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Title: History of Chemistry, Volume 1 (of 2)

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*** START OF THE PROJECT GUTENBERG EBOOK HISTORY OF
CHEMISTRY, VOLUME 1 (OF 2) ***

A HISTORY OF THE SCIENCES

HISTORY
OF

CHEMISTRY

BY
Sir EDWARD THORPE,
C.B., LL.D., F.R.S.
AUTHOR OF “ESSAYS IN HISTORICAL CHEMISTRY,” “HUMPHRY DAVY:

POET AND PHILOSOPHER,” “JOSEPH PRIESTLEY,” ETC., ETC.

TWO VOLUMES

I.
From the Earliest Times to the Middle of the Nineteenth Century

WITH ILLUSTRATIONS

G. P. PUTNAM’S SONS
NEW YORK AND LONDON
The Knickerbocker Press

1909

Copyright, 1909, by
G. P. PUTNAM’S SONS

This series is published in London by
The Rationalist Press Association, Limited

PUBLISHERS’ NOTE
A History of the Sciences has been planned to present for the
information of the general public a historic record of the great divisions of
science. Each volume is the work of a writer who is accepted as an
authority on his own subject-matter. The books are not to be considered as
primers, but present thoroughly digested information on the relations borne
by each great division of science to the changes in human ideas and to the
intellectual development of mankind. The monographs explain how the
principal scientific discoveries have been arrived at and the names of the
workers to whom such discoveries are due.
The books will comprise each about 200 pages. Each volume will
contain from 12 to 16 illustrations, including portraits of the discoverers
and explanatory views and diagrams. Each volume contains also a concise
but comprehensive bibliography of the subject-matter. The following
volumes will be issued during the course of the autumn of 1909.

The History of Astronomy.
By George Forbes, M.A., F.R.S., M. Inst. C.E.; author of The Transit
of Venus, etc.

The History of Chemistry: Vol. I. circa 2000 B.C. to
1850 A.D. Vol. II. 1850 A.D. to date.
By Sir Edward Thorpe, C.B., LL.D., F.R.S., Director of the
Government Laboratories, London; Professor-elect and Director of the
Chemical Laboratories of the Imperial College of Science and
Technology; author of A Dictionary of Applied Chemistry.

To be followed by:
The History of Geography.
By Dr. John Scott Keltie, F.R.G.S., F.S.S., F.S.A., Hon. Mem.
Geographical Societies of Paris, Berlin, Rome, Brussels, Amsterdam,

Geneva, etc.; author of Report on Geographical Education, Applied
Geography.

The History of Geology.
By Horace B. Woodward, F.R.S., F.G.S., Assistant-Director of
Geological Survey of England and Wales; author of The Geology of
England and Wales, etc.

The History of Anthropology.
By A. C. Haddon, M.A., Sc.D., F.R.S., Lecturer in Ethnology,
Cambridge and London; author of Study of Man, Magic and Fetishism,
etc.

The History of Old Testament Criticism.
By Archibald Duff, Professor of Hebrew and Old Testament Theology
in the United College, Bradford; author of Theology and Ethics of the
Hebrews, Modern Old Testament Theology, etc.

The History of New Testament Criticism.
By F. C. Conybeare, M.A., late Fellow and Praelector of Univ. Coll.,
Oxford; Fellow of the British Academy; Doctor of Theology, honoris
causa, of Giessen; Officer d’ Academie; author of Old Armenian Texts
of Revelation, etc.

Further volumes are in plan on the following subjects:
Mathematics and Mechanics.
Molecular Physics, Heat, Life, and Electricity.
Human Physiology, Embryology, and Heredity.
Acoustics, Harmonics, and the Physiology of Hearing,
together with Optics Chromatics, and Physiology of
Seeing.
Psychology, Analytic, Comparative, and Experimental.
Sociology and Economics.
Ethics.
Comparative Philology.
Criticism, Historical Research, and Legends.

Comparative Mythology and the Science of Religions.
The Criticism of Ecclesiastical Institutions.
Culture, Moral and Intellectual, as Reflected in
Imaginative Literature and in the Fine Arts.
Logic.
Philosophy.
Education.

CONTENTS

CHAPTER I
PAGE
The Chemistry of the Ancients 1
Egypt, the alleged birthplace of chemistry.
Origin of the word “chemistry.” Chemical arts
known to the ancients. Metallurgy of the
ancients. Chemical products of the Chinese,
Egyptians, Greeks, and Romans.

CHAPTER II
The Chemical Philosophy of the Ancients 19
Ancient speculations as to the origin and nature
of matter. Water the primal principle. Thales of
Miletus. Persistency of his doctrine. Its
influence on science. Theories of Anaximenes,
Herakleitos, and Pherekides. Fire as the primal
principle. The conception of four primal
principles—fire, air, water, and earth.
Deification of these by Empedocles. Plato and
Aristotle. The doctrine of the four Elements.
Influence of the Peripatetic Philosophy on
science. Arabian science. Influence of the
Moors in Spain. Atomic conceptions of
Anaxagoras, Leukippos, and Demokritos.
Germs of the atomic theory.

CHAPTER III
Alchemy 28
Influence of the Hellenic mind on the
development of chemistry. Origin of the idea of
the transmutation of metals. Philosophical
foundation for the belief in alchemy.
Alchemistic theory of the nature of metals.
Origin of the conception of the Philosopher’s
Stone. Geber. Association of alchemy with
astrology. Rhazes. Avicenna. Chemical
processes and substances known to the Arabian
chemists. The Western Alchemists. Albertus
Magnus. Roger Bacon. Raymond Lully.
Arnoldus Villanovanus. Johannes de Rupecissa.
George Ripley. Basil Valentine.

CHAPTER IV
The Philosopher’s Stone 46
Alchemy in the Middle Ages. Association of
religion with alchemy by the Christian Church.
Alleged nature of the Philosopher’s Stone. Its
character described. Its power. The Universal
Medicine. The Elixir of Youth. The Alkahest.
Opponents of alchemy: Erastius, Conringius,
and Kircher. “The Hermes of Germany”:
Rudolph II. Christian princes who had dealings
with alchemists. Fate of certain alchemists.
Persistency of alchemy and hermetic societies.
Lord Bacon on alchemy.

CHAPTER V
Iatro-Chemistry 57

Theories of the iatro-chemists. Paracelsus.
Doctrine of the tria prima. The Paracelsian
harmonies. Libavius. Van Helmont. Sylvius.
Willis. Services of iatro-chemistry to science.
Influence of iatro-chemistry on technology.
Agricola. Palissy. Glauber. Chemical products
made known by the alchemists.

CHAPTER VI
“The Sceptical Chemist”: The Dawn of Scientific
Chemistry 70
The foundation of the Royal Society and other
scientific academies. The appearance of “The
Sceptical Chemist”: its attack on the doctrines
of the Spagyrists. Boyle: his life and character.
His services to learning. Kunkel. Becher.
Mayow. Lemery. Homberg. Boerhaave.
Stephen Hales.

CHAPTER VII
Phlogistonism 91
Becher’s hypothesis of the Terra Pinguis. Its
development into the theory of phlogiston.
Stahl. Phlogiston, primarily a theory of
combustion, becomes a theory of chemistry. Its
general acceptance in Europe until the last
quarter of the eighteenth century. Prominent
phlogistians. Pott. Marggraf. Scheele: his
discoveries. Duhamel. Macquer. Black: his
essay on Magnesia Alba. Recognition of the
individuality of carbon dioxide. Priestley: his
life and character. His discoveries in pneumatic
chemistry. His observations on the influence of
vegetable life on the character of the

atmosphere. Cavendish: his life and work.
Discovery of composition of water. Influence of
phlogistonism on the development of
chemistry. Advances made during the period of
phlogistonism.

CHAPTER VIII
Lavoisier and La Révolution Chimique 109
Downfall of phlogistonism. Lavoisier: his life
and work. His death. Le principe oxygine.
Principle of the conservation of matter.
Chemistry a science of quantitative relations.
Prominent anti-phlogistians. Berthollet. The
Statique Chimique. Fourcroy. Vauquelin.
Klaproth. Proust.

CHAPTER IX
The Atomic Theory 123
The atomic hypotheses of the ancients. Newton.
Bergmann. Lavoisier. Richter. Stochiometry.
John Dalton: sketch of his life and character.
How he was led to his explanation of the laws
of chemical combination. The New System of
Chemical Philosophy. Reception of his theory
by Davy and Wollaston. Berzelius: his life and
work. His services to chemistry. First accurate
series of atomic weight determinations.
Avogadro. Prout’s hypothesis.

CHAPTER X
The Beginnings of Electro-Chemistry 140
The Voltaic Pile. Electrolytic decomposition of
water by Nicholson and Carlisle. Application of

voltaic electricity to the decomposition of the
alkalis by Davy. His life and work. Wollaston:
his life and work. Electro-chemical system of
Berzelius. Dualism. Berzelius reforms chemical
notation and nomenclature. Gay Lussac: his life
and work. Thénard: his life and work. Faraday
and the law of definite electrolytic action.

CHAPTER XI
The Foundations of Organic Chemistry 154
Nicolas Lemery divides chemistry into its two
main branches of inorganic and organic
chemistry. State of knowledge of products of
organic origin during the early years of the
nineteenth century. Animal chemistry. Doctrine
of vital force. Wöhler’s synthesis of urea.
Organic chemistry is the chemistry of the
carbon compounds. Early attempts at organic
analysis by Lavoisier, Berzelius, Gay Lussac,
and Thénard. Liebig. Discovery of isomerism
and allotropy. Cyanogen. Theory of compound
radicals. Etherin theory of Dumas and Boullay.
Memoir of Liebig and Wöhler on oil of bitter
almonds. Benzoyl theory. Investigation of
alkarsin by Bunsen. Cacodyl. Discovery of zinc
ethyl by Frankland.

CHAPTER XII
The Rise of Physical Chemistry 170
Relations of chemistry to physics. Relations of
heat to chemical phenomena. Improvements in
the mercurial thermometer. Newton.
Shuckburgh. Brooke Taylor. Cavendish. Black.
Discovery of latent heat by Black. Discovery of

specific heat. Experiments of Lavoisier and
Laplace. Law of Dulong and Petit: its value in
determining atomic weights. Specific heat of
compounds. Neumann. Discovery of
isomorphism by Mitscherlich. Foreshadowing
of the kinetic theory of gases. Discovery of the
law of gaseous diffusion by Graham.
Liquefaction of gases. Monge and Clouet.
Northmore. Faraday. Value of a knowledge of
weights of unit volumes of gases in determining
their molecular weights. Methods of vapour-
determination by Dumas and Gay Lussac.
Dalton and Henry’s law of gaseous solubility.
Work of Schröder and Kopp on volume
relations of liquids and solids. Connection
between the chemical nature of a liquid and its
boiling-point.

Bibliography 183

Index 187

HISTORY OF CHEMISTRY

CHAPTER I

The Chemistry of the Ancients

C hemistry, as an art, was practised thousands of years before the
Christian era; as a science, it dates no further back than the
middle of the seventeenth century. The monumental records of
Egypt and the accounts left us by Herodotus and other writers show that the
ancient Egyptians, among the earliest nations of whom we have any
records, had a considerable knowledge of processes essentially chemical in
their nature. Their priests were adepts in certain chemical arts, and chemical
laboratories were occasionally attached to their temples, as at Thebes,
Memphis, and Heliopolis. It is to be supposed, too, that in a cultured class,
as the priesthood undoubtedly was, there would be now and again curious
and ingenious persons who would speculate on the nature and causes of the
phenomena which they observed. But there is no certain evidence that the
Egyptians ever pursued chemistry in the spirit of science, or even in the
manner in which they and the Chaldæans followed, for example, astronomy
or mathematics. The operations of chemistry as performed by them were of
the nature of manufacturing processes, empirical in character and utilitarian
in result. It was comparatively late in the world’s history that men were
found willing to occupy themselves in chemical pursuits in order to gain an
insight into the nature of chemical change, and to learn the causes and
conditions of its action.

Although we have cited the ancient Egyptians as practising the
chemical arts, there is no proof that these arts actually originated with them.
China, India, Chaldæa have each in turn been regarded as the birthplace of
the various technical processes from which chemistry may be said to have
taken its rise. Nevertheless, it is mainly from Egyptian records, or from
writings avowedly based on information from Egyptian sources, that such

knowledge as we possess of the earliest chemical processes is derived. It is
significant that the word “chemistry” has its origin in chemi, “the black
land,” the ancient name for Egypt. The art itself was constantly spoken of as
the “Egyptian art.”
“The word chemistry,” says Boerhaave in the Prolegomena of his New
Method of Chemistry (Shaw and Chambers’s translation, London, 1727),

in Greek should be wrote χημíα, and in Latin and English chemia
and chemistry; not as usual, chymia and chymistry.
The first author in whom the word is found is Plutarch, who
lived under the Emperors Domitian, Nerva, and Trajan. That
philosopher, in his treatise of Isis and Osiris, takes occasion to
observe that Egypt, in the sacred dialect of the country, was called
by the same name as the black of the eye—viz., χημíα—by which he
seems to intimate that the word chemia in the Egyptian language
signified black, and that the country, Egypt, might take its
denomination from the blackness of the soil.
But [continues Boerhaave] the etymology and grammatical
signification of the name is not so easily dispatched. The critics and
antiquaries, among whom it has been a great subject of inquiry, will
not let it pass without some further disquisition. Instead of black,
some will have it originally denote secret, or occult; and hence
derive it from the Hebrew chaman, or haman—a mystery, whose
radix is cham. And, accordingly, Plutarch observes that Egypt, in
the same sacred dialect, is sometimes wrote in Greek χαμíα—
chamia; whence the word is easily deduced further from Cham,
eldest son of Noah, by whom Egypt was first peopled after the
deluge, and from whom, in the Scripture style, it is called the land
of Cham, or Chem. Now, that chaman, or haman, properly signifies
secret appears from the same Plutarch, who, mentioning an ancient
author named Menethes Sibonita, who had asserted that Ammon and
Hammon were used to denote the god of Egypt, Plutarch takes this
occasion to observe that in the Egyptian language anything secret or
occult was called by the same name, ἅμμον—Hammon.... Lastly, the
learned Bochart, keeping to the same sense of the word, chooses to

derive it from the Arabic chema, or kema—to hide; adding that
there is an Arabic book of secrets called by the same name Kemi.

From the whole of which Boerhaave gathers that chemistry was thus
originally denominated because it was considered of old as “not fit to be
divulged to the populace, but treasured up as a religious secret.”
If we are to credit Zozimus the Panopolite, who is said to have lived
about the beginning of the fifth century, there were sound reasons for thus
treasuring up chemistry as a religious secret, since, as it sprang from the
pretium amoris, its origin was not too reputable. “What the divine writings
relate is that the angels, enflamed with the desire of women, instructed ’em
in all the works and mysteries of nature. For which indiscretion they were
excluded heaven, as having taught men things unfit for ’em to know.” And
Scaliger asserts that “Hermes testifies as much; and all our learning, both
open and occult, confirms the account.” But who Hermes was, adds that
author, is hard to say, for none of his writings has survived to our age, “that
lately published in Italy under the name of Hermes Trismegistus being a
manifest forgery.”
This legend of the “feministic” origin of chemistry is in reality much
older than the fifth century of our era, and is but a variant of that which,
according to Jewish writers, led to the expulsion of man from Paradise. A
similar myth was current among the Phœnicians, Persians, Greeks, and
Magi. We trace it in the legend of Sibylla, who demanded, as the price of
her favour to Phœbus, not only length of years, but a knowledge of the
divine arcanum. Some of the ecclesiastics who elaborated these myths are
particular in their accounts of the mysteries thus imparted. They included
the use of charms, a knowledge of gold and silver and precious stones, the
art of dyeing, of painting the eyebrows, etc.—the kind of arcana, in fact,
which women in all ages were presumably most keen to know. It is,
however, significant that in all allusions to chemia, even after the translation
of the seat of the Roman Empire to Constantinople, it is implied that a
knowledge of it was a sacred mystery to be known only to the priesthood,
and jealously guarded by them. It was characteristic of writers who had
affixed an eternal stigma on Eve to make the sex in general answerable for
an illicit knowledge of “things unfit for men to know.”

For, in reality, chemistry originated with men, and it was not so much
in the love of women as of wine that it took its rise.
The manufacture of alcohol by processes of fermentation is probably
the oldest of the chemical arts. The word wine means, in fact, a product of
fermentation. Mosaic history relates that Noah, soon after he got to dry
land, “planted a vineyard and drank of the wine,” with results that would
appear to show that the potency of wine was not unfamiliar to him.
Diodorus Siculus, who studied Egyptian antiquities when Egypt was a
Roman province, states that the ancient Egyptians ascribed the origin of
wine to Osiris. It was a sacrificial offering even in the earliest times, as was
bread. Wine seems to have been prepared by the Chinese as far back as the
time of the Emperor Yü, circa 2220 B.C. Beer was manufactured in Egypt in
the time of Senwosret III. (Sesostris) B.C. 1880.
The Egyptians were skilled in dyeing and in the manufacture of leather,
and in the production and working of metals and alloys. They were familiar
with the methods of tempering iron. They made glass, artificial gems, and
enamels. The oldest known enamel was found as an amulet on the Egyptian
Queen Aahotep (1700 B.C.), and glass beads were made before the time of
Thutmosis III. (1475 B.C.). The Jews knew of gold, silver, copper, iron, lead,
and tin. Indeed, it is through them and the Phœnicians, who were among the
earliest of traders, that Europe was gradually made acquainted with many
technical products of Eastern origin.
The beginnings of the art of extracting and working of metals are lost
in the mists of antiquity; the chemistry of metals, indeed, has been said to
be almost coeval with mankind. Diodorus Siculus found traditions in Egypt
as to the first inventor of metallurgical processes identical with that of the
son of Lamech and Zillah, Tubal-cain, or Tuval-cain, of the Hebrews—the
Vulcan of the Romans.
Gold was undoubtedly one of the earliest metals to be made use of by
men, as it probably was one of the first to be discovered. It occurs free in
nature, and is met with in many rocks and in the sands of rivers. Its colour,
lustre, and density would early attract attention to it; and its malleability and
ductility and the ease with which it could be fashioned, together with its
unalterability, would render it valuable. Ethiopian and Nubian gold were
known from the earliest times, and quartz crushing and gold washing were

practised by the Egyptians. Representations of these processes have been
found on Egyptian tombs dating from 2500 B.C. Gold-wire was used by the
Egyptians for embroidery, and they practised plating, gilding, and inlaying
as far back as 2000 B.C.
Silver also was employed by them, and appears, like gold, to have been
coined into money. It was originally known as “white gold.” Some of the
oldest coins in existence are alloys of silver and gold, obtained probably by
the fusion of naturally occurring argentiferous gold, such as the pale gold of
the Pactolus. Such an alloy was termed electrum, from its resemblance in
colour to amber.
Copper is also found to a limited extent in the metallic state, but
probably the greater part of that used by the ancients was obtained from its
ores, which are comparatively abundant and readily smelted. It was also
used for coinage by the Egyptians, and was fashioned by them into a variety
of utensils and implements. The older writers drew no clear distinction
between copper, bronze, and brass, and the terms designating them—æs and
χαλκός—are frequently employed; as by Pliny, indiscriminately. The
statement in Deut. viii. 9—“Out of whose hills thou mayest dig brass”—
obviously cannot mean an alloy of copper and zinc, since this does not
occur naturally.
Pure copper is too soft a metal to be used for swords and cutting
instruments, but copper ores frequently contain associated metals, as, for
example, tin, which would confer upon the copper the necessary hardness to
enable it to be fashioned into weapons. Such copper would be of the
character of bronze, and it was known to the early workers that the nature of
the metal was greatly modified by the selection of ores from particular
localities. It was comparatively late in the metallurgical history of copper
that bronze was produced by knowingly adding tin to the metal.
Copper was largely used by the Romans, who obtained it from Cyprus;
it was known to them as æs Cyprium, and eventually Cuprum, whence we
obtain the chemical symbol Cu. What the Romans called æs was found also
at Chalkis, in Eubœa, whence χαλκός, the Greek word for copper.
Aurichalcum, or golden copper—that is, brass—was well known to the
early workers in copper, and was made in Pliny’s time by heating together
copper, cadmia (calamine), and charcoal.

Bell metal was employed by the Assyrians, and bronze was cast by the
Egyptians for the manufacture of mirrors, vases, shields, etc., as far back as
2000 B.C. Statuary bronze, largely used by the Romans, usually contained
more or less lead.
Tin, which was also known to the early Egyptians, would appear to
have been first obtained from the East Indies, and to have been known
under the Sanscrit name of Kastîra (Kâs, to shine), whence we have the
Arabic word for tin, Kàsdir, and the Greek κασσίτερος, used by Homer and
Hesiod. Tin ores are found in Britain (Cornwall), and were brought thence
by the Phœnicians. The group of islands, including the Scilly Islands and
the larger island to the east (Britain), was known to the Romans as the
Insulæ Cassiterides.
Pliny states that the tin is found in grains in alluvial soil, from which it
is obtained by washing; but he gives no description of the method of
smelting. The Latin word for tin was stannum; it was also known as
plumbum album, in contradistinction to lead, which was called plumbum
nigrum. Tin was used by the Romans for covering the inside of copper
vessels, and was also occasionally employed in the construction of mirrors.
Lead was well known to the Egyptians. In Pliny’s time it was mainly
procured from Spain and from Britain (Derbyshire). Leaden pipes were
used by the Romans for the conveyance of water, and sheet lead was
employed by them for roofing purposes. The Romans were also aware of
alloys of lead and tin. Argentarium was composed of equal parts of lead and
tin; tertiarium, used as a solder, consisted of two parts of lead and one part
of tin.
Iron, although now the most important of the common metals, was not
in general use until long after the discovery of gold, silver, and copper. This
was probably due to the fact that, although its ores are relatively abundant
and widely distributed, its extraction as a metal demanded greater skill and
more appliances than were possessed by the earlier races. Metallic iron was,
however, well known to the Egyptians, who employed it in the manufacture
of swords, knives, axes, and stone-chisels, both as malleable iron and as
steel. Steel was also known to the Chinese as far back as 2220 B.C., and they
were acquainted with the methods of tempering it. The good quality of
Chinese steel caused it to be highly prized by Western nations. The earliest

people to smelt iron are supposed to have been the Chalybes, a nation
inhabiting the neighbourhood of the Black Sea; it is from them that the
ancient name for steel—chalybs—is derived, and also our word
“chalybeate.”
Mercury has long been known, but there is no evidence that the ancient
Egyptians were aware of its existence, or it would probably have been
mentioned by Herodotus. It was familiar to Aristotle, and its mode of
manufacture from cinnabar is described by Theophrastus (320 B.C.), who
terms it “liquid silver.” Processes of amalgamation were known to Pliny,
who notes the readiness with which mercury dissolves gold. Pliny appears
to distinguish the native metal found in Spain, which he terms argentum
vivum (quicksilver), from that obtained by sublimation or distillation from
cinnabar, which he calls hydrargyrum, from which we get the chemical
symbol for mercury Hg.
A considerable number of metallic compounds were known to the
ancients, and were employed by them as medicines and as pigments. The
oxides of copper, known as flos æris, and scoria æris, obtained by heating
copper bars to redness and exposing them to air, were used as escharotics.
Verdigris, or ærugo, was made by the same methods as now. Blue vitriol, or
chalcantum, is described by Pliny, who says that the blue transparent
crystals are formed on strings suspended in its solution.
Chrysocolla, malachite, or copper carbonate, was used as a green
pigment. The blue κύανος of the Greeks, or cœruleum of the Romans, was
obtained by fritting together alkali, sand, and oxide of copper. Botryitis,
placitis, onychitis, ostracitis, were varieties of cadmia or oxide of zinc,
obtained by calcining calamine, and were used in the treatment of ulcers,
etc. Molybdena, which was the Latin name for litharge, was employed
externally as an astringent and in the manufacture of plaster. The lead
plaster employed by Roman surgeons was practically identical in character
and mode of preparation with that in use to-day. Cerussa, or white lead, was
made as now by exposing sheets of lead to the fumes of vinegar. It was used
in medicine, as a pigment, and in the preparation of cosmetics. Cerussa usta
was probably red lead. Its present name of minium was originally applied to
cinnabar, the red sulphide of mercury, which was frequently adulterated
with red lead.

