of Iron tinned over.
If to twenty parts of Tin one part of Copper be added, this alloy renders it
much more solid, and the mixed mass continues tolerably ductile.

If, on the contrary, to one part of Tin ten parts of Copper be added, together
with a little Zink, a semi-metal to be considered hereafter, from this
combination there results a metalline compound which is hard, brittle, and
very sonorous; so that it is used for casting bells: this composition is called
Bronze and Bell-metal.
Tin hath an affinity with the vitriolic, nitrous, and marine acids. All of them
attack and corrode it; yet none of them is able to dissolve it without great
difficulty: so that if a clear solution thereof be desired, particular methods
must be employed for that purpose; for the acids do but in a manner calcine
it, and convert it to a kind of white calx or precipitate. The solvent which
has the greatest power over it is aqua regis, which has even a greater
affinity therewith than with Gold itself; whence it follows, that Gold
dissolved in aqua regis may be precipitated by means of Tin; but then the
aqua regis must be weakened. Gold thus precipitated by Tin is of a most
beautiful colour, and is used for a red in enameling and painting on
porcelain, as also to give a red colour to artificial gems. If the aqua regis be
not lowered, the precipitate will not have the purple colour.
Tin hath the property of giving a great lustre to all red colours in general; on
which account it is used by the dyers for striking a beautiful scarlet, and tin
vessels are employed in making fine syrup of violets. Water does not act
upon this metal, as it does upon Iron and Copper; for which reason it is not
subject to rust: nevertheless, when it is exposed to the air, its surface soon
loses its polish and splendour.
Tin mixed with nitre and exposed to the fire deflagrates with it, makes it
detonate, and is immediately converted to a refractory calx: for so all
substances are called which are incapable of fusion.
Tin readily unites with sulphur, and with it becomes a brittle and friable
mass.

SECTION VI.

Of Lead.

Next to Gold and Mercury Lead is the heaviest of all metalline substances,
but in hardness is exceeded by every one of them. Of all metals also it melts
the easiest except Tin. While it is in fusion there gathers incessantly on its
surface, as on that of Tin, a blackish dusty pellicle, which is nothing but a
calx of Lead.
This calx further calcined by a moderate fire, the flame being reverberated
on it, soon grows white. If the calcination be continued it becomes yellow,
and at last of a beautiful red. In this state it is called Minium, and is used as
a pigment. Minium is not easily made, and the operation succeeds well in
large manufactures only.
To convert Lead into Litharge, which is the metal in a manner half vitrified,
you need only keep it melted by a pretty strong fire; for then as its surface
gradually calcines, it tends more and more to fusion and vitrification.
All these preparations of Lead are greatly disposed to perfect fusion and
vitrification, and for that purpose require but a moderate degree of fire; the
calx or earth of Lead being of all metalline earths that which vitrifies the
most easily.
Lead hath not only the property of turning into glass with the greatest
facility, but it hath also that of promoting greatly the vitrification of all the
other imperfect metals; and, when it is actually vitrified, procures the ready
fusion of all earths and stones in general, even those which are refractory,
that is, which could not be fused without its help.
Glass of Lead, besides its great fusibility, hath also the singular property of
being so subtile and active as to corrode and penetrate the crucibles in
which it is melted, unless they be of an earth that is exceeding hard,
compact, and withal very refractory: for Glass of Lead being one of the
most powerful fluxes that we know, if the earth of the crucible in which it is
melted be in the smallest degree fusible, it will be immediately vitrified;
especially if there be any metallic matter in its composition.
The great activity of Glass of Lead may be weakened by joining it with
other vitrifiable matters: but unless these be added in a very great
proportion, it will still remain powerful enough to penetrate common earths,
and carry off the matters combined with it.

On these properties of Lead, and of the Glass of Lead, depends the whole
business of refining Gold and Silver. It hath been shewn, that as these two
metals are indestructible by fire, and the only ones which have that
advantage, they may be separated from the imperfect metals, when mixed
therewith, by exposing the compound to a degree of fire sufficiently strong
to vitrify the latter; which, when once converted into glass, can no longer
remain united with any metal that has its metalline form. But it is very
difficult to procure this vitrification of the imperfect metals, when united
with Gold and Silver; nay, it is in a manner impossible to vitrify them
entirely, for two reasons: first, because most of them are naturally very
difficult to vitrify; secondly, because the union they have contracted with
the perfect metals defends them, in a manner, from the action of the fire,
and that so much the more effectually as the proportion of the perfect
metals is greater; which being indestructible, and in some sort coating over
those with which they are alloyed, serve them as a preservative and
impenetrable shield against the utmost violence of fire.
It is therefore clear, that a great deal of labour may be saved, and that Gold
and Silver may be refined to a much greater degree of purity than can
otherwise be obtained, if to a mixture of these metals with Copper, for
instance, or any other imperfect metal be added a certain quantity of Lead.
For the Lead, by its known property, will infallibly produce the desired
vitrification; and as it likewise increases the proportion of the imperfect
metals, and so lessens that of the perfect metals, in the mass, it evidently
deprives the former of a part of their guard, and so effects a more complete
vitrification. In conclusion, as the Glass of Lead hath the property of
running through the crucible, and carrying with it the matters which it has
vitrified, it follows, that, when the vitrification of the imperfect metals is
effected by its means, all those vitrified matters together penetrate the
vessel containing the fused metalline mass, disappear, and leave only the
Gold and Silver perfectly pure, and freed, as far as is possible, from all
admixture of heterogeneous parts.
The better to promote the separation of such parts it is usual to employ, in
this process, a particular sort of small crucibles, made of the ashes of
calcined bones, which are exceedingly porous and easily pervaded. They
are called cupels, on account of their figure, which is that of a wide-
mouthed cup: and from hence the operation takes its name; for when we

refine Gold and Silver in this manner we are said to cupel those metals. It is
easy to perceive that the more Lead is added the more accurately will the
Gold and Silver be refined; and that so much the more Lead ought to be
added as the perfect metals are alloyed with a greater proportion of the
imperfect. This is the most severe trial to which a perfect metal can be put;
and consequently any metal that stands it may be fairly considered as such.
In order to denote the fineness of Gold, it is supposed to be divided into
twenty-four parts called carats; and Gold which is quite pure and free from
all alloy is said to be twenty-four carats fine; that which contains 1/24 part
of alloy is called Gold of twenty-three carats; that which contains 2/24 of
alloy is but twenty-two carats; and so on. Silver again is supposed to be
divided into twelve parts only, which are called penny-weights: so that
when absolutely pure it is said to be twelve penny-weights fine; when it
contains 1/12 of alloy, it is then called eleven penny-weights fine; when it
contains 2/12 of alloy, it is called ten penny-weights fine, and so on.
In treating of Copper we promised to shew, under the article of Lead, how
to separate it from Iron. The process is founded on that property of Lead
which renders it incapable of mixing and uniting with Iron, though it readily
dissolves all other metalline substances. Therefore, if you have a mass
compounded of Copper and Iron, it must be fused with a certain quantity of
Lead, and then the Copper, having a greater affinity with Lead than with
Iron, will desert the latter and join the former, which being incapable of any
union with Iron, as was said, will wholly exclude it from the new
compound. The next point is to separate the Lead from the Copper; which is
done by exposing the mass compounded of these two metals to a degree of
fire strong enough to deprive the Lead of its metalline form, but too weak to
have the same effect on the Copper: and this may be done; since, of all the
imperfect metals, Lead is, next to Tin, the easiest to be calcined, and Copper
on the contrary resists the greatest force of fire longest, without losing its
metalline form. Now what we gain by this exchange, viz. by separating
Copper from Iron and uniting it with Lead, consists in this, that as Lead is
calcined with less fire than Iron, the Copper is less exposed to be destroyed:
for it must be observed that, however moderate the fire be, it is hardly
possible to prevent a certain quantity thereof from being calcined in the
operation.

Lead melted with a third part of Tin forms a compound, which being
exposed to a fire capable of making it thoroughly red-hot, swells, puffs up,
seems in some sort to take fire, and is presently calcined. These two metals
mixed together are much sooner calcined than either of them separately.
Both Lead and Tin are in some measure affected by water, and by a moist
air; but they are both much less subject than Iron or Copper to be corroded
by these solvents, and of course are much less liable to rust.
The vitriolic acid acts upon and dissolves Lead, much in the same manner
as it doth Silver.
The nitrous acid dissolves this metal with much ease, and in great
quantities; and from this solution a small portion of Mercury may be
obtained. On this subject see our Elements of the Practice of Chymistry.
When this solution of Lead is diluted with a good deal of water, the Lead
precipitates in the form of a white powder; which happens because the acid
is rendered too weak to keep the Lead dissolved.
If this solution of Lead be evaporated to a certain degree, it shoots into
crystals formed like regular pyramids with square bases. These crystals are
of a yellowish colour, and a saccharine taste: they do not easily dissolve in
water. This nitrous metalline salt has the singular property of detonating in a
crucible, without any additament, or the contact of any other inflammable
substance. This property it derives from the great quantity of phlogiston
contained in, and but loosely connected with, the Lead which is one of its
principles.
If spirit of salt, or even sea-salt in substance, be added to a solution of Lead
in the nitrous acid, a white precipitate immediately falls; which is no other
than the Lead united with the marine acid. This precipitate is extremely like
the precipitate of Silver made in the same manner, and that being called
Luna cornea hath occasioned this to be named Plumbum corneum. Like the
luna cornea it is very fusible, and being melted hardens like it into a kind of
horny substance: it is volatile, and may be reduced by means of
inflammable matters combined with alkalis. But it differs from the luna
cornea in this chiefly, that it dissolves easily in water; whereas the luna

cornea, on the contrary, dissolves therein with great difficulty, and in a very
small quantity.
As this precipitation of Lead from its solution in spirit of nitre is procured
by the marine acid, Lead is thereby proved to have a greater affinity with
the latter acid than with the former. Yet, if you attempt to dissolve Lead
directly by the acid of sea-salt, the solution is not so easily effected as by
the spirit of nitre, and it is always imperfect; for it wants one of the
conditions essential to every solution in a liquor, namely transparency.
If Lead be boiled for a long time in a lixivium of fixed alkali, part of it will
be dissolved.
Sulphur renders this metal refractory and scarce fusible; and the mass they
form when united together is friable. Hence it appears that sulphur acts
upon Lead much in the same manner as upon Tin; that is, it renders both
these metals less fusible, which are naturally the most fusible of any, while
it exceedingly facilitates the fusion of Silver, Copper, and Iron, metals
which of themselves flow with the greatest difficulty.

CHAP. VIII.

Of Quick-Silver.
treat of Quick-silver in a chapter apart, because this metallic
W
e
substance cannot be classed with the metals properly so called, and
yet has some properties which will not allow us to confound it with
the semi-metals. The reason why Quick-silver, by the Chymists commonly
called Mercury, is not reputed a metal, is, that it wants one of the essential
properties thereof, to wit, malleability. When it is pure and unadulterated
with any mixture, it is always fluid, and of course unmalleable. But as, on
the other hand, it eminently possesses the opacity, the splendour, and, above
all, the gravity of a metal, being next to Gold the heaviest of all bodies, it
may be considered as a true metal, differing from the rest no otherwise than
by being constantly in fusion; which we may suppose arises from its
aptness to flow with such a small degree of heat, that be there ever so little
warmth on earth, there is still more than enough to keep Mercury in fusion;
which would become solid and malleable if it were possible to apply to it a
degree of cold considerable enough for that purpose. These properties will
not allow us to confound it with the semi-metals. Add, that we are not yet
assured by any undoubted experiment that it can be wholly deprived of its
phlogiston, as the imperfect metals may. Indeed we cannot apply the force
of fire to it as could be wished: for it is so volatile that it flies off and
exhales in vapours, with a much less degree of fire than is necessary to
make it red-hot. The vapours of Mercury thus raised by the action of fire,
being collected and united in a certain quantity, appear to be no other than
true Mercury, retaining every one of its properties; and no experiment hath
ever been able to shew the least change thus produced in its nature.
If Mercury be exposed to the greatest heat that it can bear without
sublimation, and continued in it for several months, or even a whole year
together, it turns to a red powder, which the Chymists call Mercurius
Præcipitatus per se. But, to succeed in this operation, it is absolutely
necessary that the heat be such as is above-specified; for this metallic
substance may remain exposed to a weaker heat for a considerable number
of years, without undergoing any sensible alteration.

Some Chymists fancied, that by this operation they had fixed Mercury and
changed its nature; but without any reason: for if the Mercury thus
seemingly transmuted be exposed to a somewhat stronger degree of fire, it
sublimes and exhales in vapours as usual; and those vapours collected are
nothing else but running Mercury, which has recovered all its properties
without the help of any additament.
Mercury has the property of dissolving all the metals, Iron only excepted.
But it is a condition absolutely necessary to the success of such dissolution,
that the metalline substances be possessed of their phlogiston; for if they be
calcined, Mercury cannot touch them: and hence it follows, that Mercury
doth not unite with substances that are purely earthy. Such a combination of
a metal with Mercury is called an Amalgam. Trituration alone is sufficient
to effect it; however, a proper degree of heat also is of use.
Mercury amalgamated with a metal gives it a consistence more or less soft,
and even fluid, according to the greater or smaller proportion of Mercury
employed. All amalgams are softened by heat, and hardened by cold.
Mercury is very volatile; vastly more so than the most unfixed metals;
moreover, the union it contracts with any metal is not sufficiently intimate
to entitle the new compound resulting from that union to all the properties
of the two substances united: at least with regard to their degree of fixity
and volatility. From all which it follows, that the best and surest method of
separating it from metals dissolved by it, is to expose the amalgam to a
degree of heat sufficient to make all the Quick-silver rise and evaporate;
after which the metal remains in the form of a powder, and being fused
recovers its malleability. If it be thought proper to save the Quick-silver, the
operation must be performed in close vessels, which will confine and
collect the mercurial vapours. This operation is most frequently employed
to separate Gold and Silver from the several sorts of earths and sands with
which they are mixed in the ore; because these two metals, Gold especially,
are of sufficient value to compensate the loss of Mercury, which is
inevitable in this process: besides, as they very readily amalgamate with it,
this way of separating them from every thing unmetallic is very facile and
commodious.

Mercury is dissolved by acids; but with circumstances peculiar to each
particular sort of acid.
The vitriolic acid, concentrated and made boiling hot, seizes on it, and
presently reduces it to a kind of white powder, which turns yellow by the
affusion of water, but does not dissolve in it; it is called Turbith Mineral.
However, the vitriolic acid on this occasion unites with a great part of the
Mercury, in such a manner that the compound is soluble in water. For if to
the water which was used to wash the Turbith a fixed alkali be added, there
falls instantly a russet-coloured precipitate, which is no other than Mercury
separated from the vitriolic acid by the intervention of the alkali.
This dissolution of Mercury by the vitriolic acid is accompanied with a very
remarkable phenomenon; which is, that the acid contracts a strong smell of
volatile spirit of sulphur: a notable proof that part of the phlogiston of the
Mercury hath united therewith. And yet, if the Mercury be separated by
means of a fixed alkali, it does not appear to have suffered any alteration.
Turbith mineral is not so volatile as pure Mercury.
The nitrous acid dissolves Mercury with ease. The solution is limpid and
transparent, and as it grows cold shoots into crystals, which are a nitrous
mercurial salt.
If this solution be evaporated to dryness, the Mercury remains impregnated
with a little of the acid, under the form of a red powder, which hath
obtained the names of Red Precipitate, and Arcanum Corallinum. This
Precipitate, as well as Turbith, is less volatile than pure Mercury.
If this solution of Mercury be mixed with a solution of Copper, made
likewise in the nitrous acid, and the mixture evaporated to dryness, there
will remain a green powder called Green Precipitate. These precipitates are
caustic and corrosive; and are used as such in surgery.
Though Mercury be dissolved more easily and completely by the nitrous
acid than by the vitriolic, yet it has a greater affinity with the latter than
with the former: for if a vitriolic acid be poured into a solution of Mercury
in spirit of nitre, the Mercury will quit the latter acid in which it was
dissolved, and join the other which was added. The same thing happens
when the marine acid is employed instead of the vitriolic.

Mercury combined with spirit of salt forms a singular body; a metalline salt
which shoots into long crystals, pointed like daggers. This salt is volatile,
and sublimes easily without decomposition. It is moreover the most violent
of all the corrosives hitherto discovered by Chymistry. It is called Corrosive
Sublimate, because it must absolutely be sublimed to make the combination
perfect. There are several ways of doing this: but the operation will never
fail, if the Mercury be rarefied into vapours, and meet with the marine acid
in a similar state.
Corrosive Sublimate is dissolved by water, but in very small quantities only.
It is decompounded by fixed alkalis, which precipitate the Mercury in a
reddish yellow powder, called, on account of its colour, Yellow Precipitate.
If Corrosive Sublimate be mixed with tin, and the compound distilled, a
liquor comes over which continually emits abundance of dense fumes, and,
from the name of its inventor, is called the Smoking Liquor of Libavius.
This liquor is no other than the tin combined with the marine acid of the
Corrosive Sublimate, which therefore it hath actually decompounded:
whence it follows, that this acid hath a greater affinity with tin than with
Mercury.
The marine acid in Corrosive Sublimate is not quite saturated with
Mercury; but is capable of taking up a much greater quantity thereof. For if
Corrosive Sublimate be mixed with fresh Mercury, and sublimed a second
time, another compound will be produced containing much more Mercury,
and less acrimonious; for which reason it is named Sweet Sublimate of
Mercury, Mercurius dulcis, Aquila alba. This compound may be taken
internally, and is purgative or emetic according to the dose administered. It
may be rendered still more gentle by repeated sublimations, and then it
takes the title of Panacea Mercurialis. No way hath hitherto been found to
dissolve Mercury in aqua regis without great difficulty, and even then it is
but imperfectly dissolved.
Mercury unites easily and intimately with sulphur. If these two substances
be only rubbed together in a gentle heat, or even without any heat, they will
contract an union, though but an incomplete one. This combination takes
the form of a black powder, which has procured it the name of Æthiops
Mineral.

If a more intimate and perfect union be desired, this compound must be
exposed to a stronger heat; and then a red ponderous substance will be
sublimed, appearing like a mass of shining needles: this is the combination
desired, and is called Cinabar. In this form chiefly is Mercury found in the
bowels of the earth. Cinabar finely levigated acquires a much brighter red
colour, and is known to painters by the name of Vermilion.
Cinabar rises wholly by sublimation, without suffering any decomposition;
because the two substances of which it consists, viz. Mercury and Sulphur,
are both volatile.
Though Mercury unites and combines very well with sulphur, as hath been
said, yet it hath less affinity with that mineral than any other metal, Gold
only excepted: whence it follows, that any of the other metals will
decompound Cinabar, by uniting with its sulphur, and so setting the
Mercury at liberty to appear in its usual form. Mercury thus separated from
sulphur is esteemed the purest, and bears the name of Mercury revivified
from Cinabar.
Iron is generally used in this operation, preferably to the other metals,
because among them all it has the greatest affinity with sulphur, and is the
only one that has none with Mercury.
Cinabar may also be decompounded by means of fixed alkalis; the affinity
of these salts with sulphur being generally greater than that of any metalline
substance whatever.

CHAP. IX.

Of the Semi-Metals.

SECTION I.

Of Regulus of Antimony.
egulus of Antimony is a metallic substance of a pretty bright white

R colour. It has the splendour, opacity, and gravity of a metal: but it is
quite unmalleable, and crumbles to dust, instead of yielding or
stretching, under the hammer; on which account it is classed with the Semi-
metals.
It begins to flow as soon as it is moderately red; but, like the other Semi-
metals, it cannot stand a violent degree of fire; being thereby dissipated into
smoke and white vapours, which adhere to such cold bodies as they meet
with, and so are collected into a kind of farina called Flowers of Antimony.
If Regulus of Antimony, instead of being exposed to a strong fire, be only
heated so moderately that it shall not even melt, it will calcine, lose its
phlogiston, and take the form of a greyish powder destitute of all splendour:
this powder is called Calx of Antimony.
This calx is not volatile like the Regulus, but will endure a very violent fire;
and being exposed thereto will flow, and turn to a glass of the yellowish
colour of a hyacinth.
It is to be observed, that the more the Regulus is deprived of its phlogiston
by continued calcination, the more refractory is the calx obtained from it.
The glass thereof has also so much the less colour, and comes the nearer to
common glass.
The calx and the Glass of Antimony will recover their metalline form, like
every other Calx and Glass of a metal, if reduced by restoring to them their
lost phlogiston. Yet if the calcination be carried too far, their reduction will
become much more difficult, and a much smaller quantity of Regulus will
be resuscitated.

Regulus of Antimony is capable of dissolving the metals: but its affinities
with them are various, and differ according to the following order. It affects
Iron the most powerfully, next Copper, then Tin, Lead, and Silver. It
promotes the fusion of metals, but makes them all brittle and unmalleable.
It will not amalgamate with Mercury; and though by certain processes,
particularly the addition of water and continued trituration, a sort of union
between these two substances may be produced, yet it is but apparent and
momentary; for, being left to themselves and undisturbed, they quickly
disunite and separate[2].
The vitriolic acid, assisted by heat, and even by distillation, dissolves
Regulus of Antimony. The nitrous acid likewise attacks it: but the solution
can by no art be made clear and limpid: so that the Regulus is only calcined,
in a manner, by this acid.
The marine acid dissolves it well enough; but then it must be exceedingly
concentrated, and applied in a peculiar manner, and especially by
distillation. One of the best methods of procuring a perfect union between
the acid of sea-salt and Regulus of Antimony, is to pulverize the latter, mix
it with corrosive sublimate, and distil the whole. There rises in the operation
a white matter, thick, and scarce fluid, which is no other than the Regulus of
Antimony united and combined with the acid of sea-salt. This compound is
extremely corrosive, and is called Butter of Antimony.
It is plain that the corrosive sublimate is here decompounded; that the
Mercury is revivified, and that the acid which was combined therewith hath
quitted it to join the Regulus of Antimony, with which its affinity is greater.
This Butter of Antimony by repeated distillations acquires a considerable
degree of fluidity and limpidness.
If the acid of nitre be mixed with Butter of Antimony, and the whole
distilled, there rises an acid liquor, or a sort of aqua regis, which still retains
some of the dissolved Regulus, and is called Bezoardic Spirit of Nitre. After
the distillation there remains a white matter, from which fresh spirit of nitre
is again abstracted, and which being then washed with water is called
Bezoar Mineral. This Bezoar Mineral is neither so volatile nor so caustic as
Butter of Antimony; because the nitrous acid hath not the property of

volatilizing metallic substances, as the marine acid does, and because it
remains much more intimately combined with the reguline part.
If Butter of Antimony be mixed with water, the liquor immediately becomes
turbid and milky, and a precipitate falls, which is nothing but the metallic
matter partly separated from its acid, which is too much weakened by the
addition of water to keep it dissolved. Yet this precipitate still retains a good
deal of acid; for which reason it continues to be a violent emetic, and in
some degree corrosive. It hath therefore been very improperly called
Mercurius Vitæ.
The proper solvent of Regulus of Antimony is aqua regis; by means
whereof a clear and limpid solution of this Semi-metal may be obtained.
Regulus of Antimony mixed with nitre, and projected into a red-hot
crucible, sets the nitre in a flame, and makes it detonate. As it produces this
effect by means of its phlogiston, it must needs at the same time be
calcined, and lose its metallic properties, which accordingly happens, and
when the nitre is in a triple proportion to the Regulus, the latter is so
perfectly calcined as to leave only a white powder, which is fused with
great difficulty, and then turns to a faintly coloured glass, not very different
from common glass, and which is not reducible to a Regulus by the addition
of inflammable matter; at least it yields but a very small quantity thereof. If
less nitre be used, the calx is not so white; the glass it produces is more like
a metalline glass, and is more easily reduced. The calx of the Regulus thus
prepared by nitre is called, on account of the medicinal virtue ascribed to it,
Diaphoretic Antimony, or Diaphoretic Mineral.
Nitre always becomes an alkali by deflagration, and in the present case
retains part of the calx, which it even renders soluble in water. This calx
may be separated from the alkali, if an acid be employed to precipitate it;
and then it is called Materia Perlata. This pearly matter is a calx of
Antimony, so completely deprived of its phlogiston as to be altogether
incapable of reduction to a Regulus.
Regulus of Antimony readily joins and unites with sulphur, forming
therewith a compound which has a very faint metallic splendour. This
compound appears like a mass of long needles adhering together laterally;
and under this form it is usually found in the ore, or at least when only

separated by fusion from the stones and earthy matters with which the ore is
mixed. It is called Crude Antimony.
Antimony flows with a moderate heat, and becomes even more fluid than
other metallic substances. The action of fire dissipates or consumes the
sulphur it contains, and its phlogiston also, so as to convert it into a calx and
a glass, as it does the Regulus.
Aqua regis, which we observed to be the proper solvent of the Regulus,
being poured on Antimony, attacks and dissolves the reguline part, but
touches not the sulphur; in consequence whereof it decomposes the
Antimony, and separates its sulphur from its Regulus.
There are several other ways of effecting this decomposition, and obtaining
the reguline part of Antimony by itself: they consist either in destroying the
sulphureous part of the Antimony by combustion, or in melting the
Antimony with some substance which has a greater affinity than its reguline
part with sulphur. Most metals are very fit for this latter purpose: for though
the Regulus has a considerable affinity with sulphur, yet all the metals,
except Gold and Mercury, have a greater.
If therefore Iron, Copper, Lead, Silver, or Tin, be melted with Antimony, the
metal employed will unite with the sulphur, and separate it from the
Regulus.
It must be observed, that, as these metals have some affinity with the
Regulus of Antimony, the Regulus will be joined in the operation by some
of the metal employed as a Precipitant, (so those substances are called
which serve as the means of separating two bodies from each other); and
therefore the Regulus procured in this manner will not be absolutely pure:
on this account care is taken to distinguish each by adding the name of the
metal employed in its precipitation; and thence come these titles, Martial
Regulus of Antimony, or only Martial Regulus, Regulus Veneris; and so of
the rest.
Antimony is employed with advantage to separate Gold from all the other
metals with which it may be alloyed. It has been shewn, that all the metals
have a greater affinity than the reguline part of Antimony with sulphur,
Gold only excepted; which is incapable of contracting any union therewith:

and therefore, if a mass compounded of Gold and several other metals be
melted with Antimony, every thing in that mass which is not Gold will unite
with the sulphur of the Antimony. This union occasions two separations, to
wit, that of the sulphur of the Antimony from its reguline part, and that of
the Gold from the metals with which it was adulterated; and from the whole
two new compounds arise; namely, a combination of the metals with the
sulphur, which being lightest rises to the surface in fusion; and a metalline
mass, formed of the Gold and the reguline part of the Antimony united
together, which being much the heaviest sinks to the bottom. There is no
difficulty in parting the Gold from the Regulus of Antimony with which it is
alloyed: for the metalline mass needs only be exposed to a degree of fire
capable of dissipating into vapours all the Semi-metal it contains; which
being very volatile, the operation is much easier, and more expeditiously
finished, than if the metals with which the Gold was debased were to be
vitrified on the cupel; without taking into the account, that, if Silver were
one of them, recourse must needs be had to the process of quartation after
that of the cupel.
If equal parts of nitre and Antimony be mixed together, and the mixture
exposed to the action of fire, a violent detonation ensues; the nitre
deflagrating consumes the sulphur of the Antimony, and even a part of its
phlogiston. After the detonation there remains a greyish matter which
contains fixed nitre, vitriolated tartar, and the reguline part of the Antimony
in some measure deprived of its phlogiston, and half vitrified by the action
of the fire, which is considerably increased by the deflagration. This matter
is called Liver of Antimony.
If, instead of equal parts of nitre and Antimony, two parts of the former be
used to one of the latter, then the reguline part loses much more of its
phlogiston, and remains in the form of a yellowish powder.
Again, if three parts of nitre be taken to one of Antimony, the Regulus is
thereby entirely robbed of its phlogiston, and converted to a white calx,
which bears the name of Diaphoretic Antimony, or Diaphoretic Mineral.
The pearly matter may be precipitated by pouring an acid on the saline
substances which here remain after the detonation, in the same manner as
we shewed above was to be done with regard to the Regulus.

In the two last operations, where the nitre is in a double or triple proportion
to the Antimony, the reguline part is found after the detonation to be
converted into a calx, and not into a half-vitrified matter, which we have
seen is the effect when equal parts only of nitre and Antimony are used. The
reason of this difference is, that in these two cases the reguline part, being
wholly, or almost wholly, deprived of its phlogiston, becomes, as was
observed, more difficult to fuse, and consequently cannot begin to vitrify in
the same degree of heat as that which hath not lost so much of its
phlogiston. If, instead of performing the operation with equal parts of nitre
and Antimony alone, a portion of some substance which abounds with
phlogiston be added, in that case the sulphur only of the Antimony will be
consumed, and the Regulus will remain united with its phlogiston and
separated from its sulphur.
The Regulus prepared in this manner is absolutely pure, because no
metalline substance being employed, none can mix with and adulterate it. It
is called Regulus of Antimony per se, or only Regulus of Antimony.
It is true indeed that in this operation much of the reguline part unavoidably
loses its phlogiston and is calcined, and consequently a much smaller
quantity of Regulus is obtained than when metalline precipitants are
employed: but this loss is easily repaired, if it be thought proper, by
restoring to the calcined part its lost phlogiston.
Antimony melted with two parts of fixed alkali yields no Regulus, but is
entirely dissolved by the salt, and forms with it a mass of a reddish yellow
colour.
The reason why no precipitate is produced on this occasion is, that the
alkali uniting with the sulphur of the Antimony forms therewith the
combination called Liver of Sulphur, which by its nature is qualified to
keep the reguline part dissolved. This mass formed by the union of the
Antimony with the alkali is soluble in water. If any acid whatever be dropt
into this solution, there falls a precipitate of a reddish yellow colour;
because the acid unites with the alkali, and forces it to quit the matters with
which it was combined. This precipitate is called Golden Sulphur of
Antimony.

As in the operation for preparing Regulus of Antimony per se, some of the
nitre is, by the inflammable matters added thereto, turned to an alkali, this
alkali seizes on part of the Antimony, and therewith forms a compound like
that just described. Hence it comes, that if the scoria formed in this process
be dissolved in water, and an acid dropped into the solution, a true golden
sulphur of Antimony is thereby separated.
This union of Antimony with an alkali may also be brought about by the
humid way; that is, by making use of an alkali resolved into a liquor, and
boiling the mineral in it. The alkaline liquor, in proportion as it acts upon
the Antimony, gradually becomes reddish and turbid. If left to settle and
cool when well saturated therewith, it gradually deposites the Antimony it
had taken up, which precipitates in the form of a red powder; and this
precipitate is the celebrated remedy known by the name of Kermes Mineral.
It is plain that the kermes is nearly the same thing with the golden sulphur:
yet it differs from it in some respects; and especially in this, that being
taken inwardly it operates much more gently than the golden sulphur, which
is a violent emetic. Nitre fixed by charcoal, and resolved into a liquor, is the
only alkali employed in preparing the kermes.
It was shewn above, that Regulus of Antimony mixed and distilled with
corrosive sublimate decompounds it, disengages the Mercury, and joining
itself to the marine acid forms therewith a new combination, called Butter
of Antimony. If the same operation be performed with crude Antimony
instead of its Regulus, the same effects are produced: but then the Antimony
itself is also decomposed; that is, the reguline part is separated from the
sulphur, which being set free unites with the Mercury, now also at liberty,
and these two together form a true cinabar, called Cinabar of Antimony.

SECTION II.

Of Bismuth.
Bismuth, known also by the name of Tin-glass, is a semi-metal, having
almost the same appearance as Regulus of Antimony; yet it has a more
dusky cast, inclining somewhat to red, and even presents some changeable
streaks, especially after lying long in the air.

When exposed to the fire it melts long before it is red, and consequently
with less heat than Regulus of Antimony, which does not flow, as was
shewn above, till it begin to be red-hot. It becomes volatile, like all the
other semi-metals, when acted on by a violent fire: being kept in fusion by a
proper degree of heat it loses its phlogiston with its metallic form, and turns
to a powder or a calx; and that again is converted into glass by the
continued action of fire. The calx and glass of Bismuth may be reduced,
like any other metallic calx, by restoring their phlogiston.
Bismuth mixes with all the metals in fusion, and even facilitates the fusion
of such as do not otherwise flow readily. It whitens them by its union, and
destroys their malleability.
It amalgamates with Mercury, if they be rubbed together with the addition
of water: yet after some time these two metalline substances desert each
other, and the Bismuth appears again in the form of a powder. Hence it is
plain, that the union it contracts with Mercury is not perfect; and yet it has
the singular property of attenuating Lead, and altering it in such a manner
that it afterwards amalgamates with Mercury much more perfectly, so as
even to pass with it through shamoy leather without any separation. The
Bismuth employed in making this amalgama afterwards separates from it
spontaneously, as usual; but the Lead still continues united with the
Mercury, and always retains the property thus acquired.
The vitriolic acid does not dissolve Bismuth: its proper solvent is the
nitrous acid, which dissolves it with violence, and abundance of fumes.
Bismuth dissolved in the nitrous acid is precipitated not only by alkalis, but
even by the bare addition of water. This precipitate is extremely white, and
known by the name of Magistery of Bismuth.
The acid of sea-salt and aqua regis likewise act upon Bismuth, but with less
violence.
This semi-metal does not sensibly deflagrate with nitre; yet it is quickly
deprived of its phlogiston, and turned into a vitrifiable calx, when exposed
with it to the action of fire.
It readily unites with sulphur in fusion, and forms therewith a compound
which appears to consist of needles adhering laterally to each other.

It may be separated from the sulphur with which is combined, by only
exposing it to the fire, without any additament; for the sulphur is either
consumed or sublimed, and leaves the Bismuth behind.

SECTION III.