Cinnabar, formerly obtained from Africa, and, by the Romans, from
Spain, was also used externally in medicine, and was a highly prized
pigment, whose value was known to the Chinese from very early times. The
black sulphide of antimony, the stimmi and stibium of Dioscorides and
Pliny, was employed by women in Asia, Greece, and latterly in Western
Europe, and is still so used in the East, for blackening their eyelashes.
Preparations of antimony were used in medicine. Realgar, the scarlet
sulphide of arsenic, the sandarach of Aristotle, and the arrenichon of
Theophrastus, was employed as a pigment, and also in medicine, both
internally and externally. The yellow sulphide of arsenic or auri pigmentum
(orpiment), was also used for the same purposes.
A variety of yellow and red ochres, in addition to the pigments above
mentioned, were used by painters, such as rubrica, an iron ochre of a dark
red colour, and sinopis, or reddle, obtained from Egypt, Lemnos, and the
Balearic Isles. Oxides of manganese were used as brown pigments. The
white pigment, paratonium, was probably meerschaum. Melinum was a
variety of chalk found in Samos. The ancients were well acquainted with
indigo and madder, and with the method of manufacturing lakes, which was
employed by Grecian artists.
The famous purpurissum was chalk or clay stained by immersion in a
solution of Tyrian purple. Atramentum was lamp-black: ivory-black was
used by Apelles, and was known as elephantinum. The ink of the ancients
consisted of lamp-black suspended in a solution of gum or glue. The
atramentum indicum, imported from the East, was identical with China ink.
The ancients were well skilled in the art of dyeing, and even of calico
printing. The Tyrians produced their famous purple dye as far back as 1500
B.C. It was obtained from shell-fish, mainly species of Murex, inhabiting the
Mediterranean. Tyrian purple has been shown to be dibrom-indigo, and to
have been produced by the action of air and light upon the juices exuded
from the shell-fish. The fine linen of the Old Testament was probably
cotton, for the production of which Egypt was long celebrated. That the
Egyptians were acquainted with the use of mordants seems evident from the
following passage from Pliny, quoted by Thomson:—

There exists in Egypt a wonderful method of dyeing. The white
cloth is stained in various places, not with dye stuffs, but with

substances which have the property of absorbing colours; these
applications are not visible upon the cloth, but when they are dipped
into a hot caldron of the dye they are drawn out an instant after
dyed. The remarkable circumstance is that, though there be only one
dye in the vat, yet different colours appear upon the cloth; nor can
the colour be afterwards removed.

This passage accurately describes the process of madder dyeing on cotton,
whereby a variety of fast colours—reds, browns and purples—can be
obtained from the same vat by the employment of different mordants, such
as alumina, oxide of iron, or oxide of tin, etc.
Glass has been known from very early times. Representations of glass-
blowing were found on the monuments of Thebes and Beni Hassan, and
large quantities of glass were exported to Greece and Rome from Egypt,
mainly by Phœnicians. Aristophanes mentions it as hyalos, and speaks of it
as the beautiful transparent stone used for kindling fire. The Egyptians
made use of various metallic oxides in colouring glass. The hæmatinon of
Pliny was a red glass coloured with cuprous oxide. Cupric oxide was used
to colour glass green; and ancient blue glass has been found to contain
cobalt. The costly vasa murrhina of the Romans, obtained from Egypt,
probably consisted of fluorspar, identical with the Blue John of the
Derbyshire mines.
Stoneware has been made from time immemorial, and the Chinese have
manufactured porcelain from very remote periods. Bricks and tiles were
made by the Romans, and mortar and stucco were employed by the ancient
Egyptians.
Soap (sapo) is mentioned by Pliny, but its detergent properties were
apparently unknown to him. It appears to have been first made by the
Gauls, who prepared it from the ashes of the beech and the fat of goats, and
used it as a pomatum, as did the jeunesse d’oreé of Rome. Wood ashes, as
well as natron, were, however, used by the ancients for their cleansing
properties.
Starch, acetic acid, sulphur, alumen or crude sulphate of alumina,
beeswax, camphor, bitumen, naphtha, asphalt, nitrum (carbonate of soda),

common salt, and lime, were all known to the Egyptians, and were used by
them for many of the purposes in which they are employed to-day.
It will be evident from this brief survey that the ancients possessed a
considerable acquaintance with many operations of technical chemistry;
but, although they must necessarily have accumulated a large amount of
knowledge, very little has come down to us concerning the mode in which
their processes were conducted, or as to the precautions they employed to
ensure uniform results. Their methods were probably jealously guarded and
handed down by successive members of the crafts as precious secrets. The
experienced masters of these crafts must have met with many strange and
perplexing phenomena in the course of their operations, and a spirit of
inquiry must thereby at times have been awakened. But, under the
conditions in which their industries were prosecuted, the scientific spirit
was not free to develop, for science depends essentially upon free
intercommunication of facts and the spread of knowledge of natural
phenomena. Moreover, the great intellects of antiquity, for the most part,
had little sympathy with the operations of artisans, who, at least among the
Greeks and Romans, were, for the most part, slaves. Philosophers taught
that industrial work tended to lower the standard of thought. The priests, in
most ages, have looked more or less askance at attempts, on the part of the
laity, to inquire too closely into the causes of natural phenomena. The
investigation of nature in early times was impossible for religious reasons.
There was an outcry in Athens when the thunderbolts of Zeus were ascribed
to the collision of clouds. Anaxagoras, Diogenes of Apollonia, Plato,
Aristotle, Diagoras, and Protagoras were charged by the priests with
blasphemy and driven into exile. Prodikos, who deified the natural forces,
as did Empedokles the primal elements, was executed for impiety.
Sacerdotalism in Athens had no more sympathy with science than had the
Holy Congregation in Italy when it banned the writings of Copernicus,
Kepler, and Galileo, and sent Giordano Bruno to the stake. The educated
Greeks had no interest in observing or in explaining the phenomena of
technical processes. However prone they might be to speculation, they had
no inclination to experiment or to engage in the patient accumulation of the
knowledge of physical facts. “You Greeks,” says Plato in one of his
Dialogues, “are ever children, having no knowledge of antiquity, nor
antiquity of knowledge!” The influence of a spurious Aristotelianism, which
lasted through many centuries and even beyond the time of Boyle, was

wholly opposed to the true methods of science, and it was only when
philosophy had shaken itself free from scholasticism that chemistry, as a
science, was able to develop.

CHAPTER II

The Chemical Philosophy of the Ancients

S peculations as to the origin and nature of matter, and as to the
conditions and forces which affect it, are to be found, more or
less imperfectly developed, in the oldest systems of philosophy of
which we have any record. These speculations are not based, in any real
sense, upon the systematic observation of natural phenomena. Still, as they
appealed to human reason, they must be held to be founded upon
experience, or at least not to be consciously inconsistent with it: All the
oldest cosmogonies regarded water as the fundamental principle of things:
from Okeanos sprang the gods—themselves deified personifications of the
“elements” or principles of which the world was made.

In the course of time this doctrine of the origin and essential nature of
matter came to be more particularly associated with the name of Thales of
Miletus, who lived six centuries before our era, and who, according to
Tertullian, is to be regarded as the first of the race of the natural
philosophers—that is, the first of those who made it their business to
inquire after natural causes and phenomena. Thales is known to have passed
some years of his life in Egypt, and to have been instructed in science by
the priests of Thebes and Memphis; and it is therefore possible that he may
have been influenced by the Egyptian teaching in the formulation of his
cosmological theories.
It is significant of the tenacity with which the mind clings to dogma
and reveres authority that the teaching of Thales should have survived
through the space of twenty-four centuries. It can be shown to have affected
the course of chemical inquiry down to the close of the eighteenth century.
It influenced the experimental labours of philosophers so diverse in

character as Van Helmont, Boyle, Boerhaave, Priestley, and Lavoisier—all
of whom made attempts to prove or disprove its adequacy. Van Helmont,
indeed, was one of the most strenuous supporters of the doctrine of Thales,
and sought to establish it by observations which, in the absence of all
knowledge of the true nature of air and water, seemed at the time
irrefutable. Perhaps the one most frequently cited is his observation on the
growth of a plant which apparently had no other form of sustenance than
water. He describes how he planted a willow weighing 5 lbs. in 200 lbs. of
earth previously dried in an oven. The plant was regularly watered, when at
the end of five years it was found to weigh 169 lbs. 3 oz., whereas the earth,
after redrying, had lost only 2 oz. in weight. Hence, 164 lbs. of woody
matter, leaves, roots, etc., had been produced seemingly from water alone.
More than a century had to elapse before any clue to the true interpretation
of Van Helmont’s experiment was gained. It was first furnished by the
observations of Ingenhousz and Priestley.
Although the idea of a primal “element” or common principle is to be
found in every old-world philosophical system, the ancient philosophers
were by no means in agreement as to its character. Anaximenes, who lived
circa 500 B.C., taught that it was air, Herakleitos of Ephesus that it was fire,
and Pherekides that it was earth. The supposition that a single primordial
principle could be made to account for all forms of matter and all the
phenomena and manifestations of the material world had its difficulties.
Attempts to group qualities as principles, and to construct from these
principles the universe, were indeed made even prior to the age of Thales. It
was a comparatively simple evolutionary step to regard these principles or
“elements” as mutually convertible. Anaximenes’ theory of the formation of
rain was an implicit admission of such convertibility. This philosopher
taught that rain came by the condensation of clouds, which in their turn
were formed by the condensation of air. Everything comes from air and
everything returns to air. That water might be converted by fire into air was
surmised from the earliest times. Such a supposition naturally sprung from
the circumstance that water was everywhere recognised to disappear or to
pass into the air under the influence of fire or solar heat. The supposition
had grown into a fixed belief in the Middle Ages. Even Priestley, as late as
the end of the eighteenth century, imagined for a time that he had obtained
proof of such a mutual conversion. The possibility of the transmutation of
water into earth was a belief current through twenty centuries, and was only

definitely and finally disproved by Lavoisier in 1770. The conception of fire
as the primal principle has its germ in the fire- or sun-worship of the
Chaldeans, Scythians, Persians, Parsees, and Hindus, and it is not difficult
to trace, therefore, how heat came to be regarded either as antecedent to, or
as associated with, the other primal principles. Empedokles, apparently, was
the first whose name has come down to us to reintroduce the definite
conception of four primal elements—fire, air, water, and earth. These he
regarded as distinct, and incapable of being transmuted, but as forming all
varieties of matter by intermixture in various proportions. These principles
he deified, Zeus being the personification of the element of fire, Here of air,
Nestis of water, and Aidoneous of earth.
The doctrine of the four elements was also adopted by Plato and
amplified by Aristotle, with whose name indeed it is commonly associated.
Aristotle, the greatest scientific thinker among the Greeks, exercised an
authority almost supreme in Europe during nearly twenty centuries. His
influence is to be traced throughout the literature of chemistry long after the
time of Boyle. It may be detected even now. Probably few who write
chemical memoirs to-day, and who follow the time-honoured practice of
prefacing their own contributions to knowledge by a statement of what is
already known on the subject, are aware that in so doing they are obeying
the injunctions of Aristotle. His theory of the nature of matter is contained
in his treatise on Generation and Destruction. It mainly differed from that
of Empedokles in regarding the four “elements” as mutually convertible.
Each “element” or principle was regarded as being possessed of two
qualities, one of which was shared by another element or principle.
Thus: Fire is hot and dry; air is hot and wet; water is cold and wet;
earth is cold and dry.
In each primal “element” one quality prevails. Fire is more hot than
dry; air is more wet than hot; water is more cold than wet; earth is more dry
than cold. The relative proportion and mutual working of these qualities
determined the specific character of the “element.” Thus, if the dryness of
fire is overcome by the moisture of water, air is produced; if the heat of air
is overcome by the coldness of earth, water is formed; if the moisture of
water is overcome by the dryness of fire, earth results. Ancient chemical
literature contains many illustrations or diagrams symbolising the
convertibility or mutual relations of the four “elements.”

It has been frequently stated that the influence of the Peripatetic
philosophy has been inimical to the development of science. But, in reality,
the founder of that school, a descendant of Esculapius, and undoubtedly one
of the greatest and most enlightened thinkers of antiquity, was an ideal man
of science. This is abundantly evident from such of his works as can be
proved to be genuine. Much of what is called Aristotelianism is entirely
foreign to the spirit of the teaching of Aristotle. The Aristotelians of the
Middle Ages were mainly dialecticians, and almost wholly concerned with
the formulæ of syllogistic inference, and without real sympathy with, or
knowledge of, his system. Much, too, that was attributed to him, and which
was venerated accordingly, is undoubtedly spurious. The fame of the Master
has consequently suffered at the hands of those who, calling themselves
Peripatetics, were in no proper sense followers of his method or interpreters
of his dogma. Aristotle affirmed that natural science can only be founded
upon a knowledge of facts, and facts can only be ascertained through
observation and experiment. He illustrates this particularly by a reference to
astronomy, “which,” he says, “is based on the observation of astronomical
phenomena, and it is the case with every branch of science or art.” It is
erroneous and unjust, therefore, to suppose that Aristotle’s philosophy, as he
taught it, is opposed to the true methods of science.
A knowledge of Aristotle’s works was transferred by Byzantine writers
to Egypt; and, when that land was overrun by the Arabs in the seventh
century, they adopted his system, spreading it abroad wherever their
conquests extended. In the eighth century they carried it into Spain, where it
flourished throughout their occupation of that country. From the ninth to the
eleventh century the greater part of Europe was in a state of barbarism. The
Moslem caliphate in Spain, under the beneficent rule of Jusuf and Jaküb,
alone preserved science from extinction. Cordova, Seville, Grenada, and
Toledo were the chief seats of learning in Western Europe; and it was
mainly through “the perfect and most glorious physicist,” the Moslem Ibn-
Roshd—better known as Averroes—(1126–1198), that Christian scholiasts
like Roger Bacon acquired their knowledge of the philosophical system of
Aristotle, and mainly through the Moslems Geber and Avicenna that they
gained acquaintance with the science of the East.
The conception that matter is made up of particles or atoms, and that
these particles are in a state of ceaseless motion, is to be met with in Hindu

and Phœnician philosophy. It was taught by Anaxagoras, Leukippos, and
Demokritos to the Greeks, and by Lucretius to the Romans. Leukippos and
Demokritos explained the creation of the world as due solely to physical
agencies without the intervention of a creative intelligence. According to
their theories, the atoms are variable, not only in size, but in weight. The
smallest atoms are also the lightest. Atoms are impenetrable; no two atoms
can simultaneously occupy the same place. The collision of the atoms gives
them an oscillatory movement, which is communicated to adjacent atoms,
and these, in their turn, transmit it to the most distant ones. Anaxagoras
taught that every atom is a world in miniature, and that the living body is a
congeries of atoms derived from the aliments which sustain it. Plants are
living things, endowed like animals with respiratory functions, and, like
them, atomically constituted. This philosopher was so far in advance of his
age that his countrymen accused him of sacrilege, and he only escaped
death by flight. Further, the assumption that these atoms exert mutual
attractions and repulsions is probably as old as the fundamental conception
itself. At least, so far as can be traced, the conceptions of atoms and atomic
motion are indissolubly connected. This is not the place to develop the
subsequent history of the doctrine of the atom, nor need we now concern
ourselves with the old metaphysical quibble of its divisibility or
indivisibility. It may be, as Lucretius said, that the original atom is very far
down. It may be that the physical atom is something which is not divided,
not something that cannot be divided. This theory, dimly perceived in the
mists of antiquity, has grown and strengthened with the ages, and in its
modern application to the facts of chemistry has acquired a precision and
harmony unimagined even by the poets and thinkers of old. We shall see
later how the whole course of the science has been controlled, illumined,
and vivified by it. It is not too much to say that the chemistry of to-day is
one vast elaboration of this primeval doctrine.

CHAPTER III

Alchemy

A lthough the intellectual tendencies of the Hellenic mind were
hardly calculated to favour the development of chemistry as a
science, the speculations of the Greeks concerning the essential
nature of matter and the mutual convertibility of the “elements” led
incidentally to an extension of the art of operative chemistry. This extension
resulted from attempts to realise what was the logical outcome of the
teaching of their philosophers—viz., the possibility of the transmutation of
metals. The idea of transmutation has its germ in the oldest systems of
philosophy. It was a plausible doctrine, not wholly unsupported by the
phenomena of the organic world; and it naturally commended itself to men
who were only too prone to adopt what their cupidity and love of wealth
predisposed them to believe.

It has been assumed that alchemy at no time in its history had the
slightest claim to a philosophical foundation, but that its professors and
adepts, even at the outset, consciously traded on the credulity and greed of
their dupes. Much may be urged against such a partial view. The
supposition is not consistent with history or with evolutional tendencies. It
may be, as Davy once said, that “analogy is the fruitful parent of error;” but
the idea that metals could be modified—could even be changed one into the
other—seemed to find support in innumerable chemical phenomena well
known but imperfectly understood. The fact that alchemy—that is the
profession of making gold from other metals—came to be practised by
rogues is no proof that it never had, and never could have had, a
philosophical basis.

The changes which substances experience under the influence of fire,
air, and water, or as the result of their action on each other, are frequently so
profound that even the most superficial of the early observers of chemical
processes could not fail to be impressed by them. Many of these changes
are, in fact, far more striking as regards alteration in outward characters—
such as colour, lustre, density, etc.—than are the differences between
individual metals; say, between lead and tin, or between tin and silver, or
between brass and gold. That copper ores, by appropriate treatment with
other ores, or that copper itself by the addition of another metal, could be
made to furnish a metallic-looking substance having certain of the attributes
of gold was known to the earliest workers in metals. What is thought to be
the oldest chemical treatise in existence is a papyrus in the possession of the
University of Leyden. It consists of a number of receipts for the working of
metals and alloys, and describes methods of imitating and falsifying the
noble metals. It explains how, by means of arsenic, a white colour may be
given to certain metals, and how, by the addition of cadmia, copper acquires
the colour of gold. The same papyrus describes a method of blackening
metals by the use of preparations of sulphur. The limited knowledge of
chemical phenomena and of chemical processes which these early workers
necessarily possessed, so far from precluding a belief in the possibility of
transmutation, actually encouraged it. As nothing was known of the true
nature of brass or of its exact relation to copper, it was not unreasonable to
suppose that, if this substance could be made to acquire some of the
attributes of gold by a process essentially chemical, processes of a like
nature might cause it to acquire, if not all, at least so many of them as to
enable it to pass for gold of greater or less fineness. To them, as to us,
perfection was, in technical practice, a question of degree: the very
language of the metallurgists of old was in this respect nowise different
from that of the metallurgists of to-day.
It is not necessary to suppose that these early attempts were
deliberately and consciously fraudulent, like those of coiners who
knowingly seek to make an alloy of lead and tin simulate silver. The first
alchemists sought in good faith to make something which should be of the
true nature and essence of gold as they conceived it to be. In fact, the idea
of transmutation had a rational foundation in a theory of the intrinsic nature
of metals which may be looked upon as a development of the ancient
beliefs concerning the essential nature of all forms of matter.

Just as the Aristotelian “elements” were qualities which, according to
their degree, determined the nature of substances, so, in like manner, the
specific character of a metal depended upon the relative proportion of its
“sulphur” and “mercury.” These terms had no certain reference to what we
to-day understand by sulphur and mercury. They denoted simply qualities.
The essence or “element” of mercury conferred lustre, malleability,
ductility, and fusibility, or, speaking generally, the properties which we
connote as metallic; while to the essence or “element” of sulphur was to be
attributed the combustibility—or, speaking generally, the alterability—of
the metal by fire. By modifying the relative proportion of these constituent
elements, or by purifying them from extraneous substances by the
operations of chemistry, it was conceived that the several metals could be
changed one into the other. To effect this purification it was necessary to
add various preparations known as “medicines,” chief among which was the
Great Elixir, or Magisterium, or the Philosopher’s Stone, by which the final
transformation into the noblest of the metals could alone be achieved.
The Arabic words kímyâ and iksír were originally synonymous and
each was used to denote the agent by which the baser metals could be
transmuted into silver and gold. Ultimately the former term became
restricted to indicate the art of transmutation (alchemy), whereas iksír, or
al-iksír, continued to denote the medium by which the transmutation was
effected. By later writers the term was used to indicate a liquid preparation
—the quintessence of the philosophers—whence we have the word elixir,
which always means a liquid.
The alchemistic theory of the compound nature and mutual relations of
the metals is usually ascribed to Geber; but, although he adopted it, he
distinctly states that it did not originate with him, but that he found it in the
writings of his predecessors.
The idea of the stone, the philosophical powder, the grand
magisterium, the elixir, the tincture, the quintessence—by all of which
terms the transmuting medium is known in the literature of alchemy—is
probably connected with another conception respecting the origin of metals
which can be traced to very early times and was prevalent throughout the
Middle Ages. It was supposed of old that metals were generated within the
earth, as animals and plants were generated on its surface, and that
something akin to a seed, or semen, was needed to initiate their formation.

The great problem of alchemy was to discover this fecundating substance,
as upon it depended the genesis of the perfect metal. This idea of the
conception of metals runs through the literature of alchemy. It explains
many allusions and much of the terminology of its writers. For example, the
furnace in which the alchemist makes his projection is constantly spoken of
as the philosophical egg.
It is impossible to say with certainty when and where the art of
alchemy originated. There is no evidence that it has the antiquity which
certain of its adepts claimed for it. Oleus Borrichius referred it to the time
of Tubal-cain. The earliest writers on alchemy were probably Byzantine
ecclesiastics, some of whom professed to ascribe the art to Egypt, and
eventually to the mythological deity Hermes, whose association with
chemistry in such terms as “the hermetic art,” “hermetically sealed,” etc., is
thus explained.
This much is established—that at some period prior to the tenth century
there arose a special class of operative chemists, for the most part more
learned in the knowledge of chemical phenomena in general, and more
skilled in chemical manipulation, than the craftsmen and artisans engaged
in the manufacture of technical products. They devoted themselves to
searching for methods whereby the common and baser metals might be
converted into silver and gold. The first known definition of chemistry
relates to the aim and operations of this special class. It occurs in the
lexicon of Suidas, a Greek writer of the eleventh century, who defines
chemistry, χημíα as the preparation of silver and gold. Attempts at the
artificial preparation of the noble metals probably originated with the
Arabians, who followed the Egyptians and the Greeks in the cultivation of
chemical pursuits.
Neither Hesiod nor Homer makes mention of the art of producing gold
from any other metal, or speaks of the universal medicine. Nor are they
referred to by Aristotle or by his pupil Theophrastus. Pliny nowhere speaks
of the philosopher’s stone, although he tells the story of Caligula, who,
tempted by his avarice, sought to make gold from orpiment
(auripigmentum) by distillation. “The result was that he did indeed obtain
both, and of the finest kind; but in so small quantity, and with so much
labour and apparatus, that, the profit not countervailing the expense, he
desisted.”