Of Zinc.
Zinc to appearance differs but little from Bismuth, and has even been
confounded with it by several authors. Nevertheless, besides that it has
something of a blueish cast, and is harder than Bismuth, it differs from it
essentially in its properties, as will presently be shewn. These two metallic
substances scarce resemble each other in any thing, but the qualities
common to all semi-metals.
Zinc melts the moment it grows red in the fire, and then also begins to turn
to a calx, which, like any other metallic calx, may be reduced by means of
the phlogiston: but if the fire be considerably increased, it sublimes, flames,
and burns like an oily matter; which is a proof of the great quantity of
phlogiston in its composition. At the same time abundance of flowers rise
from it in the form of white flakes, flying about in the air like very light
bodies; and into this form may the whole substance of the Zinc be
converted. Several names have been given to these flowers, such as
Pompholyx, Philosophic Wool. They are supposed to be no other than the
Zinc itself deprived of its phlogiston; yet no body has hitherto been able to
resuscitate them in the form of Zinc, by restoring their phlogiston according
to the methods used in the reduction of metals. Though they rise in the air
with very great ease while the Zinc is calcining, yet when once formed they
are very fixed; for they withstand the utmost violence of fire, and are
capable of being vitrified, especially if joined with a fixed alkali. They are
soluble in acids.
Zinc unites with all metalline substances, except Bismuth. It has this
singular property, that being mixed with Copper, even in a considerable
quantity, such as a fourth part, it does not greatly lessen the ductility
thereof, and at the same time communicates to it a very beautiful colour not
unlike that of Gold: on which account the composition is frequently made,
and produces what is called Brass. This metal melts much more easily than

Copper alone, because of the Zinc with which it is alloyed. If it be exposed
to a great degree of heat, the Zinc which it contains takes fire, and sublimes
in white flowers, just as when it is pure.
It is to be observed, that Brass is ductile only while it is cold, and not then,
unless the Zinc used in making it was very pure; otherwise the composition
will prove but a Tombac or Prince's Metal, having very little malleability.
Zinc is very volatile, and carries off with it any metallic substance with
which it is fused, making a kind of sublimate thereof. In the furnaces where
they smelt ores containing Zinc, the matter thus sublimed is called Cadmia
Fornacum, to distinguish it from the native Cadmia called also Calamine,
or Lapis Calaminaris; which, properly speaking, is an ore of Zinc,
containing a great deal of that semi-metal, together with some Iron, and a
stony substance. The name of Cadmia Fornacum is not appropriated solely
to the metallic sublimates procured by means of Zinc, but is given in
general to all the metallic sublimates found in smelting houses.
If a violent and sudden heat be applied to Zinc, it sublimes in its metalline
form; there not being time for it to burn and be resolved into flowers.
This semi-metal is soluble in all the acids, but especially in spirit of nitre,
which attacks and dissolves it with very great violence.
Zinc has a greater affinity than iron or copper with the vitriolic acid; and
therefore it decompounds the green and blue vitriols, precipitating those
two metals by uniting with the vitriolic acid, with which it forms a metallic
salt, or vitriol, called White Vitriol, or Vitriol of Zinc.
Nitre mixed with Zinc, and projected into a red-hot crucible, detonates with
violence, and during the detonation there rises a great quantity of white
flowers, like those which appear when it is calcined by itself.
Sulphur has no power over Zinc. Even liver of sulphur, which dissolves all
other metallic substances, contracts no union with this semi-metal.
Messrs. Hellot and Malouin have bestowed a great deal of pains on this
semi-metal. An account of their experiments is to be found in the Memoirs
of the Academy of Sciences.

SECTION IV.

Of Regulus of Arsenic.
Regulus of Arsenic is the most volatile of all the semi-metals. A very
moderate heat makes it wholly evaporate, and fly off in fumes; on which
account it cannot be brought to fusion, nor can any considerable masses
thereof be obtained. It has a metallic colour, somewhat resembling Lead;
but it soon loses its splendour when exposed to the air.
It unites readily enough with metallic substances, having the same affinities
with them as Regulus of Antimony hath. It makes them brittle, and
unmalleable. It hath also the property of rendering them volatile, and
greatly facilitates their scorification.
It very easily parts with its phlogiston and its metallic form. When exposed
to the fire it rises in a kind of shining crystalline calx, which, on that
account, looks more like a saline matter than a metallic calx. To this calx or
these flowers are given the names of White Arsenic, Crystalline Arsenic,
and most commonly plain Arsenic.
The properties of this substance are very singular, and extremely different
from those of any other metallic calx. Hitherto it hath been but little
examined; and this led me to make some attempts towards discovering its
nature, which may be seen in the Memoirs of the Academy of Sciences.
Arsenic differs from every other metalline calx, first, in being volatile;
whereas the calces of all other metallic substances, not excepting those of
the most volatile semi-metals, such as Regulus of Antimony and Zinc, are
exceeding fixed; and, secondly, in having a saline character, which is not
found in any other metalline calx.
The saline character of Arsenic appears, first, from its being soluble in
water; secondly, from its corrosive quality, which makes it one of the most
violent poisons: a quality from which the other metallic substances are free,
when they are not combined with some saline matter. Regulus of Antimony
must however be excepted. But then the best Chymists agree that this semi-
metal is either nearly of the same nature with Arsenic, or contains a portion
thereof in its composition: besides, its noxious qualities never discover

themselves so plainly as when it is combined with some acid. Lastly,
Arsenic acts just like the vitriolic acid upon nitre; that is, it decompounds
that neutral salt, by expelling its acid from its alkaline basis, of which it
takes possession, and therewith forms a new saline compound.
This combination is a species of salt that is perfectly neutral. When the
operation is performed in a close vessel, the salt shoots into crystals in the
form of right-angled quadrangular prisms, terminated at each extremity by
pyramids that are also quadrangular and right angled; some of which
however, instead of ending in a point, are obtuse as if truncated. The
consequence is different when the operation is performed in an open vessel;
for then nothing is obtained but an alkaline salt impregnated with Arsenic,
which cannot be crystallized.
The cause of this different effect is, that, when the Arsenic is once engaged
in the alkaline basis of the nitre, it can never be separated from it by the
utmost force of fire, so long as it is kept in a close vessel; whereas, if you
expose it to the fire without that precaution, it readily separates from it. This
property of arsenic was never before observed by any Chymist, and
therefore this our new species of Neutral arsenical salt was absolutely
unknown till lately.
This new salt possesses many singular properties, the chief of which are
these. First, it cannot be decompounded by the intervention of any acid,
even the strongest acid of vitriol; and this, joined to its property of expelling
the nitrous acid from its basis, shews that it has a very great affinity with
fixed alkalis.
Secondly, this very salt, on which pure acids have no effect, is
decompounded with the greatest ease by acids united with metallic
substances. The reason of this phenomenon is curious, and furnishes us with
an instance of what we advanced concerning double affinities.
If to a resolution of any metallic substance whatever, made by any acid
whatever, (except that of Mercury by the marine acid, and that of Gold by
aqua regis), a certain quantity of our New Salt dissolved in water be added,
the metallic substance is instantaneously separated from the acid in which it
was dissolved, and falls to the bottom of the liquor.

All metallic precipitates obtained in this manner are found to be a
combination of the metal with Arsenic; whence it necessarily follows that
the new Neutral Salt is by this means decompounded, its arsenical part
uniting with the metallic substance, and its alkaline basis with the acid in
which that substance was dissolved.
The affinities of these several bodies must be considered as operating on
this occasion in the following manner: The acids which tend to
decompound the Neutral Salt of Arsenic, by virtue of their affinity with its
alkaline basis, are not able to accomplish it, because this affinity is
powerfully counteracted by that which the Arsenic has with the same
alkaline basis, and which is equal or even superior to theirs. But if these
acids happen to be united with a substance which naturally has a very great
affinity with the arsenical part of the Neutral Salt, then, the two parts of
which this Salt consists being drawn different ways by two several affinities
tending to separate them from each other, the Salt will undergo a
decomposition, which could not have been effected without the help of this
second affinity. Now, as metallic substances have a great affinity with
Arsenic, it is not surprising that the Neutral Salt of Arsenic, which cannot
be decompounded by a pure acid, should nevertheless yield to an acid
combined with a metal. The decomposition of this Salt, therefore, and the
precipitation which of course it produces in metallic solutions, are brought
about by the means of a double affinity; namely, that of the acid with the
alkaline basis of the Neutral Salt, and that of the metal with the arsenical
part of that salt.
Arsenic has not the same effect on sea-salt as on nitre, and cannot expel its
acid: a very singular phenomenon, for which it is hard to assign a reason;
for the nitrous acid is known to have a greater affinity than the marine acid
with alkalis, and even with the basis of sea-salt itself.
Yet Arsenic may be combined with the basis of sea-salt, and a Neutral Salt
thereby obtained, like that which results from the decomposition of nitre by
Arsenic: but for that purpose a quadrangular nitre must be first prepared,
and Arsenic applied thereto as to common nitre.
The Salt produced by uniting Arsenic with the basis of sea-salt very much
resembles the Neutral Salt of Arsenic above treated of as well in the figure

of its crystals as in its several properties.
Arsenic presents another singular phenomenon, both with the alkali of nitre
and with that of sea-salt; which is, that if it be combined with these salts in
a fluid state, it forms with them a saline compound, quite different from the
Neutral Salts of Arsenic which result from the decomposition of nitrous
salts.
This saline compound, which I call Liver of Arsenic, takes up a much
greater quantity of Arsenic than is necessary for the perfect saturation of the
alkali. It has the appearance of a glue, which is so much the thicker the
more Arsenic it contains. Its smell is disagreeable; it attracts the moisture of
the air, and does not crystallize; it is easily decompounded by any acid
whatever, which precipitates the Arsenic and unites with the alkali. Lastly,
the effects it produces on metallic solutions are different from those of our
neutral arsenical salts. But the bounds which I have set myself in this
treatise will not allow me to be more particular. Such as have the curiosity
to inquire further into the subject may consult my Dissertations on Arsenic,
published among the Memoirs of the Academy of Sciences.
Arsenic is easily reduced to a Regulus. It need only be mixed with any
matter containing the phlogiston, and by the help of a moderate heat a true
Regulus will sublime. This Regulus, as was said, is very volatile, and
calcines with the greatest ease; which is the reason why it cannot be
obtained but in small quantities, and also why, in order to obtain masses of
it, some have thought of adding thereto some metal with which it has a
great affinity, such as Copper or Iron; because, by joining with the metal, it
is partly fixed and restrained from flying off. But it is plain the Regulus
obtained by this means is not pure, as it must partake considerably of the
metal employed.
Arsenic readily unites with sulphur, and rises with it in a yellow compound,
called Orpiment.
Sulphur cannot be separated from Arsenic but by the intervention of two
bodies only; to wit, a fixed alkali and Mercury.
The property which Mercury possesses of separating sulphur from Arsenic
is founded on this, that these two metallic substances are incapable of

contracting any union; whereas, though most of the other metals and semi-
metals have a greater affinity with sulphur than Mercury hath, as was shewn
in treating of the decomposition of Cinabar, nevertheless they are all unable
to decompound Orpiment; because some of them have as great an affinity
with Arsenic as with sulphur; others have no affinity with either; and lastly,
sulphur hath as great an affinity with Arsenic as with any of them.
It must be observed that, if fixed alkalis be employed to purify Arsenic in
this manner, no more must be used than is necessary to absorb the sulphur
or the phlogiston, of which also it is their nature to deprive Arsenic; for
otherwise, as it has been shewn that Arsenic readily unites with alkalis, they
would absorb a considerable quantity thereof.

CHAP. X.

Of Oil in general.
il is an unctuous body, which burns and consumes with flame and

O smoke, and is not soluble in water. It consists of the phlogiston united
with water by means of an acid. There is, moreover, in its composition
a certain proportion of earth, more or less, according to each several sort of
Oil.
The inflammability of Oil evidently proves that it contains the phlogiston.
That an acid is one of its constituent principles many experiments
demonstrate, of which these are the chief: If certain Oils be long triturated
with an alkaline salt, and the alkali afterwards dissolved in water, crystals of
a true neutral salt will be produced: some metals, and particularly Copper,
are corroded and rusted by Oils, just as they are by acids: again, acid
crystals are found in some Oils that have been long kept. This acid in Oil
serves undoubtedly to unite its phlogiston with its water; because these two
substances having no affinity with each other cannot be united without the
intervention of such a medium as an acid, which has an affinity with both.
As to the existence of water in Oils, it appears plainly when they are
decomposed by repeated distillations, especially after mixing them with
absorbent earths. Lastly, when an Oil is destroyed by burning, a certain
quantity of earth is constantly left behind.
We are very sure that the above-mentioned principles enter into the
composition of Oils; for they may be obtained from every one of them: but
it is not absolutely certain that they consist of these only, and that they do
not contain some other principle which may escape our notice in
decomposing them; for hitherto it doth not appear, by any experiment we
can depend on, that Oil was ever produced by combining together the
principles here specified: yet such redintegrations are the only means we
have of satisfying ourselves that we know all the principles which constitute
a body.
Oils exposed to the fire in close vessels pass over almost wholly from the
containing vessel into any other applied to receive them. There remains,

however, a small quantity of black matter, which is extremely fixed, and
continues unalterable as long as it hath no communication with the external
air, be the force of the fire ever so violent. This matter is no other than part
of the phlogiston of the Oil united with its most fixed and grossest earth;
and this is what we called Charcoal, or plainly a Coal.

SECTION I.

Of Charcoal.
When Oil happens to be united to much earth, as it is in vegetable and
animal bodies, it leaves a considerable quantity of Coal or charred matter.
This Coal, exposed to the fire in the open air, burns and wastes, but without
blazing like other combustible matters: there appears only a small blueish
flame, but not the least smoke. Most commonly it only glows and sparkles,
and so gradually falls into ashes, which are nothing but the earth of the
body, combined with an alkaline salt in burning. This alkaline salt may be
separated from the earth, by lixiviating the ashes with water, which
dissolves all the salt, and leaves the earth quite pure.
Charcoal is unalterable and indestructible by any other body but fire;
whence it follows, that when it is not actually kindled and ignited, the most
powerful agents, such as the acids, though ever so strong and concentrated,
have not the least effect on it.
The case is otherwise when it is lighted, that is, when its phlogiston begins
to separate from its earth; for then the pure acid of vitriol being joined
therewith, contracts an instantaneous union with its phlogiston, and
evaporates in a volatile sulphureous spirit. If the vitriolic acid, instead of
being applied quite pure, be first clogged with some basis, especially an
alkaline one, it quits that basis, enters into a more intimate union with the
phlogiston of the burning Coal, and so forms an actual sulphur, with which
the alkali now unites and forms a hepar.
The pure acid of sea-salt hath not been observed to act in the least upon
Charcoal, especially when it is not on fire. But when this acid is
incorporated with an alkaline or metallic basis, and combined according to

a peculiar process with burning Charcoal, it in like manner quits its basis,
unites with the phlogiston, and therewith forms a phosphorus, of which we
have already taken notice.
Nor has the pure nitrous acid any effect on a charred Coal, even when
ignited: and so far is it from being able to kindle a cold one, that when
poured on a live one, it extinguishes it like water. But when this acid is
united with a basis, it quits it rapidly as soon as it touches a burning coal,
and rushes violently into an union with the phlogiston thereof. From this
union there probably arises, as we said before, a kind of sulphur or
phosphorus, which is so inflammable as to be destroyed by the fire the very
moment it is generated.
The acids of nitre and vitriol act upon Oils; but very differently, according
to the quantity of phlegm they contain. If they be weakened with much
water, they have no effect at all upon Oils; if they contain little water, or be
dephlegmated to a certain degree, they dissolve them with heat, and with
them form compounds of a thick consistence. Acids, thus combined in a
considerable proportion with Oils, render them soluble in water.

SECTION II.

Of Soap.
Alkalis also have the same property. When an Oil is combined with an acid
or an alkali in such a manner, that the compound resulting from their union
is soluble in water; such a compound may in general be called a Soap. Soap
itself hath the property of rendering fat bodies in some measure soluble in
water; on which account it is very useful for scouring or cleansing any thing
greasy.
Oily and saline substances, combined together, observe the same general
rules as all other combinations; that is, they mutually communicate the
properties belonging to each: thus Oils, which naturally are not soluble in
water, acquire, by their union with saline matters, the property of dissolving
therein; and salts lose, by their conjunction with Oils, part of their natural
tendency to incorporate with water; so that, while they serve to constitute
soap, they do not, as before, attract the moisture of the air, &c. and, in like

manner, as they are not inflammable, they considerably lessen the
inflammability of the Oils combined with them.
Acid Soaps are decompounded by alkalis, as alkaline Soaps are by acids,
according to the general rules of affinities.
The acids of nitre and vitriol, when highly concentrated, dissolve Oils with
such violence as to heat them, make them black, burn them, and even set
them on fire. How sea-salt affects Oils is not yet sufficiently ascertained.
All Oils have the property of dissolving sulphur; which is not at all
surprising, seeing each of its component principles hath an affinity with Oil.
It is also a property common to all Oils to become more fluid, subtile, light,
and limpid, the oftener they are distilled. On the contrary, by being
incorporated with saline substances they acquire a greater consistence, and
sometimes form compounds that are most solid.

CHAP. XI.

Of the several Sorts of Oils.
ils are distinguished by the substances from which they are drawn: and
O as Oils are extracted from minerals, from vegetables, and from
animals, there are of course Mineral, Vegetable, and Animal Oils.

SECTION I.

Of Mineral Oils.
In the bowels of the earth we find but one sort of Oil, called Petroleum: its
smell is strong and not disagreeable, and its colour sometimes more
sometimes less yellow. There are certain mineral substances which yield by
distillation a great deal of Oil very like Petroleum. This sort of substance is
called a Bitumen, and is, indeed, nothing but an Oil rendered consistent and
solid by being combined with an acid; as appears from hence, that by
uniting Petroleum with the acid of vitriol we can produce an artificial
Bitumen very like the native.

SECTION II.

Of Vegetable Oils.
Vegetable substances yield a very great quantity and variety of oils: for
there is not a plant, or part of a plant, that does not contain one or more
sorts thereof, generally peculiar to itself, and different from all others.
By expression only, that is, by bruising and squeezing vegetable substances,
particularly certain fruits and seeds, a sort of oil is obtained which has
scarce any smell or taste. Oils of this sort are very mild and unctuous; and,
because in this respect they resemble animal fat more than the rest do, they
are called Fat Oils.
These Oils, being exposed to the air for some time, sooner or latter grow
thick, acquire an acrid taste, and a strong disagreeable smell. Some of them

congeal with the smallest degree of cold. This sort of Oil is well adapted to
dissolve those preparations of Lead called Litharge and Minium, with
which they form a thick tenacious substance, that is used for the basis of
almost all plasters. They also dissolve Lead in its metalline form; but not so
easily as the sorts of calx above-mentioned; probably because its body is
not so much opened, nor its parts so divided.
By expression alone we also procure from certain vegetable substances
another sort of Oil, which is thin, limpid, volatile, of a pungent taste, and
retains the smell of the vegetable that yielded it; on which account it is
called an Essential Oil. Of this there are several sorts, differing from one
another, like the Fat Oils, according to the subjects from which they are
obtained.
We must observe, that it is very difficult, or rather in most cases impossible,
to force from the greatest part of vegetables, by expression only, all the
essential Oil they contain. For this purpose therefore recourse must be had
to fire: a gentle heat, not exceeding that of boiling water, will extract all the
essential Oils of vegetables; and this is the most usual and most convenient
way of procuring them.
The fat Oils cannot be obtained by the same method: these being much less
volatile than the essential Oils, require a much greater degree of heat to
raise them; which nevertheless they cannot bear without being much
spoiled and entirely changed in their nature, as shall presently be shewn. All
Oils, therefore, which rise with the heat of boiling water, and such alone,
should be called Essential Oils.
Essential Oils, in a longer or shorter time, according to the nature of each,
lose the fragrant smell they had when newly distilled, and acquire another,
which is strong, rancid, and much less agreeable: they also lose their
tenuity, becoming thick and viscid; and in this state they greatly resemble
those substances abounding in Oil which flow from certain trees, and which
are called Balsams or Resins, according as they are less or more consistent.
Balsams and Resins are not soluble in water. But there are other Oily
compounds which likewise run from trees; and, though not unlike Resins,
are however soluble in water. These are called Gums; and their property of
dissolving in water arises from their containing more water and more salt

than Resins have; or at least their saline parts are less clogged and more
disengaged.
Balsams and Resins distilled with the heat of boiling water yield great
quantities of a limpid, subtile, odoriferous, and, in one word, essential Oil.
In the still there remains a substance thicker and more consistent than the
Balsam or Resin was before distillation. The same thing happens to
essential Oils which by length of time have acquired a consistence and are
grown resinous. If they be re-distilled, they recover their former tenuity,
leaving behind them a remainder thicker and more resinous than they
themselves were. This second distillation is called the Rectification of an
Oil.
It must be observed, that an essential Oil, combined with an acid strong
enough to dissolve it, immediately becomes as thick and resinous, in
consequence of this union, as if it had been long exposed to the air: which
proves the consistence an Oil acquires by long keeping to be owing to this,
that its lightest and less acid parts being evaporated, the proportion of its
acid to the remainder is so increased, that it produces therein the same
change, as an additional acid mixed with the Oil would have wrought
before the evaporation.
This also shews us, that Balsams and Resins are only essential Oils
combined with a great proportion of acid, and thereby thickened.
If vegetable substances, from which no more essential Oil can be drawn by
the heat of boiling water, be exposed to a stronger heat, they yield an
additional quantity of Oil; but it is thicker and heavier than the essential Oil.
These Oils are black, and have a very disagreeable burnt smell, which hath
made them be called Fetid or Empyreumatic Oils. They are moreover very
acrid.
It must be observed, that, if a vegetable substance be exposed to a degree of
heat greater than that of boiling water, before the fat or the essential Oil is
extracted from it, an empyreumatic Oil only will then be obtained; because
both the fat and essential Oils, when exposed to the force of fire, are
thereby burnt, rendered acrid, acquire a smell of the fire, and, in a word,
become truly empyreumatic. There is ground to think, that an empyreumatic

Oil is nothing else but an essential or fat Oil burnt and spoiled by the fire,
and that no other Oil besides these two exists naturally in vegetables.
Empyreumatic Oils, distilled and rectified several times by a gentle heat,
acquire by every distillation a greater degree of tenuity, lightness, and
limpidity. By this means also they lose something of their disagreeable
odour; so that they gradually come nearer and nearer to the nature of
essential Oils: and if the rectifications be often enough repeated, ten or
twelve times for instance, they become perfectly like those Oils; except that
their smell will never be so agreeable, nor like that of the substances from
which they were obtained.
Fat Oils may also be brought by the same means to resemble essential Oils:
but neither essential nor empyreumatic Oils are capable of acquiring the
properties of fat Oils.

SECTION III.

Of Animal Oils.
Distillation procures us considerable quantities of Oil from all the parts of
animal bodies, and especially from their fat. This Oil at first is not very
fluid, and is extremely fetid: but by many rectifications it gradually acquires
a great degree of clearness and tenuity, and at the same time loses much of
its disagreeable odour. Animal Oils, thus rendered thin and fluid by a great
number of rectifications, have the reputation of being an excellent
medicine, and a specific in the epilepsy.

CHAP. XII.

Of Fermentation in general.
Fermentation is meant an intestine motion, which, arising
B
y
spontaneously among the insensible parts of a body, produces a new
disposition and a different combination of those parts.
To excite a Fermentation in a mixt body, it is necessary, first, that there be
in the composition of that mixt a certain proportion of watery, saline, oily,
and earthy parts: but this proportion is not yet sufficiently ascertained.
Secondly, it is requisite that the body to be fermented be placed in a certain
degree of temperate heat: for much cold obstructs fermentation; and too
much heat decomposes bodies. Lastly, the concurrence of the air is also
necessary to fermentation.
All vegetable and animal substances are susceptible of Fermentation,
because all of them contain in a due proportion the principles above
specified. However, many of them want the proper quantity of water, and
cannot ferment while they remain in such a state of dryness. But it is easy to
supply that defect, and so render them very apt to ferment.
With respect to minerals properly so called, (that is, excluding such
vegetable and animal substances as may have lain long buried in the earth),
they are not subject to any Fermentation; at least, that our senses can
perceive.
There are three sorts of Fermentation, distinguished from one another by
their several productions. The first produces wines and spirituous liquors;
for which reason it is called the Vinous or Spirituous Fermentation: the
result of the second is an acid liquor; and therefore it is called the Acetous
Fermentation: and the third generates an alkaline salt; which, however,
differs from the alkaline salts hitherto treated of, in this respect chiefly, that,
instead of being fixed, it is extremely volatile: this last sort takes the name
of the Putrid or Putrefactive Fermentation. We shall now consider these
three sorts of Fermentation and their effects a little more particularly.

These three sorts of Fermentation may take place successively in the same
subject; which proves them to be only three different degrees of
fermentation, all proceeding from one and the same cause, rather than three
distinct fermentations. These degrees of fermentation always follow the
order in which we have here placed them.

CHAP. XIII.

Of the Spirituous Fermentation.
juices of almost all fruits, all saccharine vegetable matters, all
T
he
farinaceous seeds and grains of every kind, being diluted with a
sufficient quantity of water, are proper subjects of Spirituous
Fermentation. If such liquors be exposed, in vessels slightly stopped, to a
moderate degree of heat, they begin in some time to grow turbid; there
arises insensibly a small commotion among their parts, attended with a
hissing noise; this by little and little increases, till the grosser parts appear,
like little seeds or grains, moving to and fro, agitated among themselves,
and thrown up to the surface. At the same time some air bubbles rise, and
the liquor acquires a pungent, penetrating smell, occasioned by the very
subtile vapours which exhale from it.
These vapours have never yet been collected, in order to examine their
nature; and they are known only by their noxious effects. They are so
actively pernicious, that if a man comes rashly into a close place, where
large quantities of liquors are fermenting, he suddenly drops down and
expires, as if he were knocked on the head.
When these several phenomena, begin to go off, it is proper to stop the
fermentation, if a very spirituous liquor be required: for if it be suffered to
continue longer, the liquor will become acid, and from thence proceed to its
last stage, that is, to putrefaction. This is done by stopping the containing
vessels very close, and removing them into a cooler place. Then the
impurities precipitate, and settling at the bottom leave the liquor clear and
transparent: and now the palate discovers that the sweet saccharine taste it
had before fermentation is changed to an agreeable pungency, which is not
acid.
Liquors thus fermented are in general called Wines: for though in common
life that word properly signifies the fermented juice of grapes only, and
particular names are given to the fermented juices of other vegetable
substances; as that obtained from Apples is called Cyder; that made from

malt is called Beer: yet in Chymistry it is of use to have one general term
denoting every liquor that has undergone this first degree of fermentation.
By distillation we draw from Wine an inflammable liquor, of a yellowish
white colour, light, and of a penetrating, pleasant smell. This liquor is the
truly spirituous part of the wine, and the product of fermentation. That
which comes off in the first distillation is commonly loaded with much
phlegm and some oily parts, from which it may be afterwards freed. In this
state it goes by the name of Brandy; but when freed from these
heterogeneous matters by repeated distillations, it becomes still clearer,
lighter, more fragrant, and much more inflammable, and then is called Spirit
of Wine, and Rectified Spirit of Wine, or an Ardent Spirit, if considerably
purified. The properties which distinguish an Ardent Spirit from all other
substances are its being inflammable; its burning and consuming entirely,
without the least appearance of smoke or fuliginosity; its containing no
particles reducible to a coal; and its being perfectly miscible with water.
Ardent Spirits are lighter and more volatile than any of the principles of the
mixts from which they were produced, and consequently more so than the
phlegm, the acid, and the oil of which they themselves consist. This arises
from a particular disposition of these principles, which are in a singular
manner attenuated by fermentation, and thereby rendered more susceptible
of expansion and rarefaction.
Ardent spirits are supposed to be the natural solvents of oils and oily
matters. But it is very remarkable that they dissolve essential oils only,
without touching the fat of animals, or the fat oils obtained from vegetables
by expression; yet when these oils have once undergone the action of fire,
they become soluble in spirit of wine, and even acquire a new degree of
solubility every time they are distilled. It is not so with essential oils, which
can never be rendered more soluble in ardent spirits than they are at first;
and are so far from acquiring a new degree of solubility every time they are
distilled, that on the contrary they even in some measure lose that property
by repeated rectifications.
I have taken some pains to find out the causes of these singular effects, and
the result of my inquiries is published among the Memoirs of the Academy
of Sciences for the year 1745. I therein consider ardent spirits as consisting
of an oil, or at least a phlogiston, mixed with a portion of water, in which it

is rendered soluble by means of an acid. This being laid down, I shew that
the inability of spirit of wine to dissolve some oils must be imputed to its
aqueous part, in which oils are not naturally soluble without the
intervention of a salt: and that the power which this spirit exerts in
dissolving other oils with ease, such as essential oils, must in all probability
be owing to this, that in these oils it meets with the necessary saline
medium, that is, with an acid, which numberless experiments shew they
actually contain.
On the other hand, I there prove, that the acid in essential oils is
superabundant, and in some sort foreign to their nature, or that it is but
slightly connected with them, and in part deserts them every time they are
distilled; which renders them less soluble after every new rectification:
whereas, on the contrary, the fat expressed oils in their natural state give not
the least sign of acidity, but the action of fire upon them discovers an acid
which was not perceivable before. Hence I conjecture, that these oils
contain no more acid than is just necessary to constitute them oils; that this
acid is intimately blended with their other component parts; that it is so
sheathed and entangled by these parts as to be incapable of exerting any of
its properties; and that on this account these oils in their natural state are not
soluble in spirit of wine: but that the disposition of their parts being
gradually changed by the fire, and their acid, being by that means set more
and more at liberty, at length recovers its properties, and particularly that of
rendering the oily parts soluble in an aqueous menstruum: and hence it
follows, that the fat oils become so much the more soluble in spirit of wine
the oftener they are exposed to the action of fire.
Spirit of wine doth not dissolve fixed alkalis; or at least it takes up but a
very small quantity thereof; and hence ardent spirits may be freed from
much of their phlegm by means of these salts thoroughly dried: for as they
strongly imbibe moisture, and have even a greater affinity than ardent
spirits with water, if a fixed alkali, well exsiccated, be mixed with spirit of
wine that is not perfectly dephlegmated, the alkali immediately attracts its
superfluous moisture, and is thereby resolved into a liquor, which, on
account of its gravity, descends to the bottom of the vessel. The spirit of
wine, which swims at top, is by this means as much dephlegmated, and as
dry, as if it had been rectified by several distillations. As it takes up some
alkaline particles in this operation, it is thereby qualified to dissolve oily

matters with the greater facility. When rectified in this manner, it is called
Alcoholized Spirit of Wine.
Yet spirit of wine, even when rectified to an alcohol, is not capable of
dissolving all oily matters. Those named Gums will by no means enter into
any sort of union therewith; but it readily dissolves most of those which are
known by the appellation of Resins. When it has dissolved a certain
proportion of resinous particles it acquires a greater consistence, and forms
what is called a Spirit Varnish, or a Drying Varnish, because it soon dries.
This Varnish is subject to be damaged by water. Many sorts thereof are
prepared, differing from each other according to the different resins
employed, or the proportions in which they are used. Most of these
Varnishes are transparent and colourless.
Such bitumens or resins, as spirit of wine will not touch, are dissolved in
oils by means of fire, and then form another kind of Varnish, which water
does not hurt. These Varnishes are usually coloured, and require much
longer time to dry than the Spirit Varnishes: they are called Oil Varnishes.
Spirit of wine hath a much greater affinity with water than with oily
matters: and therefore if a solution of any oil or resin in spirit of wine be
mixed with water, the liquor immediately grows turbid, and acquires a
whitish milky colour, owing entirely to the oily parts being separated from
the spirituous menstruum by the accession of water, and too finely divided
to appear in their natural form. But if the liquor stand some time quiet,
several of these particles unite together, and gradually acquire a bulk
sufficient to render them very perceptible to the eye.
Acids have an affinity with spirit of wine, and may be combined with it. By
this union they lose most of their acidity, and on that account are said to be
Dulcified. But as these combinations of acids, especially of the vitriolic
acid, with spirit of wine furnish some new productions of very singular
properties, and as an examination thereof may throw much light on the
nature of ardent spirits, it will not be amiss to take notice of them in this
place, and consider each of them particularly.
One part of highly concentrated oil of vitriol being mixed with four parts of
well dephlegmated spirit of wine, there arises immediately a considerable
ebullition and effervescence, attended with great heat, and abundance of

vapours, which smell pleasantly, but are hurtful to the lungs. At the same
time is heard a hissing like that produced by a piece of red-hot iron plunged
into water. Indeed it is proper to mix the liquors very gradually; for
otherwise the vessels in which the operation is performed will be in great
danger of breaking.
If the two liquors thus mixed be distilled with a very gentle heat, there rises
first a spirit of wine of a most penetrating and grateful odour: when about
half thereof is come over, what follows has a quicker and more sulphureous
smell, and is also more loaded with phlegm. When the liquor begins to boil
a little, there comes off a phlegm which smells very strong of sulphur, and
grows gradually more acid. On this phlegm floats a small quantity of a very
light and very limpid oil. In the still there remains a thick blackish
substance, somewhat like a resin or bitumen. From this substance may be
separated a good deal of a vitriolic but sulphureous acid. When that is
extracted, there remains a black mass like a charred coal, which being put
into a crucible, and exposed to a violent heat, leaves a small portion of
earth, very fixed, and even vitrifiable.
By rectifying the ardent spirit, which came over in distilling the above-
mentioned mixture, a very singular liquor is obtained, which differs
essentially both from oils and from ardent spirits, though in certain respects
it resembles them both. This liquor is known in Chymistry by the name of
Æther, and its chief properties are as follow.
Æther is lighter, more volatile, and more inflammable, than the most highly
rectified spirit of wine. It quickly flies off when exposed to the air, and
suddenly catches fire when any flame approaches it. It burns like spirit of
wine without the least smoke, and consumes entirely without leaving the
smallest appearance of a coal or of ashes. It dissolves oils and oily matters
with great ease and rapidity. These properties it has in common with an
ardent spirit. But it resembles an oil in that it is not miscible with water; and
this makes it essentially different from spirit of wine, the nature of which is
to be miscible with all aqueous liquors.
Another very singular property of Æther is its great affinity with gold,
exceeding even that of aqua regis. It does not indeed dissolve gold when in
a mass, and in its metalline form; but if a small quantity of Æther be added

to a solution of gold in aqua regis, and the whole shaken together, the gold
separates from the aqua regis, joins the Æther, and remains dissolved
therein.
The reason of all the phenomena above-mentioned, resulting from the
mixture of spirit of wine with oil of vitriol, is founded on the great affinity
between this acid and water. For if the vitriolic acid be weak, and as it were
over-dosed with watery parts, neither oil nor Æther can be obtained by
means thereof: but when highly concentrated, it attracts the aqueous parts
very powerfully; and therefore, being mixed with spirit of wine, lays hold
of most of the water contained in it, and even robs it of some portion of that
which is essential to its nature, and necessary to constitute it spirit of wine:
whence it comes to pass, that a certain quantity of the oily particles in its
composition being separated from the watery particles, and so brought
nearer to each other, they unite and assume their natural form; and thus the
oil that swims at top of the sulphureous phlegm is produced.
The vitriolic acid moreover thickens and even burns some of this oil; and
hence comes the bituminous residuum left at the bottom of the still, which
looks like the result of a vitriolic acid combined with common oil. Lastly,
the vitriolic acid becomes sulphureous, as it always doth when united with
oily matters, and also very aqueous, on account of the quantity of phlegm
which it attracts from the spirit of wine.
Æther may be considered as a spirit of wine exceedingly dephlegmated,
even to such a degree that its nature is thereby changed; so that the few
aqueous particles left in it are not sufficient to dissolve the oily particles and
keep them asunder; which therefore being now much nearer to one another
than in common spirit of wine, the liquor hath lost its property of being
miscible with water.
Spirit of nitre well dephlegmated, and combined with spirit of wine,
presents likewise some very singular appearances.
First, in the very instant of its mixture with spirit of wine, it produces a
greater and more violent effervescence than the vitriolic acid occasions.
Secondly, this mixture, without the help of distillation, and only by stopping
the bottle in which the liquors are contained, affords a sort of Æther,

produced probably by the vapours which ascend from, and swim at top of
the mixture. This is a very singular liquor. Dr. Navier was the first that took
notice of it, and gave a description thereof, which may be seen in the
Memoirs of the Academy of Sciences.
Thirdly, some authors pretend that, by distilling the mixture under
consideration, an oil is obtained greatly resembling that which, as we
observed above, rises from spirit of wine combined with the vitriolic acid:
others again deny this. For my part, I believe the thing depends on the
different concentration of the spirit of nitre, as well as on the quality of the
spirit of wine, which is sometimes more sometimes less oily.
Fourthly, the two liquors we are speaking of, being intimately mixed by
distillation, form a liquor slightly acid, used in medicine, and known by the
name of Sweet or Dulcified Spirit of Nitre: a very proper name, seeing the
nitrous acid, by uniting with the spirit of wine, actually loses almost all its
acidity and corrosive quality.
Fifthly and lastly, when the distillation is finished, there remains in the
bottom of the vessel a thick blackish substance, nearly resembling that
which is found after distilling oil of vitriol and spirit of wine.
Spirit of salt hath likewise been combined with spirit of wine; but it does
not unite therewith so easily or so intimately as the two acids above-
mentioned. To mix them thoroughly, the spirit of salt must be highly
concentrated, and smoking, and moreover the assistance of the still must be
called in. Some authors pretend that from this mixture also a small quantity
of oil may be obtained; which probably happens when the liquors have the
qualities above-specified. The marine acid likewise, by uniting with spirit of
wine, loses most of its acidity; on which account it is in like manner called
Sweet or Dulcified Spirit of Salt. A thick residuum is also found here after
distillation.

CHAP. XIV.

Of the Acetous Fermentation.
esides an ardent spirit, wine affords a great deal of water, oil, earth, and

B a sort of acid which shall be considered presently. When the spirituous
part is separated from these other matters, they undergo no further
change. But if all the constituent parts of wine remain combined together,
then, after some time, shorter or longer as the degree of heat in which the
wine stands is greater or less, the fermentation begins afresh, or rather
arrives at its second stage. The liquor once more grows turbid, a new
intestine motion arises, and, after some days, it is found changed into an
acid; which, however, is very different from those hitherto treated of. The
liquor then takes the name of Vinegar. The acetous fermentation differs
from the spirituous, not only in its effect, but also in several of its
concomitant circumstances. Moderate motion is of service to this, whereas
it obstructs the spirituous; and it is attended with much more warmth than
the spirituous. The vapours it produces are not noxious, like those of
fermenting wine. Lastly, Vinegar deposites no tartar, even when the wine
employed in this operation is quite new, and hath not had time to discharge
its tartar: instead of tartar, Vinegar deposites a viscid matter which is very
apt to putrify.
It must be observed, that wine is not the only substance that is susceptible
of the acetous fermentation: for several vegetable and even animal matters,
which are not subject to the spirituous fermentation, turn sour before they
putrify. But as vinous liquors possess in a very eminent degree the property
of being susceptible of the acetous fermentation, and likewise of producing
the strongest acids that can result from such fermentation, their acid shall be
more particularly considered in this place.

SECTION I.

Of Vinegar.
If wine, which has gone through this second stage of fermentation, be
distilled, instead of an ardent spirit, only an acid liquor is obtained, which is

called Distilled Vinegar.
This acid has the same properties as the mineral acids of which we have
already treated; that is, it unites with alkaline salts, absorbent earths, and
metallic substances, and therewith forms neutral saline combinations.
Its affinity with these substances observes the same order as that observed
by the mineral acids with regard to the same substances; but in general it is
weaker; that is, any mineral acid is capable of expelling the acid of Vinegar
out of all matters with which it is united.
Vinegar hath likewise a greater affinity than sulphur with alkalis: whence it
follows, that it is capable of decompounding that combination of sulphur
with an alkali called Liver of Sulphur, and of precipitating the sulphur it
contains.
The acid of Vinegar is always clogged with a certain proportion of oily
parts, which greatly weaken it, and deprive it of much of its activity; and for
this reason it is not near so strong as the mineral acids, which are not
entangled with any oil. By distillation, indeed, it may be freed from this oil,
and at the same time from the great quantity of water which in a manner
suffocates it, and by that means may be brought much nearer to the nature
of the mineral acids: but this attempt hath not yet been prosecuted with the
assiduity it deserves. Besides distillation, there is another way of freeing
Vinegar from a good deal of its phlegm; and that is, by exposing it to a hard
frost, which readily congeals the watery part into ice, while the acid retains
its fluidity.
Vinegar, saturated with a fixed alkali, forms a neutral oily salt, of a dark
colour, which is semi-volatile, melts with a very gentle heat, flames when
thrown upon burning coals, and dissolves in spirit of wine, of which,
however, it requires six parts to complete the solution. This solution being
evaporated to dryness leaves a matter in the form of leaves lying on each
other; on which account it hath obtained the name of Terra Foliata. The
same foliated matter will be obtained, though the salt be not previously
dissolved in spirit of wine; but not so readily. This salt is also called
Regenerated Tartar. Under the head of Tartar we shall see the reason of
these different appellations. Regenerated Tartar is also in some degree
capable of crystallizing: for this purpose a solution thereof in water must be

slowly evaporated to the consistence of a syrup, and then suffered to stand
quiet in a cool place; by which means it will shoot into clusters of crystals,
lying one upon another, not unlike the feathers on a quill.
With Vinegar and several absorbent earths, such as calcined pearls, coral,
shells of fish, &c. are also formed neutral saline compounds, each of which
takes the name of the particular earth employed in its composition.
Vinegar perfectly dissolves Lead, and converts it to a neutral metallic salt,
which shoots into crystals, and has a sweet saccharine taste. This compound
is called Sugar of Lead, or Sal Saturni.
If Lead be exposed to the bare vapour of Vinegar, it will be thereby
corroded, calcined, and converted into a white matter much used in
painting, and known by the name of Ceruse; or, when it is finer than
ordinary, White Lead.
Vinegar corrodes Copper likewise, and converts it into a beautiful green
rust, which also is used in painting; and distinguished by the name of
Verdegris. However, Vinegar is not commonly employed to make Verdegris:
for this purpose they use wine, or the rape of wine, from which fire
extricates an acid analogous to that of Vinegar.
In treating of the several substances which constitute wine, we mentioned
an acid matter, but did not then enter into a particular examination thereof;
because as that matter greatly resembles the acid of Vinegar, we thought it
more proper to defer the consideration of its properties till we had treated of
the acetous fermentation, and its effects.

SECTION II.

Of Tartar.
This substance is a saline compound, consisting of earthy, oily, and
especially acid parts. It is found in the form of crusts, adhering to the inner
sides of vessels in which wines have stood for some time, particularly acid
wines, such as those of Germany.

Tartar derives its origin from the superabundant quantity of acid contained
in the juice of the grape. This superfluous acid, being more than is requisite
to constitute the ardent spirit, unites with some of the oil and earth
contained in the fermented liquor, and forms a kind of salt; which for some
time continues suspended in that liquor, but, when the wine stands
undisturbed in a cool place, is deposited, as hath been said, on the sides of
the cask.
Tartar in this state contains many earthy parts, which are superfluous, and
foreign to its nature. From these it may be freed by boiling it repeatedly
with a sort of earth found in the neighbourhood of Montpelier, as may be
seen in the Memoirs of the Academy of Sciences.
When it is purified, there appears on the surface of the liquor a sort of
white, crystalline pellicle, which is skimmed off as it forms. This matter is
called Cream of Tartar. The same liquor which produces this Cream, and in
which the purified Tartar is dissolved, being set to cool, yields a great
number of white semi-transparent crystals, which are called Crystals of
Tartar. The Cream and the Crystals of Tartar are therefore no other than
purified Tartar, and differ from each other in their form only.
Though the Crystals of Tartar have every appearance of a neutral salt, yet
they are far from being such; for they have all the properties of a true acid,
which scarce differs from that of vinegar, except that it contains less water,
and more earth and oil; to which it owes its solid form, as well as its
property of not being soluble in water without much difficulty: for a very
great quantity of water is requisite to keep the Crystals of Tartar in solution;
and it must moreover be boiling hot; otherwise as soon as it cools most of
the Tartar dissolved in it separates from the liquor, and falls to the bottom in
the form of a white powder.
Tartar is decomposed by calcination in the open fire. All its oily parts are
consumed or dissipated in smoke, together with most of its acid. The other
part of its acid, uniting intimately with its earth, forms a very strong and
very pure fixed alkali, called Salt of Tartar.
It will be shewn in its proper place, that almost every vegetable matter, as
well as Tartar, leaves a fixed alkali in its ashes: yet Tartar has these peculiar
properties; first, it assumes an alkaline character even when burnt or

calcined in close vessels, whereas other substances acquire it only by being
burnt in the open air; secondly, the alkali of Tartar is stronger and more
saline than almost any that is obtained from other matters.
This alkali, when thoroughly calcined, powerfully attracts the moisture of
the air, and melts into an unctuous alkaline liquor, improperly called Oil of
Tartar per deliquium. This is the alkali generally used in making the Terra
Foliata, mentioned under the head of Vinegar; for which reason this
combination is called Terra Foliata Tartari; a name suitable enough. But
the same cannot be said of the other name, Regenerated Tartar, which is
also given it. It is true, that on this occasion an oily acid is restored to the
earth of the Tartar, analagous to that of which the fire had deprived it: but
the compound thence resulting is a neutral salt which very readily dissolves
in water; whereas Tartar is manifestly acid, and not soluble, or at least
hardly soluble, in water.
Crystals of Tartar combined with alkali of Tartar produce a great
effervescence while they are mixing, as all acids usually do; and if the
combination be brought exactly up to the point of saturation, a perfectly
neutral salt is formed, which shoots into crystals, and easily dissolves in
water; and this hath procured it the name of Soluble Tartar. It is also called
the Vegetable Salt, as being obtained from vegetables only; and again,
Tartarised Tartar, because it consists of the acid and the alkali of Tartar
combined together.
Crystals of Tartar combined with alkalis procured from the ashes of
maritime plants, such as Soda, which alkalis resemble the basis of sea-salt,
form likewise a neutral salt, which crystallizes well, and dissolves easily in
water. This salt is another sort of soluble Tartar. It is called Saignette's Salt,
from the inventor's name.
Both the Vegetable Salt and Saignette's Salt are gently purgative soaps, and
much used in Medicine.
Tartar likewise dissolves the absorbent earths, as lime, chalk, &c. and with
them forms neutral salts which are soluble in water[3]. It even attacks
metallic bodies, and when combined with them becomes soluble. A soluble
Tartar for medical use is prepared with Crystals of Tartar and Iron: the
metallic salt thereby produced hath the name of Chalybeated Soluble

Tartar. This salt attracts the moisture of the air, and is one of those which
do not crystallize.
Crystallized Tartar acts also upon several other metallic substances: for
instance, it dissolves the Regulus, Liver, and Glass of Antimony, and thence
acquires an emetic quality: it is then called Stibiated or Emetic Tartar. It
likewise dissolves Lead, and therewith forms a salt which, in the figure of
its crystals, resembles Tartarised Tartar.
It is very extraordinary that Tartar, which of itself is not soluble in water,
should be soluble therein when become a neutral salt by uniting either with
alkalis or with absorbent earths, or even with metals. With respect to alkalis,
indeed, it may be urged, that, having themselves a great affinity with water,
they communicate to Tartar some of that facility with which they naturally
unite therewith: but the same cannot be alledged concerning absorbent
earths, and metallic substances, which water dissolves not at all, or at least
with great difficulty, and in small quantity. This effect, therefore, must be
attributed wholly to some change in the disposition of its parts which is to
us unknown.
All the Soluble Tartars are easily decompounded by exposing them to a
certain degree of heat. In distillation they yield the same principles which
are obtained from Tartar; and what remains fixed in the fire, after they are
thoroughly burnt, is a compound of the alkali which Tartar naturally
produces, and of the alkaline or metallic substance with which it was
converted into a neutral salt.
As Crystal of Tartar is the weakest of all acids, on account of the oily and
earthy matters with which it is combined, Soluble Tartars are
decompounded by all the acids; by any of which crystal of Tartar may be
separated from the substance that serves it for a basis and renders it a
neutral salt.
The other acids which are procured from vegetables, and even those which
are obtainable from some animal substances, may all be referred to and
compared with either Vinegar or Tartar, according to the quantities of oil or
earth with which they are combined.

After all, these acids have not yet been thoroughly examined. There is great
reason to think that they are no other than the mineral acids, which, in
passing through the bodies of vegetables, and even of animals, undergo a
considerable change, especially by contracting an union with oily matters.
For, as we said before in treating of Vinegar, by freeing them from their oil
they are brought very near to the nature of mineral acids; and so likewise
the mineral acids acquire many of the properties of vegetable acids by being
combined with oils.

CHAP. XV.

Of the Putrid Fermentation, or Putrefaction.
very body which hath gone through the two stages of fermentation

E above described, that is, the spirituous and the acetous fermentation,
being left to itself in a due degree of warmth, which varies according to
the subject, advances to the last stage of fermentation; that is, to
putrefaction.
It is proper to observe, before we go any further, that the converse of this
proposition is not true; that is, it is not necessary that a body should
successively pass through the spirituous and the acetous fermentation,
before it can arrive at the putrid; but that, as certain substances fall into the
acetous without having gone through the spirituous fermentation, so others
begin to putrify without having undergone either the spirituous or the
acetous fermentation; of which last kind are, for instance, most animal
substances. When therefore we represented these three sorts of fermentation
as three different degrees or stages of one and the same fermentation, we
supposed it to be excited in a body susceptible of fermentation in its full
extent.
However, there is still room to think that every substance which is capable
of fermenting always passes necessarily through these three different
stages; but that the substances most disposed thereto pass with such rapidity
through the first, and even the second, that they arrive at the third before
our senses can perceive the least signs of either of the two former. This
opinion is not destitute of probability: yet it is not supported by proofs
sufficiently strong and numerous to compel our assent.
When a body is in a putrefying state it is easy to discover (as in the two
sorts of fermentation already treated of) by the vapours which rise from it,
by the opacity which invades it, if a pellucid liquor, and frequently even by
a greater degree of heat than is found in the two other sorts of fermentation,
that an intestine motion is begun among its constituent parts, which lasts till
the whole be entirely putrefied.

The effect of this intestine motion is in this, as in the two other sorts of
fermentation, to break the union, and change the disposition, of the particles
constituting the body in which it is excited, and to produce a new
combination. This is brought about by a mechanism to which we are
strangers, and concerning which nothing beyond conjectures can be
advanced: but these we neglect, resolving to keep wholly to facts, as the
only things in Natural Philosophy that are positively certain.
If, then, we examine a substance that has undergone putrefaction, we shall
soon perceive that it contains a principle which did not exist in it before. If
this substance be distilled, there rises, first, by means of a very gentle heat,
a saline matter which is exceedingly volatile, and affects the organ of
smelling briskly and disagreeably. Nor is the aid of distillation necessary to
discover the presence of this product of putrefaction: it readily manifests
itself in most substances where it exists, as any one may soon be convinced
by observing the different smell of fresh and of putrefied urine; for the latter
not only affects the nose, but even makes the eyes smart, and irritates them
so as to draw tears from them in abundance.
This saline principle which is the product of putrefaction, when separated
from the other principles of the body which affords it, and collected by
itself, appears either in the form of a liquor, or in that of a concrete salt,
according to the different methods used to obtain it. In the former state it is
called a Volatile Urinous Spirit; and in the latter a Volatile Urinous Salt. The
qualification of urinous is given it, because, as was said, a great deal thereof
is generated in putrefied urine, to which it communicates its smell. It goes
also by the general name of a Volatile Alkali, whether in a concrete or in a
liquid form. The enumeration of its properties will shew why it is called an
alkali.
Volatile Alkalis, from whatever substance obtained, are all alike, and have
all the same properties; differing only according to their degrees of purity.
The Volatile Alkali, as well as the Fixed, consists of a certain quantity of
acid combined with and entangled by a portion of the earth of the mixt body
from which it was obtained; and on that account it has many properties like
those of a Fixed Alkali. But there is moreover in its composition a
considerable quantity of a fat or oily matter, of which there is none in a
Fixed Alkali; and on this account again there is a great difference between

them. Thus the Volatility of the Alkali produced by putrefaction, which is
the principal difference between it and the other kind of Alkali whose nature
it is to be Fixed, must be attributed to the portion of oil which it contains:
for there is a certain method of volatilizing Fixed Alkalis by means of a
fatty substance.
Volatile Alkalis have a great affinity with acids, unite therewith rapidly and
with ebullition, and form with them neutral salts, which shoot into crystals,
but differ from one another according to the kind of acid employed in the
combination.
The neutral salts which have a Volatile Alkali for their basis are in general
called Ammoniacal Salts. That whose acid is the acid of sea-salt is called
Sal Ammoniac. As this was the first known, it gave name to all the rest.
Great quantities of this salt are made in Egypt, and thence brought to us.
They sublime it from the soot of cow's dung, which is the fuel of that
country, and contains sea-salt, together with a Volatile Alkali, or at least the
materials proper for forming it; and consequently all the ingredients that
enter into the composition of Sal Ammoniac. See the Memoirs of the
Academy of Sciences.
The neutral salts formed by combining the acids of nitre and of vitriol with
a Volatile Alkali are called, after their acids, Nitrous Sal Ammoniac, and
Vitriolic Sal Ammoniac: the latter, from the name of its inventor, is also
called Glauber's Secret Sal Ammoniac.
A Volatile Alkali, then, has the same property as a Fixed Alkali with regard
to acids: yet they differ in this, that the affinity of the former with acids is
weaker than that of the latter: and hence it follows, that any Sal Ammoniac
may be decompounded by a Fixed Alkali, which will lay hold of the acid,
and discharge the Volatile Alkali.
A Volatile Alkali will decompound any neutral salt which has not a Fixed
Alkali for its basis; that is, all such as consist of an acid combined with an
absorbent earth or a metallic substance. By joining with the acids in which
they are dissolved, it disengages the earths or metallic substances, takes
their place, and, in conjunction with their acids, forms Ammoniac Salts.

Hence it might be concluded, that, of all substances, next to the Phlogiston
and the Fixed Alkalis, Volatile Alkalis have the greatest affinity with acids
in general. Yet there is some difficulty in this matter: for absorbent earths,
and several metallic substances, are also capable of decompounding
Ammoniacal Salts, discharging their volatile Alkali, and forming new
compounds by uniting with their acids. This might induce us to think, that
these substances have nearly the same affinity with acids.
But it is proper to observe, that a Volatile Alkali decompounds such neutral
salts as have for their basis either an absorbent earth or a metallic substance,
without the aid of fire; whereas absorbent earths or metallic substances will
not decompound an Ammoniacal Salt, unless they be assisted by a certain
degree of heat.
Now, as all these matters are extremely fixed, at least in comparison with a
Volatile Alkali, they have the advantage of being able to resist the force of
fire, and so of acting in conjunction therewith; and fire greatly promotes the
natural action of substances upon one another: whereas the Volatile Alkali
in the Ammoniacal Salt, being unable to abide the force of fire, is
compelled to desert its acid; and that so much the more quickly, as its
affinity therewith is considerably weakened by the presence of an earthy or
metallic substance, both of which have a great affinity with acids.
These considerations oblige us to conclude, that Volatile Alkalis have a
somewhat greater affinity, than absorbent earths and metallic substances,
with acids.
Ammoniacal Salts projected upon nitre in fusion make it detonate; and the
Nitrous Sal Ammoniac detonates by itself, without the addition of any
inflammable matter. This singular effect evidently demonstrates the
existence of an oily matter in Volatile Alkalis; for it is certain that nitre will
never deflagrate without the concurrence, and even the immediate contact,
of some combustible matter.
This oily substance is often found combined with Volatile Alkalis in such a
large proportion as to disguise it, in some measure, and render it
exceedingly foul. The salt may be freed from its superfluous oil by repeated
sublimations; and particularly by subliming it from absorbent earths, which
readily drink up oils. This is called the Rectification of a Volatile Alkali.

The salt, which before was of a yellowish or dirty colour, by being thus
rectified becomes very white, and acquires an odour more pungent and less
fetid than it had at first, that is, when obtained by one single distillation
from a putrid substance.
It is proper to observe, that the rectification of a Volatile Alkali must not be
carried too far, or repeated too often; for by that means it may be entirely
decomposed at length; and particularly if an absorbent earth, and especially
chalk, be employed for that purpose, the salt may be converted into an oil,
an earth, and water.
Volatile Alkalis act upon several metallic substances, and particularly on
copper; of which they make a most beautiful blue solution. On this property
depends a pretty singular effect, which happens sometimes when we
attempt, by means of a Volatile Alkali, to separate copper from any acid
with which it is combined. Instead of seeing the liquor grow turbid, and the
metal fall, both which generally happen when any Alkali whatever is mixed
with a metallic solution, we are surprised to observe the solution of copper,
upon adding a Volatile Alkali, retain its limpidity, and let fall no precipitate;
or at least, if the liquor does grow turbid, it remains so but for a moment,
and instantly recovers its transparency.
This is occasioned by adding such a quantity of Volatile Alkali as is more
than sufficient fully to saturate the acid of the solution, and considerable
enough to dissolve all the copper as fast as it is separated from the acid. On
this occasion the liquor acquires a deeper blue than it had before; which
arises from the property which Volatile Alkalis have of giving this metal,
when combined with them, a fuller blue than any other solvent can: hence
we have a touchstone to discover copper wherever it is; for let the quantity
of this metal combined with other metals be ever so small, a Volatile Alkali
never fails to discover it, by making it appear of a blue colour.
Though a Volatile Alkali be constantly the result of putrefaction, yet it must
not therefore be imagined that none can be produced by any other means;
on the contrary, most of those substances which contain the ingredients
necessary to form it, yield no inconsiderable quantity thereof in distillation.
Tartar, for example, which by being burnt in an open fire is converted, as
was shewn, into a Fixed Alkali, yields a Volatile Alkali when it is

decomposed in close vessels; that is, when it is distilled; because, in this
latter case, the oily part is not dissipated or burnt, as it is by calcination in a
naked fire, but has time to unite with some of the earth and acid of the mixt,
in such a manner as to form a true Volatile Alkali.
To prove that on this occasion, as well as on all others, where unputrefied
bodies yield a Volatile Alkali, this salt is the product of the fire, we need
only observe, that in these distillations it never rises till after some part of
the phlegm, of the acid, and even of the thick oil of the mixt, is come over;
which never is the case when it is formed beforehand in the body which is
the subject of the operation, as it is in those which have undergone
putrefaction: for this salt, being much lighter and more volatile than those
other substances, rises of course before them in distillation.

CHAP. XVI.

A General View of Chymical Decomposition.
we have considered all the substances which enter into the
T
hough
composition of Vegetables, Animals, and Minerals, whether as primary
or as secondary principles, it will not be improper to shew in what
order we obtain these principles from the several mixts; and especially from
Vegetables and Animals, because they are much more complicated than
Minerals. This is called Analysing a compound.
The method most commonly taken to decompose bodies is by applying to
them successive degrees of heat, from the gentlest to the most violent, in
appropriated vessels, so contrived as to collect what exhales from them. By
this means the principles are gradually separated from each other; the most
volatile rise first, and the rest follow in order, as they come to be acted on
by the proper degree of heat: and this is called Distillation.
But it being observed that fire, applied to the decomposition of bodies, most
commonly alters their secondary principles very sensibly, by combining
them in a different manner with each other, or even partly decomposing
them, and reducing them to their primitive principles; other means have
been used to separate those principles without the help of fire.
With this view the mixts to be decomposed are forcibly compressed, in
order to squeeze out of them all such parts of their substance as they will by
this means part with: or else those mixts are for a long time triturated, either
along with water, which carries off all their saline and saponaceous
contents, or with solvents, such as ardent spirits, capable of taking up every
thing in them that is of an oily or resinous nature.
We shall here give a succinct account of the effects of these different
methods, as applied to the principal substances among Vegetables and
Animals, and likewise to some Minerals.

SECTION I.

The Analysis of Vegetable Substances.
A vast many vegetable substances, such as kernels and seeds, yield, by
strong compression, great quantities of mild, fat, unctuous Oils, which are
not soluble in ardent spirits: these are what we called Expressed Oils. They
are also sometimes called Fat Oils, on account of their unctuousness, in
which they exceed all other sorts of Oil. As these oils are obtained without
the aid of fire, it is certain that they existed in the mixt just as we see them,
and that they are not in the least altered: which could not have been the case
had they been obtained by distillation; for that never produces any Oils but
such as are acrid and soluble in spirit of wine.
Some vegetable matters, such as the rind of citrons, lemons, oranges, &c.
also yield, only by being squeezed between the fingers, a great deal of Oil.
This spirts out in fine small jets, which being received upon any polished
surface, such as a looking glass, run together and form a liquor that is a real
Oil.
But it must be carefully noted, that this sort of Oil, though obtained by
expression only, is nevertheless very different from the Oils mentioned
before, to which the title of Expressed Oils peculiarly belongs: for this is far
lighter and thinner; moreover, it retains the perfect odour of the fruit which
yields it, and is soluble in spirit of wine; in a word, it is a true essential Oil,
but abounds so in the fruits which produce it, and is lodged therein in such a
manner, occupying a vast number of little cells provided in the peel for its
reception, that a very slight pressure discharges it; which is not the case
with many other vegetables that contain an essential Oil.
Succulent and green plants yield by compression a great deal of liquor or
juice, which consists of most of the phlegm, of the salts, and a small portion
of the oil and earth of the plant. These juices, being set in a cool place for
some time, deposite saline crystals, which are a combination of the acid of
the plant with part of its oil and earth, wherein the acid is always
predominant. These salts, as is evident from the description here given, bear
a great resemblance to the tartar of wine treated of above. They are called
Essential Salts; so that Tartar might likewise be called the Essential Salt of
Wine.

Dried plants, and such as are of a ligneous, or acid nature, require to be long
triturated with water, before they will yield their essential salts. Trituration
with water is an excellent way to get out of them all their saline and
saponaceous contents.
A vegetable matter that is very oily yields its essential salt with much
difficulty, if at all; because the excessive quantity of oil entangles the salt so
that it cannot extricate itself or shoot into crystals. Mr. Gerike, in his
Principles of Chymistry, says, that if part of the oil of a plant be extracted
by spirit of wine, its essential salt may be afterwards obtained with more
ease and in greater quantity. This must be a very good method for such
plants as have an excessive proportion of essential oil; but will not succeed
if the essential salt be hindered from crystallizing by a redundancy of fat
oil, because fat oils are not soluble in spirit of wine.
Essential Salts are among those substances which cannot be extracted from
mixts by distillation: for the first impression of fire decomposes them.
Though the acid which predominates in the Essential Salts of plants, be
most commonly analogous to the vegetable acid, properly so called, that is,
to the acid of vinegar and tartar, which is probably no other than the
vitriolic acid disguised; yet it sometimes differs therefrom, and somewhat
resembles the nitrous or the marine acid. This depends on the places where
the plants grow which produce these salts: if they be maritime plants, their
acid is akin to the acid of sea-salt; if on the contrary they grow upon walls,
or in nitrous grounds, their acid is like that of nitre. Sometimes one and the
same plant contains salts analogous to all the three mineral acids; which
shews that the vegetable acids are no other than the mineral acids variously
changed by circulating through plants.
Liquors containing the Essential Salts of plants being evaporated by a
gentle heat to the consistence of honey, or even further, are called Extracts.
Hence it is plain, that an Extract is nothing but the essential salt of a plant,
combined with some particles of its oil and earth, that remained suspended
in the liquor, and are now incorporated by evaporation.
Extracts of plants are also prepared by boiling them long in water, and then
evaporating some part of it. But these Extracts are of inferior virtue;
because the fire dissipates many of the oily and saline parts.

Emulsions.
Substances which abound much in Oil, being bruised and triturated with
water for some time, afford a liquor of an opaque dead-white colour, like
milk. This liquor consists of such juices as the water is capable of
dissolving, together with a portion of the oil, which being naturally
indissoluble in water, is only divided and dispersed in the liquor, the
limpidity whereof is by that means destroyed. This sort of oily liquor, in
which the oil is only divided, not dissolved, is called an Emulsion. The oily
particles in Emulsions spontaneously separate from the water, when left at
rest, and uniting into greater masses rise, on account of their lightness, to
the surface of the liquor, which by that means recovers a degree of
transparency.
If vegetables abounding in essential oils and resins be digested in spirit of
wine, the menstruum takes up these oily matters, as being capable of
dissolving them; and they may afterwards be easily separated from it by the
affusion of water. The water, with which spirit of wine has a greater affinity
than with oily matters, separates them by this means from their solvent,
agreeably to the common laws of affinities.
Without the help of fire, scarce any thing, besides the substances already
mentioned, can be obtained from a plant: but, by the means of distillation,
we are enabled to analyse them more completely. In prosecuting this
method of extracting from a plant the several principles of which it consists,
the following order is to be observed.
A plant being exposed to a very gentle heat, in a distilling vessel set in the
balneum mariæ, yields a water which retains the perfect smell thereof.
Some Chymists, and particularly the illustrious Boerhaave, have called this
liquor the Spiritus Rector. The nature of this odoriferous part of plants is not
yet thoroughly known; because it is so very volatile that it is difficult to
subject it to the experiments necessary for discovering all its properties.
If, instead of distilling the plant in the balneum mariæ, it be distilled over a
naked fire, with the precaution of putting a certain quantity of water into the
distilling vessel along with it, to prevent its suffering a greater heat than that
of boiling water, all the essential oil contained in that plant will rise together
with that water, and with the same degree of heat.

On this occasion it must be observed, that no essential oil can be obtained
from a plant after the Spiritus Rector hath been drawn off; which gives
ground to think that the volatility of these oils is owing to that spirit.
The heat of boiling water is also sufficient to separate from vegetable
matters the fat oils which they contain. That, however, is to be done by the
way of decoction only, and not by distillation: because, though these oils
will swim on water, yet they will not rise in vapours without a greater
degree of heat.
When the essential oil is come over, if the plant be exposed to a naked fire,
without the addition of water, and the heat be increased a little, a phlegm
will rise that gradually grows acid; after which, if the heat be increased as
occasion requires, there will come over a thicker and heavier oil; from some
a volatile alkali; and last of all, a very thick, black, empyreumatic oil.
When nothing more rises with the strongest degree of heat, there remains of
the plant a mere coal only, called the Caput Mortuum, or Terra Damnata.
This coal when burnt falls into ashes, which, being lixiviated with water,
give a fixed alkali.
It is observable, that in the distillation of plants which yield an acid and a
volatile alkali, these two salts are often found quite distinct and separate in
the same receiver; which seems very extraordinary, considering that they
are naturally disposed to unite, and have a great affinity with one another.
The reason of this phenomenon is, that they are both combined with much
oil, which embarrasses them so that they cannot unite to form a neutral salt,
as they would not fail to do were it not for that impediment.
All vegetables, except such as yield a great deal of volatile alkali, being
burnt in an open fire, and so as to flame, leave in their ashes a large quantity
of an acrid, caustic, fixed alkali. But if care be taken to smother them, so as
to prevent their flaming while they burn, by covering them with something
that may continually beat down again what exhales, the salt obtained from
their ashes will be much less acrid and caustic; the cause whereof is, that
some part of the acid and oil of the plant being detained in the burning, and
stopped from being dissipated by the fire, combines with its alkali. These
salts crystallize, and, being much milder than the common fixed alkalis,

may be used in medicine, and taken internally. They are called Tachenius's
Salts, because invented by that Chymist.
Marine plants yield a fixed alkali analogous to that of sea-salt. As for all
other plants or vegetable substances, the fixed alkalis obtained from them, if
rightly prepared and thoroughly calcined, are all perfectly alike, and of the
very same nature.
The last observation I have to make on the production of fixed alkalis is,
that if the plant you intend to work upon be steeped or boiled in water
before you burn it, a much smaller quantity of salt will be obtained from it;
nay, it will yield none at all, if repeated boilings have robbed it entirely of
those saline particles which must necessarily concur with its earth to form a
fixed Alkali.

SECTION II.

The Analysis of Animal Substances.
Succulent animal substances, such as new-killed flesh, yield by expression
a juice or liquid, which is no other than the phlegm, replete with all the
principles of the animal body, except the earth, of which it contains but
little. The hard or dry parts, such as the horns, bones, &c. yield a similar
juice, by boiling them in water. These juices become thick, like a glue or
jelly, when their watery parts are evaporated; and, in this state, they are
truly extracts of animal matters. These juices afford no crystals of essential
salt, like those obtained from vegetables, and shew no sign either of an acid
or an alkali.
Great part of the oil which is in the flesh of animals may be easily separated
without the help of fire; for it lies in a manner by itself: it is commonly in a
concrete form, and is called Fat. This oil somewhat resembles the fat oils of
vegetables; for like them it is mild, unctuous, indissoluble in spirit of wine,
and is subtilized and attenuated by the action of fire. But there is not in
animals, as in vegetables, any light essential oil, which rises with the heat of
boiling water; so that, properly speaking, animals contain but one sort of
oil.

Few animal substances yield a perceptible acid. Ants and bees are almost
the only ones from which any can be obtained: and indeed the quantity they
yield is very small, as the acid itself is extremely weak.
The reason thereof is, that as animals do not draw their nourishment
immediately from the earth, but feed wholly either on vegetables or on the
flesh of other animals, the mineral acids, which have already undergone a
great change by the union contracted between them and the oily matters of
the vegetable kingdom, enter into a closer union and combination with
these oily parts while they are passing through the organs and strainers of
animals; whereby their properties are destroyed, or at least so impaired, that
they are no longer sensible.
Animal matters yield in distillation, first, a phlegm, and then, on increasing
the fire, a pretty clear oil, which gradually becomes thicker, blacker, more
fetid, and empyreumatic. It is accompanied with a great deal of volatile
alkali; and if the fire be raised and kept up till nothing more comes over,
there will remain in the distilling vessel a coal like that of vegetables;
except that when it is reduced to ashes, no fixed alkali, or at least very little,
can be obtained from them, as from the ashes of vegetables. This arises
from hence, that, as we said before, the saline principle in animals being
more intimately united with the oil than it is in plants, and being
consequently more attenuated and subtilized, is too volatile to enter into the
combination of a fixed alkali; on the contrary, it is more disposed to join in
forming a volatile alkali, which on this occasion does not rise till after the
oil, and therefore must certainly be the production of the fire. It must be
observed, that all we have hitherto said concerning the analysis of bodies
must be understood of such matters only as have not undergone any sort of
Fermentation.
The chyle and milk of animals which feed on plants still retain some
likeness to vegetables; because the principles of which these liquors are
composed have not gone through all the changes which they must suffer
before they enter into the animal combination.
Urine and sweat are excrementitious aqueous liquors, loaded chiefly with
the saline particles which are of no service towards the nourishment of the
animal, but pass through its strainers without receiving any alteration; such

as the neutral salts which have a fixed alkali for their basis, and particularly
the sea-salt, which happens to be in the food of animals, whether it exist
therein naturally, as it does in some plants, or whether the animals eat it to
please their palates.
The saliva, the pancreatic juice, and especially the bile, are saponaceous
liquors, that is, they consist of saline and oily particles combined together:
so that being themselves dissolved in an aqueous liquor, they are capable of
dissolving likewise the oily parts, and of rendering them miscible with
water.
Lastly, the blood being the receptacle of all these liquors partakes of the
nature of each, more or less in proportion to the quantity thereof which it
contains.