According to Boerhaave, the first author who mentions al-chemia is
Julius Firmicus Maternus, who lived under Constantine the Great, and who,
in his Mathesis, c. 15, speaking of the influences of the heavenly bodies,
affirms “that, if the moon be in the house of Saturn when a child is born, he
shall be skilled in alchemy.”
The first writer who mentions the possibility of transmuting metals
would appear to be a Greek divine called Æneas Garæus, who lived towards
the close of the fifth century, and who wrote a commentary on
Theophrastus. He was followed by Anastatius the Sinaite, Syncellus,
Stephanus, Olimpiodorus; and, says Boerhaave, “a crowd of no less than
fifty more, all Greeks, and most or all of them monks.” “The art seemed
now confined to the Greeks, and among them few wrote but the religious,
who from their great laziness and solitary way of life were led into vain,
enthusiastical speculations, to the great disservice and adulteration of the
art.... They all wrote in the natural style of the Schoolmen, full of jargon,
grimace, and obscurity.”
Experimental alchemy, as distinguished from industrial chemistry, may,
as already stated, be said to have originated with the Arabians. At first,
alchemy was regarded as a branch of the art of healing, and its professors
were invariably physicians who occupied themselves with the preparation
of chemical medicines. In fact, in the beginning its true aim was regarded as
that which Paracelsus and the school of iatro-chemists subsequently defined
it to be. Under the rule of the Caliphs the study of chemistry made
considerable progress, and its literature was greatly augmented. The most
notable name in the history of chemistry during the eighth century was
Abu-Moussah-Dschabir-Al-Sufi—otherwise Geber—(born 702, died
765), who is stated to have been either a native of Mesopotamia, or a Greek
and a Christian, who afterwards embraced Mahometanism, went to Asia,
and acquired a knowledge of Arabic. According to Leo Africanus, a Greek
who wrote of the antiquity of the Arabs, Geber’s book was originally
written in Greek and translated thence into Arabic, and he was not known
by the name Geber, which signifies a great man or a prince, till after this
version. Latin translations of what purported to be his works were first
published in the early part of the sixteenth century, and an English
rendering appeared in 1678. According to this it would seem that Geber
regarded all the metals as compounds of “sulphur” and “mercury,” the

differences between them depending upon the relative proportion and
degree of purity of these constituents. He is said to have distinguished them
by the astrological names of the planets: thus gold became Sol, silver Luna,
copper Venus, iron Mars, tin Jupiter, and lead Saturn. That an occult
connection of the metals with the stars existed was part of the creed of
alchemy, and the influence of that belief is still traceable in chemical, and
especially in pharmaceutical, literature; as, for example, in such terms as
Lunar caustic, Martian preparations, Saturnine solutions, etc.
It has been held that the idea of a universal medicine had its origin with
Geber. But this may be due to a misreading of his words, which in reality
may have reference to the transmutation of metals. He tells of a medicine
which cures all lepers. But this may be nothing but allegory. By man is
probably meant gold, and by lepers the other metals; and the medicine is
the universal solvent or agent which transmutes. Alchemistic literature is
full of allegories of this character. Berthelot has shown that in reality there
were two Gebers—one who is generally considered to be of Arab origin,
and another whose identity is not established, but who was probably a
1
Western European who appears to have lived about the year 1300.

1
There is very little doubt that the work of
“Phileletha,” which professed to be taken from an
“Uhralten MS.” preserved in the Vatican Library,
entitled Geberi des Königes der Araber, and
published by Hieron. Philipp. Nitschel, Frankfurth
and Leipzig, in 1710, is spurious.

Other notable names in the history of Arabian alchemy are Rhazes, or
Abû Bakr Mohammed ibn Zakaráyá el-Rázi, who lived circa 925, and
Avicenna, or in Arabic Abû Ali el-Hosein ibn-Abdallah ibn-Sina, born
980, died 1037. The former, a Persian, practised medicine at Baghdad as a
follower of Galen and Hippocrates. The latter, one of the most eminent of
Moslem physicians and a voluminous writer, was a native of Bokhara. He is
mainly known in the history of science by his Canon of Medicine, in which
he describes the composition and preparation of remedies. He wrote at least

one treatise on alchemy, but others attributed to him are probably
apocryphal. Of his Philosophia Orientalis, mentioned by Roger Bacon and
Averroes, no trace remains.
Although it is reasonably certain that the alchemists of the time of
Geber and of his successors had a considerable acquaintance with
manipulative chemistry, there were so many impudent literary forgeries
during the alchemical period that the precise extent of the knowledge
possessed by the early chemists must always remain uncertain.
A number of the ordinary chemical processes, such as distillation,
sublimation, calcination, filtration, appear to have been known to, and to
have been commonly practised by, the Arabian chemists; and many saline
substances, such as carbonate of soda, pearlash, sal-ammoniac, alum,
copperas, borax, silver nitrate, cinnabar, and corrosive sublimate, were
prepared by them. They seem to have known of certain of the mineral acids,
and were familiar with the solvent properties of aqua regia.
An examination of the literature of alchemy serves to show how its
principles and tenets developed. The philosopher’s stone is first heard of in
the twelfth century. Prior to that period the greater number of the Greek and
Arabian writers contented themselves with affirming the fact of
transmutation, without indicating how it might be accomplished. The
universal medicine and the elixir of life were the products of a later age; no
mention of them is known before the thirteenth century.
Alchemy flourished vigorously during the Middle Ages, and lingered
on even until the early part of the nineteenth century. Its history is simply a
long chapter in the history of human credulity. For the most part it is a
record of self-deception, imposture, and fraud. It produced an abundant
literature, mainly the work of ecclesiastics, between the seventh and
fourteenth centuries; but as regards the artificial preparation of the noble
metals or the discovery of the universal medicine or the elixir of life it was
barren of result.
Although no clear line of demarcation is possible, it may be
convenient, in dealing with the personal history of alchemy, to divide it into
the two periods before and after Paracelsus, since under his inspiration and
example alchemy underwent a great development as regards its professed
objects. These eventually became so extravagant that, wide as are the limits

of human credulity, its pretensions gradually brought it into disrepute, and it
fell by the weight of its own absurdities.
One of the most reputable of the early Western alchemists was Albert
Groot, or Albertus Magnus, born at Lauingen in 1193. He was a
Dominican monk, who became Bishop of Regensburg, but, resigning his
bishopric, retired to a convent at Cologne, where he devoted himself to
science until his death in 1282. He is credited with having written a number
of chemical tracts, for the most part in clear and intelligible language,
which is more than can be said of the greater portion of alchemistical
literature. He gives an account of the origin and main properties of the
chemical substances known in his time, and describes the apparatus and
processes used by chemists, such as the water-bath, alembics, aludels, and
cupels. He speaks of cream of tartar, alum and caustic alkali, red lead, liver
of sulphur and arsenic, green vitriol and iron pyrites.
Contemporaneously with him was Roger Bacon, Doctor Mirabilis, one
of the most erudite men of his age, who was born near Ilchester in Somerset
in 1214, and, after studying at Oxford, became a friar, occupied himself in
philosophical pursuits, and wrote numerous tracts on alchemy. He describes
what was probably gunpowder, but there is no certain proof that he invented
it. In his De Secretis Artis et Naturæ, written before 1249, he gives
instructions for refining saltpetre, and in an anagram which Colonel Hime,
in his Gunpowder and Ammunition, has interpreted, he states that a mixture
“which will produce a thundering noise and a bright flash” may be made by
taking “7 parts of saltpetre, 5 of young hazel wood, and 5 of sulphur.” He
died in 1285.
Raymund Lully, a friend and scholar of Bacon, was born in Majorca
in 1225 (others say 1235), and was buried there in 1315. A member of the
Order of Minorites, he had a great reputation as an alchemist; and a number
of books on alchemy and chemical processes are ascribed to him. He
described modes of obtaining nitric acid and aqua regia, and studied their
action upon metals. He obtained alcohol by distillation, and knew how to
dehydrate it by the aid of carbonate of potash, which he obtained by
calcining cream of tartar. He prepared various tinctures and essential oils,
and a number of metallic compounds, such as red and white precipitate. To
him is usually ascribed the first idea of a universal medicine.

There is some difficulty in believing that all that is ascribed to Lully
was actually the work of his age, for it would appear to have been a
common practice with the disciples and followers of a notable scholar to
usher in their performances under their master’s name—a practice not
unknown in later days. “So full are they of the experiments and
observations which occur in our later writers that either the books must be
suppositious, or the ancient chemists must have been acquainted with a
world of things which pass for the discoveries of modern practice”
(Boerhaave). The story is that Lully plunged into the study of chemistry
from the desire to cure a maiden of a cancered breast, and that he was
stoned to death in Africa, whither he had journeyed as a missionary. It has
been further alleged that at one period of his life he made gold in the Tower
of London by the King’s order, and that he offered Edward III. a supply of
six millions to make war against the infidels. As Boerhaave drily remarks,
“the history of this eminent adept is very much imbroiled.”
Arnoldus Villanovanus, or Arnaud de Villeneuve, a Frenchman, is
said to have been born in 1240, and to have practised medicine in
Barcelona, where he incurred the enmity of the Church by reason of his
heretical opinions, and was obliged to leave Spain. He led a wandering life,
eventually settling in Sicily, under the protection of Frederick II., and
acquired a great reputation as a physician. Summoned thence by Clement
V., who lay sick at Avignon, he lost his life by shipwreck in 1313.
Johannes de Rupecissa, or Jean de Raquetaillade, a Franciscan friar
who lived from about the middle to the end of the fourteenth century, wrote
a number of treatises on alchemy, and described methods of making
calomel and corrosive sublimate. He was accused of the practice of magic,
and, by order of Innocent VI., was thrown into prison, where he died. He
was buried at Villefranche.
George Ripley, an Englishman, Canon of Bridlington, practised
alchemy during the second half of the fifteenth century. He spent some time
in Italy in the service of Innocent VIII. On his return to England he became
a Carmelite, and died in 1490. Like Bacon, he was charged with magic.
According to Mundanus, he followed alchemy with such success that he
was able to advance to the knights of St. John of Jerusalem large amounts
of gold for the defence of the Isle of Rhodes against the Turks.

One of the most important names in connection with the history of
alchemy is that of Basil Valentine. Of his personal history nothing is
known. He was supposed to be a Benedictine monk who lived in Saxony
during the latter half of the fifteenth century; but there are grounds for the
belief that the numerous writings attributed to him are in reality the work of
various hands. The attempt made by Maximilian I. to discover the identity
of the author was unavailing, nor have subsequent inquiries had any better
result. The collection of books bearing his name, first published in the
beginning of the seventeenth century, reveals quite a remarkable number of
chemical facts up to that time not generally known. The most important of
these relate to antimony and its preparations, such as butter of antimony,
powder of algaroth, oxide of antimony, etc. He seems to have known of
arsenic, zinc, bismuth, and manganese. He described a number of mercurial
preparations, and many of the salts of lead were known to him. He mentions
fulminating gold, and was aware that iron could be coated with copper by
immersion in a solution of blue vitriol. He knew of green vitriol and the
double chloride of iron and ammonium, and gave the modes of making a
considerable number of other metallic salts, such as the sal armoniacum,
which we now know as sal ammoniac. He also appears to have prepared
ether and the chloride and nitrate of ethyl.
There is reason to believe, as stated already, that many of the published
works ascribed to these learned men are the work of obscure individuals
who traded on their fame. What may with certainty be credited to them
serves to show that their theoretical opinions had much in common. They
all regarded the transmutation of metals and the existence of the
philosopher’s stone as facts which could not be controverted. They
followed Geber in assuming that all the metals were essentially compound
in their nature, and consisted of the essence or “element” of mercury, united
with different proportions of the essence or “element” of sulphur.
The alchemists were the professional chemists of their time, and many
of them were practising physicians. Indeed, professional chemistry may be
said to have originated out of the practice of physic. As the number of
chemical products increased and their value in therapeutics became more
and more appreciated, there arose another school of alchemists, whose
energies were devoted, not to the transmutation of metals—which, however
plausible as a belief, seemed hopeless of achievement—but to the more

immediate practical benefits which it was recognised must follow from the
closer association of chemistry and medicine. This school came to be
known as the iatro-chemists. As their doctrines exercised a great influence
upon the development of chemistry, it will be desirable to treat of them and
their professors in a special chapter.

CHAPTER IV

The Philosopher’s Stone

D uring the fourteenth, fifteenth, and sixteenth centuries the cult of
alchemy attained to the dignity of a religion. Belief in
transmutation and in the virtues and powers of the philosopher’s
stone, in the universal medicine, the alkahest, and the elixir of life, formed
its articles of faith. The position it acquired was due to some extent to the
attitude towards it of the Romish Church. Many reputable bishops and
fathers were professed alchemists; and chemical laboratories, as in the
Egyptian temples, were to be found in monasteries throughout
Christendom. Pope John XXII., who had a laboratory in his palace at
Avignon, is the reputed author of a work, Ars Transmutatoria, published in
1557. But to a still larger extent it was due to the fact that alchemy appealed
to some of the strongest of human motives—the wish for health, the fear of
death, and the love of wealth. It was a cunningly devised system, which
exploited the foibles and frailties of human nature. The policy of the
Church, however, it should be said, was not consistently and uniformly
favourable to alchemy. Its practices occasionally came under the papal ban,
although at times, to suit the exigencies of Christian princes, the interdict
was removed. Theosophy and mysticism were first imported into alchemy,
not by Arabs, but by Christian workers. The intimate association of religion
with alchemy during the Middle Ages is obvious in the writings of Lully,
Albertus Magnus, Arnaud de Villeneuve, Basil Valentine, and other
ecclesiastics. Invocations to divine authority are freely scattered over their
pages. Even the lay alchemist professed to rule his life and conduct by the
example and precepts of the good Bishop of Regensburg. He was directed
to be patient, assiduous, and persevering; discreet and silent; to work alone;
to shun the favour of princes and nobles, and to ask the divine blessing on

each operation of trituration, sublimation, fixation, calcination, solution,
distillation, and coagulation.

Although alchemy, at least in its decadent days, lived for the most part
by its appeal to some of the lowest instincts of mankind, and is only worth
notice as a transient phase in the history of science, a few details concerning
the tenets and practices of its professors may be of interest to the curious
reader. And first as regards the nature of the philosopher’s stone—the grand
magistery, the quintessence. Many alchemists professed to have seen and
handled it. It is usually described as a red powder. Lully mentions it under
the name of Carbunculus. Paracelsus says that it was like a ruby,
transparent and brittle as glass; Berigard de Pisa that it was of the colour of
a wild poppy, with the smell of heated sea salt; Van Helmont that it was like
saffron, with the lustre of glass. Helvetius describes it as of the colour of
sulphur. Lastly, an unknown writer, under the pseudonym of “Kalid,” says
that it may be of any colour—white, red, yellow, sky-blue, or green. As the
substance was wholly mythical, a certain latitude of description may
reasonably be expected. Some of the alchemists were of opinion that the
magistery was of two kinds—the first, the grand magistery, needed for the
production of gold; the second, the small magistery, only capable of
ennobling a metal as far as the stage of silver. Then, as to the amounts
required to effect a transmutation, accounts are equally discrepant. Arnaud
de Villeneuve and Rupescissa assert that one part of the grand magistery
will convert a hundred parts of a base metal into gold; Roger Bacon, a
hundred thousand parts; Isaac of Holland, a million. Raymond Lully states
that philosopher’s stone is of such power that even the gold produced by
means of it will ennoble an infinitely large amount of a base metal.
It is hardly necessary to state that a preparation of such potency is
capable of effecting anything or everything; and accordingly, as time went
on, other attributes than that of transmutation came to be associated with it.
It may be, as Boerhaave surmises, that the idea of a universal medicine had
its origin in a too literal interpretation of Geber’s allegory of the six lepers.
Be this as it may, during the fourteenth and fifteenth centuries the
philosopher’s stone was gravely prescribed as a means of preserving health
and prolonging life. In case of illness one grain was directed to be dissolved
in a sufficient quantity of good white wine, contained in a silver vessel, the
draught to be taken after midnight. Recovery would follow after an interval

depending upon the severity and age of the complaint. To keep in good
health, the dose was to be repeated at the beginning of spring and autumn.
“By this means,” says Daniel Zacharias, “one may enjoy perfect health until
the end of the days assigned to one.” Isaac of Holland and Basil Valentine
are equally explicit, but in their case it is recommended that the dose should
be taken once a month: thus life would be prolonged “until the supreme
hour fixed by the king of heaven.” Other alchemists were not always so
prudent in prophecy. Artephius gave the limit of human life thus prolonged
as a thousand years; Gualdo, a Rosicrucian, was stated to have lived four
hundred years. Raymond Lully and Salomon Trismosin, we are told,
renewed their youth by means of it. The advanced age at which Noah begat
children could only be due, says Vincent de Beauvais, to his use of the
philosopher’s stone. Dickinson wrote a learned book to prove that the great
age of the patriarchs was owing to the same secret.
But not only were health and length of days the fortunate lot of him
who possessed the philosopher’s stone; increase of wisdom and virtue
equally followed from its use. As it ennobled metals, so it freed the heart
from evil. It made men as wise as Aristotle or Avicenna, sweetened
adversity, banished vain-glory, ambition, and vicious desires. Adam
received it at the hands of God, and it was given also to Solomon, although
the commentators were rather exercised to know why, as he possessed the
philosopher’s stone, he should have sent to Ophir for gold.
It would serve no good purpose to attempt to describe the recipes given
by various alchemists to prepare this precious substance. With an
affectation at times of precision, they were purposely obscure, and always
enigmatical. As Boyle said of them, they could scarcely keep themselves
from being confuted except by keeping themselves from being clearly
understood. One example of their recipes must suffice: “To fix quicksilver.
—Of several things take 2, 3 and 3, 1; 1 to 3 is 4; 3, 2 and 1. Between 4 and
3 there is 1; 3 from 4 is 1; then 1 and 1, 3 and 4; 1 from 3 is 2. Between 2
and 3 there is 1, between 3 and 2 there is 1. 1, 1, 1, and 1, 2, 2 and 1, 1 and
1 to 2. Then 1 is 1. I have told you all.” No wonder, after an equally
luminous explication, a pupil of Arnaud de Villeneuve should have
exclaimed: “But, master, I do not understand.” Upon which the master
rejoined that he would be clearer another time.

Nor is it necessary to dilate upon the other virtues which were ascribed
at various times to the philosophical powder, as, for example, its power of
making pearls and precious stones, or of its use in preparing the alkahest, or
universal solvent, invented by Paracelsus. In their attempts to fathom the
depths of human credulity the alchemists at length over-reached themselves.
The idea of a universal solvent carried with it, as Kunkel pointed out, its
own refutation: if it dissolved everything, no vessel could contain it. And
yet, says Boerhaave, a whole library could be filled with writings by the
school of Paracelsus on the alkahest. From the latter end of the sixteenth
century repeated attempts were made to expose the pretensions and
demonstrate the absurdities of alchemy. Among its adversaries may be cited
Thomas Erastius, Hermann Conringius, and the Jesuit Kircher. Many of
their dupes, potentates and princes who were powerful enough to exercise
it, occasionally visited with their vengeance those who, unmindful of the
injunctions of Albert the Great, had traded too long upon their credulity.
The Emperor Rudolph II., who earned the title of “The Hermes of
Germany,” was a zealous cultivator of alchemy, and had a well-equipped
laboratory in his palace at Prague, to which every adept was welcome.
Ferdinand III. and Leopold I. were also patrons of the hermetic art, as were
Frederick I. and his successor, Frederick II., Kings of Prussia. Indeed, at
one period nearly every Court in Europe had its alchemist, with the
privileges of the Court fool or the poet laureate. The fraud and imposture to
which the practice gave rise led occasionally to the promulgation of
stringent laws against it, and at times the pursuit of operative chemistry
became well-nigh impossible in some countries. In the fifth year of the
reign of Henry IV. (1404) it was enacted that “None from henceforth shall
use to multiply gold or silver, or use the craft of multiplication; and if the
same do he shall incur the pain of felony.” According to Watson, the true
reason for passing this Act was not an apprehension that men should ruin
their fortunes by endeavouring to make gold, but a jealousy lest
Government should be above asking aid of the subject. At the same time,
letters patent were granted to several persons, permitting them to investigate
the universal medicine and perform the transmutation of metals.
Alphonse X., of Castille, the author of the Key of Wisdom, practised
alchemy. Henry VI., of England, and Edward IV. had dealings with adepts.
Even Elizabeth Tudor, who was a shrewd enough sovereign, had the
notorious Dr. Dee in her pay. Charles VII. and Charles IX., of France,

Christian IV., of Denmark, and Charles XII., of Sweden, sought to replenish
their exhausted treasuries by the aid of the philosopher’s stone. If princes
eventually learned not to put their trust in alchemists, alchemists learned
equally to their cost not to put their trust in princes. Duke Julius, of
Brunswick, in 1575, burnt a female alchemist, Marie Ziglerin, who had
failed in her promise to furnish him with a prescription for the making of
gold. David Benther killed himself to escape the fury of the Elector
Augustus, of Saxony. Bragadino was hanged at Munich in 1590 by the
Elector of Bavaria. Leonard Thurneysser, who gained an evil notoriety in
his day as one of the most unscrupulous of the followers of Paracelsus, and
who amassed considerable wealth by the sale of cosmetics and nostrums,
was deprived of his ill-gotten gains in 1584 by the Elector of Brandenburg,
and died in misery in the convent. Borri, a Milanese adventurer, who had
deceived Frederick III., of Denmark, was imprisoned for years by that
monarch, and died in captivity in 1695. William de Krohnemann was
hanged by the Margrave of Byreuth, who, with grim irony, caused the
inscription to be fixed to his gibbet: “I once knew how to fix mercury, and
now I am myself fixed.” Hector de Klettenberg was beheaded in 1720 by
Augustus II., King of Poland.
All the followers of Hermes were not so wary or so candid as the artist
who declined an invitation to visit the Court of Rudolph II., saying: “If I am
an adept, I have no need of the Emperor; if I am not, the Emperor has no
need of me.” Well might John Clytemius, Abbot of Wiezenberg, write:
“Vanitas, fraus, dolus, sophisticatio, cupiditas, falsitas, mendacium,
stultitia, paupertas, desesperatio, fuga, proscriptio et mendicitas,
perdisæque sunt chemiæ.”
Despite the attacks of Kunkel, Boerhaave, the elder Geoffroy, Klaproth,
and other chemists of influence and repute, alchemy died hard. It found
believers in England until near the close of the eighteenth century, and was
professed even by a Fellow of the Royal Society—Dr. James Price, of
Guildford, who, in chagrin at the exposure of his pretensions, put an end to
his existence in 1783. Hermetic societies existed in Westphalia, at
Königsberg, and at Carlsruhe down to the first decade of the nineteenth
century. M. Chevreul, who lived well into that century, relates that he knew
of several persons who were convinced of the truth of alchemy, among
them “generals, doctors, magistrates, and ecclesiastics.” The strange medley

of alchemy, theosophy, thaumaturgy, and cabalisticism professed by
Christian Rosenkreuz is not without its adherents, even in this twentieth
century.
If the baser metals have not been made to furnish gold, truth at least has
followed from the practice of error. This is the only transmutation which the
art of Hermes has succeeded in effecting. To err is human. Although
alchemy is not without its special interest as one of the most remarkable
aberrations in the history of science, some of its practitioners, it must be
admitted, deceived only themselves: if misguided, they were at least honest,
and pursued their calling in a settled conviction of the soundness of their
faith. Although they never reached their goal—the discovery of the
Philosopher’s Stone and the Elixir of Life—their labours were not wholly
vain, for many new and unexpected facts came to light as the result of their
assiduity.
“Credulity in arts and opinions,” wrote Lord Bacon in De Augmentis
Scientiarum,

is likewise of two kinds—viz., when men give too much belief to
arts themselves, or to certain authors in any art. The sciences that
sway the imagination more than the reason are principally three—
viz., astrology, natural magic, and alchemy.... Alchemy may be
compared to the man who told his sons that he had left them gold,
buried somewhere in his vineyard; while they by digging found no
gold, but by turning up the mould about the roots of the vines
procured a plentiful vintage. So the search and endeavours to make
gold have brought many useful inventions of light.