SECTION III.

The Analysis of Mineral Substances.
Minerals differ greatly from vegetables, and from animals; they are not near
so complex as those organized bodies, and their principles are much more
simple; whence it follows, that these principles are much more closely
connected, and that they cannot be separated without the help of fire; which
not having on their parts the same action and the same power as on
organized bodies, hath not the same ill effect on them; I mean the effect of
changing their principles, or even destroying them entirely.
I do not here speak of pure, vitrifiable, or refractory earths; of mere metals
and semi-metals; of pure acids; or even of their simplest combinations, such
as sulphur, vitriol, alum, sea-salt: of all these we have said enough.
We are now to treat of bodies that are more complex, and therefore more
susceptible of decomposition. These bodies are compound masses, or
combinations of those above-mentioned; that is, metallic substances as they
are found in the bowels of the earth, united with several sorts of sand,
stones, earths, semi-metals, sulphur, &c. When the metallic matter is
combined with other matters, in such a proportion to the rest that it may be
separated from them with advantage and profit, these compounds are called

Ores; when the case is otherwise, they are called Pyrites, and Marcasites;
especially if sulphur or arsenic be predominant therein, which often
happens.
In order to analyse an ore, and get out of it the metal it contains, the first
step is to free it from a great deal of earth and stones, which commonly
adhere to it very slightly and superficially. This is effected by pounding the
ore, and then washing it in water; to the bottom of which the metalline parts
presently sink, as being the heaviest, while the small particles of earth and
stone remain suspended some time longer.
Thus the metallic part is left combined with such matters only as are most
intimately complicated with it. These substances are most commonly
sulphur and arsenic. Now, as they are much more volatile than other
mineral matters, they may be dissipated in vapours, or the sulphur may be
consumed, by exposing the ore which contains them to a proper degree of
heat. If the sulphur and arsenic be desired by themselves, the fumes thereof
may be catched and collected in proper vessels and places. This operation is
called Roasting an Ore.
The metal thus depurated is now fit to be exposed to a greater force of fire,
capable of melting it.
On this occasion the semi-metals and the imperfect metals require the
addition of some matter abounding in phlogiston, particularly charcoal-dust;
because these metallic substances lose their phlogiston by the action of the
fire, or of the fluxes joined with them, and therefore without this precaution
would never acquire either the splendour or the ductility of a metal. By this
means the metallic substance is more accurately separated from the earthy
and stony parts, of which some portion always remains combined therewith
till it is brought to fusion. For, as we observed before, a metallic glass or
calx only will contract an union with such matters; a metal possessed of its
phlogiston and metalline form being utterly incapable thereof.
We took notice of the cause of this separation above, where we shewed that
a metal possessed of its phlogiston and metalline form will not remain
intimately united with any calcined or vitrified matter, not even with its
own calx or glass.

The metal therefore on this occasion gathers into a mass, and lies at the
bottom of the vessel, as being most ponderous; while the heterogeneous
matters float upon it in the form of a glass, or a semi-vitrification. These
floating matters take the name of Scoriæ, and the metalline substance at
bottom is called the Regulus.
It frequently happens, that the metalline regulus thus precipitated is itself a
compound of several metals mixed together, which are afterwards to be
separated. We cannot at present enter into a detail of the operations
necessary for that purpose: they will appear in our Treatise of Practical
Chymistry: but the principles on which they are founded may be deduced
from what we have said above, concerning the properties of the several
metals and of acids.
It is proper to observe, before we quit this subject, that the rules here laid
down for analysing ores are not absolutely general: for example, it is often
adviseable to roast the ore before you wash it; for by that means some ores
are opened, attenuated, and made very friable, which would cost much
trouble and expence, on account of their excessive hardness, if you should
attempt to pound them without a previous torrefaction.
It is also frequently necessary to separate the ore from part only of its stone;
sometimes to leave the whole; and sometimes to add more to it, before you
smelt it. This depends on the quality of the stone, which always helps to
promote fusion when it is in its own nature fusible and vitrifiable. It is then
called the Fluor of the ore: but of this we must say, as we did of the
preceding article, it is sufficient for our present purpose to lay down the
fundamental principles on which the reason of every process is built; the
description of the operations themselves being reserved for our second Part.
We shall now give a succinct account of the principal ores and mineral
bodies, contenting ourselves with just pointing out the particulars of which
they severally consist.
Of the Pyrites.
The yellow Pyrites.
The yellow Pyrites is a mineral consisting of sulphur, iron, an unmetallic
earth, and frequently a little copper: the sulphur, which is the only one of

these principles that is volatile, may be separated from the rest by
sublimation: it usually makes a fourth, and sometimes a third, of the whole
weight of these Pyrites. The other principles are separated from one another
by fusion and reduction with the phlogiston, which, by metallizing the
ferruginous and cupreous earths, parts them from the unmetallic earth: for
this earth vitrifies, and cannot afterwards continue united with metallic
matters possessed of their metalline form, as hath been said before.
There is yet another way of decomposing the yellow Pyrites, which is to let
it ly till it effloresces, or begins to shoot into flowers; which is nothing but a
sort of slow accension of the sulphur it contains. The sulphur being by this
means decomposed, its acid unites with the ferruginous and cupreous parts
of the Pyrites, and therewith forms green and blue vitriols; which may be
extracted by steeping in water the Pyrites which has effloresced or been
burnt, and then evaporating the lixivium to a pellicle; for by this means the
vitriol will shoot into crystals.
Sometimes the Pyrites contains also an earth of the same nature with that of
alum; a Pyrites of this sort, after flowering, yields alum as well as vitriol.
The white Pyrites.
The white Pyrites contains much arsenic, a ferruginous earth, and an
unmetallic earth. The arsenic, being a volatile principle, may be separated
by sublimation or distillation from the rest, which are fixed: and these again
may be disjoined from each other by fusion and reduction, as was said in
relation to the yellow Pyrites.
The Copper Pyrites.
The Copper Pyrites contains sulphur, copper, and an unmetallic earth. A
great deal thereof likewise holds arsenic, and its colour approaches more or
less to orange, yellow, or white, according to the quantity of arsenic in it. It
may be decomposed by the same means as the yellow and white Pyrites.
Of Ores.
Of Gold Ores.

Gold being constantly found in its metalline form, and never combined with
sulphur and arsenic, its matrices are not, properly speaking, ores; because
the metal contained in them is not mineralized. The gold is only lodged
between particles of stone, earth, or sand, from which it is easily separated
by lotion, and by amalgamation with quick-silver. The gold thus found is
seldom pure, but is frequently alloyed with more or less silver, from which
it is to be separated by quartation.
It is also very common to find gold in most ores of other metals or semi-
metals, and even in the Pyrites; but the quantity contained therein is
generally so small, that it would not pay the cost of extracting it. However,
if any should incline to attempt it, merely out of curiosity, it would be
necessary to begin with treating these ores in the manner proper for
separating their metalline part; then to cupel the metalline regulus so
obtained; and, lastly, to refine it by quartation.
Of Silver Ores.
It is no rare thing to find silver, as well as gold, in its metalline form, only
lodged in sundry earths and stony matters, from which it may be separated
in the same manner as gold. But the greatest quantities of this metal are
usually dug out of the bowels of the earth in a truly mineral state: that is,
combined with different substances, and particularly with sulphur and
arsenic.
Several silver ores are distinguished by peculiar characteristics, and are
accordingly denoted by particular names. That which is called the Vitreous
Silver Ore, is scarce any thing else but a combination of silver and sulphur.
Another is known by the name of the Horny Silver Ore, because when in
thin plates it is semi-transparent: in this ore the silver is mineralized by
sulphur and a little arsenic. The Red Silver Ore is of the colour which its
name imports, sometimes more, sometimes less vivid; and is chiefly
composed of silver, arsenic, and sulphur: it also contains a little iron.
These three ores are very rich in silver: the first contains nearly three
fourths of its weight, and the others about two thirds of theirs.
There is a fourth, called the White Silver Ore, which, though it be heavier, is
not so rich in silver, because it contains much copper. Many other minerals

contain silver, yet are not, properly speaking, silver ores; because a much
greater quantity of other metals than of silver is found in them.
When a silver ore is to be decomposed, in order to have the silver pure, or
when silver is to be extracted out of any ore that contains it, the first thing
to be done is to roast the ore, in order to clear it of the volatile minerals: and
as silver cannot be had pure without the operation of the cupel, which
requires more or less lead to be joined with it, it is usual to mix with the
torrified silver ore a quantity of lead, proportioned to that of the
heterogeneous matters combined with the silver, and to melt the whole
together. Part of the added lead vitrifies during the fusion, and at the same
time converts some of the heterogeneous matters also into glass, with which
it forms a scoria that rises to the surface of the matter. The other part of the
lead, with which the silver is mixed, falls to the bottom in the form of a
regulus, which must be cupelled in order to have the silver pure.
Of Copper Ores.
Copper is much seldomer found in a metalline form than gold or silver: it is
commonly in a mineral state: it is mineralized by sulphur and arsenic:
almost all its ores contain also more or less of iron; sometimes a little silver,
or even gold, together with unmetallic earths and stones, as all ores do.
Most copper ores are of a beautiful green or blue, or else in shades blended
of these two colours. The minerals called mountain green, and mountain
blue, are true copper ores; not in the form of hard stones, like other ores, but
crumbly and friable like earth.
Nevertheless, there are several copper ores of different colours, as ash-
coloured, whitish, and shaded with yellow or orange; which colours arise
from the different proportions of arsenic, sulphur, and iron, which these
ores contain.
In order to decompose a copper ore, and to extract the copper it contains, it
is first of all to be freed from as many of its earthy, stony, sulphureous, and
arsenical parts, as is possible, by roasting and washing; then what remains
is to be mixed with a flux, compounded of a fixed alkali and some
inflammable matter; a little sea-salt is to be put over all, and the whole
melted by a strong fire. The salts facilitate the fusion and scorification of

the unmetallic matters, and therewith form a slag, which being the lightest
rises to the surface. The metalline matters are collected below in the form of
a shining regulus of copper; which, however, is not usually fine copper, but
requires to be purified in the manner to be shewn in our second part.
In order to separate the copper from the unmetallic matters, it is absolutely
necessary to melt its ore along with inflammable substances abounding in
phlogiston. For, as this metal is not possessed of its metalline form while it
is in a mineral state, as it is destitute of the true quantity of phlogiston, and,
though it were not, would lose it by the action of the fire, it would come to
pass, that if its ore were melted without the addition of any inflammable
matter, the cupreous earth or calx would be scorified and confounded with
the unmetallic matters; and as all metallic matters, except gold and silver,
are subject to this inconvenience as well as copper, the addition of an
inflammable substance, in fluxing all ores that contain them, is a general
rule that ought constantly to be observed.
Of Iron Ores.
Iron is seldom found pure and malleable in the earth; yet it is much
seldomer found in the mineral state, properly so called, than any of the
other metals: for most iron ores are scarce any thing more than a
ferruginous earth mixed in different proportions with unmetallic earths and
stones. Some of them, however, contain also volatile minerals, such as
sulphur and arsenic; and therefore it is necessary to roast the iron ores, like
all others, before you attempt to extract the metal out of them. That being
done, they are to be smelted with a flux consisting of fusible and
inflammable matters, as the general rule directs.
Iron is the commonest of all metals: nay, it is so universally diffused
through the earth, that it is difficult to find any stone, earth, or sand, that
does not contain some of it; and therefore none of these are usually
considered and treated as iron ores, except such as contain a great deal of
that metal, and melt easily. The hematites, emery, yellow pyrites, calamine,
all contain a pretty considerable quantity of iron; but no body attempts to
extract it from them, because they are very hard to melt.
Ferruginous earth being naturally of an orange colour, a stone or earth may
be judged to contain iron, if either naturally, or after roasting, it appears to

have one shade of yellow or red.
The singular property which iron has of being attracted by the magnet, and
of being the only body, exclusive of all others, that is so, likewise affords us
an easy method of discovering the presence of this metal among other
matters, where it often exists in such a small quantity that it could not
otherwise be found out. For this purpose the body in which iron is
suspected to lurk, must be pulverised and torrefied with some inflammable
matter; and then the powder thus roasted being touched with a magnet, or
an animated bar, if it contains any particles of iron they will infallibly
adhere to the magnet or bar.
Of Tin Ores.
Tin is never found in the earth pure and malleable, but always in a mineral
state, and always mineralized by arsenic. Tin ores are not sulphureous;
whence it comes, that though tin be the lightest of all metals, its ores are
nevertheless heavier than those of other metals, as arsenic greatly exceeds
sulphur in gravity. Some tin ores contain also a little iron. The ores of tin
are to be washed, roasted, and smelted with a reducing flux, according to
the general rules.
Of Lead Ores.
Lead, like tin, is never found but in a mineral state. It is most commonly
mineralized by sulphur; yet there are some lead ores which also contain
arsenic.
Lead ores, as well as others, must be roasted and smelted with a reducing
flux: however, as it is difficult to free them from all their sulphur by
torrefaction only, the reducing flux employed in their fusion may be made
up with a quantity of iron filings, which being incapable of any union with
lead, and having a much greater affinity than that metal with sulphur, will,
on this occasion, be of great service by interposing between them.
Of Quick-silver Ores.
Running Mercury is sometimes found in certain earths, or grey, friable
stones; but most commonly in a mineral state. It is always mineralized by
sulphur, and by sulphur alone: so that cinabar is the only ore of quick-silver

that we know of; and a very rich one it is, seeing it contains six or seven
times as much mercury as sulphur.
Roasting can be of no use towards decomposing the ore of mercury, and
separating its sulphur; because mercury being itself very volatile would be
carried off by the fire together with the sulphur. In order, therefore, to part
the two substances of which cinabar consists, recourse must necessarily be
had to some third body, which will unite with one of them, and by that
means separate it from the other. Now all the metals, except gold, having a
greater affinity than mercury with sulphur, such a body is easily found: any
metal but gold may be employed with success in this decomposition; but as
iron hath a greater affinity with sulphur than any of the rest, and is
moreover the only one that cannot unite with mercury, it must, on account
of these two qualities, be preferred to all the rest.
Fixed alkalis are also well qualified to absorb the sulphur of cinabar.
Cinabar must be decomposed in close vessels, and by the way of
distillation; otherwise the mercury, as soon as it separates from the sulphur,
will be dissipated in vapours and entirely lost.
In this operation it is needless to add either flux or phlogiston; because the
cinabar is decomposed without melting, and the mercury, though in a
mineral state, contains, like gold and silver, all the phlogiston requisite to
secure its metalline properties.
Of the Ores of Regulus of Antimony.
Regulus of Antimony is always found in a mineral state: it is mineralized by
sulphur; but sometimes, though rarely, it is also combined with a little
arsenic.
When the ore of regulus of antimony is to be decomposed, the first thing to
be done is to expose it to a degree of heat too weak to melt its earthy and
stony parts, but strong enough to fuse its reguline, together with its
sulphureous parts, which by this means are separated from the earth, and
united into one mass, known by the name of Antimony.
It is plain that this first operation, which is founded on the great fusibility of
antimony, produces, with regard to the ore of regulus of antimony, the same
effect that washing hath on other ores: so that after this first fusion nothing

more is requisite to the obtaining of a pure regulus of antimony, but to
separate it from its sulphur by roasting, and to melt it with some matter
abounding in phlogiston, in the same manner as other metallic matters are
treated. The term Calcination is generally used to express this torrefaction
of antimony, by means whereof the metallic earth of the regulus of
antimony is separated from its sulphur.
As regulus of Antimony hath, like Mercury, much less affinity with sulphur
than the other metals have, it follows that antimony may be decomposed by
the same means as cinabar; but the regulus, so obtained, is adulterated with
a portion of the additament made use of, which combines therewith.
There is still another process employed for obtaining the regulus of
antimony: it consists, as was mentioned in its place, in detonating the
mineral with a mixture of nitre and tartar, applied in such a proportion that,
after the detonation has consumed the sulphur, there may remain so much
inflammable matter as will be sufficient to furnish the metalline earth of the
antimony with the phlogiston necessary to preserve its metallic properties.
But by this method less regulus is produced, than by calcining, or
torrefying, and reducing as usual.
Of the Ores of Bismuth.
The ore of Bismuth consists of the semi-metal mineralized by arsenic, and
of an unmetallic earth. It is very easy to decompose this ore, and to extract
the bismuth it contains: for this purpose it need only be exposed to a
moderate heat, whereby the arsenic will be dissipated in vapours, and the
bismuth melted, which will then separate from the unmetallic earth. This
earth, at least, in several ores of bismuth, possesses the property of tinging
all vitrifiable matters, with which it is melted, of a beautiful blue colour.
To decompose the ore of bismuth no flux or inflammable matter is used;
because this semi-metal is possessed, even in its mineral state, of all the
phlogiston requisite to maintain its metalline properties; and its great
fusibility makes it unnecessary to melt the unmetallic earth contained in its
ore.
Of the Ores of Zinc.

Zinc is not generally obtained from a particular ore of its own; but sublimes
during the fusion of a mineral, or rather a confused mass of minerals, that
contains this semi-metal together with iron, copper, lead, sulphur, arsenic,
and, like all other ores, an unmetallic earth.
Nevertheless, there is a substance which may be considered as the proper
ore of zinc, because it contains a pretty large quantity of that semi-metal, a
little iron, and an unmetallic earth. It is called Calamine, or Lapis
Calaminaris; but hitherto the art of procuring zinc directly from this
mineral hath no where been practised. Calamine is commonly employed
only to convert copper into brass, or a yellow metal, by cementing it
therewith. Indeed, till lately, no easy or practicable method of obtaining
pure zinc from calamine was publicly known; for that semi-metal being
volatile and very inflammable, its ore cannot be fused like others. Mr.
Margraaf was the first who, by mixing powdered charcoal with calamine in
close vessels, obtained a perfect zinc from it, by the means of distillation or
sublimation, as shall be shewn in our Practical Chymistry.
Of Arsenical Minerals.
Arsenic, as well as sulphur, is naturally combined with almost all ores, or
minerals containing metallic substances. As it is very volatile, while the
matters with which it is united are fixed, at least in comparison therewith, it
is easily separated by sublimation.
The minerals that contain most arsenic are the white pyrites, orpiment, and
cobalt. We have already considered the white pyrites: as to orpiment, it
consists of sulphur and arsenic. Both these substances being very volatile, it
is difficult to separate them by sublimation: yet, with proper management,
and a due regulation of the fire, this separation may be effected; because
sulphur sublimes a little more easily than arsenic. But it is more convenient,
as well as more expeditious, to make use of some additament that hath a
greater affinity with one of those substances than with the other. Fixed
alkalis and mercury, both of which have more affinity with sulphur than
with arsenic, may be very properly employed on this occasion.
Cobalt is a mineral composed of arsenic, an unmetallic earth, and frequently
bismuth: and as none of these are very volatile, except the arsenic, this may
be easily separated from the rest by sublimation. The unmetallic earth

which remains has, like that of the ore of bismuth, the property of giving a
blue colour to any vitrifiable matters melted with it; whence it is
conjectured, that cobalt and the ore of bismuth have a great resemblance, or
are often blended with each other. Nevertheless, Mr. Brant, an ingenious
Swedish Chymist, insists that they are very different: he pretends that the
metallic substance contained in the true cobalt is a semi-metal of a peculiar
nature, which hath been erroneously confounded with bismuth: and indeed
he proves by a great number of curious experiments, related in the Memoirs
of the Academy of Upsal, that these two metallic substances have properties
that are essentially different: to that which is obtained from cobalt, he gives
the name of Regulus of Cobalt.
Besides the minerals already recited, there is found in the bowels of the
earth another species of compound body, of which we have already taken
notice; but which is supposed, with some degree of probability, to belong as
much to the vegetable as to the mineral kingdom: I mean the Bitumens;
which the best observations oblige us to consider as vegetable oils, that by
lying long in the earth have contracted an union with the mineral acids, and
by that means acquired the thickness, consistence, and other properties
observable in them.
By distillation they yield an oil, and an acid not unlike a mineral acid. Mr.
Bourdelin has even demonstrated, by a very artful and ingenious process,
that amber contains a manifest acid of sea-salt. See the Memoirs of the
Royal Academy of Sciences.

CHAP. XVII.

Explanation of the Table of Affinities.
t hath been shewn in the course of this work, that the causes of almost all

I the phenomena, which Chymistry exhibits, are deducible from the
mutual affinities of different substances, especially the simplest. We have
already explained (Chap. II.) what is meant by affinities, and have laid
down the principal laws to which the relations of different bodies are
subject. The late Mr. Geoffroy, one of the best Chymists we have had, being
convinced of the advantages which all who cultivate Chymistry would
receive from having constantly before their eyes a state of the best
ascertained relations between the chief agents in Chymistry, was the first
who undertook to reduce them into order, and unite them all in one point of
view, by means of a table. We are of opinion, with that great man, that this
Table will be of considerable use to such as are beginning to study
Chymistry, in helping them to form a just idea of the relations which
different substances have with one another; and that the practical Chymist
will thereby be enabled to account for what passes in several of his
operations, otherwise difficult to be understood, as well as to judge what
may be expected to result from mixtures of different compounds. These
reasons have induced us to insert it at the end of this Elementary Treatise,
and to give a short explanation of it here; especially as it will serve, at the
same time, for a recapitulation of the whole work, in which the several
axioms of this Table are dispersed.
You have it here just as it was drawn up by Mr. Geoffroy, without any
addition or alteration. I own, however, that it might be improved both ways:
for since the death of that great Chymist many experiments have been
made, some of which have discovered new affinities, and others have raised
exceptions to some of those laid down by him. But several reasons dissuade
me from publishing a new Table of Affinities, containing all the
emendations and innovations that might be made in the old one.
The first is, that many of the affinities lately discovered are not yet
sufficiently verified, but, on the contrary, subject to be contested: in short,

they are perhaps liable to more considerable objections, and exceptions,
than the other.
The second is, that as Mr. Geoffroy's Table contains all the fundamental
affinities, it is more suitable to an Elementary Treatise than a much fuller
one would be; seeing this would necessarily suppose the knowledge of
many things not treated of by us, and of which it was not proper to say any
thing in such a book as this.
However, as it is essential to our purpose that we lead none into error, we
shall take care in explaining the affinities delivered by Mr. Geoffroy, to
mention the principal objections and exceptions to which they are liable: we
shall, moreover, add a very few new ones, confining ourselves to such only
as are elementary and well ascertained.
The upper line of Mr. Geoffroy's Table, comprehends several substances
used in Chymistry. Under each of those substances are ranged in distinct
columns several matters compared with them, in the order of their relation
to that first substance; so as that which is the nearest to it is that which hath
the greatest affinity with it, or that which none of the substances standing
below it can separate therefrom; but which, on the contrary, separates them
all when they are combined with it, and expels them in order to join itself
therewith. The same is to be understood of that which occupies the second
place of affinity; that is, it has the same property with regard to all below it,
yielding only to that which is above it: and so of all the rest.
At the top of the first column stands the character which denotes an Acid in
general. Immediately under this stands the mark of a Fixed Alkali, being
placed there as the substance which has the greatest affinity with an Acid.
After the Fixed Alkali appears the Volatile Alkali, whose affinity with Acids
yields only to the Fixed Alkali. Next come the Absorbent Earths; and last of
all Metallic Substances. Hence it follows, that when a Fixed Alkali is united
with an acid it cannot be separated therefrom by any other substance; that a
Volatile Alkali united with an Acid cannot be separated from it by any thing
but a Fixed Alkali; that an Absorbent Earth combined with an acid may be
separated from it either by a Fixed or by a Volatile Alkali; and lastly, that
any Metallic Substance combined with an Acid may be separated from it by
a Fixed Alkali, a Volatile Alkali, or an Absorbent Earth.

There are many important remarks to be made on this first column. First, it
is making the rule too general to say that any Acid whatever has a greater
affinity with a Fixed Alkali, than with any other substance. And indeed Mr.
Geoffroy himself hath made an exception with respect to the Vitriolic Acid;
for in the fourth column, at the head of which stands that Acid, we find the
sign of the Phlogiston placed above that of the Fixed Alkali, as having a
greater affinity than the Fixed Alkali with the Vitriolic Acid. This is founded
on the famous experiment, wherein Vitriolated Tartar and Glauber's Salt are
decompounded by means of the Phlogiston, which separates the Fixed
Alkalis of these Neutral Salts, and uniting with the Vitriolic Acid contained
in them forms therewith a Sulphur.
Secondly, Nitre deflagrates, and is decomposed, by the contact of any
inflammable matter whatever that is actually ignited; and the operation
which produces Phosphorus is no other than a decomposition of sea-salt,
whose Acid quits its Alkaline basis to join with the Phlogiston: now these
facts furnish very strong reasons for believing that both these Acids, as well
as the Vitriolic, have a stronger affinity with the Phlogiston than with a
Fixed Alkali. Lastly, as several experiments shew the Vegetable Acids to be
only the Mineral Acids disguised and mortified, there are sufficient grounds
for suspecting that Acids in general have a greater affinity with the
Phlogiston than with Fixed Alkalis: so that instead of making an exception
with regard to the Vitriolic Acid, it would perhaps be better to lay down this
greater affinity as common to all Acids whatever, and to place the
Phlogiston in the first column, immediately under the character which
denotes an Acid in general. This theory, however, stands in need of
confirmation from other experiments[4].
Thirdly, in this same column the character of a Volatile Alkali is set above
that of an Absorbent Earth, as having a greater affinity with Acids; and yet
these Absorbent Earths decompose the Ammoniacal salts, drive away the
Volatile Alkali from the Acids, and assume its place. This is one of the first
objections made against Mr. Geoffroy's Table. His answer thereto is printed
in the Memoirs of the Academy of Sciences for 1718, where his Table also
is to be found. We have already declared our opinion about this matter in
treating of a Volatile Alkali.

Fourthly, in 1744, Mr. Geoffroy, brother to the author of the Table, who
hath done no less honour to Chymistry than that eminent physician, gave in
a Memoir containing an exception to the last affinity in the first column;
namely, that which places Absorbent Earths above Metallic substances. He
therein shews, that Alum may be converted into Copperas by boiling it in
iron vessels; that, on this occasion, the iron precipitates the Earth of the
Alum, separates it from its Acid, and assumes its place; so that of course it
must have a greater affinity, than the Absorbent Earth of Alum, with the
Vitriolic Acid.
At the head of the second column stands the character of the Marine Acid,
which signifies that the affinities of this Acid are the subject of the column.
Immediately below it is placed the mark of Tin. As this is a metalline
substance, and as the first column places metalline substances in the lowest
degree of affinity with all Acids, it is plain we must suppose Fixed Alkalis,
Volatile Alkalis, and Absorbent Earths, to be placed here in order after the
Marine Acid, and before Tin. Tin, then, is of all Metalline substances that
which has the greatest affinity with the Marine Acid; and then follow
Regulus of Antimony, Copper, Silver, Mercury. Gold comes last of all; and
there are no less than two vacant places above it. By this means it is in some
sort excluded from the rank of substances that have an affinity with the
Marine Acid. The reason thereof is, that this Acid alone is not capable of
dissolving Gold and combining therewith, necessarily requiring for that
purpose the aid of the Nitrous Acid, or at least of the Phlogiston.
The third column exhibits the affinities of the Nitrous Acid, the character
whereof stands at its head. Immediately below it is the sign of Iron, as the
metal which has the greatest affinity with this Acid; and then follow other
metals, each according to the degree of its relation; to wit, Copper, Lead,
Mercury, and Silver. In this column, as in the preceding one, we must
suppose the substances, which in the first column stand above Metallic
substances, to be placed in their proper order before Iron.
The fourth column is intended to represent the Affinities of the Vitriolic
Acid. Here Mr. Geoffroy has placed the Phlogiston as the substance which
has the greatest affinity with this Acid, for the reason given in our
explanation of the first column. Below it he has ranked Fixed Alkalis,
Volatile Alkalis, and Absorbent Earths, to shew that this is an exception to

the first column. As to Metalline substances, he has set down but three,
being those with which the Vitriolic Acid has the most perceptible affinity:
these metals, placed in the order of their affinities, are Iron, Copper, and
Silver.
The fifth column shews the affinities of Absorbent Earths. As these Earths
have no sensible affinity but with Acids, this column contains only the
characters of the Acids ranked according to the degree of their strength, or
affinity with the Earths; to wit, the Vitriolic, the Nitrous, and the Marine
Acids. Underneath this last might be placed the Acid of Vinegar, or the
Vegetable Acid.
The sixth column expresses the Affinities of Fixed Alkalis with Acids,
which are the same with those of Absorbent Earths. Moreover, we find
Sulphur placed here below all the Acids; because Liver of Sulphur, which is
a combination of Sulphur with a Fixed Alkali, is actually decompounded by
any Acid: for any Acid precipitates the Sulphur and unites with the Alkali.
Immediately over the Sulphur, or in the same square with it, might be set a
mark denoting the Volatile Sulphureous Spirit; because, like Sulphur, it has
less affinity than any other Acid with Fixed Alkalis. Oils might also be
ranked with Sulphur, because they unite with Fixed Alkalis, and therewith
form Soaps, which are decompounded by any acid whatever.
The seventh column points out the affinities of Volatile Alkalis, which are
likewise the same as those of Absorbent Earths; and the Vegetable Acid
might be placed here also under the Marine Acid.
The eighth column specifies the affinities of Metallic substances with
Acids. The affinities of the Acids, which, with respect to Fixed Alkalis,
Volatile Alkalis, and Absorbent Earths, succeeded each other uniformly, do
not appear in the same order here. The Marine Acid, instead of being placed
below the Vitriolic and Nitrous Acids, stands, on the contrary, at their head;
because, in fact, this Acid separates Metalline substances from all the other
Acids with which they happen to be united, and, forcing these Acids to quit
possession, intrudes into their place. Nevertheless, this is not a general rule;
for several Metalline substances must be excepted, particularly Iron and
Copper.

The ninth column declares the affinities of Sulphur. Fixed Alkalis, Iron,
Copper, Lead, Silver, Regulus of Antimony, Mercury, and Gold, stand
below it in the order of their affinities. With regard to Gold it must be
observed, that it will not unite with pure Sulphur: it suffers itself to be
dissolved only by the Liver of Sulphur, which is known to be a composition
of Sulphur and Fixed Alkali.
At the head of the tenth column appears Mercury, and beneath it several
Metalline substances, in the order of their affinities with it. Those Metalline
substances are Gold, Silver, Lead, Copper, Zinc, and Regulus of Antimony.
It is proper to remark on this column, that Regulus of Antimony, which
stands the lowest, unites but very imperfectly with Mercury; and that after a
seeming union of these two Metallic substances hath been obtained, by a
tedious triture with the addition of water, they do not continue long united,
but spontaneously separate from each other in a short time. Iron and Tin are
here excluded; the former with great reason, because hitherto it hath not
been clearly proved, by any known experiment, that ever Mercury was
united with Iron: but the same objection cannot be made to Tin, which
amalgamates very well with Mercury, and might therefore be placed in this
column nearly between Lead and Copper. I use the word nearly, because
the different degrees of affinity between Metalline substances and Mercury
are not so exactly determined, as the other relations before considered;
seeing they generally unite with it, without excluding one another. We can
therefore scarce judge of the degree of affinity that belongs to each, but by
the greater or less readiness of each to amalgamate therewith.
The eleventh column shews, that Lead has a greater affinity with Silver than
with Copper.
The twelfth, that Copper has a greater affinity with Mercury than with
Calamine.
The thirteenth, that Silver has a greater affinity with Lead than with Copper.
The fourteenth contains the affinities of Iron. Regulus of Antimony stands
immediately underneath it, as being the Metallic substance which has the
greatest affinity with it. Silver, Copper, and Lead, are placed together in the

next square below, because the degrees of affinity which those metals have
with Iron are not exactly determined.
The same is to be said of the fifteenth column: Regulus of Antimony stands
at its head; Iron is immediately below it; and below the Iron the same three
metals occupy one square as before.
Lastly, the sixteenth column indicates that Water has a greater affinity with
Spirit of Wine than with Salts. By this general expression must not be
understood any Saline substance whatever; but only the Neutral Salts,
which Spirit of Wine frees from the water that kept them in solution. Fixed
Alkalis, on the contrary, as well as the Mineral Acids, have a greater affinity
than Spirit of Wine with water: so that these Saline substances, being well
dephlegmated, and mixed with Spirit of Wine; imbibe the water it contains
and rectify it.
To these might be added another short column, having Spirit of Wine at its
head: immediately below it should be the character of Water, and below that
the mark of Oil. This column would shew that the Spirit of Wine has a
greater affinity with Water than with Oils; because any Oily matter
whatever, that is dissolved in Spirit of Wine, may be actually separated
from it by the affusion of Water. This rule admits of no exception but in one
case; which is when the oily substance partakes of the nature of soap, by
having contracted an union with some saline matter. But as this must be
imputed wholly to that adventitious saline matter being superadded to the
oily substance, it is no just foundation for an exception, and the affinity in
question is nevertheless general.
We have now delivered every thing material that we had to say concerning
Mr. Geoffroy's Table of Affinities. It is, as we observed before, of exceeding
great service, as it collects into one view the principal truths laid down in
this Treatise. Indeed the most advantageous way of using it is, not to delay
consulting it till you have read the book through, but to turn to it while you
are reading, as oft as any affinity between bodies is treated of; which it will
imprint more strongly on your mind, by representing it in a manner before
your eyes.

CHAP. XVIII.