CHAPTER V

Iatro-Chemistry

T he term “iatro-chemistry” denotes a particular phase in the history of
medicine and of chemistry. The iatro-chemists were a school of
physicians who sought to apply chemical principles to the
elucidation of vital phenomena. According to them, human illnesses result
from abnormal chemical processes within the body, and these could only be
counteracted by appropriate chemical remedies. Although this idea did not
originate with him, the chief exponent of this school is commonly said to be
Paracelsus.

A man of violent passions, coarse, drunken, arrogant, and
unscrupulous, Philippus Aureolus Theophrastus Paracelsus Bombastus
von Hohenheim—to give him his full name—would seem to have
possessed none of the attributes needed by the successful leader of an
intellectual revolution.
Born at Etzel in Switzerland in 1493, son of a physician, William
Bombast von Hohenheim, who combined the practice of astrology with that
of alchemy, Paracelsus, even as a youth, became a wanderer, passing from
province to province and cloister to cloister, living by telling fortunes and
practising sometimes as a quack and at other times as an army surgeon, and
gaining, as he tells us, much curious information from old women, gipsies,
conjurers, and chemists. If we may trust his own account of himself, he had,
before he was thirty-three, wandered over the whole of Europe, and even
into Africa and Asia, everywhere performing miraculous cures and
constantly getting into trouble. In 1526 he secured the appointment of
Professor of Physic in the University of Basle, and signalised his occupancy
of the chair by a course of lectures—a farrago of confused German and

barbarous Latin—in which he assailed with extraordinary vigour and
unexampled coarseness the medical system of the school of Galen.
Scandalised as his professional brethren might be, Paracelsus expressed,
intentionally or unintentionally, the feeling of impatience with which the
laity viewed a system of therapeutics based only on tradition. In this revolt
against authority he initiated a movement which, whatever might have been
its influence on medicine, served eventually, under the guidance of worthier
men, to emancipate chemistry from the thraldom of alchemy.
Paracelsus did little more than initiate. Although his many tracts show
that he was familiar with nearly every chemical preparation of his time,
many of which he used in his practice, he added no new substance to
science. A man of great ability and extraordinary talent, he squandered his
powers in dissipation. His intemperate conduct soon lost him his chair at
Basle; and, after an ignoble quarrel with the magistracy, he fled the town,
and, resuming his wandering life, died, under wretched circumstances, at
Salzburg, in his forty-eighth year.
Space will not permit of any account of the philosophical opinions of
Paracelsus—of his mysticism, his theosophy, his pantheism, his
extraordinary doctrine of the Archæus and Tartarus, his association of
astrology with medicine. His chief merit lies in his insistence that the true
function of chemistry was not to make gold artificially, but to prepare
medicines and substances useful to the arts. He thereby made chemistry
indispensable to medicine, and thenceforward chemistry began to be taught
in the universities and in the schools as an essential part of a medical
education.
Paracelsus is usually regarded as a typical alchemist—the kind of man
made familiar to us by the paintings of Teniers, Van Ostade, and Stein—a
boorish, maudlin knave, who divided his time between the pothouse and the
kitchen in which he prepared his extracts, simples, tinctures, and the other
nostrums which he palmed off upon a credulous world, as ignorant and
superstitious as himself. There is much in the personal history of Paracelsus
that serves to justify such a view of him. That he was in the main an
impudent charlatan, ignorant, vain, and pretentious, there can be little
doubt. He had an astonishing audacity and a boundless effrontery; and it
was largely by the exercise of these qualities that he secured such
professional success as he enjoyed.

To judge from the number of the published works associated with his
name, he was an active and industrious writer. Considering that during the
greater part of his waking time he was more or less intoxicated, it is
difficult to conceive what opportunity he had for composing them. Only one
or two are known to be genuine. These, according to Operinus, his
publisher, he dictated; and from their incoherence and obscurity, their
mystical jargon, and misuse of terms, they read like the ravings of one
whom drunkenness had deprived of reason. Many of the tracts and larger
works appeared after his death—some of them years after; and there is no
certain proof that he was the actual author. Even if we regard them as
suppositious, the fact that they should be published under his name is
significant of the influence and notoriety which this extraordinary man
succeeded in achieving during his short and chequered career.
The immediate followers of Paracelsus—among whom may be named
Thurneysser, Dorn, Severinus, Duchesne—distinguished themselves only
by the boldness with which they promulgated his doctrines, and the
unscrupulous use which they made of his methods. They were all zealous
anti-Galenists, who professed to believe that the sum and perfection of
human knowledge was to be found in the Cabala, and that the secrets of
magical medicine were contained in the Apocalypse. They adopted
pantheism in all its grossness: everything that exists eats, drinks, and voids
excrement; even minerals and liquids assimilate food, and eliminate what
they do not incorporate. Sylphs inhabit the air, nymphs the water, pigmies
the earth, and salamanders the fire. Thus even the Aristotelian elements
were animated. Mercury, sulphur, and salt were, according to Paracelsus,
the primal principles which entered into the composition of all things,
material and immaterial, visible and invisible. The following so-called
“harmonies” were essential articles of faith with a Paracelsian:—

Soul Spirit Body
Mercury Sulphur Salt
Water Air Earth

The laws of the Cabala were held to explain the functions of the body. The
sun rules the heart, the moon the brain, Jupiter the liver, Saturn the spleen,
Mercury the lungs, Mars the bile, Venus the kidneys. Gold was a specific

against diseases of the heart; the liquor of Luna (solution of silver) cures
diseases of the brain. “The remedies,” said Paracelsus, “are subjected to the
will of the stars, and directed by them. You ought, therefore, to wait until
heaven is favourable before ordering a medicine.”
The Paracelsian physicians, for the most part, were a set of dangerous
fanatics, who, in their contempt for the principles of Hippocrates, Galen,
and Avicenna, and in their reckless use of powerful remedies, many of them
metallic poisons, wrought untold misery and mischief. The inevitable
reaction set in, and certain of the faculties, particularly that of Paris,
prohibited their licentiates, under severe penalties, from using chemical
remedies. It is not to be supposed, however, that all iatro-chemists were
unscrupulous charlatans. Some of them clearly perceived the significance
and true value of the movement which Paracelsus may be credited with
having originated.
Andreas Libavius, or Libau, originally a physician, born in Halle, is
best known by his Alchymia, published in 1595, which contains an account
of the main chemical facts known in his time, and is written in clear and
intelligible language, in strong contrast to the mystery and obscurity of his
predecessors. He was the discoverer of stannic chloride, still known as the
fuming liquor of Libavius, and described a method of preparing oil of
vitriol in principle identical with that now made use of on a manufacturing
scale. He died in 1616.
John Baptist van Helmont, a scion of a noble Brabant family, was
born in Brussels in 1577. After studying philosophy and theology at the
University of Louvain, he directed his attention to medicine, and made
himself familiar, in turn, with every system from Hippocrates to Paracelsus.
Having spent some time in travel, he settled on his estate at Vilvorde, and
occupied himself with laboratory pursuits until his death in 1644.
Van Helmont was a scholarly, studious man, and a philosopher. A
theosophist and prone to mysticism, he had many of the mental
characteristics of Paracelsus, without his fanaticism and overweening
egotism. He narrowed the number of Aristotle’s elements down to one, and,
like Thales, considered water to be the true principle of all things,
supporting his theory by ingenious observations on the growth of plants
(see p. 20). He first employed the term gas, and was aware of the existence

of various æriform substances, anticipating Hales, who has been styled the
father of pneumatic chemistry, in the discovery of many gaseous
phenomena. He gave an accurate description of carbonic acid gas, which he
termed gas sylvestre, and showed that it is produced from limestone and
potashes in the fermentation of wine and beer, and that it is formed in the
body and in the earth. The doctrines of the iatro-chemists were further
spread by Sylvius in Holland, and by Willis in England.
Francis de le Boë Sylvius, born at Hanau in 1614, became Professor of
Medicine in the University of Leyden, where he exercised great influence
as a teacher until his death in 1672. Medicine he treated simply as a branch
of applied chemistry, and the vital processes of the animal body as purely
chemical. He freed the theory of physic from much of the mystical
absurdity introduced into it by Paracelsus and van Helmont, and by his
practice brought chemical remedies once more into vogue. He was aware of
the distinction between venous and arterial blood, and that the red colour of
the latter was due to the influence of air. Combustion and respiration he
regarded as analogous phenomena.
Thomas Willis was born in Wiltshire in 1621, and while a student at
Christchurch bore arms in the Royalist army when Oxford was garrisoned
for Charles I. In 1660 he became Sedleian Professor of Natural Philosophy,
and ultimately settled in London as a physician. He died in 1675, and was
buried in Westminster Abbey.
Willis imagined that all vital actions were due to different kinds of
fermentation, and that diseases were caused by abnormalities in the
fermentative process. Although a Paracelsian as regards his theory of the
constitution of matter, he followed Sylvius and his pupil Tachenius in
banishing mysticism from medicine. He was a skilful anatomist, and gave
the first accurate description of the brain and nerves.
Other notable iatro-chemists were Angelus Sala, Daniel Sennert,
Turquet de Mayerne (who became body physician to James I.), Oswald
Croll, Adrian van Mynsicht, and Thomas Lieber. Croll introduced the use of
potassium sulphate and succinic acid into medicine, and Van Mynsicht that
of tartar emetic. Various antimonial preparations had previously been
employed by chemical physicians since the time of Basil Valentine, despite
the ban of the Parliament of Paris on their use.

The chief service of iatro-chemistry to science consisted in its influence
in bringing chemistry within the range of professional study, whereby a
great extension in its pursuit was effected, with the result that a largely
increased number of substances was discovered. Moreover, this wider
experience of chemical processes familiarised workers with chemical
phenomena in general, and thereby contributed to lay the foundations of a
general theory of chemical action, which a succeeding age strove to
complete.
During the period of iatro-chemistry, which may be said to have
extended from the first quarter of the sixteenth century to the latter half of
the seventeenth, chemistry was advanced along practical lines by the
labours of many men, chief of whom were Agricola the metallurgist, Palissy
the potter, and Glauber the technologist. These men were primarily
experimental chemists, who took little or no part in the fruitless polemics of
the period, but followed their avocation in the true spirit of investigators,
and thereby enriched science with many new and well-ascertained facts.
George Agricola, born at Glauchau in Saxony in 1494, was a
contemporary of Paracelsus. After studying medicine at Leipzig, he devoted
himself to metallurgy and mineralogy, first at Joachimsthal, and published a
number of works which were long deservedly regarded as the leading
treatises on these subjects.
In his Libri XII. de re Metallica he gives an account of what was
known in his time respecting the extraction, preparation, and testing of ores.
He describes the smelting of copper and the recovery of the silver which
might be associated with it. He also describes methods of obtaining
quicksilver, and of purifying it by treatment with salt and vinegar. He gives
a full description of the method of obtaining gold by amalgamation, and of
recovering the mercury by distillation. He gives accounts of the smelting of
lead, tin, iron, bismuth, and antimony, and describes the manufacture of
salt, nitre, alum, and green vitriol.
The whole work, which is of folio size, is illustrated by wood-cuts,
which give a faithful idea of the nature of the several operations, and of the
character of furnaces, trompes, bellows, and tools employed in them. It is
by far the most important technical work of the sixteenth century, and it
exercised great influence on the art of metallurgy. The descriptions—at least

as regards European processes—are evidently the result of personal
observation. Agricola visited the mines, and faithfully noted the different
methods of sorting and washing the ores, the characters of which he
accurately describes. His accounts of the various smelting operations are so
detailed that it is obvious they must have been put together after personal
inquiry. The study of metallurgy, indeed, was the main object of his life;
and he devoted to its pursuit even the pension which had been settled on
him by Maurice, Elector of Saxony. He became Mayor of Chemnitz, died
there in 1555, and was buried at Zeitz.
Bernard Palissy lived throughout the greater portion of the sixteenth
century. Although not a professed chemist, nor a follower of any particular
school, he was an ardent self-taught experimentalist and a keen and
accurate observer, who greatly enriched ceramic art by his discoveries.
Johann Rudolf Glauber was born at Karlstadt, in Bavaria, in 1604,
and after a restless life died in Amsterdam in his sixty-fourth year. He
published an encyclopædia of chemical processes, in which he describes the
preparation of a great variety of substances of technical importance. The
greater number of the pharmacopœias of the seventeenth century are
indebted to him for their descriptions of the mode of manufacture of their
official preparations. He discovered sodium sulphate—his sal mirabile, still
frequently named after him—and introduced it into medicine.
During this period the common mineral acids—sulphuric, hydrochloric,
and nitric—became ordinary articles of commerce, and were used in the
manufacture of a number of useful products, chiefly inorganic salts. A
considerable number of metallic oxides were also in common use, and were
applied to a variety of purposes in the arts. The knowledge of definite
organic substances was much more limited. Acetic acid had long been
known, but was first obtained in a concentrated form during this period by
the distillation of verdigris. A number of other acetates were also known, as
well as certain tartrates—as, for example, salt of sorrel, Rochelle or
seignette salt, and tartar emetic. Succinic and benzoic acid were introduced
into medicine, and Tachenius discovered one of the characteristic acids of
fat and oil (stearic acid). Spirit of wine was, of course, largely made and
used in the preparation of tinctures and essences. Ether, originally known as
oleum vitrioli dulce verum, was first discovered by Valerius Cordus; and a

mixture of it with alcohol, long known as Hoffmann’s drops, appears to
have been employed as a medicine by Paracelsus.

CHAPTER VI

“The Sceptical Chemist”: The Dawn of
Scientific Chemistry.

T he latter half of the seventeenth century was a remarkable period in
the history of the intellectual development of Europe. At that
time nearly every department of human knowledge seemed to
have become permeated by an eager spirit of scepticism, inquiry, and
reform. The foundation of the Royal Society of London for Improving
Natural Knowledge, the Accademia del Cimento of Florence, the Academie
Royale at Paris, the Berlin Academy, all within a few years of each other,
was significant of the times. Chemistry was no longer to be a sacred
mystery, to be known only to priests, and its secrets jealously guarded by
them. Science had chafed under the domination of the schoolmen; it was
now contemptuous of the dialectics of the Spagyrists. Experimentarian
philosophy became even fashionable; and the purely deductive methods of
the Peripatetics gradually gave place to the only sound method of advancing
natural knowledge. The supremacy of the old philosophy may be said to
have been first distinctly challenged by Robert Boyle. The appearance in
1661 of his book, The Sceptical Chemist, marks a turning-point in the
history of chemistry. The “Chemico-physical Doubts and Paradoxes” raised
by Boyle “touching the experiments whereby vulgar Spagyrists are wont to
endeavour to evince their Salt, Sulphur, and Mercury to be the true
Principles of Things,” eventually sealed the fate of the doctrine of the tria
prima, and of the tenets of the school of Paracelsus.

In this treatise Boyle sets out to prove that the number of the peripatetic
elements or principles hitherto assumed by chemists is, to say the least,

doubtful. The words “element” and “principle” are used by him as
equivalent terms, and signify those primitive and simple bodies of which
compounds may be said to be composed, and into which these compounds
are ultimately resolvable. He considered that the matter of all bodies was
originally divided into small particles of different shapes and sizes, and that
these particles might unite into small “parcels,” not easily separable again;
that a great variety of compounds may arise from a few ingredients; that
various substances are obtainable from bodies by fire; that fire is not the
true and genuine analyser of bodies, since it does not separate the principles
of a body, but variously alters its nature; and that some things obtained from
a body by fire were not its proper or essential ingredients. Three is not
precisely and universally the number of the distinct substances or elements
into which all compound bodies are resolvable by fire, inasmuch as some
bodies afford more than three principles. Earth and water are as much
chemical principles as salt, sulphur, and mercury. Even the limitation to five
chemical principles is too narrow. Such is proved to be the case by the
mode in which bodies, animals and vegetable, grow, and by the analysis of
minerals and metals. The chemical theory of “qualities” of the Spagyrists is
narrow, defective, and uncertain; supposes things not proved; is often
superfluous, and frequently contradicts the phenomena of nature. The
“principles” found in bodies cannot be the cause of their qualities, since
contrary qualities are ascribed to the same body. He concludes, therefore,
that the Paracelsian elements—their “salt,” “sulphur,” and “mercury”—are
not the first and most simple principles of bodies; but that these consist, at
most, of concretions of corpuscles or particles more simple than they, and
possessing the radical and universal properties of volume, shape, and
motion.

Robert Boyle.
From a painting by F. Kerseboom in the possession of the Royal Society.

Robert Boyle, fourteenth child and the seventh and youngest son of
Richard the “Great” Earl of Cork, and Lord High Chancellor of Ireland, was
born at Lismore in 1626. He was educated at Eton under Sir Henry Wotton,
and, after spending some years on the Continent, settled at Stalbridge in
Dorset, where he owned a manor. He became a member of what was known
as the Invisible College, a small association of men interested in the new
philosophy, who met at each other’s houses in London, and occasionally at
Gresham College, “to discourse and consider of philosophical inquiries and
such as related thereunto.” The meetings were subsequently held in Oxford,
and Boyle took up his residence there in 1654. Here—in association with

Wilkins; John Wallis and Seth Ward, the two Savilian Professors of
Geometry and Astronomy; Thomas Willis, the physician, then student of
Christ Church; Christopher Wren, then Fellow of All Souls’ College;
Goddard, Warden of Merton; and Ralph Bathurst, Fellow of Trinity, and
afterwards its President—they sought to cultivate the new philosophy,
“being satisfied that there was no certain way of arriving at any competent
knowledge unless they made a variety of experiments upon natural bodies.
In order to discover what phenomena they would produce, they pursued that
method by themselves with great industry, and then communicated their
discoveries to each other.” The Invisible College eventually grew into the
Royal Society, which received its charter in 1663. Boyle removed to
London in 1668, and died there on December 31st, 1691, in the sixty-fifth
year of his age.
A man of integrity, modest, simple, and unassuming, Boyle was an
assiduous and true student of science, and practically the whole of his life
was given to its pursuit. His social position, his example, the purity of his
private life, and the fame of his discoveries made his personal influence
very considerable, to the great advantage of science in this country. His
experimental work was of a high order. He introduced the air-pump into
England, and his “pneumatical engine” enabled him to discover many of the
fundamental properties of a gas, notably the relation of its volume to
pressure. He also discovered the dependence of the boiling point of a liquid
upon atmospheric pressure, explained the action of the syphon, the effect of
the air on the vibration of a pendulum and on the propagation of sound, and
made experiments on the nature of flame, and on the relation of air to
combustion and respiration. In his History of Fluidity he seeks to show that
a body seems to be fluid by consisting of corpuscles touching one another
only in some parts of their surfaces; whence, by reason of the numerous
spaces between them, they easily glide along each other till they meet with
some resisting body to whose internal surface they exquisitely
accommodate themselves. He considers the requisites of fluidity to be
chiefly these: The smallness of the component particles, their determinate
figure, the vacant spaces between them, and the fact of their being agitated
variously and apart by their own innate motion or by some thinner
substance which tosses them about in its passage through them. His
published works contain many well-authenticated chemical facts, which are
commonly held to be the discovery of a later time. He prepared acetone by

the distillation of the acetates of lead and lime; and he isolated methyl
alcohol from the products of the destructive distillation of wood. He was
one of the earliest to insist on the necessity of studying the forms of
crystals. He saw in their formation proof that the internal motions,
configuration, and position of the integral parts are all that is necessary to
account for alterations and diversities in outward character. Some of the
stock illustrations of our lecture-rooms were of his contrivance. Thus he
illustrated the expansive power of freezing water by bursting a plugged
gun-barrel filled with water by solidifying the water by means of a mixture
of snow and salt—a freezing mixture which he first introduced.
Boyle was the first to formulate our present conception of an element in
contradistinction to that of the Greeks and the schoolmen who influenced
the theories of the iatro-chemists. In the sense understood by him, the
Aristotelian elements were not true elements, nor were the salt, sulphur, and
mercury of the school of Paracelsus. He was also the first to define the
relation of an element to a compound, and to draw the distinction we still
make between compounds and mixtures. He revived the atomic hypothesis,
and explained chemical combination on the basis of affinity. He contended
that one of the main objects of the chemist was to ascertain the nature of
compounds; and thereby he stimulated the application of analysis to
chemistry. Boyle discovered a number of qualitative reactions, and applied
them to the detection of substances, either free or in combination.
But Boyle’s greatest service to learning consisted in the new spirit he
introduced into chemistry. Henceforward chemistry was no longer the mere
helpmeet of medicine. She became an independent science, the principles of
which were to be ascertained by experiment; a science to be studied with
the object of discovering the laws regulating the phenomena with which it
is concerned—and hence elucidating truth for truth’s sake. The old
philosophy of the Greeks had, as we have seen, become merged into the
doctrine of the iatro-chemists; and this was now to be purified from the
theosophical mysticism with which Paracelsus and his followers had
enshrouded it. “The dialectical subtleties of the schoolmen much more,”
says Boyle, “declare the wit of him that uses them than increase the
knowledge or remove the doubts of sober lovers of truth.... For in such
speculative inquiries where the naked knowledge of the truth is the thing
principally aimed at, what does he teach me worth thanks, that does not, if

he can, make his notion intelligible to me, but by mystical terms and
ambiguous phrases darkens what he should clear up, and makes me add the
trouble of guessing at the sense of what he equivocally expresses, to that of
learning the truth of what he seems to deliver.” The influence of the new
spirit thus infused into the science by Boyle is seen in the general style of
chemical literature at the end of the seventeenth century, when compared
with that of the close of the sixteenth. The mysticism and obscurity of the
alchemists were no longer tolerated.
Boyle was slender and tall, with a countenance pale and emaciated. His
constitution was delicate and his body feeble, and it was only by strict
attention to diet and regularity of exercise that he accomplished what he
did. Although he suffered occasionally from an excessive lowness of spirits,
there was nothing morose or ascetic in his nature. He was never married,
although, says his friend John Evelyn, “few men were more facetious and
agreeable in conversation with the ladies whenever he happened to be
engaged among them.”
Kindly, courteous, charitable; unaffected, and temperate in his manner
of life, Boyle enjoyed the respect and esteem of all his contemporaries. It
was said of him that he was never known to have offended any person in his
whole life by any part of his deportment. He allowed himself a great deal of
decent cheerfulness, and had about him all the tenderness of good nature, as
well as all the softness of friendship. These gave him a large share of other
men’s concerns, for he had a quick sense of the miseries of mankind.
Although a philosopher in the broadest sense of that term, his peculiar and
favourite study was chemistry, “in which,” says Bishop Burnet, “he
engaged with none of those ravenous and ambitious designs that drew many
into them. His design was only to find out nature, to see into what
principles things might be resolved, and of what they were compounded.”
John Kunkel, born in 1630, was the son of an alchemist attached to the
Court of the Duke of Holstein. After serving his father for some years, he
obtained employment as chemist and pharmacist under the Dukes Charles
and Henry, of Lauenburg. He subsequently entered the laboratory at
Dresden of John George II., Elector of Saxony, and, after teaching
chemistry at the University of Wittenburg, then famous as a medical school,
he accepted an invitation to take charge of the glass works and laboratory of
the Elector of Brandenburg, at Berlin. The laboratory was burnt down, and

then Charles XI. of Sweden called him to Stockholm and ennobled him as
Baron von Lowenstiern. He died in Stockholm in 1702. Kunkel’s chief
work is his Laboratorium Chymicum, published after his death. It was
written in German. In it Kunkel relates how he acquired possession of a
knowledge of the manufacture of Baldwin’s phosphorus, and of the
phosphorus discovered by Brand—perhaps the most important, as it
certainly was one of the most striking, of the chemical discoveries of the
seventeenth century. Kunkel did much to liberate chemical literature from
the mysticism and obscurity of alchemy. He was scornful of the theories of
the adepts, and contemptuous of their tria prima.

I, old man that I am, who have been occupied with chemistry
for sixty years, have never yet been able to discover their fixed
sulphur, or how it enters into the composition of metals....
Moreover, they are not agreed among themselves respecting the
kind of sulphur. The sulphur of one is not the sulphur of the other.
To that one may reply that each is at liberty to baptise his child as he
likes. I agree: you may even, if you are so disposed, call an ass a
cow; but you will never make anyone believe that your cow is an
ass.

As to the alkahest he says:—

There has been much discussion concerning this grand natural
solvent. Some derive it from the Latin—akali est; others from the
two German words all geist (all gas); lastly, others say it is from
alles est (that’s all). As to myself, I do not believe in Van Helmont’s
universal solvent. I call it by its true name—alles Lügen heist, or
alles Lügen ist (it is all a lie).

Kunkel discovered the secret of the manufacture of aventurine glass
and of ruby glass by means of the purple of Cassius—a product from gold
first obtained by a doctor of medicine of that name in Hamburg. He made
observations on fermentation and putrefaction—recognised that alum was a
double salt (salduplicatum); described the present method of repairing pure
silver, and of parting gold and silver by means of sulphuric acid. He also
described the mode of preparing a number of essential oils, detected the
presence of stearopten in oils, and discovered nitrous ether.

John Joachim Becher, the son of a Lutheran minister, was born at
Speyer in 1635. Owing to the death of his father and the devastation of the
family property during the Thirty Years’ War, Becher had a hard struggle
with poverty during his youth, and led a restless, wandering life. In 1666 he
was Professor of Medicine in the University of Mayence. Subsequently he
went to Munich as head of the finest laboratory in Europe, but, quarrelling
with the Chancellor of the Bavarian Court, betook himself to Vienna. After
a short stay there, he quitted Austria for Holland, and established himself in
Haarlem. Here he proposed to the States-General to extract gold from the
sand-dunes; but, the project failing, he left for England and visited the
Cornish mines. On the invitation of the Duke of Mecklenburg-Güstrow, he
returned to Germany. Shortly afterwards (in 1682) he died, in the forty-
seventh year of his age. Becher’s name is remembered mainly in connection
with his theory of combustion, which, as we shall see, was subsequently
developed by Stahl into the theory of Phlogiston—a generalisation which
dominated chemistry until near the close of the eighteenth century.
John Mayow, born in Cornwall in 1645, was a practising physician,
whose name chiefly lives by virtue of his clear recognition of the substance
or principle in the air which is concerned in combustion, the calcination of
metals, respiration, and the conversion of venous into arterial blood. This
substance, which he found to be contained in saltpetre, he called spiritus
igno-aëreus or nitro aëreust. Mayow died at the age of thirty-four. Had he
been able to follow up his observations, he might have influenced very
materially the development of theoretical chemistry. As it was, he was
practically overlooked by his contemporaries, and the real significance of
his work was not appreciated until long afterwards.
Nicolas Lemery, also born in 1645, wrote a Cours de Chimie, one of
the best text-books of the time, which passed through as many as thirteen
editions, and was translated into English, German, Latin, Italian, and
Spanish.
In this book he strove, as he says, to express himself clearly, and to
avoid the obscurities which were to be found in the authors who had
preceded him.

The fine imaginations of other philosophers concerning their
physical principles may elevate the spirit by their grand ideas, but

they prove nothing demonstratively. And, as chemistry is a science
of observation, it can only be based on what is palpable and
demonstrative.

Nicolas Lemery, who is not to be confounded with his son Louis, also a
chemist, made a considerable number of contributions to pharmaceutical
chemistry; and his Pharmacopée Universelle, Dictionnaire Universel des
Drogues Simples, and Traité de l’Antimoine were standard works in their
day.
Lemery was at one time a Protestant, and on the revocation of the Edict
of Nantes fled to England; but, embracing Catholicism, he returned to Paris,
re-established his pharmacy, and was elected into the Academy in 1699. He
died in 1715.
William Homberg, born in Batavia in 1652, was originally intended
for the profession of law, but, becoming attached to science, studied botany
and medicine in Padua, chemistry at Bologna and in London, mechanics
and optics at Rome, and anatomy at Leyden. In the course of his travels he
visited the mines of Germany, Hungary, Bohemia, and Sweden. In 1682 he
was invited to Paris by Colbert, and in 1691 was made a member of the
Academy and was placed by the Duke of Orleans in charge of his
laboratory—then one of the finest in Europe. Homberg married the
daughter of Dodart, the physician. She became an expert préparateur, and
was of great assistance to him in his experimental inquiries. He first made
known the existence of phosphorus in France, discovered by Brand, of
Hamburg, and he described the phosphorescent salt associated with his
name. He made important observations on the saturation of alkalis by acids,
and was aware that they combined in different proportions. He was an
industrious worker, and, with the exception of Cassini, was the most active
member of the Academy. He died on September 24th, 1715.
Next to Boyle, perhaps the most active agent in emancipating
chemistry from the yoke of alchemy was Boerhaave, who, by his teaching
as Professor of Physic, raised the University of Leyden to the summit of its
fame.
Hermann Boerhaave, the son of a minister, was born near Leyden, in
1668. He occupied himself in turn with theology, classics, mathematics,

chemistry, and botany, when he turned to physic, and, after a course of
study at the University of Harderwyk, in Gelderland, began to practise. In
1702 he was appointed to a lectureship, and eventually to the Chair of
Medicine, in the University of Leyden, of which he became Rector in 1714.
His reputation as a teacher spread throughout Europe, and steadily
increased until his death.

HERMANNUS BOERHAAVE
Medicinæ, Botanices, Chemiæ
& Collegii practici, in ACAD. LUGD. BAT.
PROFESSOR ORDINARIUS.

After a painting by T. Wandelaar

Boerhaave was one of the most learned men of his age, and singularly
well cultured, not only in science but in history, poetry, and polite literature.
He conversed in English, French, and German, and read Italian and Spanish

with facility. “The Latin he spoke extempore in lectures or conversation
was so clear that, with his action, method, and the aptness of his similes, he
2
could level the most abstruse points to the meanest capacities.” He was
fond of music, and a good performer on several instruments, particularly the
lute. He delighted to welcome musicians to his house. His profession as a
physician brought him wealth, much of which he spent in horticulture; and
the garden of his country seat, nearly eight acres in extent, was enriched
with all the exotic trees he could procure and induce to flourish in the
climate of Holland.

2
Burton, Life of Boerhaave, p. 58 et seq.

Boerhaave was of a robust frame and healthy constitution, early inured
to constant exercise and the inclemencies of weather. His stature was rather
tall, and his habit corpulent. He had a large head, short neck, florid
complexion, light brown curled hair (for he did not wear a wig), an open
countenance, and resembled Socrates in the flatness of his nose and his
natural urbanity. He died at Leyden on September 23rd, 1738, in the
seventieth year of his age.
As a chemist Boerhaave is chiefly known by his Elementa Chemia,
published in 1732—the most complete and most luminous chemical treatise
of its time, translations of which appeared in the chief European languages.
The work is divided into three main parts. The first is concerned with the
origin and progress of the art, and with the personal history of its most
distinguished cultivators. The second and largest part deals with the attempt
to form a system of chemistry based on such observational matter as
seemed well established. The third consists of a collection of chemical
processes relating to the analysis or decomposition of bodies, grouped
under the heads of “vegetables,” “animals,” and “fossils”—the beginnings,
in fact, of subdivision of the science into organic and inorganic chemistry.
As regards his belief in alchemy, Boerhaave was an agnostic: he neither
affirmed nor denied the possibility of transmutation. In this respect he
resembled Newton and Boyle. Boyle, indeed, was singularly cautious and

reticent in his references to alchemistic matters. As was said of him by
Shaw, he was too wise to set any bounds to nature: he was not prone to say
that every strange thing must needs be impossible, for he saw strange things
every day, and was well aware that there are powerful forces in the world of
whose laws and modes of action he knew nothing. With that wariness which
was habitual to him, he was wont to say that “those who had seen them
might better believe them than those who had not”; and he was modest
enough to suppose that Paracelsus or Helmont might conceivably know of
agents of which he was ignorant.
Boerhaave unquestionably spent much time in the study of alchemical
works, particularly those of Paracelsus and Helmont, which he repeatedly
read. The Philosophical Transactions of the Royal Society contain the
results of a laborious but fruitless investigation by him on quicksilver,
which he undertook in the hope of discovering the seminal or engendering
matter which, on the old theory of the generation of metals, was supposed
to be contained in mercury. But although, as he relates, he tortured it by
“conquassation, trituration, digestion, and by distillation, either alone or
amalgamated with lead, tin, or gold, repeating this operation to 511 or even
to 877 distillations,” the mercury appeared only “rather more bright and
liquid, without any other variation in its form or virtues, and acquired very
little, if any, increase of its specific gravity.”
Stephen Hales (1677–1761), an ingenious divine—he held the
perpetual curacy of Teddington, and lived practically the greater part of his
life there—distinguished as a physiologist and inventor, occupied himself in
chemical pursuits, and made a number of observations on the production of
gaseous substances. His results were communicated to the Royal Society
and subsequently republished, in a collected form, under the title of Statical
Essays. In these experiments he used methods very similar in principle to
those subsequently employed by Priestley. It is evident from his description
of his experiments that he must have prepared a considerable number of
gaseous substances—hydrogen, carbonic acid, carbonic oxide, sulphur
dioxide, marsh gas, etc.—but he seems to have made no systematic attempt
to study their properties, as he considered that they were simply air,
modified or “tinctured” by the presence of substances which he regarded as
more or less fortuitous. Prior to the time of Black all forms of gaseous
substance were regarded as substantially identical—in fact, as being air, as

understood by the Ancients—a simple elementary substance. It was Black’s
study of carbonic acid which first clearly established that there were
essentially distinct varieties of gaseous matter.

CHAPTER VII

Phlogistonism

E ven before the appearance of The Sceptical Chemist there was a
growing conviction that the old hypotheses as to the essential
nature of matter were inadequate and misleading. We have seen
how the four “elements” of the Peripatetics had become merged into the tria
prima—the “salt,” “sulphur,” and “mercury”—of the Paracelsians. As the
phenomena of chemical action became better known, the latter iatro-
chemists—or, rather, that section of them which recognised that chemistry
had wider aims than to minister merely to medicine—felt that the
conception of the tria prima, as understood by Paracelsus and his followers,
was incapable of being generalised into a theory of chemistry. Becher, while
clinging to the conception of three primordial substances as making up all
forms of matter, changed the qualities hitherto associated with them.
According to the new theory, all matter was composed of a mercurial, a
vitreous, and a combustible substance or principle, in varying proportions,
depending upon the nature of the particular form of matter. When a body
was burnt or a metal calcined, the combustible substance—the terra pinguis
of Becher—escaped.

This attempt to connect the phenomena of combustion and calcination
with the general phenomena of chemistry was still further developed by
Stahl, and was eventually extended into a comprehensive theory of
chemistry, which was fairly satisfactory so long as no effort was made to
test its sufficiency by an appeal to the balance.
George Ernest Stahl, who developed Becher’s notion into the theory
of phlogiston (φλογιοτός—burnt), and thereby created a generalisation
which first made chemistry a science, was born at Anspach in 1660, became

Professor of Medicine and Chemistry at Halle in 1693, physician to the
King of Prussia in 1716, and died in Berlin in 1734.
Stahl contributed little or nothing to practical chemistry; and no new
fact or discovery is associated with his name. His service to science consists
in the temporary success he achieved in grouping chemical phenomena, and
in explaining them consistently by a comprehensive hypothesis.
The theory of phlogiston was originally broached as a theory of
combustion. According to this theory, bodies such as coal, charcoal, wood,
oil, fat, etc., burn because they contain a combustible principle, which was
assumed to be a material substance and uniform in character. This substance
was known as phlogiston. All combustible bodies were to be regarded,
therefore, as compounds, one of their constituents being phlogiston: their
different natures depended partly upon the proportion of phlogiston they
contain, and partly upon the nature and amount of their other constituents.
A body, when burning, was parting with its phlogiston; and all the
phenomena of combustion—the flame, heat, and light—were caused by the
violence of the expulsion of that substance. Certain metals—as, for
example, zinc—could be caused to burn, and thereby to yield earthy
substances, sometimes white in colour, at other times variously coloured.
These earthy substances were called calces, from their general resemblance
to lime. Other metals, like lead and mercury, did not appear to burn; but on
heating them they gradually lost their metallic appearance, and became
converted into calces. This operation was known as calcination. In the act of
burning or of calcination phlogiston was expelled. Hence metals were
essentially compound: they consisted of phlogiston and a calx, the nature of
which determined the character of the metal. By adding phlogiston to a calx
the metal was regenerated. Thus, on heating the calx of zinc or of lead with
coal, or charcoal, or wood, metallic zinc or lead was again formed. When a
candle burns, its phlogiston is transferred to the air; if burned in a limited
supply of air, combustion ceases, because the air becomes saturated with
phlogiston.
Respiration is a kind of combustion whereby the temperature of the
body is maintained. It consists simply in the transference of the phlogiston
of the body to the air. If we attempt to breathe in a confined space, the air
becomes eventually saturated with the phlogiston, and respiration stops.
The various manifestations of chemical action, in like manner, were

attributed to this passing to and fro of phlogiston. The colour of a substance
is connected with the amount of phlogiston it contains. Thus, when lead is
heated, it yields a yellow substance (litharge); when still further heated, it
yields a red substance (red lead). These differences in colour were supposed
to depend upon the varying amount of phlogiston expelled.
The doctrine of phlogiston was embraced by nearly all Stahl’s German
contemporaries, notably by Marggraf, Neumann, Eller, and Pott. It spread
into Sweden, and was accepted by Bergman and Scheele; into France,
where it was taught by Duhamel, Rouelle, and Macquer; and into Great
Britain, where its most influential supporters were Priestley and Cavendish.
It continued to be the orthodox faith until the last quarter of the eighteenth
century, when, after the discovery of oxygen, it was overturned by
Lavoisier.
During the sway of phlogiston chemistry made many notable advances
—not by its aid, but rather in spite of it. As a matter of fact, until the time of
Lavoisier few, if any, investigations were made with the express intention of
testing it, or of establishing its sufficiency. When new phenomena were
observed the attempt was no doubt made to explain them by its aid,
frequently with no satisfactory result. Indeed, even in the time of Stahl,
facts were known which it was difficult or impossible to reconcile with his
doctrine; but these were either ignored, or their true import explained away.
Although, therefore, these advances were in no way connected with
phlogiston, it will be convenient to deal with the more important of them
now, inasmuch as they were made during the phlogistic period.
With the exception of Marggraf, Stahl’s German contemporaries
contributed few facts of first-rate importance to chemistry. Pott, who was
born at Halberstadt in 1692 and become Professor of Chemistry in Berlin in
1737, is chiefly remembered by his work on porcelain, the chemical nature
and mode of origin of which he first elucidated. Marggraf, born in Berlin
in 1709, was one of the best analysts of his age. He first clearly
distinguished between lime and alumina, and was one of the earliest to
point out that the vegetable alkali (potash) differed from the mineral alkali
(soda). He also showed that gypsum, heavy spar, and potassium sulphate
were analogous in composition. He clearly indicated the relation of
phosphoric acid to phosphorus, described a number of methods of preparing
that acid, and explained the origin of the phosphoric acid in urine.

Of the Swedish chemists of that period, the most notable was Scheele.
Carl Wilhelm Scheele was born in 1742 at Stralsund. When fourteen
years of age he was apprenticed to an apothecary at Gothenburg, and began
the study of experimental chemistry, which he continued to prosecute as an
apothecary at Malmö, Stockholm, Upsala, and eventually at Köping on
Lake Malar, where he died in 1786, in the forty-third year of his age.
During the comparatively short period of his scientific activity Scheele
made himself the greatest chemical discoverer of his time.

Carl Wilhelm Scheele.
From the statue by Börjeson at Stockholm.

He first isolated chlorine, and determined the individuality of
manganese and baryta. He was an independent discoverer of oxygen,
ammonia, and hydrogen chloride. He discovered also hydrofluoric, nitro-
sulphonic, molybdic, tungstic, and arsenic, among the inorganic acids; and

lactic, gallic, pyrogallic, oxalic, citric, tartaric, malic, mucic, and uric acids
among the organic acids. He isolated glycerine and milk-sugar; determined
the nature of microcosmic salt, borax, and Prussian blue, and prepared
hydrocyanic acid. He demonstrated that graphite is a form of carbon. He
discovered the chemical nature of sulphuretted hydrogen, arsenuretted
hydrogen, and the green arsenical pigment known by his name. He invented
new processes for preparing ether, powder of algaroth, phosphorus,
calomel, and magnesia alba. He first prepared ferrous ammonium sulphate,
showed how iron may be analytically separated from manganese; and
described the method of breaking up mineral silicates by fusion with
alkaline carbonates. Scheele’s contributions to chemical theory were slight
and unimportant, but as a discoverer he stands pre-eminent.
Of the French phlogistians we have space only to mention Duhamel
and Macquer.
Henry Louis Duhamel du Monceau was born at Paris in 1700. He
was one of the earliest to make experiments on ossification, and one of the
first to detect the difference between potash and soda.
Peter Joseph Macquer was born in 1718 at Paris. He investigated the
nature of Prussian blue (discovered by Diesbach, of Berlin, in 1710),
worked on platinum, wrote one of the best text-books of his time, published
a dictionary of chemistry, and was an authority of the chemistry of dyeing.
In addition to those already mentioned, the most notable names as
workers in chemistry in Great Britain during the eighteenth century are
Black, Priestley, and Cavendish.
Joseph Black was born in 1728 at Bordeaux, where his father was
engaged in the wine trade. A student of the University of Glasgow, he
became its Professor of Chemistry in 1756. In 1766 he was transferred to
the Chemical Chair of the University of Edinburgh, and died in 1799. Black
published only three papers, the most important of which is entitled
Experiments upon Magnesia Alba, Quicklime, and Other Alkaline
Substances. He proved that magnesia is a peculiar earth differing in
properties from lime. Lime is a pure earth, while limestone is carbonate of
lime. He showed that magnesia will also combine with carbonic acid, and
he explained that the difference between the mild and caustic alkalis is that
the former contain carbonic acid, whereas the latter do not. He also

explained how lime is able to convert the mild alkalis into caustic alkalis.
Simple and well known as these facts are to-day, their discovery in 1755
excited great interest, and marked an epoch in the history of chemistry.
Black’s name is associated with the discovery of latent and specific heat,
and he made the first determinations of the amount of heat required to
convert ice into water.

Joseph Priestley.
From a mezzotint after Fuseli in the possession of the Royal Society.

Joseph Priestley, the son of a clothdresser, was born in 1733 at
Fieldhead, near Leeds. When seven years of age, on the death of his mother,
he was taken charge of by his aunt, and was educated for the Nonconformist
ministry, eventually becoming a Unitarian. He was first attracted to science
by the study of electricity, of which he compiled a history. At Leeds, where
he had charge of the Mill Hill congregation, he turned his attention to
chemistry, mainly from the circumstance that he lived near a brewery and
had the opportunity of procuring large quantities of carbonic acid, the
properties of which he carefully studied. He abandoned the ministry for a
time to become librarian and literary companion to Lord Shelburne, with
whom he remained seven years. During this time he industriously pursued
chemical inquiry, and discovered a large number of æriform bodies—viz.,
nitric oxide, hydrogen chloride, sulphur dioxide, silicon fluoride, ammonia,
nitrous oxide, and, most important of all from the point of view of chemical
theory, oxygen gas. Priestley’s work gave a remarkable impetus to the study
of pneumatic chemistry. It exercised great influence on the extension of
chemical science, and—in other hands than his—on the development of
chemical theory. The most important of his contributions to science are
contained in his Experiments and Observations on Different Kinds of Air.
This work not only gives an account of the methods by which he isolated
the gases he discovered, but describes a great number of incidental
observations, such as the action of vegetation on respired air, showing that
the green parts of plants are able in sunlight to decompose carbonic acid
and to restore oxygen to the atmosphere. He was, in fact, one of the earliest
to trace the specific action of animals and plants on atmospheric air, and to
show how these specific actions maintained its purity and constancy of
composition. He initiated the art of eudiometry (gas analysis), and was the
first to establish that the air is not a simple substance, as imagined by the
ancients. Priestley is to be credited with the invention of soda-water, which
he prepared as a remedy for scurvy; and his name is connected with the so-
called pneumatic trough—a simple enough piece of apparatus, but one
which proved to be of the greatest service to him in his inquiries.
After leaving Lord Shelburne, Priestley removed to Birmingham and
resumed his ministry. His religious and political opinions made him
obnoxious to the Church and State party; and during the riots of 1791 his
house was wrecked, his books and apparatus destroyed, and his life
endangered. Eventually he emigrated to America, and settled at

Northumberland, where he died on February 6th, 1804, in the seventy-first
year of his age.

From a drawing by Alexander in the Print Room of the British
Museum.

Henry Cavendish was born at Nice in 1731, and died in London in
1810. He was a natural philosopher in the widest sense of that term, and

occupied himself in turn with nearly every branch of physical science. He
was a capable astronomer and an excellent mathematician, and he was one
of the earliest to work on the subject of specific heat, and to improve the
thermometer and the methods of making thermometric observations. He
also determined the mean density of the earth. He made accurate
observations on the properties of carbonic acid and hydrogen, greatly
improved the methods of eudiometry, and first established the practical
uniformity of the composition of atmospheric air. His greatest discovery,
however, was his determination of the composition of water. He was the
first to prove that water is not a simple or elementary substance, as
supposed by the ancients, but is a compound of hydrogen and oxygen. In
certain of his trials he found that the water formed by the union of oxygen
and hydrogen was acid to the taste; and the search for the cause of this
acidity led him to the discovery of the composition of nitric acid. He was
the first to make a fairly accurate analysis of a natural water, and to explain
what is known as the hardness of water.
Phlogistonism may be said to have dominated chemistry during three-
fourths of the eighteenth century. Although radically false as a conception
and of little use in the true interpretation of chemical phenomena, it cannot
be said to have actually retarded the pursuit of chemistry. Men went on
working and accumulating chemical facts uninspired and, for the most part,
uninfluenced by it. Even Priestley, perhaps one of the most conservative of
the followers of Stahl, regarded his dogma with a complacent tolerance; and
as its inconsistencies became apparent he was more than once on the point
of renouncing it. Of one thing he was quite convinced, and that was that
Stahl had greatly erred in his conception of the real nature of phlogiston.
Perhaps the most signal disservice which phlogiston did to chemistry was to
delay the general recognition of Boyle’s views of the nature of the elements.
The alchemists, it will be remembered, regarded the metals as essentially
compound. Boyle was disposed to believe that they were simple. Becher
and Stahl and their followers, until the last quarter of the eighteenth century,
also regarded them as compounds, phlogiston being one of their
constituents. On the other hand, what we now know to be compounds—
such as the calces, the acids, and water itself—were held by the phlogistians
to be simple substances.