The Theory of Constructing the Vessels most commonly used in
Chymistry.
hymists cannot perform the operations of their art without the help of a

C considerable number of vessels, instruments, and furnaces, adapted to
contain the bodies on which they intend to work, and to apply to them
the several degrees of heat required by different processes. It is therefore
proper, before we advance to the operations themselves, to consider
particularly and minutely what relates to the instruments with which they
are to be performed.
Vessels intended for Chymical Operations should, to be perfect, be able to
bear, without breaking, the sudden application of great heat and great cold;
be impenetrable to every thing, and unalterable by any solvent;
unvitrifiable, and capable of enduring the most violent fire without melting:
but hitherto no vessels have been found with all these qualities united.
They are made of sundry materials; namely, of metal, of glass, and of earth.
Metalline vessels, especially those made of Iron or Copper, are apt to be
corroded by almost every saline, oily, or even aqueous substance. For this
reason, in order to render the use of them a little more extensive, they are
tinned on the inside. But, notwithstanding this precaution, they are on many
occasions not to be trusted; and should never be employed in any nice
operations which require great accuracy: they are, moreover, incapable of
resisting the force of fire.
Earthen vessels are of several sorts. Some, that are made of a refractory
earth, are capable of being suddenly exposed to a strong fire without
breaking, and even of sustaining a great degree of heat for a considerable
time: but they generally suffer the vapours of the matters which they
contain, as well as vitrified metals, to pass through them, especially the
glass of lead, which easily penetrates them and runs through their pores as
through a sieve. There are others made of an earth that, when well baked,
looks as if it were half vitrified: these being much less porous, are capable
of retaining the vapours of the matters which they contain, and even glass

of lead in fusion; which is one of the severest trials a vessel can be put to:
but then they are more brittle than the other sort.
Good glass vessels should constantly be employed in preference to all
others, whenever they can possibly be used: and that not only because they
are no way injured by the most active solvents, nor suffer any part of what
they contain to pass through, but also because their transparency allows the
Chymist to observe what passes within them: which is always both curious
and useful. But it is pity that vessels of this sort should not be able to endure
a fierce fire without melting. We shall take care, when we come to describe
the several sorts of chymical instruments, and the manner of using them, to
note what vessels are to be preferred to others on different occasions.
Distillation, as hath been already said, is an operation by which we separate
from a body, by the help of a gradual heat, the several principles of which it
consists.
There are three methods of distilling. The first is performed by applying the
heat over the body whose principles are to be extracted. In this case, as the
liquors, when heated and converted into vapours, constantly endeavour to
fly from the center of heat, they are forced to re-unite in the lower part of
the vessel, that contains the matter in distillation, and so passing through the
pores or holes of that vessel, they fall into another cold vessel applied
underneath to receive them. This way of distilling is on this account called
distilling per Descensum. It requires no other apparatus than two vessels
figured like segments of hollow spheres, whereof that which is pierced with
little holes, and intended to contain the matter to be distilled, should be
much less than the other, which is to contain the fire, and to fill its aperture
exactly; the whole together to be supported vertically upon a third vessel,
which is to serve the purpose of a recipient, admitting into its mouth the
convex bottom of the vessel containing the matter to be distilled, which
must accurately fill it. This method of distilling is but little used.
The second method of distilling is performed by applying the heat
underneath the matter to be decomposed. On this occasion the liquors being
heated, rarefied, and converted into vapours, rise, and are condensed in a
vessel contrived for that purpose, which we shall presently describe. This
way of distilling is called distilling per Ascensum, and is much used.

The vessel in which this distillation per Ascensum is performed we call an
Alembic.
There are several sorts thereof, differing from one another both in the
matter of which, and the manner in which, they are made.
Those employed to draw the odoriferous waters and essential oils of plants
are generally made of copper, and consist of several pieces. The first, which
is designed to contain the plant, is formed nearly like a hollow cone, the
vertex whereof is drawn out in the shape of a hollow cylinder or tube: this
part is named the Cucurbit, and its tube the Neck of the Alembic. To the
upper end of this tube another vessel is soldered: this is called the Head,
and commonly has likewise the form of a cone, joined to the neck of the
alembic by its base, round which, on the inside, is hollowed a small groove,
communicating with an orifice that opens at its most depending part. To this
orifice is soldered a small pipe in a direction sloping downwards, which is
called the Nose, Spout, or Beak of the alembic.
As soon as the matters contained in the alembic grow hot, vapours begin to
arise from them, and ascending through the neck of the alembic into the
head, are by the sides thereof stopped and condensed: from thence they
trickle down in little streams to the groove, which conveys them to the
spout; and by that they pass out of the alembic into a glass vessel with a
long neck, the end of the spout being introduced into that neck, and luted
thereto.
To facilitate the refrigeration and condensation of the vapours circulating in
the head, all alembics of metal are moreover provided with another piece,
which is a kind of large pan of the same metal, fitted and soldered round the
head. This piece serves to keep cold water in, which incessantly cools the
head, and therefore it is called the Refrigeratory. The water in the
refrigeratory itself grows hot after some time, and must therefore be
changed occasionally; the heated water being first drawn off by means of a
cock fixed near the bottom of the refrigeratory. All copper alembics should
be tinned on the inside for the reasons already given.
When saline spirits are to be distilled, alembics of metal must not be used;
because the saline vapours would corrode them. In this case recourse must
be had to alembics of glass. These consist of two pieces only; namely, a

Cucurbit, whose superior orifice is admitted into and exactly luted with its
Head, which is the second piece.
In general, as alembics require that the vapours of the matter to be distilled
should rise to a considerable heighth, they ought to be used only when the
most volatile principles are to be drawn from bodies: and the lighter and
more volatile the substances to be separated by distillation are, the taller
must the alembic be; because the most ponderous parts, being unable to rise
above a certain heighth, fall back again into the cucurbit as soon as they
arrive there, leaving the lighter to mount alone, whose volatility qualifies
them to ascend into the head.
When a matter is to be distilled, that requires a very tall alembic, and yet
does not admit of a metalline vessel, the end will be best answered by a
glass vessel of a round or oval shape, having a very long neck, with a small
head fitted to its extremity. Such a vessel serves many purposes: it is
sometimes employed as a receiver, and at other times as a digesting vessel;
on which last occasion it goes under the name of a Matrass. When one of
these, provided with a head, is applied to the purpose of distilling, it forms a
sort of alembic.
There are some alembics of glass, blown in such a manner by the workmen,
that the body and head form but one continued piece. As these alembics do
not stand in need of having their several pieces luted together, they are very
useful on some occasions, when such exceeding subtile vapours rise as are
capable of transpiring through lutes. The head must have an aperture at the
top, provided with a short tube, through which, by means of a funnel with a
long pipe, the matter to be distilled may be introduced into the cucurbit.
This is to be exactly closed with a glass stopple, the surface whereof must
be made to fit the inside of the tube in every point, by rubbing those two
pieces well together with emery.
Another sort of alembic hath also been invented, which may be used with
advantage when Cohobation is required; that is, when the liquor obtained
by distillation is to be returned upon the matter in the cucurbit; and
especially when it is intended that this cohobation shall be repeated a great
number of times. The vessel we are speaking of is constructed exactly in the
same manner as that last described; except that its beak, instead of being in

a straight line, as in the other alembics, forms a circular arch, and re-enters
the cavity of the cucurbit, in order to convey back again the liquor collected
in the head. This instrument hath commonly two beaks opposite to each
other, both turned in this manner, and is called a Pelican: it saves the artist
the trouble of frequently unluting and reluting his vessels, as well as the
loss of a great many vapours.
There are certain substances which in distillation afford matters in a
concrete form, or rise wholly in the form of a very light powder, called
Flowers. When such substances are to be distilled, the cucurbit which
contains them is covered with a head without a nose, which is named a
Blind-head.
When the flowers rise in great quantities and very high, a number of heads
is employed to collect them; or rather a number of a kind of pots, consisting
of a body only without any bottom, which fitting one into the other form a
canal, that may be lengthened or shortened at pleasure, according as the
flowers to be sublimed are more or less volatile. The last of the heads,
which terminates the canal, is quite close at one end, and makes a true
blind-head. These vessels are called Aludels; they are usually of earthen or
stone ware.
All the vessels above-mentioned are fit only for distilling such light volatile
matters as can be easily raised and brought over; such as phlegm, essential
oils, fragrant waters, acid oily spirits, volatile alkalis, &c. But when the
point is to procure by distillation principles that are much less volatile, and
incapable of rising high, such as the thick fetid oils, the vitriolic, the nitrous,
and the marine acids, &c. we are under a necessity of having recourse to
other vessels, and another manner of distilling.
It is easy to imagine, that such a vessel must be much lower than the
alembic. It is indeed no more than a hollow globe, whose upper part
degenerates into a neck or tube, that is bent into a horizontal position; for
which reason this instrument is called a Retort: it is always of one single
piece.
The matter to be distilled is introduced into the body of the retort by means
of a ladle with a long tubular shank. Then it is set in a furnace built
purposely for this use, and so that the neck of the retort coming out of the

furnace may, like the nose of the alembic, stand in a sloping position, to
facilitate the egress of the liquors, which by its means are conveyed to a
receiver, into which it is introduced, and with which it is luted. This way of
distilling, in which the vapours seem rather to be driven out of the vessel
horizontally and laterally, than raised up and sublimed, is for that reason
called Distillation per Latus.
Retorts are, of all the instruments of distillation, those that must sustain the
greatest heat, and resist the strongest solvents; and therefore they must not
be made of metal. Some, however, which are made of iron may do well
enough on certain occasions: the rest are either of glass or earth. Those of
glass, for the reasons above given, are preferable to the other sort, in all
cases where they are not to be exposed to such a force of fire as may melt
them. The best glass, that which stands both heat and solvents best, is that
in which there are fewest alkaline salts. Of this sort is the green German
glass: the beautiful white crystal glass is far from being equally serviceable.
Retorts, as well as alembics, may be of different forms. For example, some
matters are apt to swell, and rise over the neck of the retort in substance,
without suffering any decomposition; when such matters are to be distilled
in a retort, it is proper that the body of the vessel, instead of being globular,
be drawn out into the form of a pear, so as nearly to resemble that of a
cucurbit. In a retort of this kind, the distance between the bottom and the
neck being much greater than in those whose bodies are spherical, the
matters contained have much more room for expansion; so that the
inconvenience here mentioned is thereby prevented. Retorts of this form are
called English retorts. As they hold the middle place between alembics and
common retorts, they may be used to distil such matters as have a mean
degree of volatility between the greatest and the least.
It is moreover proper to have, in a laboratory, sundry retorts with necks of
different diameters. Wide necks will be found the fittest for conveying thick
matters, and such as readily become fixed; for instance, some very thick
fetid oils, butter of antimony, &c.; for as these matters acquire a consistence
as soon as they are out of the reach of a certain degree of heat, they would
soon choak a narrow neck, and by stopping the vapours which rise at the
same time from the retort, might occasion the bursting of the vessels.

Some retorts are also made with an opening on their upper side, like that of
tubulated glass alembics, which is to be closed in the same manner with a
glass stopple. These retorts are also called Tubulated retorts, and ought
always to be used whenever it is necessary to introduce fresh matter into the
retort during the operation; seeing it may be done by means of this
invention, without unluting and reluting the vessels; which ought always to
be avoided as much as possible.
One of the things that most perplexes the Chymists, is the prodigious
elasticity of many different vapours, which are frequently discharged with
impetuosity during the distillation, and are even capable of bursting the
vessels with explosion, and with danger to the artist. On such occasions it is
absolutely necessary to give these vapours vent, as we shall direct in its
proper place: but as that can never be done without losing a great many of
them; as some of them in particular are so elastic that scarce any at all
would remain in the vessel; for instance, those of the spirit of nitre, and
especially those of the smoking spirit of salt; the practice is to make use of
very large receivers, of about eighteen or twenty inches diameter, that the
vapours may have sufficient room to circulate in, and by applying to the
wide surface presented them by the extensive inside of such a large vessel,
may be condensed into drops. These huge receivers are commonly in the
form of hollow globes, and are called Ballons.
To give these vapours still more room, ballons have been contrived with
two open gullets in each, diametrically opposite to one another; whereof
one admits the neck of the retort, and the other is received by one of the
gullets of a second ballon of the same form, which is joined in like manner
to a third, and so on. By this artifice the space may be enlarged at pleasure.
These ballons with two necks are called Adopters.
Operations on bodies that are absolutely fixed, as metals, stones, sand, &c.
require only such vessels as are capable of containing those bodies, and
resisting the force of fire. These vessels are little hollow pots, of different
dimensions, which are called Crucibles. Crucibles can hardly be made of
any thing but earth; they ought to have a cover of the same material fitted to
shut them close. The best earth we know is that whereof those pots are
made in which butter is brought from Bretagne: these pots themselves are

exceeding good crucibles; and they are almost the only ones that are
capable of holding glass of lead in fusion, without being penetrated by it.
For the roasting of ores, that is, freeing them, by the help of fire, from their
sulphureous and arsenical parts, little cups of the same material with
crucibles are used; but they are made flat, shallow, and wider, above than
below, that these volatile matters may the more freely exhale. These vessels
are called Tests, or Scorifiers: they are scarce ever used but in the
Docimastic art, that is, in making small Assays of ores.

CHAP. XIX.

The Theory of Constructing the Furnaces most commonly used in
Chymistry.
in conducting and applying fire properly, and determining its
S
kill
different degrees, is of very great consequence to the success of
Chymical operations.
As it is exceeding difficult to govern and moderate the action of fire, when
the vessels in which any operation is performed are immediately exposed to
it, Chymists have contrived to convey heat to their vessels, in nice
operations, through different mediums, which they place occasionally
between those vessels and the fire.
Those intermediate substances in which they plunge their vessels are called
Baths. They are either fluid or solid: the fluid baths are water or its vapours.
When the distilling vessel is set in water, the bath is called Balneum Mariæ,
or the Water Bath; and the greatest degree of heat of which it is susceptible
is that of boiling water. When the vessel is exposed only to the vapours
which exhale from water, this forms the Vapour Bath; the heat of which is
nearly the same with that of the Balneum Mariæ. These baths are useful for
distilling essential oils, ardent spirits, sweet-scented waters; in a word, all
such substances as cannot bear a greater heat, without prejudice either to
their odour, or to some of their other qualities.
Baths may also be made of any other fluids, such as oils, mercury, &c.
which are capable of receiving and communicating much more heat: but
they are very seldom used. When a more considerable degree of heat is
required, a bath is prepared of any solid matter reduced to a fine powder,
such as sand, ashes, filings of iron, &c. The heat of these baths may be
pushed so far as to make the bottom of the vessel become faintly red. By
plunging a thermometer into the bath, by the side of the vessel, it is easy to
observe the precise degree of heat applied to the substance on which you
are working. It is necessary that the thermometers employed on this
occasion be constructed on good principles, and so contrived as to be easily
compared with those of the most celebrated natural philosophers. Those of

the illustrious Réaumur are most used and best known, so that it would not
be amiss to give them the preference. When a greater heat is required than
any of those baths can give, the vessels must be set immediately on live
coals, or in a flaming fire: this is called working with a naked fire; and, in
this case it is much more difficult than in the other to determine the degrees
of heat.
There are several ways of applying a naked fire. When the heat or flame is
reflected upon the upper part of a vessel which is exposed to the fire, this is
called a Reverberated heat. A Melting heat is that which is strong enough to
fuse most bodies. A Forging heat is that of a fire which is forcibly excited
by the constant blast of a pair of bellows, or more.
There is also another sort of fire which serves very commodiously for many
operations, because it does not require to be fed or frequently mended: this
is afforded by a lamp with one or more wicks, and may be called a Lamp-
heat. It is scarce ever employed but to heat baths, in operations which
require a gentle and long continued warmth: if it hath any fault, it is that of
growing gradually hotter.
All the different ways of applying fire require Furnaces of different
constructions: we shall therefore describe such as are of principal and most
necessary use.
Furnaces must be divided into different parts or stories, each of which has
its particular use and name.
The lower part of the furnace, designed for receiving the ashes and giving
passage to the air, is called the Ash-hole. The ash-hole is terminated above
by a grate, the use of which is to support the coals and wood, which are to
be burnt thereon: this part is called the Fire-place. The fire-place is in like
manner terminated above by several iron bars, which lie quite across it from
right to left, in lines parallel to each other: the use of these bars is to sustain
the vessels in which the operations are to be performed. The space above
these bars to the top of the furnace is the upper story, and may be called the
Laboratory of the furnace. Lastly, some furnaces are quite covered above by
means of a kind of vaulted roof called the Dome.

Furnaces have moreover several apertures: one of these is at the ash-hole,
which gives passage to the air, and through which the ashes that fall through
the grate are raked out; this aperture is called the ash-hole Door: another is
at the fire-place, through which the fire is supplied with fuel, as occasion
requires; this is called the mouth or door of the Fire-place, or the Stoke-
hole: there is a third in the upper story, through which the neck of the vessel
passes; and a fourth in the dome for carrying off the fuliginosities of
combustible matters, which is called the Chimney.
To conclude, there are several other openings in the several parts of the
furnace, the use whereof is to admit the air into those places, and also, as
they can be easily shut, to incite or slacken the activity of the fire, and so to
regulate it; which has procured them the title of Registers. All the other
openings of the furnace should be made to shut very close, the better to
assist in governing the fire; by which means they likewise do the office of
registers.
In order to our forming a just and general idea of the construction of
furnaces, and of the disposition of the several apertures in them, with a view
to increase or diminish the activity of the fire, it will be proper to lay down,
as our ground-work, certain principles of natural philosophy, the truth of
which is demonstrated by experience.
And first, every body knows that combustible matters will not burn or
consume unless they have a free communication with the air; insomuch that
if they be deprived thereof, even when burning most rapidly, they will be
extinguished at once: that consequently combustion is greatly promoted by
the frequent accession of fresh air, and that a stream of air, directed so as to
pass with impetuosity through burning fuel, excites the fire to the greatest
possible activity.
Secondly, it is certain that the air which touches, or comes near ignited
bodies is heated, rarefied, and rendered lighter than the air about it, that is,
farther distant from the center of heat; and consequently that this air, so
heated and become lighter, is necessarily determined thereby to ascend and
mount aloft, in order to make room for that which is less heated and not so
light, which by its weight and elasticity tends to occupy the place quitted by
the other. Another consequence hereof is, that if fire be kindled in a place

enclosed every where but above and below, a current of air will be formed
in that place, running in a direction from the bottom to the top; so that if any
light bodies be applied to the opening below, they will be carried up
towards the fire; but, on the contrary, if they be held at the opening above,
they will be impelled by a force which will drive them up, and carry them
away from the fire.
Thirdly and lastly, it is a truth demonstrated in hydraulics, that the velocity
of a given quantity of any fluid, determined to flow in any direction
whatever, is so much the greater the narrower the channel is to which that
fluid is confined; and consequently that the velocity of a fluid will be
increased by making it run from a wider through a narrower passage.
These principles being established, it is easy to apply them to the
construction of furnaces. First, if a fire be kindled in the fire-place of a
furnace, which is open on all sides, it burns nearly as if it were in the open
air. It has with the surrounding air a free communication; so that fresh air is
continually admitted to facilitate the entire combustion of the inflammable
matters employed as fuel. But there being nothing to determine that air to
pass with rapidity through the fire in this case, it does not at all augment the
activity thereof, but suffers it to waste away quietly.
Secondly, if the ash-hole or dome of a furnace, in which a fire is burning, be
shut quite close, then there is no longer any free communication between
the air and the fire: if the ash-hole be shut, the air is debarred from having
free access to the fire; if the dome be stopt, the egress of the air rarefied by
the fire is prevented; and consequently the fire must in either case burn very
faintly and slowly, gradually die away, and at last go quite out.
Thirdly, if all the openings of the furnace be wholly closed, it is evident that
the fire will be very quickly extinguished.
Fourthly, if only the lateral openings of the fire-place be shut, leaving the
ash-hole and upper part of the furnace open; it is plain that the air entering
by the ash-hole will necessarily be determined to go out at top, and that
consequently a current of air will be formed, which will pass through the
fire, and make it burn briskly and vigorously.

Fifthly, if both the ash-hole and the upper story of the furnace be of some
length, and form canals either cylindric or prismatic, then the air being kept
in the same direction through a longer space, the course of its stream will be
both stronger and better determined, and consequently the fire will be more
animated by it.
Sixthly and lastly, if the ash-hole and the upper part of the furnace, instead
of being cylindric or prismatic canals, have the form of truncated cones or
pyramids, standing on their bases, and so ordered that the upper opening of
the ash-hole, adjoining to the fire-place, may be wider than the base of the
superiour cone or pyramid, then the stream of air, being forced to pass
incessantly from a larger channel through a smaller, must be considerably
accelerated, and procure to the fire the greatest activity which it can receive
from the make of a furnace.
The materials fittest for building furnaces are, 1. Bricks, joined together
with potters clay mixed with sand and moistened with water. 2. Potters clay
mingled with potsherds, moistened with water, and baked in a violent fire.
3. Iron; of which all furnaces may be made, with this precaution, that the
inside be provided with a great many prominent points, as fastenings for a
coat of earth, with which the internal parts of the furnace must necessarily
be covered to defend it from the action of the fire.
The reverberating furnace is one of those that are most employed in
Chymistry: it is proper for distillations by the retort, and should be
constructed in the following manner.
First, the use of the ash-hole being, as was said, to give passage to the air
and to receive the ashes, no bad consequence can attend its being made
pretty high: it may have from twelve to twenty or twenty-four inches in
heighth. Its aperture should be wide enough to admit billets of wood, when
a great fire is to be made.
Secondly, the ash-hole must be terminated at its upper part by an iron grate,
the bars of which should be very substantial, that they may resist the action
of the fire: this grate is the bottom of the fire-place, and destined to support
the coals. In the lateral part of the fire-place, and nearly about the same
heighth with the grate, there should be a hole of such a size that it may
easily admit charcoal, as well as little tongs and shovels for managing the

fire. This aperture or mouth of the fire-place should be perpendicularly over
the mouth of the ash-hole.
Thirdly, from six to eight or ten inches high above the grate over the ash-
hole, little apertures must be made in the walls of the furnace, of eight or
ten lines in diameter, an inch from one another, and those in one side must
be diametrically opposite to those in the other. The use of these holes is to
receive bars of iron for the retort to rest on; which should be, as I said, at
different heights, in order to accommodate retorts of different sizes. At the
upper extremity of this part of the furnace, which reaches from the iron bars
to the top, the heighth whereof should be somewhat less than the width of
the furnace, must be cut a semi-circular aperture for the neck of the retort to
come through. This hole must by no means be over the doors of the fire-
place and ash-hole; for then, as it gives passage to the neck of the retort, it
must of course be opposite to the receiver, and in that case the receiver itself
would stand over against those two apertures; which would be attended
with this double inconvenience, that the receiver would not only grow very
hot, but greatly embarrass the operator, whose free access to the fire-place
and ash-hole would be thereby obstructed. It is proper therefore that the
semi-circular cut we are speaking of be so placed that when the greatest
ballons are luted to the retort they may leave an open passage to the fire-
place and ash-hole.
Fourthly, in order to cover in the laboratory of the reverberating furnace,
there must be a roof made for it in the form of a cupola, or concave
hemisphere, having the same diameter as the furnace. This dome should
have a semi-circular cut in its rim, answering to that above-directed to be
made in the upper extremity of the furnace, so that, when adjusted to each
other, the two together may form a circular hole for the neck of the retort to
pass through. At the top of this dome there must also be a circular hole of
three or four inches diameter, carrying a short tapering funnel of the same
diameter, and three inches high, which will serve for a chimney to carry off
all fuliginosities, and accelerate the current of the air. This passage may be
shut at pleasure with a flat cover. Moreover, as it is necessary that the dome
should be taken off and put on with ease, it should have two ears or handles
for that purpose: a portative or moveable furnace should also have a pair of
handles, fixed opposite to each other, between the ash-hole and the fire-
place.

Sixthly and lastly, a conical canal must be provided of about three feet long,
and sufficiently wide at its lower end to admit the funnel of the aperture at
the top of the dome. This conical tube is to be applied to the dome when the
fire is required to be extremely active: it tapers gradually from its base
upwards, and breaks off as if truncated at top, where it should be about two
inches wide.
Besides the apertures already mentioned as necessary to a reverberating
furnace, there must also be many other smaller holes made in its ash-hole,
fire-place, laboratory, and dome, which must all be so contrived as to be
easily opened and shut with stopples of earth: these holes are the registers
of the furnace, and serve to regulate the activity of the fire, according to the
principles before laid down.
When the action of the fire is required to be exactly uniform and very brisk,
it is necessary to stop carefully with moist earth all the little chinks in the
juncture of the dome with the furnace, between the neck of the retort and
the circular hole through which it passes, and which it never fills exactly,
and, lastly, the holes which receive the iron bars that sustain the retort.
It is proper to have, in a laboratory, several reverberating furnaces of
different magnitudes; because, they must be proportioned to the size of the
retorts employed. The retort ought to fill the furnace, so as to leave only the
distance of an inch between it and the inside of the furnace.
Yet when the retort is to be exposed to a most violent fire, and especially
when it is required that the heat shall act with equal force on all parts of the
furnace, and as strongly on its vault as on its bottom, a greater distance
must be left between the retort and the inside of the furnace; for then the
furnace may be filled with coals, even to the upper part of the dome. If
moreover some pieces of wood be put into the ash-hole, the conical canal
fitted on to the funnel of the dome, and all the apertures of the furnace
exactly closed, except the ash-hole and the chimney, the greatest heat will
then be excited that this furnace can produce.
The furnace now described may also be employed in many other chymical
operations. If the dome be laid aside, an alembic may very well be placed
therein: but then the space, which will be left between the body of the
alembic and the top of the upper part of the furnace, must be carefully filled

up with Windsor-loam moistened; for without that precaution the heat will
soon reach the very head, which ought to be kept as cool as possible, in
order to promote the condensation of the vapours. On this occasion
therefore it will be proper to leave no holes open in the fire-place, but the
lateral ones; of which also those over-against the receiver must be stopped.
A pot, or broad-brimmed earthen pan, may be placed over this furnace, and
being so fitted to it as to close the upper part thereof accurately, and filled
with sand, may serve for a sand-heat to distil with.
The bars designed to support distilling vessels being taken out, a crucible
may stand therein, and many operations be performed that do not require
the utmost violence of fire. In a word, this furnace is one of the most
commodious that can be, and more extensively useful than any other.
The Melting furnace is designed for applying the greatest force of heat to
the most fixed bodies, such as metals and earths. It is never employed in
distilling: it is of no use but for calcination and fusion; and consequently
need not admit any vessels but crucibles.
The ash-hole of this furnace differs from that of the reverberating furnace
only in this, that it must be higher, in order to raise the fire-place to a level
with the artist's hand; because in that all the operations of this furnace are
performed. The ash-hole therefore must be about three feet high: and this
heighth procures it moreover the advantage of a good draught of air. For the
same reason, and in consequence of the principles we laid down, it should
be so built that its width lessening insensibly from the bottom to the top, it
may be narrower where it opens into the fire-place than any where below.
The ash-hole is terminated at its upper end, like that of the reverberating
furnace, by a grate, which serves for the bottom of the fire-place, and ought
to be very substantial, that it may resist the violence of the fire. The inside
of this furnace is commonly an elliptic curve; because it is demonstrated by
mathematicians that surfaces having that curvature reflect the rays of the
sun, or of fire, in such a manner, that meeting in a point, or a line, they
produce there a violent heat. But, to answer this purpose, those surfaces
must be finely polished; an advantage hardly procurable to the internal
surface of this furnace, which can be made of nothing but earth: besides, if
it were possible to give it a polish, the violent action of the fire that must be

employed in this furnace would presently destroy it. Yet the elliptical figure
must not be entirely disregarded: for, if care be taken to keep the internal
surface of the furnace as smooth as possible, it will certainly reflect the heat
pretty strongly, and collect it about the center.
The fire-place of this furnace ought to have but four apertures.
First, that of the lower grate, which communicates with the ash-hole.
Secondly, a door in its fore-side, through which may be introduced coals,
crucibles, and tongs for managing them: this aperture should be made to
shut exactly with a plate of iron, having its inside coated with earth, and
turning on two hinges fixed to the furnace.
Thirdly, over this door a hole slanting downwards, towards the place where
the crucible is to stand. The use of this hole is to give the operator an
opportunity of examining the condition of the matters contained in his
crucible without opening the door of the fire-place: this hole should be
made to open and shut easily, by means of a stopple of earth.
Fourthly, a circular aperture of about three inches wide in the upper part or
vault of the furnace, which should gradually lessen and terminate, like that
of the dome of the reverberating furnace, in a short conical funnel of about
three inches long, and fitted to enter the conical pipe before described,
which is applied when the activity of the fire is to be increased.
When this furnace is to be used, and a crucible to be placed in it, care must
be taken to set on the grate a cake of baked earth, somewhat broader than
the foot of the crucible. The use of this stand is to support the crucible, and
raise it above the grate, for which purpose it should be two inches thick.
Were it not for this precaution the bottom of the crucible, which would
stand immediately on the grate, could never be thoroughly heated, because
it would be always exposed to the stream of cold air which enters by the
ash-hole. Care should also be taken to heat this earthen bottom red-hot
before it be placed in the furnace, in order to free it from any humidity,
which might otherwise happen to be driven against the crucible during the
operation, and occasion its breaking.
We omitted to take notice, in speaking of the ash-hole, that, besides its door,
it should have about the middle of its heighth a small hole, capable of

receiving the nosel of a good perpetual bellows, which is to be introduced
into it and worked, after the door is exactly shut, when it is thought proper
to excite the activity of the fire to the utmost violence. The Forge is only a
mass of bricks of about three feet high, along whose upper surface is
directed the nose or pipe of a pair of large perpetual bellows, so placed that
the operator may easily blow the fire with one hand. The coals are laid on
the hearth of the forge near the nose of the bellows; they are confined, if
necessary, to prevent their being carried away by the wind of the bellows,
within a space inclosed by bricks; and then by pulling the bellows the fire is
continually kept up in its greatest activity. The forge is of use when there is
occasion to apply a great degree of heat suddenly to any substance, or when
it is necessary that the operator be at liberty to handle frequently the matters
which he proposes to fuse or calcine.
The Cupelling furnace is that in which gold and silver are purified, by the
means of lead, from all alloy of other metallic substances. This furnace
must give a heat strong enough to vitrify lead, and therewith all the alloy
which the perfect metals may contain. This furnace is to be built in the
following manner.
First, of thick iron plates, or of some such composition of earth as we
recommended for the construction of furnaces, must be formed a hollow
quadrangular prism, whose sides may be about a foot broad, and from ten to
eleven inches high; and extending from thence upwards may converge
towards the top, so as to form a pyramid truncated at the heighth of seven or
eight inches, and terminated by an aperture of the width of seven or eight
inches every way. The lower part of the prism is terminated, and closed, by
a plate of the same materials of which the furnace is constructed.
Secondly, in the fore-side or front of this prism there is an opening of three
or four inches in heighth, by five or six inches in breadth: this opening,
which should be very near the bottom, is the door of the ash-hole.
Immediately over this opening is placed an iron grate, the bars of which are
quadrangular prisms of half an inch square, laid parallel to each other, and
about eight or nine inches asunder, and so disposed that two of their angles
are laterally opposite, the two others looking one directly upwards and the
other downwards. As in this situation the bars of the grate present to the
fire-place very oblique surfaces, the ashes and very small coals do not

accumulate between them, or hinder the free entrance of the air from the
ash-hole. This grate terminates the ash-hole at its upper part, and serves for
the bottom of the fire-place.
Thirdly, three inches, or three and a half, above the grate, there is in the
fore-side of the furnace another opening, terminated by an arch for its upper
part, which consequently has the figure of a semi-circle: it ought to be four
inches wide at bottom, and three inches and an half high at its middle. This
opening is the door of the fire-place; yet it is not intended for the same uses
as the door of the fire-place in other furnaces: the purpose for which it is
actually destined shall be explained when we come to shew how the furnace
is to be used. An inch above the door of the fire-place, still in the fore-side
of the furnace, are two holes of about an inch diameter, and at the distance
of three inches and a half from each other, to which answer two other holes
of the same size, made in the hinder part, directly opposite to these. There
is, moreover, a fifth hole of the same width about an inch above the door of
the fire-place. The design of all these holes shall be explained when we
describe the manner in which these furnaces are to be used.
Fourthly, the fore-part of the furnace is bound by three iron braces, one of
which is fixed just below the door of the ash-hole; the second occupies the
whole space between the ash-hole door and the door of the fire-place, and
has two holes in it, answering to those which we directed to be made in the
furnace itself about this place; and the third is placed immediately over the
door of the fire-place. These braces must extend from one corner of the
front of the furnace to the other, and be fastened thereto with iron pins, in
such a manner that their sides next to the doors may not lie quite close to
the body of the furnace, but form a kind of grooves for the iron plates to
slide in, that are designed to shut the two doors of the furnace when it is
necessary. Each of these iron plates should have a handle, by which it may
be conveniently moved; and to each door there should be two plates, which
meeting each other, and joining exactly in the middle of the door-place,
may shut it very close. Each of the two plates belonging to the door of the
fire-place ought to have a hole in its upper part; one of these holes should
be a slit of about two lines wide, and half an inch long; the other may be a
semi-circular opening of one inch in heighth and two in breadth. These
holes should be placed so that neither of them may open into the fire-place

when the two plates are joined together in the middle of the door to shut it
close.
Fifthly, to terminate the furnace above, there must be a pyramid formed of
the same materials with the furnace, hollow, quadrangular, three inches high
on a base of seven inches, which base must exactly fit the upper opening of
the furnace: the top of this pyramidal cover must end in a tube of three
inches in diameter and two in heighth, which must be almost cylindrical,
and yet a little inclining to the conical form. This tube serves, as in the
furnaces already described, to carry the conical funnel, which is fitted to the
upper part when a fire of extraordinary activity is wanted.
The furnace thus constructed is fit to serve all the purposes for which it is
designed: yet before it can be used another piece must be provided, which,
though it does not properly belong to the furnace, is nevertheless necessary
in all the operations performed by it; and that is a piece contrived to contain
the cupels, or other vessels which are to be exposed to the fire in this
furnace. It is called a Muffle, and is made in the following manner.
On an oblong square, of four inches in breadth, and six or seven in length, a
concave semi-cylinder is erected, in the form of a vault, which makes a
semi-circular canal, open at both ends. One of these is almost entirely
closed, except that near the bottom two small semi-circular holes are left. In
each of its sides likewise two such holes are made, and the other end is left
quite open.
The Muffle is intended to bear and communicate the fiercest heat; and
therefore it must be made thin, and of an earth that will resist the violence
of fire, such as that of which crucibles are made. The Muffle being thus
constructed, and then well baked, is fit for use.
When it is to be used it must be put into the furnace by the upper opening,
and set upon two iron bars, introduced through the holes made for that
purpose below the door of the fire-place. The Muffle must be placed on
these bars in the fire-place in such a manner that its open end shall stand
next to, and directly against the door of the fire-place, and may be joined to
it with lute. Then the cupels are ranged in it, and the furnace is filled up, to
the heighth of two or three inches above the Muffle, with small coals not
bigger than a walnut, to the end that they may lie close round the Muffle,

and procure it an equal heat on every side. The chief use of the Muffle is to
prevent the coals and ashes from falling into the cupels, which would be
very prejudicial to the operations carrying on in them: for the lead would
not vitrify as it ought, because the immediate contact of the coals would
continually restore its phlogiston; or else the glass of lead, which ought to
penetrate and pass through the cupels, would be rendered incapable of so
doing; because the ashes mixing therewith would give it such a consistence
and tenacity as would destroy that property, or at least considerably lessen
it. The openings, therefore, which are left in the lower part of the Muffle,
should not be so high as to admit coals or ashes to get into the cupels; the
use of them is to procure an easier passage for the heat and the air to those
vessels. The Muffle is left quite open in its fore-part, that the operator may
be at liberty to examine what passes in the cupels, to stir their contents, to
remove them from one place to another, to convey new matters into them,
&c. and also to promote the free access of the air, which must concur with
the fire towards the evaporation necessary to the vitrification of lead; which
air, if fresh were not often enough admitted, would be incapable of
producing that effect; because it would soon be loaded with such a quantity
of vapours that it could not take up any more.
The government of the fire in this furnace is founded on the general
principles above laid down for all furnaces. Yet as there are some little
differences, and as it is very essential to the success of the operations for
which this furnace is intended, that the artist should be absolutely master of
his degree of heat, we shall in few words shew how that may be raised or
lowered.