The discovery, in 1774, of oxygen—the dephlogisticated air of
Priestley—and the recognition of the part it plays in the phenomena which
phlogiston was invoked to explain, mark the termination of one era in
chemical history and the beginning of another. Before entering upon an
account of the new era it is desirable to take stock of the actual condition of
chemical knowledge at the end of the phlogistic period, and to show what
advances had been made in pure and applied chemistry during that time.
During the eighteenth century greater insight was gained into the
operations of the form of energy with which chemistry is mainly concerned,
and views concerning chemical affinity and its causes began to assume
more definite shape, chiefly owing to the labours of Boerhaave, Bergman,
Geoffroy, and Rouelle. It was clearly recognised that the large group of
substances comprised under the term “salts” were compound, and made up
of two contrasted and, in a sense, antagonistic constituents, classed
generically as acids and bases.
On the practical side chemistry made considerable progress. Analysis—
a term originally applied by Boyle—greatly advanced. It was, of course,
mainly qualitative; but, thanks to the labours of Boyle, Hoffmann,
Marggraf, Scheele, Bergman, Gahn, and Cronstedt, certain reactions and
reagents came to be systematically applied to the recognition of chemical
substances, and the precision with which these reagents were used led to the
detection of hitherto unknown elements. The beginnings of a quantitative
analysis were made even before the time of Boyle, but its principles were
greatly developed by him, and were further extended by Homberg,
Marggraf, and Bergman. Marggraf accurately determined the amount of
silver chloride formed by adding common salt to a solution of a known
weight of silver, and Bergman first pointed out that estimations of
substances might be conveniently made by weighing them in the form of
suitably prepared compounds, which, it was implicitly assumed, were of
uniform and constant composition. The foundations of an accurate system
of gaseous analysis were made by Cavendish; and various forms of physical
apparatus were applied to the service of chemistry.
To the elements which were known prior to Boyle’s time, although not
recognised as such, there were added phosphorus (Brand, 1669), nitrogen
(Rutherford), chlorine (Scheele, 1774), manganese (Gahn, 1774), cobalt
(Brandt, 1742), nickel (Cronstedt, 1750), and platinum (Watson, 1750).

Baryta was discovered by Scheele, and strontia by Crawford. Phosphoric
acid was discovered by Boyle, and its true nature determined by Marggraf;
Cavendish first made known the composition of nitric acid. As already
stated, Scheele first isolated molybdic and tungstic acids and determined the
existence of a number of the organic acids (p. 75). Other discoveries—such
as the true nature of limestone and magnesia alba and their relations
respectively to lime and magnesia by Black, the many gaseous substances
by Priestley, and the compound nature of water by Cavendish—have
already been referred to.
Technical chemistry also greatly developed during the eighteenth
century, thanks to the efforts of Gahn, Marggraf, Duhamel, Reaumur,
Macquer, Kunkel, and Hellot; and many important industrial processes—
such as the manufacture of sulphuric acid by Ward of Richmond, and
subsequently by Roebuck at Birmingham, and the Leblanc process of
conversion of common salt into alkali—had their origin during this period.

CHAPTER VIII

Lavoisier and La Révolution Chimique

W e have seen how chemistry made a new departure during the
political upheaval which occurred in this country about the
middle of the seventeenth century. It acquired a new impetus
and took a fresh course during the political cataclysm which overwhelmed
France and alarmed Europe towards the close of the eighteenth century. The
instigator and leader of this second revolution in chemistry was Lavoisier,
one of the most distinguished men of his age, and himself a victim of the
political fury of his own people.

Antoine-Laurent Lavoisier was born in Paris in 1743. At the Jardin du
Roi he came under the influence of Rouelle, one of the best teachers of his
time, who eventually shaped his career as a chemist. In 1765 he sent to the
Academy his first paper on gypsum, which is noteworthy as giving for the
first time the true explanation of the “setting” of plaster of Paris, and the
reason why overburnt gypsum will not rehydrate. Three years later he
became a member of the Ferme-général—a company of financiers to whom
the State conceded, for a fixed annual sum, the right of collecting the
indirect taxes of the country. It was this connection that brought Lavoisier
to the scaffold during the revolution of 1794. Like Stahl, Lavoisier
discovered no new substance; but, also like Stahl, he created a new epoch
by destroying the philosophical system which Stahl had established.
It is commonly stated that the exception is a proof of the rule. The
history of science can show many instances whereby the rule has been
demolished by the exception. Little facts have killed big theories, even as a
pebble has slain a giant. During the reign of phlogiston a few of such facts

were not unknown—at least to some of the better informed of Stahl’s
followers.
Some of the alchemists had discovered that a metal gained, not lost,
weight by calcination. This was known as far back as the sixteenth century.
It had been pointed out by Cardan and by Libavius. Sulzbach showed that
such was the case with mercury. Boyle proved it in the case of tin, and Rey
in that of lead. Moreover, as knowledge increased it became certain that
Stahl’s original conception of the principle of combustion as a ponderable
substance—he imagined, with Becher, that it was of the nature of an earth
—was not tenable. The later phlogistians were disposed to regard it as
probably identical with hydrogen. But even hydrogen has weight, and facts
seemed to require that phlogiston, if it existed at all, should be devoid of
weight.
Towards the latter half of the eighteenth century clearer views began to
be held concerning the relations of atmospheric air to the phenomena of
combustion and of calcination; many half-forgotten facts relating to these
phenomena were recalled, and the inconsistencies and insufficiency of
phlogiston as a dogma became gradually manifest. Three cardinal facts
conspired to bring about its overthrow—the isolation of oxygen by
Priestley; the recognition by him of the nature of atmospheric air, and of the
fact that one of its constituents is oxygen; and, lastly, the discovery by
Cavendish that water is a compound, and that its constituents are oxygen
and hydrogen. The significance of these facts was first clearly grasped by
Lavoisier, and to him is due the credit of their true interpretation. By
reasoning and experiment he proved conclusively that all ordinary
phenomena of burning are so many instances of the combination of the
oxygen of the air with the combustible substance; that calcination is a
process of combination of the oxygen in the air with the metal, which
thereby increases in weight by the amount of oxygen combined. Water—no
longer a simple substance—is formed by the union, weight for weight, of
oxygen and hydrogen. Lavoisier’s reasoning was so sound and his
experimental evidence so complete that his views gradually gained
acceptance in France. The phlogiston myth was thus exploded. Inspired by
Lavoisier, a small band of French chemists—Berthollet, Fourcroy, Guyton
de Morveau—thereupon set to work to remodel the system of chemistry and
to recast its nomenclature so as to eliminate all reference to phlogiston. The

very names “oxygen,” “hydrogen,” “nitrogen,” corresponding respectively
to the “dephlogisticated air,” “phlogiston,” and “phlogisticated air” of
Priestley, were coined by the new French school. For a time le principe
oxygine was regarded by this school in much the same relation as
phlogiston was regarded by Stahl and his followers. The one fetich was
exchanged for the other. The combustible principle—phlogiston—was
renounced for the acidifying principle—oxygen. The new chemistry for a
time centred itself round oxygen, just as the old chemistry had centred itself
round phlogiston. The views of the French school met with no immediate
acceptance in Germany, the home of phlogistonism, or in Sweden or
England, possibly owing, to some extent, to national prejudices. The spirit
of revolution, even although it might be an intellectual revolution, had not
extended to these countries. Priestley, Cavendish, and Scheele could not be
induced to accept the new doctrine. It was, however, accepted by Black, and
its principles taught by him in Edinburgh; and before the end of the century
it had practically supplanted phlogistonism in this country. Some of those
who, like Kirwan, had energetically opposed the new theory ended by
enthusiastically embracing it. Its introduction into Germany was mainly due
to the influence of Klaproth.
We further owe to Lavoisier the recognition of the principle which lies
at the basis of chemical science—the principle of the conservation of
matter. Lavoisier was not the first to introduce the use of the balance into
chemistry: quantitative chemistry did not actually originate with him.
Boyle, Black, and Cavendish, as a matter of fact, preceded him in
recognising the importance of studying the quantitative relations of
substances. Nevertheless, no one before him so clearly foreshadowed the
doctrine of the indestructibility of matter, and it was mainly through his
teaching that the balance came to be recognised as indispensable to the
pursuit of chemistry. Before his untimely death he had succeeded in
impressing upon the science the main features which at present characterise
it.
Lavoisier was one of the most distinguished men of his age, and his
merits as a philosopher were recognised throughout Europe. Indeed, it is not
too much to say that at the time of his death he was the dominant figure in
the chemical world of the eighteenth century. In addition to his position as a
member of the Ferme-général he was made by Turgot a commissioner of

the Régie des Poudres; and in this capacity he effected improvements in the
manufacture and refining of saltpetre, and greatly increased the ballistic
properties of gunpowder. He became Secretary of the Committee of
Agriculture, and drew up reports on the cultivation of flax, of the potato,
and on the liming of wheat; he prepared a scheme for the establishment of
experimental farms, and for the collection and distribution of agricultural
implements. He introduced the cultivation of the beet root in the Blesois,
and improved the breed of sheep by the importation of rams and ewes from
Spain. He was successively member of the Assembly of the Orléanais,
Député suppléant of the States-General, and of the Commune of Paris. In
1791 he was named Secretary and Treasurer of the famous Commission of
Weights and Measures, out of which grew the international system, based
theoretically on a natural unit, known as the metric system, and now
adopted by most civilised countries in the world. He was not only the
administrative officer of the Commission: he contributed to the
nomenclature of the system, and directed the determination of the physical
constants on which the measurements rested, and especially the
determination of the weight of the unit volume of water on which the value
of the standard of mass was based. Lastly he was Treasurer of the French
Academy until its suppression in 1793 by the Convention, which shortly
afterwards ordered the arrest of Lavoisier and others of the Fermiers-
généraux—twenty-eight in all. They were sentenced to be executed within
twenty-four hours, and their property confiscated. Coffinhal, who
pronounced their doom, declared: “La republique n’a pas besoin de
savants.” Thus in the fifty-first year of his age, perished the creator of
modern chemistry—a victim to the senseless, sanguinary fury of the
“Friends of the People.” His rectitude, his public services, the purity of his
private life, the splendour of his scientific achievements—all were
unheeded. As Lagrange said to Delambre: “It required but a moment to
strike off this head; a hundred years may not suffice to reproduce such
another.”

Lavoisier and Berthollet
in the Laboratory of the Sorbonne, Paris.

Of the men who were associated with Lavoisier in the creation of what
was known at the period as the antiphlogistic chemistry, the most eminent
was Berthollet.
Claude-Louis Berthollet was born in Savoy in 1748, and, after a
medical education, became physician to the Duke of Orleans. Devoting
himself to chemistry, in 1781 he was made a member of the Academy, and
he became Government Commissary and Director of the Gobelins, the chief
tinctorial establishment of France. Although in the main in agreement with

Lavoisier, he never wholly subscribed to the idea that all acids contained
oxygen. He discovered the bleaching power of chlorine, prepared potassium
chlorate, and investigated prussic acid and fulminating silver.
In his Statique Chimique, published in 1803, he combated the partial
and imperfect views of Bergman and Geoffroy with regard to the operation
of chemical affinity, and showed that the direction of a chemical change is
modified by the relative proportion of the reacting substances and the
physical conditions—temperature, pressure, etc.—under which the change
is effected. He was one of the first to draw attention to a class of
phenomena known as reversible reactions, and gave a number of instances
of their occurrence. Berthollet pushed his conclusions so far that he was led
to doubt that chemical combination took place in fixed and definite
proportions; and his views gave rise to a memorable controversy between
him and Proust, in which the latter eventually triumphed.
Berthollet enjoyed a great reputation in his time, and played a
considerable part in the political history of his country. It was largely to his
zeal, sagacity, and skill in developing her internal resources at a critical
period when she was hemmed round by foreign troops and her ports
blockaded by British ships, that France was saved from conquest. His life
was more than once in jeopardy when France was governed by a
Committee of Public Safety; but his honesty, sincerity, and courage even
impressed Robespierre, and he escaped the perils of the Great Terror. He
was an intimate friend of Napoleon, and accompanied him to Egypt as a
member of the Institute. He died at Arcueil in 1822.
Davy, who visited him at his country house in 1813, says of him:—

Berthollet was a most amiable man; when the friend of
Napoleon, even, always good, conciliatory, and modest, frank and
candid. He had no airs, and many graces. In every way below La
Place in intellectual powers, he appeared superior to him in moral
qualities. Berthollet had no appearance of a man of genius; but one
could not look on La Place’s physiognomy without being convinced
that he was a very extraordinary man.

Other notable men of this period were Fourcroy, Vauquelin, Klaproth,
and Proust.

Antoine-François Fourcroy, the son of a pharmacist, was born at
Paris in 1755, and started his career as a dramatic author. On the advice of
Vicq d’Azir, the anatomist, he turned to medicine, and in 1784, by the
influence of Buffon, obtained the chair of Chemistry at the Jardin du Roi, in
succession to Macquer. He was an excellent teacher—clear, orderly, and
methodical. He had, indeed, a talent for oratory. This he assiduously
cultivated, and became one of the most popular lecturers of his time in
France. Ambitious and time-serving, he became embroiled in the turbulent
politics of the period, and, after a chequered career, died, embittered and
disappointed, in the fifty-fourth year of his age. His chief services to
science consisted in his works, Système des Connaissances Chimiques and
Philosophie Chimique. These, no less than his public lectures, did much to
popularise the doctrines of Lavoisier among his countrymen.
Louis Nicolas Vauquelin, the son of a Norman peasant, was born in
1763, and while a boy became assistant to an apothecary in Rouen. In 1780
he came to Paris, and entered Fourcroy’s laboratory. Much of the
experimental work published in Fourcroy’s name was actually done by
Vauquelin. He became a member of the Academy in 1791, Professor of
Chemistry at the Mining School, Assayer to the Mint, and subsequently
Professor of Chemistry at the Jardin des Plantes. On Fourcroy’s death he
was made Professor of Chemistry of the Medical Faculty of Paris.
Vauquelin was no theorist; he was, however, an excellent practical chemist,
and one of the best analysts of the period. He made a large number of
mineral analyses, more particularly for Hauy, the crystallographer. He
discovered the element chromium in the so-called red-lead ore (lead
chromate) from Siberia. He also first made known the existence of
glucinum in beryl. He described a method of separating the platinum
metals, and worked upon iridium and osmium. He investigated the
hyposulphites, cyanates, and malates. He discovered the presence of
benzoic acid in the urine of animals; with Robiqet, he first isolated
asparagin; with Buniva, allantoic acid; and with Bouillon de la Grange,
camphoric acid.
Vauquelin lived wholly for science, and had no other interests than in
his laboratory. He was pensioned in 1822, and died at his birthplace—St.
André d’Héberlot—in the sixty-sixth year of his age.

Martin Heinrich Klaproth, born in 1743 at Wernigerode, in the Hartz,
began life, like Vauquelin, as an apothecary’s apprentice at Quedlinburg.
Thence he went to Hanover, and ultimately to Berlin, where he studied
under Pott and Marggraf and entered the pharmacy of Valentine Rose,
father of Heinrich Rose, the distinguished chemist, and Gustav Rose, the
mineralogist. In 1788 he became a member of the Berlin Academy, and, on
the creation of the Berlin University in 1809, was made Professor of
Chemistry. As already stated, he was the first chemist of eminence in
Germany to adopt the antiphlogistic theory. He was distinguished as an
analyst. He discovered tellurium, analysed pitchblende and uranit, and first
made known the existence of uranium, zirconium, and cerium, which he
termed “ochroita.” He analysed corundum, and was an independent
discoverer of titanium and glucinum, termed by him beryllium. He made a
large number of analyses of minerals, such as leucite, chrysoberyl, hyacinth,
granite, olivin, wolfram, malachite, pyromorphite, etc. He continued
actively at work until his death, in the seventy-fourth year of his age.
Analytical chemistry is under great obligations to Klaproth. He
established a standard of accuracy never before approached; and much of
his analytical work, both as regards processes and results, is of permanent
value.
Joseph Louis Proust, the son of a pharmacist was born at Angers in
1761. He received his early training in chemistry from his father, and, after
studying under Rouelle in Paris, obtained an appointment at the Salpetrière.
Proust has the credit of being the first chemist to make a balloon ascent—in
a Montgolfier balloon with Pilatre de Rozier. On the invitation of the King
of Spain, he went to that country to superintend certain chemical
manufacturing processes. He became Professor of Chemistry at the
University of Salamanca, and subsequently went to Madrid, where he was
installed in a well-equipped laboratory to enable him to examine the
mineral riches of Spain. On the breaking out of war his work was
interrupted, and he was obliged to leave Madrid. His laboratory was
completely destroyed, and his valuable collection of apparatus and
specimens dissipated. Through the good offices of Berthollet, Proust was
offered a considerable sum of money by Napoleon in order to induce him to
turn his discovery of grape sugar to practical account. Proust was, however,
too broken in health to undertake the work of a factory manager, and he

retired to Mayence. On the restoration of the Monarchy he was made a
member of the French Academy, his honorarium as an Academician being
augmented by a pension from Louis XVIII. He died in 1826, while on a
visit to Angers, his native place.
Proust is the discoverer of what is now styled “the law of constant
proportion,” which states that the same body is invariably composed of the
same elements, united in the same proportion. He was a skilful analyst, and
made numerous analyses of minerals; and he was one of the earliest to
undertake a systematic study of metallic salts of organic acids.

CHAPTER IX

The Atomic Theory

T he opening years of the nineteenth century were made memorable
by the promulgation of the atomic theory by John Dalton. The
enunciation of this theory, which affords a simple and adequate
explanation of the fundamental laws of chemical combination, marks an
epoch in the history of chemistry.

It may be desirable to trace, as briefly as possible, the successive steps
which led up to the generalisation which more than any other has served to
stamp chemistry as an exact science. That matter was discrete—that is, that
it was not continuous, but was composed of ultimate particles—was, as
already stated, imagined by the ancients, and was part of the philosophy of
Leukippus, Demokritus, and Leucretius. But this supposition, although
favoured by Newton and other thinkers, had little or no scientific basis prior
to the middle of the eighteenth century. From that time onward a variety of
chemical facts gradually accumulated, many of which at the time of their
discovery had no obvious connection with pre-existing facts. It was
reserved for Dalton to point out how an extension and more precise
definition of the old doctrine would suffice to connect and explain them.
The first germ of an atomic theory based on chemical fact may be
traced in the observation of Toburn Bergmann (b. 1735, d. 1784),
Professor of Chemistry at Upsala, that neutral solutions of certain metals in
contact with other metals gave a precipitate without the neutrality of the
solution being disturbed, and without gas being evolved. One metal had
simply replaced the other in solution. Bergmann thus incidentally
discovered the fact of the chemical equivalence of metals. He was of
opinion, however, that the phenomenon meant a transference of phlogiston

from one metal to another, and that the process might be made a mode of
determining the relative amount of phlogiston in various metals. Lavoisier
extended Bergmann’s observations, and sought to show, in effect, that the
process afforded a means of determining the amounts of the several metals
which combined with one and the same quantity of oxygen. But neither
Bergmann nor Lavoisier really grasped the idea of equivalence as we
understand it to-day. It began to be appreciated as the result of the work of
Jeremiah Benjamin Richter (b. 1762, d. 1807) and of G. E. Fischer on
the mutual action of salts in solutions, and on the determinations of the
amounts of acid and bases which respectively combine with one another.
Methods of measurement of the proportions in which substances combine
were grouped by Richter under the term Stochiometry.
However desirable it may be in the interests of history to indicate the
sequence of the surmises and facts which preceded the formulation of the
atomic theory, it is very doubtful whether Dalton was, to any material
extent, influenced by them. A self-educated man of lowly origin, sturdily
independent and highly original, he was accustomed to rely upon his own
faculty of observation and experiment for his facts, and upon his own
intellectual powers and mental energy for their interpretation.
John Dalton, the son of a Quaker hand-loom weaver, was born at
Eaglesfield, in Cumberland, in 1766. While still a boy he took to school-
teaching, and acquired, in his leisure and by his own exertions, a competent
knowledge of mathematics and physical science. In 1793 he was called to
give instruction in mathematics, natural philosophy, and chemistry at the
Manchester New College, the Nonconformist academy—now moved from
Warrington—in which Priestley had formerly lectured. Here he remained
six years, leaving the college to take up an independent position as a private
tutor, so as to enable him the more freely to pursue his scientific inquiries.
In 1800 he became Secretary of the Philosophical Society of Manchester,
and remained connected, as an official, with that institution until his death
in 1844. The greater number of his scientific communications were
published by that society. In the outset of his scientific career he was
attracted to meteorology; and it was probably its problems which led him in
the first place to experiment, and to speculate on the physical constitution of
gases. In the course of these observations he was led to the discovery of the
law of thermal expansion of gases, with which his name is now generally

associated. His speculations concerning the physical constitution of gaseous
substances, arising from the contemplation of gaseous phenomena, led him
to the conception that a gas is composed of particles that repel one another
with a force decreasing as the distance of their centres from each other; and
it is probable that in this manner he familiarised himself with the idea of the
existence of atoms. His first insight into the laws of the chemical
combination of these atoms seems to have originated from his discovery
that, when two substances unite in different proportions, these proportions
may be expressed in simple multiples of whole numbers. Thus he found, on
examining the composition of marsh gas and of ethylene, both
hydrocarbons, that for the same weight of hydrogen there was twice the
amount of carbon in ethylene that there was in marsh gas. He then
examined the oxides of nitrogen, and found a similar regularity to hold
good in these compounds. Some time prior to the autumn of 1803 Dalton
was led to the supposition that these regularities could be satisfactorily
explained by the assumption that matter is composed of atoms having sizes
and weights differing with each substance, but of identical weight and size
for any particular substance, and that chemical combination consists in the
approximation of these atoms. This simple hypothesis explained all the
facts then known. It explained the constancy in the chemical composition of
substances, which may be said to have been established by Proust, and
which is now formulated as the Law of Constant Proportion—that the same
body is invariably composed of the same elements, united in the same
proportion. It explained also the fact discovered by Dalton that, when an
element unites with another in different proportions, the higher proportions
are multiples of the lowest—now formulated as the Law of Multiple
Proportion. It further explained the fact, which may be said to have been
foreshadowed by Richter, that when two bodies, A and B, separately
combine with a third body, C, the proportions of A and B which unite with
C are measures or multiples of the proportions in which A and B combine
together. This is known as the Law of Reciprocal Proportion.

John Dalton.
From a painting by B. R. Faulkner in the possession of the Royal Society

Dalton’s theory was first made generally known by Thomas Thomson,
in the third edition of his System of Chemistry, published in 1807, and was
employed by Thomson in his paper on “The Oxalates of Strontium,”
published the same year in the Philosophical Transactions. The first printed
account by Dalton himself is contained in Part I. of his New System of
Chemical Philosophy, published in 1808, the substance of which had been
previously given in a course of lectures at the Royal Institution, London,
and subsequently repeated in Edinburgh and Glasgow.

The statement of his theory is contained in chapter iii. of this work,
under the heading “Of Chemical Synthesis,” and is accompanied by a plate
and explanation, of which a facsimile is given on pp. 130–1.
The facts upon which Dalton based his theory are incontrovertible; but
Dalton’s explanation of them was not universally accepted at the time he
gave it. Davy, who, of course, was familiar with the conception of atoms as
part of the Newtonian philosophy, objected to the term “atomic weight”
introduced by Dalton, and suggested the expression “combining
proportion”; and Wollaston, for similar reasons, proposed the term
“equivalent,” as denoting the constant quantity with which bodies went in
and out of combination. There is no doubt that the use of these terms
retarded the general acceptance of Dalton’s doctrine, and, moreover,
brought into the science a confusion which was not finally dispelled, as we
shall see, until during the second half of the century.

ELEMENTS
Simple
Binary
Ternary
Quaternary
Quinquenary & Sextenary
Septenary

The illustration on the preceding page contains the arbitrary
marks or signs chosen to represent the several chemical elements or
ultimate particles.

Fig.
1. Hydro. its rel. weight 1
2. Azote 5
3. Carbone or charcoal 5
4. Oxygen 7
5. Phosphorus 9
6. Sulphur 13
7. Magnesia 20
8. Lime 23
9. Soda 28
10. Potash 42
11. Strontites 46
12. Barytes 68
13. Iron 38
14. Zinc 56
15. Copper 56
16. Lead 95
17. Silver 100
18. Platina 100
19. Gold 140
20. Mercury 167
21. An atom of water or steam, composed of 1 of oxygen and
1 of hydrogen, retained in physical contact by a
strong affinity, and supposed to be surrounded by a
common atmosphere of heat; its relative weight = 8
22. An atom of ammonia, composed of 1 of azote and 1 of
hydrogen 6
23. An atom of nitrous gas, composed of 1 of azote and 1 of
oxygen 12
24. An atom of olefiant gas, composed of 1 of carbone and 1
of hydrogen 6

25. An atom of carbonic oxide composed of 1 of carbone and
1 of oxygen 12
26. An atom of nitrous oxide, 2 azote + 1 oxygen 17
27. An atom of nitric acid, 1 azote + 2 oxygen 19
28. An atom of carbonic acid, 1 carbone + 2 oxygen 19
29. An atom of carburetted hydrogen, 1 carbone + 2
hydrogen 7
30. An atom of oxynitric acid, 1 azote + 3 oxygen 26
31. An atom of sulphuric acid, 1 sulphur + 3 oxygen 34
32. An atom of sulphuretted hydrogen, 1 sulphur + 3
hydrogen 16
33. An atom of alcohol, 3 carbone + 1 hydrogen 16
34. An atom of nitrous acid, 1 nitric acid + 1 nitrous gas 31
35. An atom of acetous acid, 2 carbone + 2 water 26
36. An atom of nitrate of ammonia, 1 nitric acid + 1
ammonia + 1 water 33
37. An atom of sugar, 1 alcohol + 1 carbonic acid 35

Dalton’s estimations of the relative weights of the atoms, or, to use
Davy’s phrase, the values of their combining proportions, were, as might be
expected, very rough approximations to the truth. This arose partly from
inadequate experimental data, and partly from uncertainty as to the relative
number of the constituent atoms which made up a compound. Neither
Dalton nor his immediate successors had any rational or consistent method
of determining the latter point. The view taken of the composition of the
compound decided what particular multiples or sub-multiples of the values
of the atomic weights of its constituents were to be adopted. As Dalton, in
many cases, had no real criterion to guide him, he made the simplest
possible assumptions; but these might or might not be valid; and subsequent
experience showed that in some cases they were erroneous.
It was, however, generally recognised that these atomic weights,
combining proportions, or equivalents, as they were for a time indifferently
termed, were chemical constants of the highest importance, both to the
scientific chemist, who, apart from their theoretic interest, had need of them
in the course of quantitative analysis, and to the manufacturing chemist,
who required them for the intelligent exercise of his operations; and

accordingly a number of chemists, very shortly after the promulgation of
Dalton’s theory, attempted to determine their values with all possible
precision. Chief among these was the Swedish chemist Berzelius, to whom
science was indebted for a series of estimations of atomic weights, which
were long regarded as models of quantitative accuracy, and stamped their
author as the greatest master of determinative chemistry of his age.
Jöns Jakob Berzelius, the son of a schoolmaster, was born near
Linköping, in East Gothland, Sweden, in 1779. Entering Upsala with a view
to the profession of medicine, he was attracted, under the influence of
Afzelius—or, rather, in spite of it—to the study of chemistry, and, later, of
voltaic electricity, then in its infancy. While holding a number of minor
appointments as a teacher of medicine, pharmacy, physics, and chemistry,
he was elected, in 1808, a member of the Swedish Academy of Sciences, of
which he became President in 1810. In 1818 he was made permanent
Secretary of the Academy, and, by means of a yearly subsidy, was enabled
to devote himself wholly to experimental science. He was ennobled in
1818, and on the occasion of his marriage, in 1835, was created a baron of
the Scandinavian kingdom. He died in 1848.
Berzelius occupies a pre-eminent position in the history of chemistry,
and during a considerable portion of his lifetime exercised an almost
unassailable authority as a chemical philosopher. He is distinguished as an
experimenter, as a discoverer, as a critic and interpreter, and as a lawgiver.
His contributions to chemical knowledge range over every department of
the science. He shares with Davy the honour of having established the
fundamental laws of electro-chemistry. His experimental work on the
atomic weights of the elements—the great work of his life—was of
supreme importance at this particular period of the development of
chemistry: it served not only to give precision to, and enhance the
significance and value of, Dalton’s generalisation, but it furnished chemists,
for the first time, with a set of constants, ascertained with the highest
exactitude of which operative chemistry was then capable, thereby
contributing to the expansion of quantitative analysis, and to a more exact
knowledge of the composition of substances. Berzelius, indeed, was an
analyst of the first rank—conscientious, patient, and painstaking; an
ingenious and skilful manipulator; inventive and resourceful. What
determinative chemistry owes to his labours, and not less to his example, is

obvious from even the most superficial examination of its literature during
the first third of the last century.
As a discoverer, Berzelius first made known the existence of cerium
(1803), of selenium (1818), and of thorium (1828); and he prepared and
investigated a large number of their combinations. He isolated silicon
(1823), zirconium (1824), tantalum (1824), and studied the compounds of
vanadium, discovered by his countryman Sefström. He largely extended our
knowledge of groups of substances in which sulphur replaces oxygen;
investigated compounds of fluorine (1824), platinum (1828), and tellurium
(1831–1833), and made many analyses of minerals, meteorites, and
mineral-waters. He discovered racemic acid and investigated the
ferrocyanides. It was his investigation of racemic acid—which has the same
percentage composition as tartaric acid—that first enabled him to grasp the
conception of isomerism, a term which we owe to him, and of metamerism
and polymerism. He was the first to study the phenomena of contact-
actions, which he comprehended under the term catalysis.

Jöns Jakob Berzelius.
From a painting by J. G. Sandberg.

As an author his literary activity was astonishing. His new system of
mineralogy marks an epoch in the history of that branch of science. His
text-book on chemistry was long the leading manual, and went through
many editions, being constantly revised by him. His annual reports on the
progress of physics and chemistry extended to twenty-seven volumes and
constitute a monument to his industry, thoroughness, perspicacity, and
critical ability.
Although holding no university appointment, and with a laboratory of
the most modest dimensions and character, Berzelius, exercised great
influence as a teacher. Some of the most notable chemists of the last

century, such as Heinrich and Gustav Rose, Dulong, Mitscherlich, Wöhler,
Chr. Gmelin, and Mosander, were among his pupils; and many of them
have testified to his stimulating power as an investigator of nature, and to
his merits as a worthy, genial man.
The reasonableness of Dalton’s conjecture received further support
from the discovery by Gay Lussac in 1808, that gases always combine in
simple proportions by volume, and that the volume of the gaseous product
formed, when measured under comparable conditions of temperature and
pressure, stands in a simple relation to the volumes of the constituents. The
law of pressure discovered by Boyle, that of thermal expansion by Dalton,
and of volumes by Gay Lussac (which, it ought to be stated, was previously
and independently made by Dalton), are explained on the assumption that
equal numbers of the particles—either as simple particles or as compound
particles—are present in the same volume of the gas. This method of
explanation was first clearly stated by the Italian physicist Avogadro in
1811, but its significance, as will be seen subsequently, was not appreciated
until half a century later.
As the values for the atomic weights gradually became more exact,
speculations arose as to the significance of the numerical relations which
were observed to exist among them. In 1815 William Prout threw out the
supposition that the atomic weights of the gaseous elements are multiples
by whole numbers of that of hydrogen. Extended into a generalisation, this
might be held to indicate that all kinds of matter are so many forms of a
primordial substance. Subsequent inquiry showed that Prout’s “Law,” as it
is sometimes called, was not tenable in its original form. Certain elements,
it was conclusively proved, had atomic weights which were not whole
numbers. Dumas subsequently modified the law, after a redetermination of
a large number of atomic weights, by assuming that the substance common
to the so-called elements had a lower atomic weight than unity. Although
there are a considerable number of elements whose atomic weights, based
upon the most accurate determinations, are remarkably close to whole
numbers, the investigations of Stas and others afford no valid reason for
believing that Prout’s hypothesis, and the underlying supposition to which it
has been held to point, are justified by experimental evidence.

CHAPTER X

The Beginnings of Electro-Chemistry

T he first year of the nineteenth century is further memorable on
account of the invention of the voltaic pile, and by reason of its
application by William Nicholson and Sir Anthony Carlisle to
the electrolytic decomposition of water. This mode of resolving water into
its constituents made a great sensation at the time, mainly because of the
extraordinary method by which it was effected. It afforded an independent
and unlooked-for proof of the compound nature of water by a method
altogether differing in principle from that by which its composition had
been previously ascertained. The formation of water by the combustion of
hydrogen brought no conviction of its real nature to a confirmed phlogistian
like Priestley; and it is even doubtful whether Cavendish ever fully realised
the true significance of his great discovery. But the fact that the quantitative
results of the analysis thus effected were identical with those of its
synthesis, as made by Cavendish and Lavoisier, admitted of only one
interpretation. This cardinal discovery may be said to have completed the
downfall of phlogiston.

The value of the voltaic pile as an analytical agent was nowhere more
quickly appreciated than in England. In the hands of Humphry Davy its
application to the analysis of the alkalis and alkaline earths led to
discoveries of the greatest magnitude.
Humphry Davy was born in Penzance in 1778. In the course of his
studies for the profession of medicine he was attracted to chemistry; and he
became chemical assistant to Dr. Beddoes, a former teacher of chemistry at
Oxford, but then living at Clifton, near Bristol. While in the capacity of
assistant and operator in Beddoes’s Pneumatical Institute, Davy discovered

the intoxicating properties of nitrous oxide (so called laughing gas), which
brought him into prominence and led to his engagement by the managers of
the newly-created Royal Institution in London as lecturer in chemistry in
succession to Garnett. He early began to experiment on galvanism, and
soon succeeded in developing the fundamental laws of electro-chemistry;
and in 1807 he effected the decomposition of potash and soda by the
application of voltaic electricity—thereby establishing, what indeed had
been surmised previously, that the alkalis are compound substances. He
subsequently proved that this was also the case with the alkaline earths.
Davy thus added some five or six metallic elements to those already known.
These discoveries, perhaps the most brilliant of their time, afforded
additional evidence of the invalidity of Lavoisier’s assumption that oxygen,
as the name implies, was the “principle of acidity.” The surmise, in fact,
was already disproved by the case of water—a neutral substance and devoid
of all the recognised attributes of an acid. It was still further disproved by
the cases of potash and soda—strongly alkaline compounds.
Additional evidence was adduced by Davy in demonstrating, in 1810,
that the so-called oxymuriatic acid, the dephlogisticated marine acid
discovered by Scheele, contained no oxygen, but was a simple, indivisible
substance. For the old designation, which connoted a compound body, he
substituted the name chlorine, in allusion to the characteristic colour of the
element. In the course of his investigation on this substance he discovered
the penta- and trichloride of phosphorus, chlorophosphamide and chlorine
peroxide. He was also the discoverer of telluretted hydrogen and an
independent discoverer of nitrosulphonic acid.

Sir Humphry Davy.
From a painting by Lawrence in the possession of the Royal Society.

He worked on iodine and the iodates, on the diamond, on the so-called
fuming liquor of Cadet, on nitrogen chloride, and on the pigments of the
ancients. Lastly, he invented the miner’s safety lamp, with which his name
will always be associated, effecting thereby what was practically a
revolution in coal-mining. He became President of the Royal Society in
1820, and died at Geneva on May 29th, 1829, in the fifty-first year of his
age. Davy was a singularly gifted man, of great mental vigour and
imaginative power; quick, lively and ingenious; an eloquent teacher and a
daring and brilliant experimenter.

Another noteworthy name in the chemical history of this period is
Wollaston. William Hyde Wollaston, born at East Dereham, in Norfolk, in
1766, was educated at Cambridge with a view to the profession of
medicine, but, failing to secure a practice, he devoted himself to the pursuit
of science, and especially to optics and chemistry. He devised a method of
working platinum, and was the first to make known the existence of
palladium and rhodium. He was one of the most ingenious and acute
analysts of his time, and possessed remarkable inventive powers. He
investigated the nature of urinary calculi and chalk stones. His paper on the
oxalates of potash was of great service at the time as a demonstration of the
law of multiple proportions. He first drew attention to the existence in the
solar spectrum of what were subsequently termed the Fraunhofer lines; and
he invented the reflecting goniometer and the camera lucida, and a slide
rule for chemical calculations. He resembled Cavendish in temperament
and mental habitudes, and, like him, was distinguished for the range and
exactitude of his scientific knowledge, his habitual caution, and his cold and
reserved disposition. He died in 1828.

William Hyde Wollaston.
From a painting by J. Jackson, R.A., in the possession of the Royal Society.

Almost immediately after the publication of Volta’s discovery attempts
were made—notably by Berzelius in Sweden and by Davy in England—to
prove that electrical and chemical phenomena are correlated and mutually
dependent. This assumption was more fully worked out by Berzelius in
1812, and it served as the basis of a chemical system which exercised
considerable influence on chemical doctrine during the first half of the
nineteenth century.
Berzelius assumed that electric polarity was an attribute of all atoms—
that these were bipolar, in fact, but that in them either positive or negative

electricity predominated. Hence the elements were capable of being divided
into two classes—that is, positive or negative, depending upon the excess of
either charge. Which of the electricities predominated might be ascertained
by determining the particular pole at which the element was separated on
electrolysis. Combinations of dissimilar elements—or, in other words,
chemical compounds—were also endowed with polarity. The chemical
affinities of elements and compounds were related to the excess of either
kind of electricity resident in them; and chemical combination resulted
from, and was a consequence of, the more or less perfect neutralisation of
the two kinds. From a study of the electrical deportment of the elements
Berzelius sought to arrange them in series, starting with oxygen as the most
electro-negative member.
These conceptions were employed by him as the basis of a method of
classification. The attempt is historically interesting as being the first
systematic endeavour to gain an insight into the constitution of chemical
compounds—that is, to determine the manner in which the constituent
atoms are grouped or arranged with respect to one another, or, in other
words, to distinguish between the empirical and the rational composition of
substances, which is the ultimate aim of modern chemistry.
A necessary consequence of these views was that every compound was
to be considered as made up of two parts in electrically different states.
Thus baryta, consisted of a combination of the electro-positive barium,
combined with the electro-negative oxygen; it combined with sulphuric
oxide because the preponderating positive electricity it contained met with
the negative electricity which prevailed in the sulphuric oxide.
Generalising, it may be said that the basic oxides are invariably the positive
constituents of salts, whereas the acid oxides are the negative constituents,
as proved by the mode in which the two kinds of oxides separated at the
poles on electrolysis. Barium sulphate, then, was to be regarded as made up
of two entities—BaO and SO3—and hence was to be called sulphate of
baryta. Berzelius extended this conception in order to explain the formation
of double salts—such, for example, as potash alum, which he regarded as a
binary compound of positive potassium sulphate and negative aluminium
sulphate, each of which, in its turn, could be resolved into an acidic and a
basic oxide of opposite electricities.

The dualistic notions of Berzelius led him to the construction of a
system of chemical nomenclature and notation which, in its main features,
has persisted to this day, and is universally current, with certain
modifications, in modern chemical literature. We owe to him the grouping
of the elements into metals and metalloids, and also our present system of
symbolic notation, whereby even complicated chemical reactions may be
expressed in a concise and intelligible manner. Chemical symbols were
used by the alchemists; but Berzelius first suggested that a chemical symbol
should not only represent the element to which it refers, but also its relative
atomic weight. Chemical equations became quantitative as well as
qualitative expressions of the facts they denote. Such equations implicitly
assumed that, to use Davy’s words, chemistry had passed under the
dominion of the mathematical sciences. Professed mathematicians were,
however, slow to recognise that the phenomena of chemical action were
capable of formal mathematical treatment. Davy relates that on speaking to
Laplace of the atomic theory in chemistry, and expressing his belief that the
science would ultimately be referred to mathematical laws similar to those
he had so profoundly and successfully established with respect to the
mechanical properties of matter, the idea was treated in a tone bordering on
contempt.
Berzelius’s electro-chemical system, and the dualistic ideas associated
with it, were of considerable service when applied to the inorganic branch
of the science; but attempts to fit them to the facts of organic chemistry,
which began to accumulate rapidly after the first quarter of the century,
failed. Its inadequacy as a comprehensive generalisation became more and
more manifest, and it eventually fell. In fact, it may be said to have received
its death-blow by Davy’s discovery of the elementary nature of chlorine,
and by the recognition of the fact that the acids do not necessarily contain
oxygen. Davy and, later, Dulong made it obvious that, if any one element
was to be regarded as the acidifying principle, it was hydrogen, and not
oxygen; and, in a sense, this view ultimately prevailed in the recognition of
the acids as salts of hydrogen.
In France the study of electro-chemistry was undertaken by Gay Lussac
and Thénard, largely owing to the action of the Emperor Napoleon, who
furnished the funds for the construction of a powerful galvanic battery. The
results were published, in 1811, under the title, Recherches Physico-

Chimiques, faites sur la Pile, etc. Gay Lussac, whose name has already
been mentioned as one of the discoverers of the Law of Combination of
Gases, played a considerable part in the history of chemistry at this period.
He was one of the earliest to appreciate the importance of Dalton’s
generalisation, and to point out the significance of his own discovery in
strengthening it. He was probably led, in the first instance, to the
recognition of the law of gaseous combination by Berthollet’s work on the
volumetric composition of ammonia gas, and by his own discovery—made
in 1805, in conjunction with Humboldt, in the course of their analysis of
atmospheric air—that one volume of oxygen combined with exactly two
volumes of hydrogen to form water. The regularities thus indicated he found
to be general: all gases which are capable of chemical union combine in
simple proportions by volume, and the volume of the product, if a gas,
always stands in some simple relation to the volumes of the constituents.
Joseph Louis Gay Lussac was born in 1778, at Saint Leonard, studied
chemistry in Paris, and was associated in chemical inquiry with Berthollet.
As Eleve-Ingenieur in the École Nationale des Ponts et des Chaussées he
began the experimental work in physics and chemistry upon which his fame
rests. In 1804 he undertook, with Biot, a series of balloon ascents for the
purpose of investigating the physics and chemistry of the upper regions of
the atmosphere. In 1806 he became Professor of Chemistry at the École
Polytechnique, and in 1832 Professor at the Jardin des Plantes. He was one
of the chief assayers of the French Mint, and, as member of many
commissions, exerted considerable influence in official circles. He died in
1850.
Gay Lussac and Thénard were the first to devise a method of obtaining
potassium and sodium by a purely chemical process, whereby these metals
could be procured in far larger quantities than was at that time possible by
electrolytic means. They were thus enabled to make use of the strong
deoxidising power of these metals to effect a number of reductions, notably
that of boric oxide to boron. Gay Lussac and Thénard were also the first to
make known the existence of boron fluoride. We further owe to Gay Lussac
the discovery of cyanogen, the first of the so-called compound radicals. He
first prepared ethyl iodide, investigated sulphovinic acid and grape sugar,
studied etherification and fermentation, etc. We are also indebted to him for
a method of determining vapour densities which proved of great service in

ascertaining the molecular weights of substances. He worked on iodine and
its compounds, discovered, with Welter, thiosulphuric acid, and investigated
fulminic acid in collaboration with Liebig.
Among his services to analytical chemistry were his method for the
analysis of gunpowder, his volumetric estimation of silver (wet silver
assay), chlorometric analysis, alkalimetry, etc. He devised the system still in
use in France for the estimation of alcohol in spirits of wine.
Louis Jacques Thénard was born in 1777 at Nogent-Sur-Seine, and
was a pupil of Vauquelin and of Berthollet. In 1797 he became repétiteur at
the Polytechnic School of Paris, and eventually its professor. He
subsequently occupied the chair of chemistry at the Collège de France, and
of the Faculty of Science of the University of Paris. He was ennobled by
Charles X. in 1824, and died at Paris in the eightieth year of his age.
In addition to his work with Gay Lussac already mentioned, we owe to
Thénard the discovery of hydrogen peroxide and hydrogen persulphide.
Together with Dulong he studied the catalytic action of platinum on
mixtures of oxygen and hydrogen. He investigated the fatty acids, and
worked on fermentation and on ether-formation; and he was the first to
isolate citric and malic acids. He also occupied himself with the chemistry
of bile, perspiration, albumen, the acids of urine and milk, and with the
theory of mordants.
In 1834 Faraday made known the important fact that on passing the
same galvanic current through a number of electrolytes—water,
hydrochloric acid, solutions of metallic chloride—these were decomposed
in such manner that definite amounts of hydrogen or metal were separated
at the negative pole, and corresponding amounts of oxygen or chlorine were
evolved at the positive pole. These observations were comprehended by
Faraday under his “law of definite electrolytic action.” The electro-chemical
equivalents thus obtained were in some cases identical with the atomic
weights deduced by Berzelius; in others they were not; but, nevertheless,
when they differed, they stood in some simple relation to the assumed
atomic weight. The significance of Faraday’s observation was not lost sight
of, although his anticipation that the determination of electro-chemical
equivalents would be of use in fixing atomic weights was not immediately
appreciated. A clear distinction between the equivalent, the atom, and the

molecule was not then apprehended. As will be subsequently shown, it was
only during the latter half of the nineteenth century that the discrepancies
and inconsistencies thus revealed were definitely reconciled and cleared up.

CHAPTER XI

The Foundations of Organic Chemistry

A s the horizon of chemistry widened and its operations extended, it
became necessary to treat its subject-matter methodically.
Accordingly attempts were made in the various systematic
treatises which began to appear in the seventeenth century to group its facts
into an orderly and rational arrangement. One of the earliest of such
systematic treatises was the Cours de Chimie of Nicolas Lemery, published
in 1675. Although this work was styled by Boerhaave “a tumultuary mass
of pharmaceutical processes, without any certain design or coherence,” it is
noteworthy as being the first of its kind to divide the science into its present
main branches of inorganic and organic chemistry.