When the furnace is filled with coals and kindled, if the door of the ash-hole
be set wide open, and that of the fire-place shut very close, the force of the
fire is increased; and if, moreover, the pyramidal cover be put on the top,
and the conical funnel added to it, the fire will become still more fierce.
Seeing the matters contained in this furnace are encompassed with fire on
all sides, except in the fore-part opposite to the door of the fire-place, and as
there are occasions which require that the force of the fire should be applied
to this part also, an iron box, of the shape and size of the door, hath been
contrived to answer that purpose. This box is filled with lighted coals, and
applied immediately to the door-place, by which means the heat there is
considerably augmented. This help may be made use of at the beginning of
the operation, in order to accelerate it, and bring the heat sooner to the
desired degree; or in case a very fierce heat be required; or at a time when
the air being hot and moist will not make the fire burn with the necessary
vigour.
The heat may be lessened by removing the iron box, and shutting the door
of the fire-place quite close. It may be still further and gradually
diminished, by taking off the conical funnel from the top; by shutting the
door of the fire-place with one of its plates only, that which has the least, or
that which has the greatest aperture in it; by taking off the pyramidal cover;
by shutting the ash-hole door wholly or in part; and, lastly, by setting the
door of the fire-place wide open: but, in this last case, the cold air
penetrates into the cavity of the Muffle, and refrigerates the cupels more
than is almost ever necessary. If it be observed, during the operation, that
the Muffle grows cold in any particular part, it is a sign there is a vacuity
left by the coals in that place: in this case an iron wire must be thrust into
the furnace, through the hole which is over the door of the fire-place, and
the coals stirred therewith, so as to make them fall into their places and fill
up the vacant interstices.
It is proper to observe, that, besides what has been said concerning the ways
of increasing the activity of the fire in the cupelling furnace, several other
causes also may concur to procure to the matters contained in the Muffle a
greater degree of heat: for example, the smaller the Muffle is, the wider and
more numerous the holes in it are; the nearer to its bottom, or further end,

the cupels are placed, the more will the matters therein contained be
affected with heat.
Besides the operations to be performed by the cupel, this furnace is very
useful, and even necessary, for many chymical experiments; such, for
instance, as those relating to sundry vitrifications and enamelling. As it is
pretty low, the best way is to place it, when it is to be used, on a base of
brick-work that may raise it to a level with the operator's hand.
A Lamp-furnace is exceeding useful for all operations that require only a
moderate, but long-continued, degree of heat. The furnace for working with
a lamp-heat is very simple: it consists only of a hollow cylinder, from
fifteen to eighteen inches high, and five or six in diameter, having at its
bottom an aperture large enough for a lamp to be introduced and withdrawn
with ease. The lamp must have three or four wicks, to the end that by
lighting more or fewer of them a greater or less degree of heat may be
produced. The body of the furnace must moreover have several small holes
in it, in order to supply the flame of the lamp with air enough to keep it
alive.
On the top of this furnace stands a bason five or six inches deep, which
ought to fill the cavity of the cylinder exactly, and to be supported at its
circumference by a rim which may entirely cover and close the furnace: the
use of this bason is to contain the sand through which the lamp-heat is
usually conveyed.
Besides this, there must be a kind of cover or dome made of the same
material with the furnace, and of the same diameter with the sand-bath,
without any other opening than a hole, nearly circular, cut in its lower
extremity. This dome is a sort of reverberatory, which serves to confine the
heat and direct it towards the body of the retort; for it is used only when
something is to be distilled in a vessel of this fashion; and then the hole at
its bottom serves for a passage to the neck of the retort. This dome should
have an ear or handle, for the conveniency of putting it on and taking it off
with ease.
Of Lutes.

Chymical vessels, especially such as are made of glass, and the earthen
vessels commonly called stone-ware, are very subject to break when
exposed to sudden heat or cold: whence it comes, that they often crack
when they begin to heat, and also when being very hot they happen to be
cooled, either by fresh coals thrown into the furnace, or by the access of
cold air. There is no way to prevent the former of these accidents, but by
taking the pains to warm your vessel very slowly, and by almost insensible
degrees. The second may be avoided by coating the body of the vessel with
a paste or lute, which being dried will defend it against the attacks of cold.
The fittest stuff for coating vessels is a composition of fat earth, Windsor-
loam, fine sand, filings of iron, or powdered glass, and chopped cow's hair,
mixed and made into a paste with water. This lute serves also to defend
glass vessels against the violence of the fire, and to prevent their melting
easily.
In almost all distillations it is of great consequence, as hath been said, that
the neck of the distilling vessel be exactly joined with that of the receiver
into which it is introduced, in order to prevent the vapours from escaping
into the air and so being lost: and this junction is effected by means of a
lute.
A few slips of paper applied round the neck of the vessels with common
size will be sufficient to keep in such vapours as are aqueous or not very
spirituous.
If the vapours are more acrid, or more spirituous, recourse may be had to
slips of bladder long steeped in water, which containing a sort of natural
glue, close the junctures of the vessels very well.
If it be required to confine vapours of a still more penetrating nature, it will
be proper to employ a lute that quickly grows very hard; particularly a paste
made with quick-lime and any sort of jelly, whether vegetable or animal;
such as the white of an egg, stiff size, &c. This is an excellent lute, and not
easily penetrated. It is also used to stop any cracks or fractures that happen
to glass vessels. But it is not capable of resisting the vapours of mineral acid
spirits, especially when they are strong and smoking: for that purpose it is
necessary to incorporate the other ingredients thoroughly with fat earth
softened with water; and even then it frequently happens that this lute is

penetrated by acid vapours, especially those of the spirit of salt, which of all
others are confined with the greatest difficulty.
In such cases its place may be supplied with another, which is called Fat
Lute, because it is actually worked up with fat liquors. This lute is
composed of a very fine cretaceous earth, called tobacco-pipe clay,
moistened with equal parts of the drying oil of lint-seed, and a varnish made
of amber and gum copal. It must have the consistence of a stiff paste. When
the joints of the vessels are closed up with this lute, they may, for greater
security, be covered over with slips of linen smeared with the lute made of
quick-lime and the white of an egg.
Chymical vessels are liable to be broken in an operation by other causes
besides the sudden application of heat or cold. It frequently happens, that
the vapours of the matters exposed to the action of fire rush out with such
impetuosity, and are so elastic, that, finding no passage through the lute
with which the joints of the vessels are closed, they burst the vessels
themselves, sometimes with explosion and danger to the operator.
To prevent this inconvenience, it is necessary that in every receiver there be
a small hole, which being stopped only with a little lute may easily be
opened and shut again as occasion requires. It serves for a vent-hole to let
out the vapours, when the receiver begins to be too much crowded with
them. Nothing but practice can teach the artist when it is requisite to open
this vent. If he hits the proper time, the vapours commonly rush out with
rapidity, and a considerable hissing noise; and the vent should be stopped
again as soon as the hissing begins to grow faint. The lute employed to stop
this small hole ought always to be kept so ductile, that, by taking the figure
of the hole exactly, it may entirely stop it. Besides, if it should harden upon
the glass, it would stick so fast that it would be very difficult to remove it
without breaking the vessel. This danger is easily avoided by making use of
the fat lute, which continues pliant for a long time, when it is not exposed to
an excessive heat.
This way of stopping the vent-hole of the receiver has yet another
advantage: for if the hole be of a proper width, as a line and half, or two
lines, in diameter, then, when the vapours are accumulated in too great a
quantity, and begin to make a great effort against the sides of the receiver,

they push up the stopple, force it out, and make their way through the vent-
hole: so that, by this means, the breaking of the vessels may always be
certainly prevented. But great care must be taken that the vapours be not
suffered to escape in this manner, except when absolute necessity requires
it; for it is generally the very strongest and most subtile part of a liquor
which is thus dissipated and lost.
Heat being the chief cause that puts the elasticity of the vapours in action,
and prevents their condensing into a liquor, it is of great consequence in
distillation that the receiver be kept as cool as possible. With this view a
thick plank should be placed between the receiver and the body of the
furnace, to intercept the heat of the latter, and prevent its reaching the
former. As the vapours themselves rise very hot from the distilling vessel,
they soon communicate their heat to the receiver, and especially to its upper
part, against which they strike first. For this reason it is proper that linen
cloths, dipt in very cold water, be laid over the receiver, and frequently
shifted. By this means the vapours will be considerably cooled, their
elasticity weakened, and their condensation promoted.
By what hath been said in this first part, concerning the properties of the
principal agents in Chymistry, the construction of the most necessary
vessels and furnaces, and the manner of using them, we are sufficiently
prepared for proceeding directly to the operations, without being obliged to
make frequent and long stops, in order to give the necessary explanations
on those heads.
Nevertheless, we shall take every proper occasion to extend the theory here
laid down, and to improve it by the addition of several particulars, which
will find their places in our Treatise of Chymical Operations.

ELEMENTS
OF THE
PRACTICE of CHYMISTRY;
WHEREIN
The Fundamental Operations are described, and illustrated by Observations
on each Process.

ELEMENTS
OF THE
PRACTICE OF CHYMISTRY.

INTRODUCTION.

s the Elements of the Theory of Chymistry, delivered in the former
A part of this work, were intended for the use of persons supposed to be
altogether unacquainted with the art, they could not properly admit of
any thing more than fundamental principles, so disposed as constantly to
lead from the simple to the compound, from things known to things
unknown: for which reason I could not therein observe the usual order of
Chymical Decomposition, which is not susceptible of such a method. I

therefore supposed all the analyses made, and bodies reduced to their
simplest principles; to the end that, by observing the chief properties of
those primary elements, we might be enabled to trace them through their
several combinations, and to form some sort of judgment a priori of the
qualities of such compounds as may result from their junctions.
But this latter part is of a different nature. It is a practical Treatise, intended
to contain the manner of performing the principal Operations of Chymistry;
the operations which serve as standards for regulating all the rest, and
which confirm the fundamental truths laid down in the Theory.
As these operations consist almost wholly of analyses and decompositions,
there can be no doubt concerning the order proper to be observed in giving
an account of them: it evidently coincides with that of the analysis itself.
But as all bodies, which are the subjects of Chymical operations, are
divided by nature into three classes or kingdoms, the mineral, the vegetable,
and the animal, the analysis thereof may naturally be divided into three
branches: some difference may also arise from the different order in which
these three may be treated of.
As the reasons assigned for beginning with one kingdom rather than with
another have never been thoroughly canvassed, and may perhaps seem
equally good when viewed in a particular light, Chymical writers differ in
their opinions on this point. For my part, without entering into a discussion
of the motives which have determined others to follow a different order, I
shall only produce the reasons that led me to begin with the mineral
kingdom, to examine the vegetable in the second place, and to conclude
with the animal.
First, then, seeing vegetables draw their nourishment from minerals, and
animals derive theirs from vegetables, the bodies which constitute these
three kingdoms seem to be generated the one by the other, in a manner that
determines their natural rank.
Secondly, this disposition procures us the advantage of tracing the
principles, from their source in the mineral kingdom, down to the last
combinations into which they are capable of entering, that is, into animal

matters; and of observing the successive alterations they undergo in passing
out of one kingdom into another.
Thirdly and lastly, I look upon the analysis of minerals to be the easiest of
all; not only because they consist of fewer principles than vegetables and
animals, but also because almost all of them are capable of enduring the
most violent action of fire, when that is necessary to their decomposition,
without any considerable change or diminution of their principles, to which
those of other substances are frequently liable.
Besides, I am not singular in this distribution of the three classes of bodies,
which are the subjects of the chymical analysis: as it is the most natural, it
has been adopted by several authors, or rather by most who have published
Treatises of Chymistry. But there is something peculiarly my own in the
manner wherein I have treated the analysis of each kingdom. In the mineral
kingdom, for instance, will be found a considerable number of operations
not to be met with in other Treatises of Chymistry; the authors having
probably considered them as useless, or in some measure foreign, to the
purpose of Elementary Books, and as constituting together a distinct art. I
mean the processes for extracting saline and metallic substances from the
minerals containing them.
Yet, if it be considered that salts, metals, and semi-metals are far from being
produced by nature in a state of perfection, or in that degree of purity which
they are commonly supposed to have when they are first treated of in Books
of Chymistry; but that, on the contrary, these substances are originally
blended with each other, and adulterated with mixtures of heterogeneous
matters, wherewith they form compound minerals; I imagine it will be
allowed, that the operations by which these minerals are decomposed, in
order to extract the metals, semi-metals, and other simpler substances,
especially as they are founded on the most curious properties of these
substances, are so far from being useless or foreign to the purposes of an
Elementary Treatise, that they are, on the contrary, absolutely necessary
thereto.
After I had made these reflections, I could not help thinking that an analysis
of minerals, which should treat of saline and metallic substances, without
taking any notice of the manner in which their matrices must be analysed,

in order to extract them, would be no less defective than a treatise of the
analysis of vegetables, in which Oils, essential Salts, fixed and volatile
Alkalis, should be amply treated of, without saying one word of the manner
of analysing the plants from which these several substances are obtained. I
therefore thought myself indispensably obliged to describe the manner of
decomposing every ore or mineral, before I attempted to treat of the saline
or metallic substance which it yields.
For example: as the Vitriolic Acid, with the consideration of which I begin
my Mineral Analysis, is originally contained in Vitriol, Sulphur, and Alum;
and as these substances again derive their origin from the sulphureous and
ferruginous Pyrites, the first operations I describe under this head are the
processes for decomposing the Pyrites in order to extract its Vitriol,
Sulphur, and Alum. I then proceed to the particular analysis of each of these
substances, with a view to extract their Vitriolic Acid; and afterwards
deliver, in their order, the other operations usually performed on this Acid.
Thus it appears, that this saline substance occasions my describing the
analyses of the Pyrites, Vitriol, Sulphur, and Alum. The whole of the
Treatise on Minerals proceeds on the same plan.
The operations by which we decompose ores and minerals are of two sorts:
those employed in working by the great, and those for trying in small the
yield of any ore. These two manners of operating are sometimes a little
different; yet in the main they are the same, because they are founded on the
same principles, and produce the same effects.
As my chief design was to describe the operations that may be conveniently
performed in a laboratory, I have preferred the processes for small assays:
especially as they are usually performed with more care and accuracy than
the operations in great works: and here I must acknowledge, that I am
obliged to M. Cramer's Docimasia, or Art of Assaying, for all the operations
of this kind in my analysis of minerals. As M. Hellot's work on that subject
did not appear till after I had finished this, M. Cramer's Docimasia, in
which sound Theory is joined with accurate practice, was the best book of
the kind I could at that time consult. I therefore preferred it to all others;
and as I have not quoted it in my analysis of minerals, because the
quotations would have been too frequent, let what I say here serve for a
general quotation. I have been careful to name, as often as occasion

required, the other authors whose processes I have borrowed: it is a tribute
justly due to those who have communicated their discoveries to the public.
Though I have told the reader that in my analysis of minerals he will find
the processes for extracting out of each the saline or metallic substances
contained in it, yet he must not expect that this book will instruct him in all
that is necessary he should know to be able to determine, by an accurate
assay, the contents of every mineral. My intention was not to compose a
Treatise of Assaying; and I have taken in no more than was absolutely
necessary to make the analysis of minerals perfectly understood, and to
render it as complete as it ought to be in an Elementary Treatise. I have
therefore described only the principal operations relating thereto; the
operations which are fundamental, and which, as I said before, are to serve
as standards for the rest, abstracted from such additional circumstances as
are of consequence only to the Art of Assaying, properly so called.
Such therefore as are desirous of being fully instructed in that Art, must
have recourse to those works which treat professedly of the subject; and
particularly to that published by M. Hellot: a performance most esteemed
by such as are best skilled in Chymistry, and rendered so complete by the
numerous and valuable observations and discoveries of the Author, that
nothing better of the kind can be wished for. I thought it proper to give
these notices in relation to my analysis of minerals; and shall now proceed
to shew the plan of my analyses of vegetables and of animals.
Seeing all vegetable matters are susceptible of fermentation, and when
analysed after fermentation, yield principles different from those we obtain
from them before they are fermented, I have divided them into two classes;
the former including vegetables in their natural state, before they have
undergone fermentation; and the latter those only which have been
fermented. This analysis opens with the processes by which we extract from
vegetables all the principles they will yield without the help of fire: and
then follow the operations for decomposing plants by degrees of heat, from
the gentlest to the most violent, both in close vessels, and in the open air.
I have not made the same division in the animal kingdom, because the
substances that compose it are susceptible only of the last degree of
fermentation, or putrefaction; and moreover the principles they yield,

whether putrefied or unputrefied, are the very same, and differ only with
regard to their proportions, and the order in which they are extricated during
the analysis.
I begin this analysis with an examination of the milk of animals that feed
wholly on vegetables; because, though this substance be elaborated in the
body of the animal, and by that means brought nearer to the nature of
animal matters, yet it still retains a great similitude to the vegetables from
which it derives its origin, and is a sort of intermediate substance between
the vegetable and animal. Then I proceed to the analysis of animal matters
properly so called, those which actually make a part of the animal body. I
next examine the excrementitious substances, that are thrown out of the
animal body as superfluous and useless. And then I conclude this latter part
with operations on the Volatile Alkali; a saline substance of principal
consideration in the decomposition of animal matters.
Though, in the general view here given of the order observed in this
Treatise of Practical Chymistry, I have mentioned only such processes as
serve for analysing bodies, yet I have also inserted some other operations of
different kinds. The book would be very defective if it contained no more:
for the design of Chymistry is not only to analyse the mixts produced by
nature, in order to obtain the simplest substances of which they are
composed, but moreover to discover by sundry experiments the properties
of those elementary principles, and to recombine them in various manners,
either with each other, or with different bodies, so as to reproduce the
original mixts with all their properties, or even form new compounds which
never existed in nature. In this book therefore the reader will find processes
for combining and recompounding, as well as for resolving and
decomposing bodies. I have placed them next to the processes for
decomposition, taking all possible care not to interrupt their order, or break
the connection between them.

PART I.
Of MINERALS.

SECTION I.

Operations performed on Saline Mineral Substances.

CHAP. I.

Of the Vitriolic Acid.

PROCESS I.

To extract Vitriol from the Pyrites.
ake any quantity you please of Iron Pyrites; leave them for some time

T exposed to the air: they will crack, split, lose their brightness, and fall
into powder. Put this powder into a glass cucurbit, and pour upon it
twice its weight of hot water; stir the whole with a stick, and the liquor will
grow turbid. Pour it, while it is yet warm, into a glass funnel lined with
brown filtering paper; and having placed your funnel over another glass
cucurbit, let the liquor drain into it. Pour more hot water on the powdered
Pyrites, filter as before, and so go on, every time lessening the quantity of
water, till that which comes off the Pyrites appears to have no astringent
vitriolic taste.

Put all these waters together into a glass vessel that widens upwards; set it
on a sand-bath, and heat the liquor till a considerable smoke arises; but take
care not to make it boil. Continue the same degree of fire till the surface of
the liquor begins to look dim, as if some dust had fallen into it; then cease
evaporating, and remove the vessel into a cool place: in the space of four
and twenty hours will be formed therein a quantity of crystals, of a green
colour and a rhomboidal figure: these are Vitriol of Mars, or Copperas.
Decant the remaining liquor; add thereto twice its weight of water; filter,
evaporate, and crystallize as before; repeat these operations till the liquor
will yield no more crystals, and keep by themselves the crystals obtained at
each crystallization.
OBSERVATIONS.
The Pyrites are minerals which, by their weight and shining colours,
frequently impose on such as are not well acquainted with ores. At first
sight they may be taken for very rich ones; and yet they consist only of a
small quantity of metal combined with much sulphur or arsenic, and
sometimes with both.
They strike fire with a steel as flints do, and emit a sulphureous smell: so
that they may be known by this extemporaneous proof. The metal most
commonly and most abundantly found in the Pyrites is iron; the quantity
whereof sometimes equals, or even exceeds, that of the sulphur. Besides
metallic and sulphureous matters, the Pyrites contain also some unmetallic
earth.
There are several sorts of Pyrites: some of them contain only iron and
arsenic. They have not all the property of efflorescing spontaneously in the
air, and turning into vitriol: none do so but such as consist only of iron and
sulphur, or at least contain but a very small portion of copper, or of arsenic:
and even amongst those that are composed of iron and sulphur alone, there
are some that will continue for years together exposed to the air without
shooting, and indeed without suffering the least sensible alteration.
The efflorescence of the Iron Pyrites, and the changes they undergo, are
phenomena well worth our notice. They depend on the singular property
which iron possesses of decomposing sulphur by the help of moisture. If
very fine iron-filings be accurately mingled with flowers of sulphur, this

mixture, being moistened with water, grows very hot, swells up, emits
sulphureous vapours, and even takes fire; what remains is found converted
into Vitriol of Mars. On this occasion, therefore, the sulphur is decomposed;
its inflammable part is dissipated or consumed; its acid combines with the
iron, and a Vitriol arises from that conjunction.
This is the very case with the Pyrites that consist only of iron and sulphur;
yet some of them, as we said before, do not effloresce spontaneously and
turn to Vitriol. The reason probably is, that, in such minerals, the particles
of iron and sulphur are not intimately mixed together, but separated by
some earthy particles.
In order to procure Vitriol from Pyrites of this kind, they must be for some
time exposed to the action of fire, which, by consuming part of their
sulphur, and rendering their texture less compact, makes way for the air and
moisture, to which they must be afterwards exposed, to penetrate their
substance, and produce in them the changes with which those others are
affected that germinate spontaneously.
The Pyrites which contain copper and arsenic, and for that reason do not
effloresce, must likewise undergo the action of fire; which, besides the
effects it produces on Pyrites that consist of iron and sulphur only,
dissipates also the greatest part of the arsenic. These Pyrites being first
roasted, and then exposed to the air for a year or two, do also yield Vitriol;
but then it is not a pure Vitriol of Iron, but is combined with a portion of
blue Vitriol, the basis of which is Copper.
Sometimes also there is Alum in the vitriolic waters drawn off the Pyrites. It
was on account of this mixture of different salts that we recommended the
keeping apart the crystals obtained from each different crystallization: for
by this means they may be examined separately, and the species to which
they belong discovered.
When Vitriol of Iron is adulterated with a mixture of the Vitriol of Copper
only, it is easy to purify it and bring it to be entirely martial, by dissolving it
in water, and setting plates of iron in the solution: for iron having a greater
affinity than copper with the vitriolic acid, separates the latter from it, and
assuming its place produces a pure Vitriol of Mars.

In large works for extracting Vitriol from the Pyrites they proceed thus.
They collect a great quantity of Pyrites on a piece of ground exposed to the
air, and pile them up in heaps of about three feet high. There they leave
them exposed to the action of the air, sun, and rain, for three years together;
taking care to turn them every six months, in order to facilitate the
efflorescence of those which at first lay undermost. The rain-water which
has washed those Pyrites is conveyed by proper channels into a cistern; and
when a sufficient quantity thereof is gathered, they evaporate it to a pellicle
in large leaden boilers, having first put into it a quantity of iron, some part
of which is dissolved by the liquor, because it contains a vitriolic acid that
is not fully saturated therewith. When it is sufficiently evaporated, they
draw it off into large leaden or wooden coolers, and there leave it to shoot
into crystals. In these last vessels several sticks are placed, crossing each
other in all manner of directions, in order to multiply the surfaces on which
the crystals may fasten.
The Pyrites are not the only minerals from which Vitriol may be procured.
All the ores of iron and copper that contain sulphur may also be made to
yield green or blue Vitriol, according to the nature of each, by torrefying
them, and leaving them long exposed to the air: but this use is seldom made
of them, as there is more profit to be got by extracting the metals they
contain. Besides, it is easier to obtain Vitriol from the Pyrites than from
those other mineral substances.

PROCESS II.

To extract Sulphur from the Pyrites, and other sulphureous Minerals.
educe to a coarse powder any quantity of yellow Pyrites, or other

R Mineral containing Sulphur. Put this powder into an earthen or glass
retort, having a long wide neck, and so large a body that the matter
may fill but two thirds of it. Set the retort in a sand-bath fixed over a
reverberating furnace: fit to it a receiver half full of water, and so placed
that the nose of the retort may be about an inch under the water: give a
gradual fire, taking care you do not make it so strong as to melt the matter.
Keep the retort moderately red for one hour, or an hour and half, and then
let the vessels cool.

Almost all the Sulphur separated by this operation from its matrix will be
found at the extremity of the neck of the retort, being fixed there by the
water. You may get it out either by melting it with such a gentle heat as will
not set it on fire, or by breaking the neck of the retort.
OBSERVATIONS.
Of all minerals the Pyrites contain the most Sulphur; those especially which
have the colour of fine brass, a regular form, such as round, cubical,
hexagonal, and being broken present a number of shining needles, all
radiating, as it were, from a center.
A very moderate heat is sufficient to separate the Sulphur they contain. We
directed that the retort employed should have a long and wide neck, with a
view to procure a free passage for the Sulphur: the water set in the receiver
detains the Sulphur, fixes it, and prevents it from flying off; so that it is
unnecessary to close the joints of the vessels. But it is proper to take notice,
that whenever you use an apparatus for distilling, which requires the beak
of the retort to be under water, it is of very great consequence that the fire
be constantly so regulated, that the retort may not cool in the least; for, in
that case, as the rarefied air contained therein would be condensed, the
water in the receiver would rise into the retort and break it.
If in distilling Sulphur, according to the present process, the matter
contained in the retort should happen to melt, the operation would be
thereby considerably protracted, and it would require a great deal more time
to extract all the Sulphur; because all evaporation is from the surface only,
and the matter, while it remains in a coarse powder, presents a much more
extensive surface than when it is melted.
This remark holds with regard to all other distillations. Any quantity of
liquor, set to distil in its fluid state, will take much more time to rise in
vapours, and pass from the retort into the receiver, than if it be incorporated
with some solid body reduced to minute parts, so that the whole shall make
a moist powder; and this though the very same degree of fire be applied in
both cases.
If the matter from which it is proposed to extract Sulphur be such as will
melt with the degree of fire necessary to this operation; that is, with a heat

which will make the retort but faintly red, it must be mixed with some
substance that is not so fusible. Very pure coarse sand, or clean gravel, may
be used with success: but absorbent earths are altogether improper for this
purpose, because they will unite with the Sulphur.
The sulphureous minerals which are most apt to fuse are the cupreous
Pyrites, or yellow copper ores: common lead ores are also very fusible.
The Pyrites are by this operation deprived of almost all the Sulphur they
contain; and consequently little is left behind, but the particles of iron and
copper, together with a portion of unmetallic earth, which we shall shew
how to separate from these metals, when we come to treat of them. I say
that by this operation the Pyrites are deprived of almost all, and not entirely
of all their Sulphur; because, this separation being made in close vessels
only, there always remains a certain quantity of Sulphur, which adheres so
obstinately to the metals, that it would be almost impossible to get it all out,
even though a much stronger fire than that directed in the process were
applied for this purpose, and though choice had been, as it ought to be,
made of such Pyrites, or other sulphureous Minerals as part most easily
with their sulphur. Nothing but a very strong fire in the open air is capable
of carrying it wholly off, or consuming it entirely.
In several places are found great quantities of native Sulphur. The
Volcanoes abound with it, and people gather it at the foot of those burning
mountains. Several springs of mineral waters also yield Sulphur, and it is
sometimes found sublimed to the vaulted roofs of certain wells, and among
others in one at Aix-la-Chapelle.
The Germans and Italians have large works for extracting Sulphur in
quantities out of Pyrites, and other minerals which abound therewith. The
process they work by is the same with that here delivered; but with this
difference only, that Sulphur being but of small value they do not use so
many precautions. They content themselves with putting the sulphureous
minerals into large crucibles, or rather earthen cucurbits, which they place
in the furnace in such a manner that, when the sulphureous part melts, it
runs into vessels filled with water, and is thereby fixed.
The Sulphur obtained, either by distillation or by simple fusion, is not
always pure.

When it is obtained by distillation, if the matters from which you extract it
contain moreover some other minerals of nearly the same volatility, such,
for instance, as Arsenic, or Mercury, these minerals will come over with it.
This is easily perceived: for pure sublimed Sulphur is always of a beautiful
yellow, inclining to a lemon colour. If it look red, or have a reddish cast, it
is a sign that some Arsenic hath risen along with it.
Mercury sublimed with Sulphur likewise gives it a red colour; but Sulphur
is very seldom adulterated with this metallic substance: for Arsenic is
frequently found combined with the Pyrites, and other sulphureous
minerals; whereas, on the contrary, we very rarely meet with any Mercury
in them.
But if Mercury should happen to rise with the Sulphur in distillation, it may
be discovered by examining the sublimate; which, in that case, will have the
properties of Cinabar: on being broken its inside will appear to consist of
needles adhering laterally to each other; its weight will be very
considerable; and, lastly, the great heat of the place where it is collected will
furnish another mark to know it by; for, as Cinabar is less volatile than
Arsenic or Sulphur, it fastens on places too hot for either Sulphur or Arsenic
to bear.
Sulphur may also be adulterated with such fixed matters, either metallic or
earthy, as it may have carried up along with it in the distillation, or as may
have been sublimed by the Arsenic, which has a still greater power than
Sulphur to volatilize fixed bodies.
If you desire to free the Sulphur from most of these heterogeneous matters,
it must be put into an earthen cucurbit, and set in a sand-bath. To the
cucurbit must be fitted one or more aludels, and such a degree of heat
applied as shall but just melt the Sulphur; which is much less than that
necessary to separate the Sulphur from its matrix. As soon as the Sulphur is
melted it will sublime in lemon-coloured flowers, that will stick to the
insides of the aludels.
When nothing more appears to rise with this degree of heat, the vessels
must be suffered to cool. At the bottom of the cucurbit will be found a
sulphureous mass, containing the greatest part of the adventitious matters

that were mixed with the Sulphur, and more or less red or dark-coloured,
according to the nature of those matters.
When we come to treat of Arsenic and Mercury, we shall give the methods
of separating Sulphur entirely from those metallic substances.

PROCESS III.

To extract Alum from aluminous Minerals.
ake such minerals as are known or suspected to contain Alum. Expose

T them to the air, that they may effloresce. If they remain there a year
without any sensible change, calcine them, and then leave them
exposed to the air, till a bit thereof being put on the tongue imparts an
astringent aluminous taste.
When your matters are thus prepared, put them into a leaden or glass vessel;
pour upon them thrice their weight of hot water; boil the liquor; filter it; and
repeat these operations till the earth be so edulcorated that the water which
comes off it hath no taste. Mix all these solutions together, and let them
stand four and twenty hours, that the gross and earthy parts may settle to the
bottom; or else filter the liquor: then evaporate till it will bear a new-laid
egg. Now let it cool, and stand quiet four and twenty hours: in that time
some crystals will shoot, which are most commonly vitriolic; for Alum is
rarely obtained by the first crystallization. Remove these vitriolic crystals: if
any crystals of Alum be found amongst them, these must be dissolved anew,
and set to crystallize a second time in order to their purification; because
they partake of the nature as well as of the colour of vitriol. By this method
extract all the Alum that the liquor will yield.
If you get no crystals of Alum by this means, boil your liquor again, and
add to it a twentieth part of its weight of a strong alkaline lixivium, or a
third part of its weight of putrefied urine, or a small quantity of quick-lime.
Experience and repeated trials must teach you which of these three
substances is to be preferred, according to the particular nature of the
mineral on which you are to operate. Keep your liquor boiling, and if there
be any alum in it, there will appear a white precipitate: in that case let it
cool and settle. When the white precipitate is entirely fallen, decant the

clear, and leave the crystals of Alum to shoot at leisure, till the liquor will
yield no more: it will then be exceeding thick.
OBSERVATIONS.
Alum is obtained from several sorts of Minerals. In some parts of Italy, and
in sundry other places, it effloresces naturally on the surface of the earth.
There it is swept together with brooms, and thrown into pits full of water.
This water is impregnated therewith till it can dissolve no more. Then it is
filtered, and set to evaporate in large leaden vessels; and when it is
sufficiently evaporated, and ready to shoot into crystals, it is drawn off into
wooden coolers, and there left for the salt to crystallize.
In aluminous soils there are often found springs strongly impregnated with
Alum: so that to obtain it, the water need only be evaporated.
In the country about Rome there is a very hard stone, which is hewn out of
the quarry just like other stones for building; this stone yields a great deal of
Alum. In order to extract it, the stones are calcined for twelve or fourteen
hours; after which they are exposed to the air in heaps, and carefully
watered three or four times a-day for forty days together. In that time they
begin to effloresce, and to throw out a reddish matter on their surface. Then
they are boiled in water, which dissolves all the Alum they contain, and,
being duly evaporated, gives it back in crystals. This is the Alum called
Roman Alum.
Several sorts of Pyrites also yield a great deal of Alum. The English have a
stone of this kind, which, in colour, is very like a slate. This stone contains
much Sulphur, which they get rid of by roasting it. After this they steep the
calcined stone in water, which dissolves the Alum it contains, and to this
solution they add a certain quantity of a lye made of the ashes of sea-weeds.
The Swedes have a Pyrites of a bright golden colour, variegated with silver
spots, from which they procure Sulphur, Vitriol, and Alum. They separate
from it the Sulphur and the Vitriol by the methods above prescribed. When
the liquor which hath yielded Vitriol is become thick, and no more vitriolic
crystals shoot in it, they add an eighth part of its weight of putrefied urine,
mixed with a lye made of the ashes of green wood. Upon this there appears
and falls to the bottom a copious red sediment. They decant the liquor from

this precipitate, and, when it is duly evaporated, find it shoot into beautiful
crystals of Alum.
What hath been said, concerning the several matrices from which Alum is
obtained, sufficiently shews, that it is seldom solitary in the waters with
which aluminous subjects have been lixiviated. It is almost always
accompanied with a certain quantity of Vitriol, or other saline mineral
matters, which obstruct its crystallization, and prevent its being pure. It is
with a view to free it from these matters, that the waters impregnated with
Alum are mixed with a certain quantity of the lye of some fixed Alkali, or
with putrefied urine, which contains much volatile Alkali. These Alkalis
have the property of decompounding all the Neutral salts which have for
their basis either an absorbent earth or a metallic substance; and such as
have a metallic substance for their basis more readily than those whose
basis is an earth. Consequently, if they are mixed with a liquor in which
both these sorts of salts are dissolved, they must decompound that sort
whose basis is metallic sooner than the other whose basis is an earth. This is
what comes to pass in a solution of Alum and Vitriol. The metallic part of
the latter is separated from its acid by the Alkalis when mixed with that
solution; and it is this metallic part, which is generally iron, that appears in
the form of a reddish precipitate, as above-mentioned.
But because Alkalis decompound also those Neutral salts which have an
earth for their basis, care must be taken that too much thereof be not added;
else what you put in, more than is necessary to decompound the vitriolic
salts in your liquor, will attack the Alum, and decompound it likewise.
The Alkali made use of to promote the crystallization of the Alum joins
with the Vitriolic Acid, which had dissolved the substances now
precipitated, and therewith forms different Neutral salts according to its
particular nature. If the Alkali be a lixivium of common wood-ashes, the
Neutral salt will be a vitriolated Tartar; if a lixivium of the ashes of a
maritime plant like Soda, the Neutral salt will be a Glauber's salt; if
putrefied urine, the Neutral salt will be a vitriolic Ammoniacal salt. Some of
these salts incorporate with the Alum, which in large works crystallizes in
vast lumps: and hence it comes that some sorts of Alum when mixed with a
fixed Alkali smell like a volatile Alkali.

The crystals of Alum are octaedral, that is, they are solids with eight sides.
These octaedral solids are triangular pyramids, having their angles cut
away, so that four of their surfaces are hexagons, and the other four
triangles.
Sulphur, Vitriol, and Alum are the three principal subjects in which we
certainly know that the universal or Vitriolic Acid particularly resides, and
from which we extract it when we want to have it pure. For this reason we
thought it proper, before we treated of the extraction of this Acid, to shew
the method of separating those matters themselves from the other minerals
out of which we obtain them.
Moreover, all the other matrices, in which the Vitriolic Acid is most
commonly lodged, may be referred to one or other of the matters which
serve as bases to these three minerals.
To Sulphur we may refer all combinations of the Vitriolic Acid with an
inflammable matter: but we must take care not to confound Sulphur with
those Bitumens in which the Vitriolic Acid may be found: for the basis of
those bitumens is a real Oil; whereas the basis of Sulphur is the pure
Phlogiston. Yet as Oils themselves contain the Phlogiston, which, in union
with the Vitriolic Acid forms a true Sulphur, it follows that such bitumens
may in a certain respect be classed with Sulphur.
The same is to be said of Vitriol. The name is usually given to such
combinations only as are formed of the Vitriolic Acid with Iron or Copper,
which make the green and blue Vitriol; and to a third species of Vitriol,
which is white, and has Zinc for its basis: but as the Vitriolic Acid may, by
particular combinations, be united with many other metallic substances, all
such Metallic Salts must be referred to the class of Vitriols.
The same may also be said of Alum, which is no other than a combination
of the Vitriolic Acid with a particular kind of absorbent earth; so that all
combinations of this Acid with any earth whatever may be placed in the
same class.
This last class of mixts is the most extensive of all that contain the Vitriolic
Acid; because there are a vast many earths, all differing from one another,
with which that Acid may be united. Alum properly so called, the Gypsums,

Talcs, Selenites, Boles, and all the other compounds of this kind, differ from
each other only in their particular earths.
The different properties of these earthy salts depend on the nature of their
bases. Those which are of the aluminous kind retain much water in
crystallizing, which makes them very soluble in water, and gives them the
property of acquiring readily the aqueous fluor when exposed to the fire.
Those which are of the nature of the Selenites admit but very little water in
their crystals, and consequently are almost insoluble in water; nor does the
fire give them an aqueous fluor. Lastly, the Gypsums and Talcs are still
more destitute of these properties. The natures of the earths in these several
compounds are hitherto but very imperfectly known, and may give the
Chymists occasion for inquiries equally curious and useful.
The Vitriolic Acid is sometimes found complicated with a fixed alkaline
basis. This is almost always the Alkali of Sea-salt; so that the compound is a
Glauber's Salt. Some mineral waters are impregnated therewith; which
happens when these waters contain Vitriol or Alum, together with Sea-salt.
From the principles laid down, in our Elements of the Theory, it appears
that the Vitriolic Acid hath not so great an affinity with earthy and metallic
substances as with fixed Alkalis; and also that it is stronger than the Marine
Acid, and hath a greater affinity with fixed Alkalis. This being allowed, the
generation of native Glauber's Salts is easily accounted for. The Acid of
aluminous or vitriolic Salts quits the earth or the metal with which it was
combined, and expelling the Acid of Sea-salt unites with its basis. Warmth
greatly promotes these decompositions.
If the common fossil salt, usually called Sal Gem, or any other kind of Sea-
salt, should happen to be near a Volcano, when it discharges flaming
Sulphur, as is frequently the case, and if this Sulphur should run among the
Sea-salt, a Glauber's Salt would instantly be formed in that place; because
when Sulphur burns, its Acid is separated and set at liberty.
Lastly, if aluminous or vitriolic matters, or burning Sulphur, should meet
with the ashes of plants or trees consumed by fire, a vitriolated Tartar would
be formed, because these ashes contain a fixed Alkali of the same nature
with that of Tartar.

The Vitriolic Acid when combined with an earthy basis adheres strongly
thereto; so that the force of fire is able to expel very little or none of it.
There is no way of separating it from such a basis, but by presenting to it an
Alkaline Salt, with which it will unite: nor is it ever extracted from such
matters when it is required pure. It does not adhere so firmly to metallic
substances; but is separated from them by the force of fire: so that it may be
obtained from the several sorts of Vitriol. It is usually drawn from Green
Vitriol; that being the commonest sort.
As to Sulphur, the Phlogiston which is its basis being the substance
wherewith the Vitriolic Acid hath the greatest affinity, it would be
altogether impossible to decompose it, and to separate its Acid, if it were
not inflammable; but by burning it the Phlogiston is destroyed, and leaves
the Acid at liberty. By this means therefore it may be separated. We shall
now give the processes for extracting the Acid from Vitriol and Sulphur.

PROCESS IV.

To extract the Vitriolic Acid from Green Vitriol.
ake any quantity of Green Vitriol: put it in an unglazed earthen vessel,

T and heat it gradually. Vapours will soon begin to rise. Increase the fire a
little, and it will liquefy by means of the water contained in it, and
acquire what we called an aqueous fluor. Continue the calcination, and it
will become less and less fluid, grow thick, and turn of a greyish colour.
Now raise your fire, and keep it up till the salt recover its solidity, acquire
an orange colour, and begin to grow red where it immediately touches the
sides of the vessel. Then take it out, and reduce it to powder.
Put the Vitriol thus calcined and pulverized into a good earthen retort, of
which one half at least must remain empty. Set the retort in a reverberatory
furnace: fit thereto a large glass receiver, and, having luted the joint well,
give fire by degrees. You will soon see white clouds rise into the receiver,
which will render it opaque, and heat it. Continue the same degree of fire
till these clouds disappear: they will be succeeded by a liquor which will
trickle down the sides of the receiver in veins. Still keep up the fire to the
same degree as long as these veins appear. When they begin to abate,
increase the fire, and push it to the utmost extremity: upon this, there will

come over a black, thick liquor: it will even be found congealed, and prove
the icy Oil of Vitriol, if care hath been taken to change the receiver, keep
the vessels perfectly close, and give a sufficient degree of heat. Proceed
thus till nothing more comes over, or at least very little. Let the vessels
cool, unlute them, pour the contents of the receiver into a bottle, and seal it
hermetically.
OBSERVATIONS.
Green Vitriol retains much water in crystallizing; and, in order to free it
from that superfluous phlegm, it must be calcined before you distil it.
Without this precaution the operation will be exceedingly protracted, and a
great deal of time wasted in distilling such a quantity of water; which will
moreover greatly weaken the Acid by commixing with it, unless care be
taken to change the recipient as soon as the water is all come over.
But there is also another advantage in calcining the Vitriol before you put it
into the retort: for otherwise this salt would melt on the first application of
heat, and run into a mass; which would prove a great hindrance to its
distillation. This inconvenience is avoided by a previous calcination, in
consequence whereof the Vitriol is easily reduced to a powder which never
becomes fluid.
Vitriol calcined as directed in the process grows so hard, and adheres so
firmly to the vessel in which the calcination is performed, that it requires no
small pains to separate and pulverize it. Care must be taken to put it into the
retort as soon as it is pulverized, and to stop that vessel very close if you do
not begin the distillation immediately: for otherwise it will naturally attract
from the air almost all the moisture it hath lost.
The Acid which Vitriol yields by distillation is sulphureous; probably
because it still retains some of the Phlogiston, with which it was united
when under the form of sulphur in the Pyrites; or else hath laid hold on a
portion of that belonging to the iron which served for its basis in Vitriol.
But this sulphureous part is volatile, and flies off in time.
This decomposition of Vitriol in close vessels is a difficult and laborious
process. To carry the operation to its utmost perfection requires a fire of
extreme violence, kept up without intermission during four or five days;

such in short as few vessels are able to bear. Of course this operation is
seldom performed in laboratories. The French Chymists fetch their Oil of
Vitriol from Holland, where it is extracted from Vitriol in large quantities,
by means of furnaces erected for the purpose, in which many retorts are
employed at once.
In the Memoirs of the Academy of Sciences M. Hellot hath given us the
most material circumstances of a very fine experiment of this kind, in which
he pushed the distillation of Green Vitriol to the utmost. Into a German
retort[5] he put six pounds of Green English Vitriol calcined to redness,
which he exposed to a fire of the extremest violence, constantly kept up
during four days and four nights. At the expiration of that time he found in
the vessels employed as receivers an Icy Oil of Vitriol, which was
altogether in a crystalline form and black. The precautions necessary to
make this experiment succeed, he represents, in the following terms.
"The success of this operation, which produces an Oil of Vitriol perfectly
Icy and without any liquor, depends on the care taken to prevent the acid
vapours, driven by the fire out of Vitriol calcined to redness, from having
any communication with the external air while they are distilling: for
otherwise they will attract from it a moisture which will keep them fluid in
the receiver. The receiver must be at such a distance from the furnace that it
may remain cool enough for the vapours to condense in it. There must also
be sufficient room for those vapours to circulate in, and to prevent the
sulphureous explosions, which are every now and then discharged out of the
retort, from bursting the vessels: for though the previous calcination of the
Vitriol hath carried off the most volatile, yet there still remains enough of
the inflammable principle, even in the iron itself, to form a Sulphur with the
Acid as it is extricated, or at least a mixt that would be as apt to take fire as
common Sulphur, if it were not over-dosed with the Acid.
"As the best means of gaining these ends, M. Hellot contrived to adapt to
the neck of his retort a receiver with two necks, the lowermost of which was
inserted into a large ballon. Receivers applied to each other in this manner
are called Adopters.
"It is no easy matter to get this Icy Oil out of the ballon: for as soon as the
air touches it such a thick cloud of sulphureous fumes arises, that it is

absolutely necessary to place the vessel on some shelf over head, because a
man cannot stand exposed thereto for a single minute without being
suffocated."
This Icy Acid must be shut up with all possible expedition in a crystal bottle
accurately closed with a glass stopple, which should be ground with emery
in its neck so as to fit it exactly: for it attracts moisture so powerfully, that,
unless exceeding great care be taken to prevent all communication with the
external air, it will soon dissolve into a fluid.
"The Icy Oil is black; because the acid vapours carry over with them
something of a greasy matter, from which Vitriol is seldom free, and which
always appears, after repeated solutions and crystallizations of this Salt, in
the mother-water which will shoot no more. Now the smallest portion of
inflammable matter presently blackens the most highly rectified Oil of
Vitriol, which is perfectly clear.
"The Vitriolic Acid, when forced over by a violent heat, carries along with it
some ferruginous particles also, that want nothing but to be united with a
phlogiston to become true iron. They are easily discovered, either in the
common black Oil of Vitriol, or in the blackish crystals of the Icy Oil, by
only dissolving them in a large quantity of distilled water: for after seven or
eight days digestion a light powder or downy sediment precipitates, which
being calcined in a violent fire is partly attracted by the magnet; and being
again calcined with bees-wax becomes almost entirely iron."
The Caput mortuum of this distillation of Vitriol is the ferruginous earth of
this Salt, and is called Colcothar. When this Colcothar hath undergone a
violent fire, as in the experiment now related, scarce any Acid remains
therein. Out of six pounds of Vitriol that M. Hellot used, he could recover
no more, by lixiviating what was left in the retort, than two ounces of a
Vitriolic Salt; and even that was very earthy.
If Vitriol be exposed to a fire neither so violent nor so long continued, its
Colcothar will yield a greater quantity of Vitriol that hath not been
decomposed. A white crystalline salt is also obtained from it, and called Salt
of Colcothar; which is no other than the small portion of Alum usually
contained in Vitriol, and not so easily decomposed by the the action of fire.

PROCESS V.

To decompose Sulphur, and extract its Acid, by burning it.
ake any quantity of the purest Sulphur: fill therewith a crucible or other

T earthen dish: heat it till it melts; then set it on fire, and, when its whole
surface is lighted, place it under a large glass head, taking care that the
flame of the Sulphur do not touch either its sides or bottom; that the air
have free access, in order to make the Sulphur burn clear; and that the head
incline a little toward the side on which its beak is, that, as the vapours
condense therein, the liquor may run off with ease. To the beak of this
vessel fit a receiver: the fumes of the lighted sulphur will be condensed, and
gather into drops in the head, out of which they will run into the receiver.
There, when the Sulphur has done burning, you will find an Acid liquor,
which is the Spirit of Sulphur.
OBSERVATIONS.
In the burning of Sulphur, the Phlogiston which serves for its basis is
dissipated, and separated from the acid which is left at liberty. The acid
fumes which rise from the lighted sulphur strike against the inside of the
head placed over it, are there condensed, and appear in the form of a liquor.
But as Sulphur, like all other inflammable bodies, Nitre excepted, will not
burn in close vessels, it is necessary that the air be freely admitted here;
which occasions the loss of a great deal of the Acid of the Sulphur, as is
evident from the pungent suffocating smell perceived in the laboratory
during the operation.
This Acid, while combined with the Phlogiston, is incapable of contracting
any union with water; but when alone is very apt to mix therewith: it is even
proper to put some in its way, that it may incorporate therewith as soon as it
is discharged from the Sulphur; for it is then very free from phlegm, very
volatile, and consequently very little disposed to condense into a liquor, but,
on the contrary, very apt to fly off in vapours. The water, which it imbibes
with a kind of avidity, fixes and detains it; so that by this means a much
greater quantity thereof is obtained from Sulphur, than if it were distilled
without this precaution.

It is proper, therefore, now and then, to introduce a dish full of hot water
under the head which receives the fumes of the Sulphur. The vapours that
exhale from the water be-dew the inside of the head, and procure the
advantage we are speaking of.
The same thing may be effected several other ways: thus, the crucible
containing the Sulphur may be set on a foot placed in an earthen dish with
some water in it; which, however, must not rise above the foot; for if it
should reach the crucible, it might cool and fix the sulphur. The dish thus
prepared must be placed on a sand-bath hot enough to make the water
smoke continually; and over all is to be placed the head as directed in the
process.
The size and form of the vessel which immediately receives the sulphureous
fumes may also contribute to increase the quantity of the Acid Spirit. A very
large vessel, with a hole at bottom no wider than is just sufficient to admit
the vapours, is the properest for this operation.
After the Sulphur has burnt for some time, it often happens that a sort of
skin or crust forms on its surface, which is not inflammable, but gradually
lessens the quantity and vigour of the flame as it increases in thickness, and
at last puts it quite out. This crust proceeds from the impurities, and
heterogeneous uninflammable particles contained in the sulphur. Care must
be taken to remove it with an iron wire as fast as it forms.
Two quantities of sulphur may also be kept in two crucibles, and heated
alternately. That in which the Sulphur is hot and melted may be substituted
for the other in which the Sulphur is grown cold and fixed; because cold
Sulphur does not burn well.
The Spirit of Sulphur is at first pungent and volatile, because it still retains a
small portion of the Phlogiston: but that sulphureous part flies off,
especially if the bottle in which the Spirit is kept be left for some time
unstopped.
The Acid obtained from Sulphur appears by all chymical proofs perfectly
like that obtained from Vitriol: they differ in this only, that the former is the
purest; for the Acid obtained from Vitriol carries over with it some metallic

parts, as we observed before, which can never happen to that obtained from
Sulphur.
If linen rags dipped in a solution of Fixed Alkali be exposed to the fumes of
burning brimstone, the Spirit of Sulphur joins with the Alkali, and therewith
forms a Vitriolated Tartar. This Salt is known to be formed when the rags
grow stiff, and appear spangled with a vast many glittering points, which
are nothing but little crystals of the Salt we are speaking of.
When the Sulphur burns very gently and slowly the Spirit that exhales from
it is so much the more sulphureous and volatile: and hence the Salt formed
by the combination of this Spirit with the Alkali exposed to it in linen rags,
as in the above-mentioned experiment, is not at first a Vitriolated Tartar; but
a Neutral Salt of a particular kind, which is capable of being decomposed
by any other Mineral Acid, the sulphureous Acid having less affinity than
any of the rest with Alkalis. Nevertheless, this Salt becomes in time a true
Vitriolated Tartar, because the sulphureous part which weakened its Acid
easily quits it and flies off.

PROCESS VI.

To concentrate the Vitriolic Acid.
ake the Vitriolic Acid you intend to concentrate, that is, to dephlegmate

T and make stronger: pour it into a good glass retort, of such a size that
your quantity of Acid may but half fill it: set this retort in the sand-bath
of a reverberating furnace: fit to it a receiver; lute it on, and give a gradual
fire. There will come over into the receiver a clear liquor, the first drops of
which will be but faintly acid: this is the most aqueous part.
When the drops begin to follow one another much more slowly, raise your
fire, till the liquor begin to bubble a little in the middle. Keep it thus gently
boiling, till one half or two thirds thereof be come over into the receiver.
Then let your vessels cool; unlute them; what remains in the retort pour into
a crystal bottle, and stop it exactly with a glass stopple rubbed with emery.
OBSERVATIONS.

The Acid obtained from Sulphur is generally very aqueous; either because
in preparing it water must necessarily be administered, that it may unite
therewith as it separates from the Sulphur; or because it is so greedy of
moisture as to attract a great deal from the air, which must needs be
admitted to make the Sulphur burn.
The Acid obtained from Vitriol, excepting that which rises last, is also
mixed with a pretty considerable quantity of phlegm; because the Vitriol,
though calcined, still retains a great deal thereof, which rises with the Acid
in distillation. Now, as there are many chymical experiments that will not
succeed without Acids exceedingly dephlegmated, it is proper to have in a
laboratory all the Acids thus conditioned; because if they happen to be too
strong for particular operations, as is sometimes the case, it is very easy to
lower them to the desired degree, by adding a sufficient quantity of water.
The Vitriolic Acid is much heavier and much less volatile than water. If
therefore a mixture of these two liquors be exposed to the fire, the aqueous
part will rise with a degree of heat which is not able to carry up the Acid: by
this means they may be separated from each other; and thus is the Vitriolic
Acid concentrated.
Nevertheless, as this Acid combines most closely with water, and is in a
manner strongly connected with it, the water carries up some portion
thereof along with it; and hence it comes, that the liquor which rises into the
receiver is acid: it is called Spirit of Vitriol.
As the fire carries off the most aqueous part, the other which remains in the
retort increases in specific gravity. The Acid particles are brought nearer
together, retain the aqueous particles more obstinately, and therefore to
separate them the degree of heat must be increased.
It is usual to draw off one half or two thirds of the liquor that was put into
the retort: but this depends on the degree of strength the Acid was of before
concentration, and the degree of concentration intended to be given it.
If the Acid to be concentrated be Oil of Vitriol, from being brown or black it
grows clearer as the operation advances, and at last becomes perfectly
colourless and transparent; because the fat matter which tinged it black is
dissipated during the process. Some of it deposites a white crystalline earth.

A sulphureous smell is generally perceived about the vessels in this
operation. This arises from a small portion of the Phlogiston from which the
Acid is not free; and it is this inflammable matter which gives the Oil of
Vitriol its black colour: for the clearest and best rectified Oil of Vitriol will
become brown, and even black, in a short time, if any inflammable matter,
though in a very small quantity, be dissolved therein.
The vessels are luted in this operation, to prevent any loss of the Spirit of
Vitriol, which being very acid is of use in many chymical experiments, and
may itself also be again concentrated.
We observed, that in this operation it is necessary the retort should be of
very good glass. Indeed the Acid is so active, and so strong, that if the glass
be tender and have a little too much salt in its composition, it will be so
corroded thereby that it will fall to pieces.
Though we directed the retort to be set in a sand-bath for this operation, it
does not follow that it may not also be placed in a naked fire: on the
contrary, when the heat is not conveyed through a bath the operation
advances faster, and is much less tedious. But then great caution must be
used, and the closest attention given to the management of the fire, which
must be raised by almost imperceptible degrees, especially at the beginning
of the operation; otherwise it is next to a certainty that the vessels will
break. In general, a naked fire may be employed in almost all distillations
which require a greater degree of heat than that of boiling water, or the
balneum mariæ: the operation will be sooner finished; but it requires an
experienced hand, that has by practice acquired a habit of governing the fire
with judgment.
There is moreover another advantage in not using the sand-bath; which is,
that if in the time of the operation you perceive the fire too fierce, you can
quickly check it, either by stopping close all the apertures of the furnace, or
by drawing out all or part of the lighted coals. This inconvenience is not
near so easily remedied when you use the sand-bath; because when once
heated it retains its heat very long after the fire is quite extinguished.

PROCESS VII.

To decompose Vitriolated Tartar by means of the Phlogiston; or to compose
Sulphur by combining the Vitriolic Acid with the Phlogiston.
equal parts of Vitriolated Tartar, and very dry Salt of Tartar,
T
ake
separately reduced to powder; add an eighth part of their weight of
charcoal-dust; and mix the whole together very accurately. Throw this
mixture into a red-hot crucible, placed in a furnace filled with burning
coals. Cover it very close, and keep it very hot; till the mixture melt, which
may be known by uncovering the crucible from time to time. There will
then appear a blueish flame, accompanied with a pungent smell of Sulphur.
Take the crucible out of the fire: dissolve its contents in hot water: filter the
solution through brown paper supported by a glass funnel: drop into the
filtered liquor by little and little any Acid whatever. As you add the acid the
liquor will grow more and more turbid, and let fall a grey precipitate.
Continue dropping in more Acid till the liquor will yield no more
precipitate. Filter it a second time, to separate it from the precipitate: what
remains on the filter is a true inflammable Sulphur, which you may either
melt or sublime into flowers.
OBSERVATIONS.
All bodies that contain the Vitriolic Acid may contribute, as well as
Vitriolated Tartar, to the generation of Sulphur: so that all the neutral salts in
which this Acid is a principle, the Alums, Selenites, Gypsums, Vitriols, may
be substituted for it in this experiment. All these matters, with the addition
of charcoal-dust only, being fused in a crucible, constantly produce
Sulphur; because the Vitriolic Acid having a greater affinity with the
Phlogiston than with any thing else, will quit its basis, whatever it be, to
join with the Phlogiston of the charcoal, and therewith form a Sulphur.
The fixed Alkali added thereto helps to promote the fusion of the
ingredients, which is necessary for effecting the desired combination. It also
serves to unite with the Sulphur, when formed; and thus makes the
combination called Liver of Sulphur, which prevents the Sulphur from
being consumed as soon as formed: for the fixed Alkalis, which are
incombustible, hinder Sulphur from burning so easily as it would do if they
were not joined with it. They may afterwards be separated from each other,
by the means of any Acid whatever.

This process, in which Sulphur is regenerated by recombining together the
principles of which it was originally composed, is one of the most beautiful
experiments that modern Chymistry hath produced. We are indebted for it
to M. Stahl; and Dr. Geoffroy hath given a particular account of it in the
Memoirs of the Academy of Sciences.
Before these gentlemen Glauber and Boyle had indeed published methods
of producing Sulphur, Glauber made use of his Sal mirabile and powdered
charcoal: Boyle employed the Vitriolic Acid and Oil of Turpentine. But
neither of those Chymists understood the true theory of their operations:
they did not thoroughly know the principles of Sulphur: they did not
imagine they had composed Sulphur: they thought they only extracted what
they supposed to exist previously in the matters they employed in their
experiments.
M. Stahl was the first who discovered and explained the nature of Sulphur,
and proved that in Glauber's and Boyle's experiments Sulphur was actually
produced, by uniting together the principles of which it is constituted. This
beautiful experiment gives the strongest lustre of evidence to the theory of
the composition of that mixt, which acts such a capital part in Chymistry;
and it can no longer be doubted, that Sulphur is actually a combination of
the Vitriolic Acid with the Phlogiston.
Besides this important truth, our process for composing Sulphur by art
proves several others that are equally essential and fundamental.
The first is, that the Vitriolic Acid hath a greater affinity with the Phlogiston
than with any other thing, seeing it quits metallic and earthy substances, as
well as Alkaline salts, in order to combine therewith.
The second is, that Sulphur combines with fixed Alkalis without suffering
any decomposition; seeing it may be separated from them entire and
unaltered; and seeing that very Sulphur, which is naturally indissoluble in
water, is rendered soluble therein by the union it hath contracted with the
fixed alkali.
The third is, that the Vitriolic Acid, which, when it is pure, hath the greatest
affinity with Alkalis of any Acid whatever, loses a great deal of that affinity
by contracting an union with the Phlogiston; seeing the weakest acids are

capable of decomposing the Liver of Sulphur, and separating the Sulphur
from the Alkali. And this also confirms one of the general propositions
concerning affinities advanced in our theory; to wit, that the affinities of
compound or mixed substances are weaker than those of the same
substances in a purer or more simple state.

CHAP. II.

Of the Nitrous Acid.

PROCESS I.

To extract Nitre out of nitrous Earths and Stones. The Purification of Salt-
petre. Mother of Nitre. Magnesia.
ake any quantity of nitrous earths or stones; reduce them to powder;

T and therewith mix a third part of the ashes of green-wood and quick-
lime. Put this mixture into a barrel or vat, and pour on it hot water to
about twice the weight of the whole mass. Let it stand thus for twenty-four
hours, stirring it from time to time with a stick. Then filter the liquor
through brown paper, or pass it through a flannel bag, till it come clear: it
will then have a yellowish colour. Boil this liquor, and evaporate till you
perceive that a drop of it let fall on any cold body coagulates. Then stop the
evaporation, and set your liquor in a cool place. In the space of four and
twenty hours crystals will be formed in it, the figure of which is that of an
hexagonal prism, having its opposite planes generally equal, and terminated
at each extremity by a pyramid of the same number of sides. These crystals
will be of a brownish colour, and deflagrate on a live coal.
Decant the liquor from these crystals; mix it with twice its weight of hot
water; evaporate and crystallize as before. Repeat the same operation till the
liquor will yield no more crystals: it will then be very thick, and goes by the
name of Mother of Nitre.
OBSERVATIONS.

Earths and stones that have been impregnated with animal or vegetable
juices susceptible of putrefaction, and have been long exposed to the air, but
sheltered from the sun and rain, are those which yield the greatest quantity
of Nitre. But all sorts of earths and stones are not equally fit to produce it.
None is ever found in flints or sands of a crystalline nature.
Some earths and stones abound so with Nitre, that it effloresces
spontaneously on their surface, in the form of a crystalline down. This Nitre
may be collected with brooms, and accordingly has the name of Salt-petre
Sweepings. Some of this sort is brought from India.
Hitherto we are much in the dark as to the origin and generation of Nitre.
Some Chymists pretend that the Nitrous Acid is diffused through the air,
and gradually deposited in such earths and stones as are qualified to receive
it.
Others, considering that none of it is ever obtained but from earths that have
been impregnated with vegetable or animal juices, have from thence
concluded those two kingdoms to be the general repositories of the Nitrous
Acid; that if we do not perceive it to exist in such matters at all, or at least
in any great quantity, till they have undergone putrefaction, and are in some
measure incorporated with suitable earths and stones, it is because the Acid
is so entangled with heterogeneous particles that it requires the assistance of
putrefaction, and much more of filtration through an earth, to disengage it,
and enable it to appear in its proper nature.
Lastly, others are of opinion that this Acid is no other than the universal or
Vitriolic Acid; disguised indeed by a portion of the Phlogiston, which is
combined with it in a peculiar manner by the means of putrefaction. They
ground this opinion chiefly on the analogy or resemblance which they find
between the Nitrous Acid and the Volatile Sulphureous Spirit. Its volatility,
its pungent smell, its properties of taking fire, and of destroying the blue
and violet colours of vegetables, serve them as so many proofs.
Their opinion is the more probable on this account, that even though the
Nitrous Acid should actually be produced by vegetable and animal
substances, yet as these substances themselves draw all their component
principles from the earth, and as the Vitriolic Acid is diffused through all
the soils which afford them nourishment, there is great reason to think that

the Nitrous Acid is no other than the Vitriolic Acid altered by the changes
and combinations it hath undergone in its passage into and through those
substances. In 1750 the Royal Academy of Sciences at Berlin proposed an
account of the generation of Nitre as the subject for their prize, which was
conferred on a Memoir wherein this last opinion was supported by some
new and very judicious experiments.
The process by which our Salt-petre makers extract Nitre in quantities, out
of rubbish and nitrous earths, is very nearly the same with that here set
down; so that I shall not enter into a particular account of it. I shall only
take notice of one thing, which it is of some consequence to know; namely,
that there is no nitrous earth which does not contain sea-salt also. The
greatest quantities of this salt are to be found in those earths which have
been drenched with urine, or other animal excrements. Now as the rubbish
of old houses in great cities is in this class, it comes to pass that when the
Salt-petre workers evaporate a nitrous lixivium drawn from that rubbish, as
soon as the evaporation is brought to a certain pitch, a great many little
crystals of sea-salt form in the liquor, and fall to the bottom of the vessel.
The Salt-petre workers in France call these saline particles the Grain, and
take care to separate them from the liquor (which, as long as it continues
hot, keeps the salt-petre dissolved) before they set it to crystallize. This fact
seems a little singular, considering that sea-salt dissolves in water more
easily than salt-petre, and crystallizes with more difficulty.
In order to discover the cause of this phenomenon, we must recollect some
truths delivered in our theoretical Elements. The first is, that water can keep
but a determinate quantity of any salt in solution, and that if water fully
saturated with a salt be evaporated, a quantity of salt will crystallize in
proportion to the quantity of water evaporated. The second is, that those
salts which are the most soluble in water, particularly those which run in the
air, will dissolve in cold and in boiling water equally; whereas much greater
quantities of the other salts will dissolve in hot and boiling water than in
cold water. These things being admitted, when we know that sea-salt is one
of the first sort, and salt-petre of the second, the reason why sea-salt
precipitates in the preparation of salt-petre appears at once. For,

When the solution of Salt-petre and Sea-salt comes to be evaporated to such
a degree that it contains as much Sea-salt as it possibly can, this salt must
begin to crystallize, and continue to do so gradually as the evaporation
advances. But because at the same time it does not contain as much salt-
petre as it can hold, seeing it is capable of dissolving a much greater
quantity thereof when it is boiling hot than when it is cold, this last-named
salt will not crystallize so soon. If the evaporation were continued till the
case of the Salt-petre came to be the same with that of the Sea-salt, then the
salt-petre also would begin to crystallize gradually in proportion to the
water evaporated, and the two salts will continue crystallizing
promiscuously together: but it is never carried so far; nor is it ever
necessary: for, as the water cools, it becomes more and more incapable of
holding in solution the same quantity of salt-petre as when it was boiling
hot.
And then comes the very reverse, with regard to the crystallizing of the two
salts; for then the Salt-petre shoots, and not the Sea-salt. The reason of this
fact also is founded on what has just been said. The Sea-salt, of which cold
water will dissolve as much as boiling water, and which owed its
crystallizing before only to the evaporation, now ceases to crystallize as
soon as the evaporation ceases; while the Salt-petre, which the water kept
dissolved only because it was boiling hot, is forced to crystallize merely by
the cooling of the water.
When the solution of Salt-petre has yielded as many crystals of that Salt as
it can yield by cooling, it is again evaporated, and being then suffered to
cool yields more crystals. And thus they continue evaporating and
crystallizing, till the liquor will afford no more crystals. It is plain that as
the Salt-petre crystallizes, the proportion of Sea-salt to the dissolving liquor
increases; and as a certain quantity of water evaporates also during the time
employed in crystallizing the Salt-petre, a quantity of Sea-salt, proportioned
to the water so evaporating, must crystallize in that time: and this is the
reason why Salt-petre is adulterated with a mixture of Sea-salt. It likewise
follows that the last crystals of Nitre, obtained from a solution of Salt-petre
and Sea-salt, contain much more Sea-salt than the first.
From all that has been said concerning the crystallization of Salt-petre and
Sea-salt, it is easy to deduce the proper way of purifying the former of these

two Salts from a mixture of the latter. For this purpose the Salt-petre to be
refined need only be dissolved in fair water. The proportion between the
two salts in this second solution is very different from what it was in the
former; for it contains no more Sea-salt than what had crystallized along
with the Salt-petre under favour of the evaporation, the rest having been left
dissolved in the liquor that refused to yield any more nitrous crystals.
As there is therefore a much greater quantity of Salt-petre than of Sea-salt
in this second solution, it is easy to evaporate it to such a degree that a great
deal of Salt-petre shall crystallize, while much more of the water must
necessarily be evaporated before any of the Sea-salt will crystallize.
However, the Salt-petre is not yet entirely freed from all mixture of Sea-salt
by this first purification; for the crystals obtained from this liquor, in which
Sea-salt is dissolved, are still encrusted, and, as it were, infected therewith:
hence it comes, that, to refine the Salt-petre thoroughly, these
crystallizations must be repeated four or five times.
The Salt-petre men commonly content themselves with crystallizing it
thrice, and call the produce Salt-petre of the first, second, or third shoot,
according to the number of crystallizations it has undergone. But their best
refined Salt-petre, even that of the third shooting, is not yet sufficiently pure
for Chymical experiments that require much accuracy: so that it must be
further purified; but still by the same method.
The Nitrous Acid is not pure in the earths and stones from which it is
extracted. It is combined partly with the very earth in which it is formed,
and partly with the Volatile Alkali produced by the putrefaction of the
vegetable or animal matters that concurred to its generation. A Fixed Alkali
and Quick-lime are added to the lixivium of a nitrous earth, in order to
decompose the nitrous Salt formed in that earth, and to separate the Acid
from the Volatile Alkali and the absorbent earth with which it is united:
thence comes that copious sediment which appears in the lye at the
beginning of the evaporation. These matters form with that Acid a true
Nitre, much more capable than the original Nitrous Salts of crystallization,
detonation, and the other properties which are essential thereto. The basis of
Nitre is therefore a Fixed Alkali mixed with a little lime.

The Mother of Nitre, which will yield no more crystals, is brown and thick:
by evaporation over a fire it is further inspissated, and becomes a dry, solid
body; which, however, being left to itself soon gives, and runs into a liquor.
This water still contains a good deal of Nitre, Sea-salt, and the Acids of
these Salts united with an absorbent earth. It contains moreover a great deal
of a fat, viscid matter, which prevents its crystallizing.
All saline solutions in general, after having yielded a certain quantity of
crystals, grow thick, and refuse to part with any more, though they still
contain much Salt. They are all called Mother-waters, as well as that which
hath yielded Nitre. The Mother-waters of different Salts may prove the
subjects of curious and useful inquiries.
If a Fixed Alkali be mixed with the Mother of Nitre, a copious white
precipitate immediately falls, which being collected and dried is called
Magnesia. This precipitate is nothing but the absorbent earth that was
united with the Nitrous Acid, together with a good deal of the lime that was
added, and was also united with that Acid, from which they are now
separated by the Fixed Alkali, according to the usual laws of affinities.
The Vitriolic Acid poured upon Mother of Nitre causes many Acid vapours
to rise, which are a compound of the Nitrous and Marine Acids, that is, an
Aqua Regia. On this occasion also there falls a large quantity of a white
powder, which is still called Magnesia; yet it differs from the former in that
it is not, like it, a pure absorbent earth, but combined with the Vitriolic
Acid.
An Aqua regis may also be drawn from nitrous earths by the force of fire
only, without the help of any additament.

PROCESS II.

To decompose Nitre by means of the Phlogiston. Nitre fixed by Charcoal.
Clyssus of Nitre. Sal Polychrestum.
ake the purest Salt-petre in powder; put it into a large crucible, which it

T may but half fill; set the crucible in a common furnace, and surround it
with coals. When it is red-hot the Nitre will melt, and become as fluid
as water. Then throw into the crucible a small quantity of charcoal-dust: the

Nitre and the Charcoal will immediately deflagrate with violence; and a
great commotion will be raised, accompanied with a considerable hissing,
and abundance of black smoke. As the charcoal wastes, the detonation will
abate, and cease entirely as soon as the coal is quite consumed.
Then throw into the crucible the same quantity of charcoal-dust as before,
and the same phenomena will be repeated. Let this coal also be consumed:
then add more, and go on in the same manner till you can excite no further
deflagration; always observing to let the burning coal be entirely consumed
before you add any fresh. When no deflagration ensues, the matter
contained in the crucible will have lost much of its fluidity.
OBSERVATIONS.
Nitre will not take fire, unless the inflammable matter added to it be
actually burning, or the Nitre itself red-hot, and so thoroughly ignited, as
immediately to kindle it. Therefore, if you would procure the detonation of
Nitre with charcoal, and make use of cold charcoal, as in the process, the
Nitre in the crucible must be red-hot, and in perfect fusion: but you may
also use live coals, and then the Nitre need not be red-hot.
It is proper that the crucible used in this experiment should be only half full;
for during the detonation its contents swell, and might run over without this
precaution. For the same reason the charcoal-dust is to be thrown in by little
and little; and that first put in must be entirely consumed before any fresh
be added.
The matter remaining in the crucible after the operation is a very strong
Fixed Alkali. Being exposed to the air it quickly attracts the moisture
thereof, and runs into a liquor. It is called Alkalizated Nitre, or, to
distinguish it from Nitre alkalizated by other inflammable matters, Nitre
fixed by charcoal.
However, this Alkali is not absolutely pure. It still contains a portion of the
Nitre that hath not been decomposed. For when there remains but a little of
this salt mixed with a great quantity of Alkali, which is not inflammable, the
Alkali in some measure shelters it, coats it over, and obstructs that
immediate contact with the inflammable matters applied, which is
necessary to make it deflagrate.

If the Fixed Alkali be desired perfectly free from any mixture of
undecomposed Nitre, the fire about the crucible must be considerably
increased as soon as the detonation is entirely over; the matter must be
made to flow, which requires a much stronger heat than would melt Nitre,
and kept thus in fusion for about an hour. After this no perfect Nitre will be
found therein: for the little that was left, being unable to abide the force of
the fire, as not being extremely fixed, either is entirely dissipated, or loses
its Acid, which is carried off by the violence of the heat.
Fixed Nitre contains also a portion of the earth that constituted the basis of
the Nitre, which is no other than the lime employed in its crystallization, or
else some of the earth with which its Acid was originally combined, and
which it retained in crystallizing. When Nitre is deflagrated with such
matters as produce ashes, these ashes likewise furnish a certain quantity of
earth, which mixes with the Fixed Alkali. To separate these several earths
from the Alkali, nothing more is requisite than to let it run per deliquium, or
to dissolve it in water, and filter the solution through brown paper.
Whatever is saline will pass through the filtre with the water, and the earthy
part will be left upon it.
The Nitrous Acid is not only dissipated during the deflagration of the Nitre,
but is even destroyed, and perfectly decomposed. The smoke that rises
during the operation has not the least odour of an Acid. Its nature may be
accurately examined by catching it in proper vessels, and condensing it into
a liquor.
Nitre differs from Sulphur, and from all other inflammable bodies whatever,
in this, that the free access of the air is indispensably necessary to make any
of the others burn; whereas Nitre, and Nitre only, is capable of burning in
close vessels: and this property furnishes us with the means of collecting
the vapours which it discharges in deflagration.
For this purpose, to a tubulated earthen retort you must fit two or three large
adopters: set the retort in a furnace; and under it make a fire sufficient to
keep its bottom moderately red. Then take a small quantity, two or three
pinches for example, of a mixture of three parts of Nitre with one of
charcoal-dust, and drop it into the retort through its tube, which must be
uppermost, and immediately stopped close. A detonation instantly ensues,

and the vapours that rise from the inflamed mixture of Nitre and charcoal,
passing out through the neck of the retort into the adopters, circulate therein
for a while, and at last condense into a liquor.
When the detonation is over, and the vapours condensed, or nearly so, drop
into the retort another equal quantity of the mixture; and repeat this till you
find there is liquor enough in the recipients to be examined with ease and
accuracy. This liquor is almost insipid, and shews no tokens of acidity; or at
most but very slight ones. It is called Clyssus of Nitre.
It is easy to perceive why several adopters are required in this experiment,
and why a very small quantity of the mixture must be introduced into the
retort at once. The explosion, and the quantity of air and vapours discharged
on this occasion, would quickly burst the vessels, if all these precautions
were not attended to. This plainly appears from the terrible effects of gun-
powder, which is nothing but a composition of Nitre, Sulphur, and
Charcoal.
Nitre is also decomposed and takes fire by the means of Sulphur; but the
circumstances and the result differ widely from those produced therewith by
charcoal, or any other inflammable body.
Nitre deflagrates with Sulphur on account of the Phlogiston which the latter
contains. If one part of Sulphur be mixed with two or three parts of Nitre,
and the mixture thrown by little and little into a red-hot crucible, upon
every projection there arises a detonation accompanied with a vivid flame.
The vapours discharged on this occasion have the mingled smell of a
Sulphureous Spirit and Spirit of Nitre; and if they be collected by means of
a tubulated retort, and such an apparatus of vessels as was used in the
preceding experiment, the liquor contained in the recipients is found to be
an actual mixture of the Acid of Sulphur, the Sulphureous Spirit, and the
Acid of Nitre; the first being in greater quantity than the other two, and the
second greater than the last.
Nor is the remainder after detonation a Fixed Alkali, as in the former
experiments; but a Neutral Salt, consisting of the Acid of Sulphur combined
with the Alkali of Nitre; a sort of Vitriolated Tartar known in medicine by
the name of Sal Polychrestum.

There are evidently two essential differences between this last experiment
and the preceding one. What remains after the deflagration of Nitre with
Sulphur is not a Fixed Alkali: and, moreover, the vapours emitted in the
operation are impregnated with a quantity of the Nitrous Acid; which is not
the case when Nitre is decomposed by any other inflammable matter which
contains no Vitriolic Acid.
The reason of these differences is naturally deducible from what hath been
already said concerning the properties of the Vitriolic and Nitrous Acids.
We have seen that by burning Sulphur its Acid is not decomposed, but only
separated from its Phlogiston. We also know, that its Acid has a great
affinity with Fixed Alkalis. These things being granted, it follows that, as
soon as the Nitrous Acid quits its Alkaline basis, by deflagrating with the
Phlogiston of the Sulphur, the Acid of this very Sulphur, being set at liberty
by that deflagration, must unite with the Alkaline basis deserted by the Acid
of Nitre, and therewith form a Neutral Salt. Hence, instead of a Fixed
Alkali, we find at the end of the operation a sort of Vitriolated Tartar; the
Acids of Sulphur and of Vitriol being the same, as is evident from what hath
been above said concerning them.
In order to discover the cause of the other phenomenon, we must recollect
two things advanced in our Elements of the Theory; to wit, that the affinity
of the Vitriolic Acid with Fixed Alkalis is greater than that of the Nitrous
Acid; and again, that the Nitrous Acid is not capable of combining and
taking fire with the Phlogiston, but when it is in the form of a Neutral Salt,
that is, when it is united with some alkaline, earthy, or metallic basis. If
these two principles be applied to the effect in question, the solution is easy
and natural. For, in the deflagration of Nitre with Sulphur, the Phlogiston is
not the only substance capable of separating the Nitrous Acid from its basis:
the Acid of the Sulphur, more and more of which is set at liberty as the
Phlogiston is consumed, is also capable of producing the same effect; but
with this difference, that the portion of the Nitrous Acid which is detached
from its Alkali by the Phlogiston is at the same instant set on fire and
decomposed by that union; whereas the portion thereof which is separated
by the Vitriolic Acid, being when so separated incapable of uniting with the
Phlogiston, and of consuming therewith, is preserved entire, and rises in
vapours, together with that portion of the Vitriolic Acid which could not
unite with the basis of the Nitre.

PROCESS III.

To decompose Nitre by means of the Vitriolic Acid. The Smoking Spirit of
Nitre. Sal de duobus. The Purification of Spirit of Nitre.
ake equal parts of well purified Nitre and Green Vitriol: dry the Nitre

T thoroughly, and bruise it to a fine powder. Calcine the Vitriol to
redness: reduce it likewise to a very fine powder; and mingle these two
substances well together. Put the mixture into an earthen long-neck, or a
good glass retort coated, of such a size that it may be but half full.
Set this vessel in a reverberating furnace covered with its dome; apply a
large glass receiver, having a small hole in its body, stopped with a little
lute. Let this receiver be accurately luted to the retort with the fat lute, and
the joint covered with a slip of canvas smeared with lute made of quick-
lime and the white of an egg. Heat the vessels very gradually. The receiver
will soon be filled with very dense red vapours, and drops will begin to
distil from the nose of the retort.
Continue the distillation, increasing the fire a little when you observe the
drops to follow each other but slowly, so that above two thirds of a minute
passes between them; and, in order to let out the redundant vapours, open
the small hole in the receiver from time to time. Towards the end of the
operation raise the fire so as to make the retort red. When you find that,
even when the retort is red-hot, nothing more comes over, unlute the
receiver, and without delay pour the liquor it contains into a crystal bottle,
and close it with a crystal stopple ground in its neck with emery. This liquor
will be of a reddish yellow colour, smoking exceedingly, and the bottle
containing it will be constantly filled with red fumes like those observed in
the receiver.
OBSERVATIONS.
The Vitriolic Acid having a greater affinity with Fixed Alkalis than with any
other substance, the Phlogiston excepted, and being in the Vitriol united
with a ferruginous basis, will naturally quit that basis to join with the Fixed
Alkali of the Nitre; the Acid whereof being weaker than the Vitriolic, as we
have already observed on several occasions, must needs be thereby expelled

from its basis. The Nitre therefore is decomposed by the Vitriol, and its
Acid being set at liberty, is carried up by the force of the fire.
Indeed the Nitrous Acid, being thus separated from its alkaline basis, might
be expected to combine with the ferruginous basis of the Vitriol: but as it
has, like all other Acids, much less affinity with Metallic substances than
with Alkalis, even a moderate degree of fire is sufficient to separate it from
them. Moreover, this Acid hath either no effect, or very little, upon iron that
has lost much of its Phlogiston by contracting an union with any Acid;
which is the case of the ferruginous basis of Vitriol.
By the process here delivered a very strong, perfectly dephlegmated, and
vastly smoking Spirit of Nitre is obtained. If the precautions of drying the
Nitre and calcining the Vitriol be neglected, the Acid that comes over,
greedily attracting the water contained in these salts, will be very aqueous,
will not smoke, and will be almost colourless, with a very slight tinge of
lemon.
The fumes of highly concentrated Spirit of Nitre, such as that obtained by
the above process, are light, corrosive, and very dangerous to the lungs;
being no other than the most dephlegmated part of the Nitrous Acid. The
person therefore who unlutes the vessels, or pours the liquor out of the
receiver into the bottle, ought with the greatest caution to avoid drawing
them in with his breath; and for that reason ought to place himself so that a
current of air, either natural or artificial, may carry them off another way. It
is also necessary that care be taken, during the operation, to give the
vapours a little vent every now and then, by opening the small hole in the
recipient; for they are so elastic, that, if too closely confined, they will burst
the vessels.
When the operation is over, you will find a red mass at the bottom of the
retort, cast, as it were, in a mould. This is a Neutral Salt of the nature of
Vitriolated Tartar, resulting from the union of the Acid of the Vitriol with
the Alkaline basis of the Nitre.
The ferruginous basis of the Vitriol, which is mixed with this salt, gives it
the red colour. To separate it therefrom, you must pulverise it, dissolve it in
boiling water, and filter the solution several times through brown paper;
because the ferruginous earth of the Vitriol is so fine, that some of it will

pass through the first time. When the solution is very clear, and deposites no
sediment, let it be set to shoot, and it will yield crystals of Vitriolated Tartar;
to which Chymists have given the peculiar title of Sal de duobus.
In this Caput mortuum we frequently find, besides the ferruginous earth of
Vitriol, a portion of Nitre and Vitriol not decomposed; either because the
two salts were not thoroughly mingled, or because the fire was not raised
high enough towards the end of the operation.
Nitre may also be decomposed, and its acid obtained, by the interposition of
any of the other Vitriols, Alums, Gypsums, Boles, Clays; in short, by means
of any compound in which the Vitriolic Acid is found, provided it have not
a Fixed Alkali for its basis.
The distillers of Aqua fortis, who make large quantities at a time, and who
use the least chargeable methods, do their business by the means of earths
impregnated with the Vitriolic Acid; such as Clays and Boles. With these
earths they accurately mix the Nitre from which they intend to draw their
Spirit: this mixture they put into large oblong earthen pots, having a very
short curved neck, which enters a recipient of the same matter and form.
These vessels they place in two rows opposite to each other in long
furnaces, and cover them over with bricks cemented with Windsor-loam,
which serves for a reverberatory: then they light the fire in the furnace,
making it at first very small, only to warm the vessels; after which they
throw in wood, and raise the fire till the pots grow quite red-hot, in which
degree they keep it up till the distillation is entirely finished.
The Acid of Nitre may also be separated from its basis by means of the pure
Vitriolic Acid. For this purpose the Nitre from which you mean to extract
the Acid must be finely pulverized, put into a glass retort, and a third of its
weight of concentrated Oil of Vitriol poured on it: the retort must be placed
in a reverberating furnace, and a receiver, like that used in the preceding
operation, expeditiously applied.
As soon as the Oil of Vitriol touches the Nitre the mixture grows hot, and
copious red fumes begin to appear: some drops of the Acid come over even
before the fire is kindled in the furnace.

On this occasion the fire must be moderate; because the Vitriolic Acid,
being clogged by no basis, acts upon the Nitre much more briskly, and with
much greater effect, than when it is not pure.
This operation may be performed by a sand-heat; which is a speedy and
commodious way of obtaining the Nitrous Acid. In other respects the
precautions recommended in the preceding experiment must be carefully
observed here, both in distilling the Acid and in taking it out of the receiver.
The Spirit of Nitre extracted by this method is as strong, and smokes as
much, as that obtained by calcined Vitriol, provided the Oil of Vitriol made
use of be well concentrated; but it is generally tainted by the admixture of a
small portion of the Vitriolic Acid, which, having no basis of its own to
restrain it, is carried up by the heat before it can lay hold of the basis of the
Nitre.
There are several experiments in Chymistry that succeed equally well
whether the Nitrous Acid be or be not thus adulterated with a mixture of the
Vitriolic Acid; but there are some, as we shall see, that will not succeed
without a Spirit of Nitre so mixed. If the Acid be distilled with a view to
such experiments, it must be kept as it is. But most experiments require the
Spirit of Nitre to be absolutely pure; and if it be intended for such, it must
be perfectly cleansed from the Vitriolic taint.
This is easily effected by mixing your Spirit with very pure Nitre, and
distilling it a second time. The Vitriolic Acid, with which this Spirit of Nitre
is adulterated, coming in contact with a great quantity of undecomposed
Nitre, unites with its Alkaline basis, and expels a proportionable quantity of
the Nitrous Acid.
In the retort made use of to distil the Nitrous Acid, by means of the pure
Vitriolic Acid, is found a Caput mortuum, differing from that left after the
distillation of the same Acid by the interposition of Vitriol, in as much as it
contains no red ferruginous earth. This is a very white saline mass, moulded
in the bottom of the retort: if you pound it, dissolve it in boiling water, and
evaporate the solution, it will shoot into crystals of Vitriolated Tartar:
sometimes also it contains a portion of undecomposed Nitre, which shoots
after the Vitriolated Tartar, because it is much more soluble in water.

CHAP. III.

Of the Marine Acid.

PROCESS I.

To extract Sea-salt from Sea-water, and from Brine-springs. Epsom Salt.
ilter the salt-water from which you intend to extract the salt: evaporate

F it by boiling till you see on its surface a dark pellicle: this consists
wholly of little crystals of salt just beginning to shoot: now slacken the
fire, that the brine may evaporate more slowly, and without any agitation.
The crystals, which at first were very small, will become larger, and form
hollow truncated pyramids, the apices whereof will point downwards, and
their bases be even with the surface of the liquor.
These pyramidal crystals are only collections of small cubical crystals
concreted into this form. When they have acquired a certain magnitude they
fall to the bottom of the liquor. When they come to be in such heaps as
almost to reach the surface of the liquor, decant it from them, and continue
the evaporation till no more crystals of Sea-salt will shoot.
OBSERVATIONS.
The Acid of Sea-salt is scarce ever found, either in sea-water or in the earth,
otherwise than united with a fixed alkali of a particular kind, which is its
natural basis; and consequently it is in the form of a Neutral Salt. This salt
is plentifully dissolved in the waters of the ocean, and when obtained
therefrom bears the name of Sea-salt. It is also found in the earth in vast
crystalline masses, and is then called Sal-gem: so that Sea-salt and Sal-gem
are but one and the same sort of salt, differing very little from each other,
except as to the places where they are found.
In the earth are also found springs and fountains, whose waters are strong
brines, a great deal of Sea-salt being dissolved in them. These springs either
rise directly from the sea, or run through some mines of Sal-gem, of which
they take up a quantity in their passage.

As the same, or at least nearly the same, quantity of Sea-salt will continue
dissolved in cold water as boiling water will take up, it cannot shoot, as
Nitre does, by the mere cooling of the water in which it is dissolved: it
crystallizes only by the means of evaporation, which continually lessens the
proportion of the water to the salt; so that it is always capable of containing
just so much the less Sea-salt the more there is crystallized.
The brine should not boil after you perceive the pellicle of little crystals
beginning to form on its surface; for the calmness of the liquor allows them
to form more regularly, and become larger. Nor after this should the
evaporation be hurried on too fast; for a saline crust would form on the
liquor, which, by preventing the vapours from being carried off, would
obstruct the crystallization.
If the evaporation be continued after the liquor ceases to yield any crystals
of Sea-salt, other crystals will be obtained of an oblong four-sided form,
which have a bitter taste, and are almost always moist. This sort of salt is
known by the name of Epsom Salt, which it owes to a salt spring in
England, from the water of which it was first extracted. This salt, or rather
saline compound, is a congeries of Glauber's salt and Sea-salt, in a manner
confounded together, and mixed with some of the Mother of Sea-salt, in
which is contained a kind of bituminous matter. These two Neutral Salts,
which constitute the Epsom Salt, may be easily separated from each other,
by means of crystallization only. Epsom Salt is purgative and bitter; and
therefore named Sal Catharticum Amarum, or bitter purging Salts.
There are different methods used in great works for obtaining Sea-salt out
of water in which it is dissolved. The simplest and easiest is that practised
in France, and in all those countries which are not colder. On the sea-shore
they lay out a sort of broad shallow pits, pans, or rather ponds, which the
sea fills with the tide of flood. When the ponds are thus filled, they stop
their communication with the sea, and leave the water to evaporate by the
heat of the sun; by which means all the salt contained in it necessarily
crystallizes. These pits are called Salt Ponds. Salt can be made in this way
in the summer-time only; at least in France, and other countries of the same
temperature: for during the winter, when the sun has less power and rains
are frequent, this method is not practicable.

For this reason, as it often rains in the province of Normandy, the
inhabitants take another way to extract Salt from sea-water. The labourers
employed for this purpose raise heaps of sand on the shore, so that the tide
waters and drenches them when it flows, and leaves the sand dry when it
ebbs. During the interval between two tides of flood the sun and the air
easily carry off the moisture that was left, and so the sand remains
impregnated with all the salt that was contained in the evaporated water.
Thus they let it acquire as much salt as it can by several returns of flood,
and then wash it out with fresh water, which they evaporate over a fire in
leaden boilers.
To obtain the Salt from brine-springs, the water need only be evaporated:
but as several of these springs contain too little salt to pay the charges that
would be incurred, if the evaporation were effected by the force of fire only,
the manufacturers have fallen upon a less expensive method of getting rid
of the greatest part of the water, and preparing the brine for crystallization,
in much less time, and with much less fire, than would otherwise have been
necessary.
The method consists in making the water fall from a certain heighth on a
great many small spars of wood, which divide it into particles like rain. This
is performed under sheds open to all the winds, which pass freely through
this artificial shower. By this means the water presents to the air a great
extent of surface, being indeed reduced almost entirely to surface, and the
evaporation is carried on with great ease and expedition. The water is raised
by pumps to the heighth from which it is intended to fall[6].

PROCESS II.

Experiments concerning the decomposition of Sea-salt, by means of the
Phlogiston. Kunckel's Phosphorus.
f pure urine that has fermented five or six days take a quantity in

"O proportion to the quantity of phosphorus you intend to make: it
requires about one third part of a hogshead to make a dram of
Phosphorus. Evaporate it in iron pans, till it become clotted, hard, black,
and nearly like chimney-soot; at which time it will be reduced to about a
sixtieth part of its original weight before evaporation.

"When the urine is brought to this condition put it in several portions into so
many iron pots, under which you must keep a pretty brisk fire so as to make
their bottoms red, and stir it incessantly till the volatile salt and the fetid oil
be almost wholly dissipated, till the matter cease to emit any smoke, and till
it smell like peach-blossoms. Then put out the fire, and pour on the matter,
which will now be reduced to a powder, somewhat more than twice its
weight of warm water. Stir it about in this water, and leave it to soak therein
for twenty-four hours. Pour off the water by inclination; dry the drenched
matter, and pulverize it. The previous calcination carries off from the matter
about a third of its weight, and the lixiviation washes out half the remainder.
"With what remains thus calcined, washed, and dried, mix half its weight of
gravel, or yellow freestone rasped, having sifted out and thrown away all
the finest particles. River sand is not proper on this occasion, because it
flies in a hot fire. Then add to this mixture a sixteenth part of its weight of
charcoal, made of beech, or of any other wood except oak, because that also
flies. Moisten the whole with as much water as will bring it to a stiff paste,
by working and kneading it with your hands: now introduce it into your
retort, taking care not to daub its neck. The retort must be of the best earth,
and of such a size, that when your matter is in it, a full third thereof shall
still be empty.
"Place your retort, thus charged, in a reverberating furnace, so proportioned,
that there may be an interval of two inches all round between the sides of
the furnace and the bowl of the retort, even where it contracts to form the
neck, which should stand inclined at an angle of sixty degrees. Stop all the
apertures of the furnace, except the doors of the fire-place and ash-hole.
"Fit on to the retort a large glass ballon two thirds full of water, and lute
them together, as in distilling the Smoking Spirit of Nitre. In the hinder part
of this ballon, a little above the surface of the water, a small hole must be
bored. This hole is to be stopped with a small peg of birch-wood, which
must slip in and out very easily, and have a small knob to prevent its falling
into the ballon. This peg is to be pulled out from time to time, that by
applying the hand to the hole it may be known whether the air, rarefied by
the head of the retort, issues out with too much or too little force.

"If the air rushes out with too much rapidity, and with a hissing noise, the
door of the ash-hole must be entirely shut, in order to slacken the fire. If it
do not strike pretty smartly against the hand, that door must be opened
wider, and large coals thrown into the fire-place to quicken the fire
immediately.
"The operation usually lasts four and twenty hours; and the following signs
shew that it will succeed, provided the retort resist the fire.
"You must begin the operation with putting some unlighted charcoal in the
ash-hole, and a little lighted charcoal at the door thereof, in order to warm
the retort very slowly. When the whole is kindled, push it into the ash-hole,
and close the door thereof with a tile. This moderate heat brings over the
phlegm of the mixture. The same degree of fire must be kept up four hours,
after which some coals may be laid on the grate of the fire-place, which the
fire underneath will kindle by degrees. With this second heat brought nearer
the retort, the ballon grows warm, and is filled with white vapours, which
have the smell of fetid oil. In four hours after, this vessel will grow cool and
clear; and then you must open the door of the ash-hole one inch, throw fresh
coals into the fire-place every three minutes, and every time shut the door
of it, lest the cold air from without should strike against the bottom of the
retort and crack it.
"When the fire has been kept up to this degree for about two hours, the
inside of the ballon begins to be netted over with a volatile salt of a singular
nature, which cannot be driven up but by a very violent fire, and which
smells pretty strong of peach-kernels. Care must be taken that this concrete
salt do not stop the little hole in the ballon: for in that case it would burst,
the retort being then red-hot, and the air exceedingly rarefied. The water in
the ballon, being heated by the vicinity of the furnace, exhales vapours
which dissolve this sprigged salt, and the ballon clears up in half an hour
after it has ceased rising.
"In about three hours from the first appearance of this salt, the ballon is
again filled with new vapours, which smell like Sal Ammoniac thrown upon
burning coals. They condense on the sides of the receiver into a salt which
is not branched like the former, but appears in long perpendicular streaks,
which the vapours of the water do not dissolve. These white vapours are the

fore-runners of the Phosphorus, and a little before they cease to rise they
lose their first smell of Sal Ammoniac, and acquire the odour of garlic.
"As they ascend with great rapidity, the little hole must be frequently
opened, to observe whether the hissing be not too strong: for, in that case, it
would be necessary to shut the door of the ash-hole quite close. These white
vapours continue two hours. When you find they cease rising, make a small
passage through the dome, by opening some of its registers, that the flame
may just begin to draw. Keep up the fire in this mean state till the first
volatile Phosphorus begin to appear.
"This appears in about three hours after the white vapours first begin to rise.
In order to discover it, pull out the little birchen peg once every minute, and
rub it against some hot part of the furnace, where it will leave a trail of
light, if there be any Phosphorus upon it.
"Soon after you observe this sign, there will issue out through the little hole
of the ballon a stream of blueish light, which continues of a greater or
shorter extent to the end of the operation. This stream or spout of light does
not burn. If you hold your finger against it for twenty or thirty seconds, the
light will adhere to it; and if you rub that finger over your hand, the light
will besmear it, and render it luminous.
"But from time to time this streamer darts out to the length of seven or eight
inches, snapping and emitting sparks of fire; and then it burns all
combustible bodies that come in its way. When you observe this, you must
manage the fire very warily, and shut the door of the ash-hole quite close,
yet without ceasing to throw coals into the fire-place every two minutes.
"The Volatile Phosphorus continues two hours; after which the little spout
of light contracts to the length of a line or two: and now is the time for
pushing your fire to the utmost: immediately set the door of the ash-hole
wide open, throw billets of wood into it, unstop all the registers of the
reverberatory, supply the fire-place with large coals every minute: in short,
for six or seven hours all the inside of the furnace must be kept of a white
heat, so that the retort shall not be distinguishable.
"In this fierce extremity of heat the true Phosphorus distils like an oil, or
like melted wax: one part thereof floats on the water in the recipient, the

other falls to the bottom. At last, the operation is known to be quite over
when the upper part of the ballon, in which the volatile Phosphorus appears
condensed in a blackish film, begins to grow red: for this shews that the
Phosphorus is burnt where the red spot appears. You must now stop all the
registers, and shut all the doors of the furnace, in order to smother the fire;
and then close up the little hole in the ballon with fat lute or bees-wax. In
this condition the whole must be left for two days; because, the vessels
must not be separated till they are perfectly cold, lest the Phosphorus should
take fire.
"As soon as the fire is out, the ballon, which is then in the dark, presents a
most agreeable object: all the empty part thereof above the water seems
filled with a beautiful blue light: which continues for seven or eight hours,
or as long as the ballon keeps warm, never disappearing till it is cooled.
"When the furnace is quite cold take out the vessels, and separate them
from each other as neatly as possible. With a linen cloth wipe away all the
black stuff you find in the mouth of the ballon; for if that filth should mix
with the Phosphorus, it would hinder it from being transparent when
moulded. This must be done with great expedition: after which pour into the
ballon two or three quarts of cold water, to accelerate the precipitation of
the Phosphorus that swims at top. Then agitate the water in the ballon, to
rinse out all the Phosphorus that may stick to the sides: pour out all the
water thus shaken and turbid, into a very clean earthen pan, and let it stand
till it grows clear. Then decant this first useless water, and on the blackish
sediment, left at the bottom of the pan, pour some boiling water to melt the
Phosphorus; which thereupon unites with the fuliginous matter, or volatile
Phosphorus, that precipitated with it, both together forming a mass of the
colour of slate. When this water, in which you have melted the Phosphorus,
is cool enough, take out the Phosphorus, throw it into cold water, and
therein break it into little bits in order to mould it.
"Then take a matras, having a long neck somewhat wider next the body
than at its mouth: cut off half the body, so as to make a funnel of the neck-
part, the smaller end of which must be stopped with a cork. The first mould
being thus prepared, plunge it endwise, with its mouth uppermost, in a
vessel full of boiling water, and fill it with that water. Into this funnel throw
the little bits of your slate-like mass, which will melt again in this hot water,

and fall so melted to the bottom of the tube. Stir this melted matter with an
iron wire, to promote the separation of the Phosphorus from the fuliginous
matter with which it is fouled, and which, being less ponderous than the
Phosphorus, will gradually rise above it towards the upper part of the
cylinder.
"Keep the water in the vessel as hot as at first, till, on taking out the tube,
you see the Phosphorus clean and transparent. Let the clear tube cool a
little, and then set it in cold water, where the Phosphorus will congeal as it
cools. When it is perfectly congealed, pull out the cork, and with a small
rod, near as big as the tube, push the cylinder of Phosphorus towards the
mouth of the funnel, where the feculency lies. Cut off the black part of the
cylinder, and keep it apart: for when you have got a quantity thereof, you
may melt it over again in the same manner, and separate the clean
Phosphorus which it still contains. As to the rest of the cylinder which is
clean and transparent, if you intend to mould it into smaller cylinders, you
may cut it in slices, and melt it again by the help of boiling water in glass
tubes of smaller dimensions."
OBSERVATIONS.
This process for making Phosphorus is copied from the Memoirs of the
Academy of Sciences for the Year 1737; where it is described by M. Hellot,
with so much accuracy, clearness, and precision, that I thought I could not
do better than transcribe it, without departing from the author's own
expressions, for the sake of such as may not have those Memoirs. We shall
take occasion, in these observations, to point out some essential
circumstances which I have omitted in the description of the Process, that I
might not break the connection between the phenomena that happen in the
course of this experiment.
It is proper to observe, in the first place, that one of the most usual causes of
miscarriage in this operation is a defect of the requisite qualities in the retort
employed. It is absolutely necessary to have that vessel made of the best
earth, and so well made that it shall be capable of resisting the utmost
violence of fire, continued for a very long time; as appears by the
description of the process. The retorts commonly sold by potters, and other

earthen-ware men, are not fit for this operation; and M. Hellot was obliged
to send to Hesse-Cassel for such as he wanted.
We shall, in the second place, observe with M. Hellot, that, "before you set
your retort in the furnace, it is proper to make an essay of your matter, to
see if there be reason to hope for success. For this purpose put about an
ounce thereof into a small crucible, and heat it till the vessel be red. The
mixture, after having smoked, ought to chop or crack without puffing up, or
even rising in the least. From these cracks will issue undulating flames,
white and blueish, darting upwards with rapidity. This is the first volatile
Phosphorus, which occasions all the danger of the operation. When these
first flashes are over, increase the heat of your matter by laying a large live
coal upon the crucible. You will then see the second Phosphorus, like a
luminous, steady vapour, of a colour inclining to violet, covering the whole
surface of the matter: it continues for a very long time, and diffuses a smell
of garlic, which is the distinguishing odour of the Phosphorus you are
seeking.
"When this luminous vapour is entirely gone, pour the red hot matter out of
the crucible upon an iron plate. If you do not find one drop of salt in fusion,
but that, on the contrary, the whole falls readily into powder, it is a proof
that your matter was sufficiently lixiviated, and that it contains no more
fixed Salt, or Sea-salt, if you will, than is requisite. If you find on the plate a
drop of salt coagulated, it shews that there is too much left in, and that there
is danger of your miscarrying in the operation; because the redundant salt
would corrode, and eat through the retort. In this case your matter must be
washed again, and then sufficiently dried."
Our third observation shall be concerning the furnace proper to be
employed in this operation. This furnace must be so constructed, that,
within a narrow compass it may give a heat at least equal to that of a glass-
house furnace, or rather greater, especially during the last seven or eight
hours of the operation. M. Hellot in his Memoir gives an exact description
of such a furnace.
"As certain accidents may happen in the course of the operation, some
precautions are to be taken against them. For instance, if the ballon should
break while the Phosphorus is distilling, and any of it should fall on