It may be desirable to indicate, as briefly as possible, the general state
of knowledge respecting the chemistry of organic substances down to the
early years of the last century. As already mentioned, such substances as
acetic acid, turpentine, starch, sugar, certain dye stuffs, and oils, had long
been known; and such processes as saponification and fermentation had
been practised from very early times. The alchemists had prepared a variety
of essential oils, aliphatic ethers, and esters; and the iatro-chemists had
obtained benzoic and succinic acids, and acetic acid from wood. Milk sugar
was first prepared by Fabrizio Bartoletti in 1619. Grape sugar was first
mentioned as occurring in honey by Glauber in 1660. Boyle first detected
the presence of a spirit among the products of the destructive distillation of
wood. Few of the followers of Stahl occupied themselves with organic
products; and it was only towards the end of the phlogistic period that
attention was once more directed to products of animal and vegetable
origin. Scheele isolated glycerin in 1784, and obtained ethyl chloride by the

distillation of a mixture of common salt, pyrolusite, oil of vitriol, and
alcohol. Ethyl acetate was first prepared by Lauraquais in 1759. Arvidson
obtained ethyl formate in 1777. Oxalic ether was first made by Savary in
1773. What was long known as oil of wine appears to have been first
mentioned by Libavius, but its true nature was discovered by Hennel in
1826. The formation of aldehyde was first recognised by Scheele in 1774,
and it was in turn investigated by Fourcroy and Vauquelin, Döbereiner, and
Gay Lussac; but it was first definitely isolated in 1835 by Liebig, who gave
it its name.
The first organic acid known was vinegar (acetic acid), and for a long
time all naturally occurring organic acids having a sour taste were regarded
as identical with or as forms of vinegar. It was only during the second half
of the eighteenth century that it was clearly ascertained that a variety of
organic acids exist, perfectly distinct from acetic acid. Glacial acetic acid
was first obtained by Löwiz in 1789. Acetic acid, as a product of the
destructive distillation of wood, was first obtained by Göttling in 1779. The
acetic fermentation has been studied from very early times. Surmises as to
the mode in which wine was converted into vinegar are to be met with in
the works of Basil Valentine, Becher (1669), Lemery (1675), and Stahl
(1667). Priestley, for a time, held the opinion that vinegar contained a
vegetable acid air, but he subsequently discovered and corrected his error.
The direct conversion of spirit of wine (ethyl alcohol) into acetic acid was
studied by Lavoisier and Berthollet, who first clearly recognised that it was
a process of oxidation. The quantitative composition of acetic acid was first
established by Berzelius in 1814. Many of the acetates have been known
from early times. Verdigris is mentioned by Theophrastus, Dioscorides, and
Pliny. Zinc acetate was known to Geber, and potassium acetate to Pliny,
who mentions its use in medicine. Ammonium acetate was also used in
medicine as far back as the beginning of the seventeenth century, and was
particularly recommended by the physician, Raymond Minderer. Sodium
acetate was prepared by Duhamel in 1736. Lead acetate was known in the
fifteenth century, and was styled by Libavius saccharum plumbi
quintessentiale, in allusion to its sweet taste. What was called by the
alchemists lac virginis was a turbid solution of basic lead acetate, and it was
frequently used in medicine, more particularly by Goulard in 1760. What
we now call acetone was first observed by Libavius, in 1595, and
subsequently by Boyle, during the destructive distillation of lead acetate: its

formation from other acetates was noticed by Trommsdorff, Derosne, and
Chenevix, by whom it was termed pyroacetic spirit. Its true nature and
composition were first ascertained by Liebig in 1831.
The formation of tartar in the manufacture of wine has been known
from the earliest times. It was regarded as, and originally styled, the faex
vini. The word “Tartarus” is first met with in alchemistic literature in the
eleventh century, and is the Latinised form of an Arabic word. Marggraf, in
1764, recognised that the tartar of wine contained potash; but tartaric acid
itself was first isolated by Scheele in 1769.
The double tartrate of potash and soda was first prepared in 1672 by
Peter Seignette, an apothecary of Rochelle, and was used by him in
medicine. Tartar emetic was discovered by Adrian von Mynsicht in 1631,
and its true nature explained by Bergmann in 1773. Racemic acid was first
mentioned by a wine manufacturer named Kestner, and was recognised as
an acid in 1819. Its relation to tartaric acid, with which it is isomeric, was
first explained by Berzelius, who gave it its name.
The naturally occurring oxalates were long considered as identical with
tartar. Oxalic acid was obtained by Scheele in 1776 by means of the action
of nitric acid upon sugar. This acid was further investigated by Bergmann,
who observed its decomposition by heat with the formation of a gas burning
with a blue flame. The identity of the naturally occurring oxalic acid with
that prepared from sugar was established by Scheele in 1784. The
quantitative composition of oxalic acid was first ascertained by Dulong in
1815. Mucic acid was discovered by Scheele in 1780, and was studied by
Fourcroy, who gave it the name it now bears. Pyromucic acid was also
known to Scheele, and was observed by Hermbstädt and Houton-
Labillardière. Camphoric acid was first recognised by Bouillon-Lagrange
and Vauquelin. Suberic acid was discovered by Brugnatelli in 1787.
That gum benzoin yielded a product (benzoic acid) by sublimation was
known in the sixteenth century. It was introduced into medicine by Turquet
de Mayerne as flowers of benzoin. Scheele showed how this acid might be
obtained by wet methods from gum-benzoin. It was detected in Peru-balsam
by Lehmann in 1709. Rouelle found it in the urine of the cow and the
camel. Liebig, in 1829, detected the difference between hippuric acid and

benzoic acid. The characteristic acid in amber (succinic acid) was first
detected by Pott in 1753.
Formic acid was first isolated by Wray in 1676. Lactic acid was
discovered by Scheele in sour milk in 1780. For a time it was regarded as
impure acetic acid, until it was detected in muscle juice by Berzelius, and
its individuality established. Its true composition was ascertained by
Mitscherlich and by Liebig in 1832. Citric acid has been known since the
thirteenth century, but it was first definitely isolated by Scheele in 1784.
Apple juice was used in medicine in the sixteenth century, and the soda salt
of its characteristic acid (malic acid) was prepared by Donald Monro in
1767.
It was known to the ancients that extract of gall nuts acquired a black
colour when mixed with a solution of iron vitriol; and Boyle and Bergmann
ascribed this phenomenon to the presence of a peculiar acid. Gallic acid
was first isolated by Scheele in 1785, and its composition established by
Berzelius in 1814. Tannic acid was definitely recognised as distinct from
gallic acid by Seguin in 1795.
Mellite, or honey-stone, is mentioned in mineralogical treatises in the
sixteenth century. That it consisted of the alumina salt of a special acid
(mellic acid) was shown by Klaproth in 1799.
Prussian blue was accidentally discovered in 1710 by a dyer named
Diesbach. Its mode of manufacture was first made known by Woodward in
1724. The peculiar reaction by which it was obtained was made the subject
of investigation by many chemists of the period without any decisive result.
Scheele observed that, when the salt which occasioned the blue colour with
vitriol was distilled with sulphuric acid, a volatile acid, inflammable and
soluble in water, was obtained. This acid received from Bergmann the name
of acidum cœrulei berolinensis, or “Berlin-blue acid,” subsequently
shortened by Guyton de Morveau to prussic acid. Scheele also prepared the
cyanides of silver and ammonium. That prussic acid was free from oxygen
was established by Berthollet. Anhydrous prussic acid was first obtained by
Von Ittner, who first established its highly poisonous nature. Bolim, in
1802, had previously observed the presence of prussic acid in oil of bitter
almonds, the poisonous character of which was known to Dioscorides.
Porret first definitely isolated potassium ferrocyanide, and subsequently

discovered the thiocyanates, the quantitative composition of which was
ascertained by Berzelius in 1820. That prussic acid was a compound of
hydrogen and cyanogen was established by Gay Lussac in 1815.
Cyanic acid was discovered by Wöhler in 1822, in which year also L.
Gmelin discovered the ferricyanides.
Fulminating mercury was first prepared by Howard in 1800, and
fulminating silver by Brugnatelli in 1802. These were recognised by Liebig,
in 1822, to contain a peculiar acid, which he termed fulminic acid, and
which he showed to have the same composition as the cyanic acid
discovered by Wöhler. Uric acid, so named by Fourcroy, was discovered in
gall stones by Scheele in 1776. Urea was first definitely isolated by
Fourcroy and Vauquelin in 1799, and was synthetically prepared by Wöhler
in 1828.
The bitter principles of plants and their medicinal virtues early attracted
attention, but the first attempt to isolate them was made by Fourcroy and
Vauquelin in the case of the Peruvian bark, long known for its power as a
febrifuge. In 1806 Vauquelin obtained quinic acid. Cinchonine was first
isolated by Gomes in 1811.
The chemical nature of opium was the subject of numerous inquiries in
the early years of the nineteenth century. In 1805 Sertürner detected the
existence of meconic acid, and in 1817 that of morphine, which he
recognised as an alkaloid. Narcotine was discovered by Robiquet in 1835.
The investigation of other bitter substances was undertaken by Pelletier and
Caventou, who in 1818 discovered strychnine, brucine (1819), and
veratrine (1820).
The contemporaries and immediate followers of Lavoisier were the
first to make a systematic attempt to elucidate the chemical nature of
organic products of animal origin. To this period belongs the work of
Fourcroy and Vauquelin on animal chemistry. Chevreul, a pupil of Fourcroy
worked on urine, adipocire, and the animal fats in the first decade of the last
century. Kirchhoff in 1811, discovered the method of converting starch into
sugar; and Döbereiner, in 1822, described a method of preparing formic
acid artificially. Dumas and Boullay, in 1827–1828, prepared a number of
new derivatives of ethyl alcohol; and in 1834 Dumas and Peligot studied in
like manner the chemistry of methyl alcohol, and pointed out many

analogies which their compounds possessed, not only among themselves,
but also to inorganic substances.
Although a considerable amount of information as to the existence,
modes of occurrence, and properties of bodies found in the animal and
vegetable kingdoms had been accumulated by the end of the first quarter of
the nineteenth century, no serious attempt was made to study them
systematically until after that period. In fact, they were not even regarded as
coming within the operations of laws found to be applicable to the products
of the inorganic world, by the investigation, of which products, indeed,
those laws had been discovered.
Down to 1828 it was considered that inorganic and organic substances
were sharply differentiated by the circumstance that, whereas the former
might be prepared by artificial means, and even built up from their elements
by synthetic processes in the laboratory, the latter could only be formed in
the bodies of animals and plants as the result of vital force. In that year
Wöhler showed that urea, pre-eminently a product of animal metabolism,
could be prepared synthetically from inorganic materials. Other instances of
a similar kind were discovered in rapid succession; and the idea that organic
substances could alone be formed by vital processes was proved to be
invalid. Moreover, large numbers of substances of a character analogous to
those produced by physiological action, but not known to occur in the
animal or vegetable kingdom, were prepared. There is, therefore, no
absolute distinction to be drawn between the chemistry of the inorganic and
organic worlds.
At the present day we mean by “organic compounds” simply the
compounds of carbon. These are so numerous, and frequently so complex,
that it is convenient to group them together and study them as a special
section of the science. At the outset it was supposed that only very few
elements entered into the composition of organic substances. This, indeed,
was held to be a point of fundamental distinction between organic and
inorganic compounds. Lavoisier was of opinion that all organic bodies were
combinations of carbon, hydrogen, and oxygen. Berthollet first discovered
the presence of nitrogen in a product of animal origin. Sulphur and
phosphorus were detected later. There is apparently no à priori reason why
any element should not be associated with carbon, and enter into the
composition of an organic compound.

Lavoisier was one of the first to devise methods for ascertaining the
composition of organic (carbon) compounds, and to indicate the general
principles by which the proportion of the elements met with in these
substances can be ascertained. So imperfectly, however, were these methods
worked out that it was not established until the close of the first decade of
the nineteenth century that organic compounds even obeyed the law of
multiple proportions. Thanks to the efforts of Berzelius, Gay Lussac, and
Thénard, and especially of Liebig, in 1830, methods of organic analysis
were so far perfected that it became possible to ascertain the empirical
composition of these compounds with certainty. This point reached, the
development of this section of chemistry proceeded with unexampled
rapidity. Not only was the composition of numbers of products, such as
sugar, starch, the vegetable acids, certain alkaloids, etc., established, but
altogether unlooked-for facts became manifest. One of the most surprising
of these was that of isomerism.
Up to the close of the first quarter of the nineteenth century it seemed
self-evident that substances of the same percentage composition are
necessarily identical. In 1823 Liebig showed that the silver cyanate of
Wöhler had the same composition as silver fulminate. Faraday, in 1825,
found a hydrocarbon in oil gas, which had the same composition as olefiant
gas, but was otherwise different from it; and in 1828 Wöhler discovered
that urea and ammonium cyanate—perfectly dissimilar substances—were
identical in elementary composition. Lastly, Berzelius found this to be true
of tartaric and racemic acids; and he thereupon proposed the term
isomerism to denote the general fact. He further pointed out that the
phenomenon could only be explained by supposing that the relative
positions of the atoms in isomeric compounds are different.
But the influence of molecular or atomic grouping in determining the
specific character of a substance is not confined to compounds. The same
phenomenon is observed to occur among the elements. It was conclusively
established by Lavoisier that the diamond and charcoal are chemically the
same thing—both forms of carbon. Scheele showed that graphite was a
third form of carbon. Phosphorus, sulphur, and oxygen were subsequently
shown to be each capable of existence in various modifications. Instances
of this character were grouped together in 1841 by Berzelius under the term
allotropy.

The recognition of the fact of isomerism exerted a great influence on
the development of organic chemistry. It ultimately led to the assumption
that particular groups of elements or atomic complexes, so-called radicals,
were to be found in organic compounds—a conception based originally on
Gay Lussac’s discovery of cyanogen, a combination of carbon and nitrogen,
which was found to behave like a simple substance, such as chlorine, and to
give rise to compounds analogous to the corresponding chlorides. This idea
of the existence of compound radicals was greatly strengthened by a
memorable investigation by Liebig and Wöhler, in 1832, on oil of bitter
almonds and its derivatives, in which they showed that these substances
might be represented as containing a special group or radical termed
benzoyl, which behaved like an element. The idea of groups of elements
going in and out of combination like a simple substance was not new to
chemists: there was not only the case of cyanogen, discovered by Gay
Lussac in 1815. The attempt had been made by Dumas and Boullay in 1828
to classify the derivatives of alcohol and ether as compounds containing a
common radical etherin. Gay Lussac had pointed out that the vapour
density of ethyl alcohol seemed to show that it consisted of equal volumes
of ethylene and water. Robiquet had also shown that ethyl chloride might be
assumed to be a compound of hydrochloric acid and ethylene; and
Döbereiner had regarded anhydrous oxalic acid as a combination of
carbonic acid with carbonic oxide.
But the investigation of Liebig and Wöhler served to give precision to
the conception. It thereby exercised a profound influence on the
development of organic chemistry by demonstrating, in effect, that this
branch of the science might be regarded as the chemistry of the compound
radicals, in contradistinction to inorganic chemistry—the chemistry of the
simple radicals. Additional support for this view was afforded by the
remarkable research by Bunsen on the so-called alkarsin, the “fuming
liquor of Cadet”—an evil-smelling substance long known as being formed
when an acetate is heated with arsenious oxide. Bunsen showed that this
liquid contained a compound radical having arsenic as a constituent; and he
prepared a series of derivatives, all of which might be formulated as
combinations of this radical, which he termed cacodyl. The study of the
electrolytic decomposition of the acetates by Kolbe and the discovery of
zinc-ethyl by Frankland afforded powerful support to the doctrine of
combined radicals.

Although there can be no doubt that this doctrine greatly stimulated the
pursuit of organic chemistry, it was gradually perceived that to regard
inorganic and organic chemistry as the chemistry respectively of the simple
and of the compound radicals was an imperfect and misleading conception
of the true relations of the two main divisions of the science. Facts showed
that the properties of a substance depend more on the arrangement of its
atoms than on their nature. The doctrine of compound radicals was
implicitly an attempt to extend the dualistic conceptions of Berzelius to the
facts of organic chemistry; and as such it was welcomed by the great
Swedish chemist. But dualism was found to have its limitations, even in
inorganic chemistry; and these were still more apparent when it was sought
to apply it in the other main branch of the science. Attempts were therefore
made—notably by the French chemists Laurent, Dumas, and Gerhardt—to
formulate organic substances by methods in which the electro-chemical and
dualistic conceptions of Berzelius and his followers had no part. How these
attempts developed, and how they subsequently grew into the organic
chemistry of to-day, will be shown in the second part of this work.
It will be convenient also to delay any account of the personal history
of the creators of the science of organic chemistry—Liebig, Wöhler, Dumas
—until we are in a position to give a fuller statement of their labours, and of
the results which flowed from them. Although the foundations of organic
chemistry may be said to have been laid during the closing years of the first
half of the nineteenth century, the superstructure was not erected until the
second half.

CHAPTER XII

The Rise of Physical Chemistry

P hysics and Chemistry are twin sisters—daughters of Natural
Philosophy; like Juno’s swans, coupled and inseparable. Physics
is concerned with the forms of energy which affect matter;
chemistry with the study of matter so affected. Each, then, is
complementary to the other. Philosophers of old drew no practical
distinction between them, at least as regards their own studies. Men like
Boyle, Black, Cavendish, Lavoisier, Dalton, Faraday, Graham, Bunsen,
were pioneers “on a very broad gauge,” pushing their inquiries into
territories common to the two branches as their genius or inclinations
directed them. Accordingly, it has happened that many so-called physical
laws have been discovered by men who were professed chemists. It has also
happened that men who began their scientific career as chemists, like
Dalton, Regnault, and Magnus, eventually gave the whole of their energies
to physical measurements; or, like Black, Faraday, and Graham, devoted
themselves to the elucidation of physical problems. As certain of these
physical laws and problems have greatly influenced the progress of
chemistry, it becomes necessary, in any historical treatment of the subject,
to give some account of their origin, and to show how they affected the
development of chemical theory.

The relations of heat to chemical phenomena are so obvious and so
intimate that the study of their connection necessarily attracted attention in
very early times. But it was only when this study became quantitative that
any important generalisations became possible. Most quantitative
estimations of heat depend eventually upon the thermometer; and

thermometry is indebted to Englishmen in the first instance for attempts to
render the instrument trustworthy.
In this connection may be mentioned the names of Newton and
Shuckburgh. Brooke Taylor, in 1723, made a special study of the mercurial
thermometer as a measurer of temperature. In other words, he sought to
discover whether equal differences of expansion or contraction of mercury
corresponded to equal additions or abstractions of heat. The results showed
that the principle of the mercurial thermometer is valid within at least the
limits of temperature between the boiling and freezing-points of water.
These experiments were subsequently repeated and confirmed by
Cavendish, and, independently, by Black.
The discovery of the phenomenon of latent heat by Black some time
prior to 1760 marks an epoch in the history of science. It was then for the
first time clearly recognised that the state of aggregation of a substance is
associated with a definite thermal quantity, and that, in order to effect a
change, a definite amount of energy, in the form of heat, must be employed.
The quantitative connection that exists between work and energy was thus
foreshadowed.
The doctrine of specific heat was taught by Black in his lectures at
Glasgow between 1761 and 1765. The subject was subsequently
investigated experimentally by Irvine between 1765 and 1770, and by
Crawford in 1779. A series of determinations was published in 1781 by
Wilcke, in the Transactions of the Swedish Academy. In these the term
specific caloric, since changed to specific heat, was first used. About this
time the determination of the amount of heat required to raise substances
through a definite interval of temperature was made the subject of
experiment by many observers, notably by Lavoisier and Laplace, who
greatly improved the calorimetric arrangements. The values they obtained
long remained the most trustworthy estimations of the specific heats of
substances. Their joint research had a further influence on the development
of thermo-chemistry by indicating the general experimental conditions
which were needed to ensure accuracy in such determinations. Lavoisier
and Laplace also measured, in 1782–1783, the heat disengaged by the
combustion of substances, and that evolved during respiration. In 1819
Dulong and Petit pointed out that the specific heat of a number of
substances, more particularly the metals, were inversely proportional to

their atomic weights; or, in other words, the product of the specific heat into
the atomic weight was a constant. The nature of the relation will be seen
from the following table of certain of the results obtained by Dulong and
Petit:—

Element. At. wt. Spec. heat. Atomic heat.

Bismuth 208 0.0288 6.0
Lead 207 0.0293 6.0
Gold 197 0.0298 5.8
Platinum 195 0.0314 6.1
Silver 108 0.0570 6.1
Copper 63 0.0952 6.0
Iron 56 0.1138 6.4

It will be seen that these various elements have an uniform, or nearly
uniform, atomic heat—approximately 6.2 on the average.
This would appear to prove that, as Dulong and Petit expressed it, “the
atoms of simple substances have equal capacities for heat.” The variations
from a constant value are due partly to errors of observation, but more
particularly to the circumstance that the substances compared are not all in
a strictly comparable condition—e.g., they are not all equally remote from
their melting points. It was shown, moreover, that the amount of heat
needed to raise a substance through a definite interval of temperature
increased with the temperature. The range of temperature through which a
determination was made in a particular instance affected, therefore, the
value of the specific heat. The most noteworthy departures from a uniform
value were observed to occur among the metalloids—e.g., carbon, the
various modifications of which had different specific heats—and generally
among elements of low atomic weight, in which the variation of specific
heat with temperature was particularly rapid.
Nevertheless, the significance of the generalisation discovered by
Dulong and Petit, in spite of its limitations, was quickly appreciated, as it
was perceived that a knowledge of the specific heat of an element might be
of great value in determining its atomic weight. The immediate effect was
that a certain number of the atomic weights fixed by Berzelius mainly on

chemical considerations were required to be halved. Although subsequent
experience has proved that the law of Dulong and Petit is not capable of the
simple mathematical expression they gave it, it has shown itself to be of
great value in fixing doubtful atomic weights.
Pierre Louis Dulong was born in 1785 at Rouen, and, after studying
chemistry and physics at the Polytechnic School at Paris, became its
Professor of Chemistry and subsequently its Professor of Physics. In 1830
he was made its Director of Studies; and in 1832 he became permanent
Secretary of the Academy of Sciences. As a young man he worked with
Berzelius, with whom he made the first approximately accurate
determination of the gravimetric composition of water. In 1811 he
discovered the highly explosive nitrogen chloride, in the investigation of
which he was severely injured, losing an eye and several fingers. He died in
1838. His collaborator, Alexis Therese Petit, was born in 1791 at Vesoul,
and died, when holding the position of Professor of Physics at the Lycée
Bonaparte, in 1820.
The attempt made by Neumann to extend Dulong and Petit’s “law” to
compound substances was only partially successful. Nor has any important
generalisation followed from our knowledge of the specific heat of liquids.
Almost simultaneously with the publication of Dulong and Petit’s “law,”
Mitscherlich made known the fact that similarity in chemical constitution is
frequently accompanied by identity of crystalline form. Boyle, as far back
as the middle of the seventeenth century, had insisted upon the importance
of the forms of crystals in throwing light upon the internal structure of
bodies. Romé de l’Isle and Hauy had remarked that many different
substances had the same crystalline form. It had been observed that a crystal
of potash alum would continue to grow and preserve its shape in a solution
of ammonia alum; and similar observations had been shown to occur in the
case of vitriols. The invention of the reflecting goniometer by Wollaston
greatly facilitated the investigation of such phenomena. Mitscherlich
showed that the phosphates and arseniates of analogous composition had
the same crystalline shape, or, in other words, were isomorphous. The same
fact was observed to occur in the case of the analogously constituted
sulphates and selenates, and in that of the oxides of magnesium and zinc,
etc. The value of isomorphous relations in determining the group-
relationships of the elements and in deducing the composition of salts was

at once recognised by Berzelius, who styled the discovery of isomorphism
by his pupil Mitscherlich as “the most important since the establishment of
the doctrine of chemical proportions.” The quantities of the isomorphously
replacing elements in a compound were regarded by him as a measure of
their atomic weights; and the principle was subsequently constantly
employed by him, whenever possible, as a criterion in fixing their values.
Other investigators have followed his example in this respect; and
isomorphism is still regarded as an important consideration in establishing
the genetic relations of an element.
Eilhard Mitscherlich, the son of a minister, was born in 1794 at Neu
Ende, near Jever, in Oldenburg, and, after studying philology and oriental
languages at Heidelberg, went to Paris, and thence to Göttingen, where he
occupied himself with natural science. In 1818 he repaired to Berlin and
commenced to work on the arseniates and phosphates, the similarity in the
crystal-forms of which he was the first to detect. His friend Gustav Rose,
the mineralogist, thereupon instructed him in the methods of
crystallography; to enable him to verify his discovery and to establish it by
goniometric measurements. In 1821 he joined Berzelius at Stockholm,
where he pursued his inquiries on the connection between crystal-form and
chemical composition. It was at the suggestion of Berzelius that he adopted
the term “isomorphy” to express this connection—the mechanical
consequence of identity of atomic constitution. In the same year he was
appointed Klaproth’s successor in Berlin, where he died in 1863.
Mitscherlich also worked on the manganates and permanganates, on
selenic acid, on benzene and its derivatives, and on the artificial production
of minerals.
The study of the physical phenomena of gases, initiated in 1660 by
Boyle’s discovery of the law of gaseous pressure, has greatly contributed to
our knowledge of their intrinsic nature. Boyle himself only proved his law
in the case of atmospheric air; but the observation was subsequently (1676)
generalised by Marriotte. Charles, Dalton, and Gay Lussac independently
showed that gases have the same rate of thermal expansion.
That gases are made up of particles possessing an internal movement
was surmised by the Greeks; but experimental evidence for such a view of
their constitution was first presented by Thomas Graham in 1829–1831,

when he discovered that gases move, or are diffused, at rates inversely
proportional to the square roots of their densities. Observations of a like
character, which found their explanation in Graham’s discovery, had
previously been made by Priestley, Döbereiner, and Saussure. This
interchange in the position of their particles is a property inherent in gases.
Inequality of density is not essential to diffusion. Graham proved this by
connecting together two vessels, one containing nitrogen and the other
carbonic oxide, which have the same density. After the expiration of a
certain time both gases were found to be uniformly diffused through the
vessels.
How these laws were found to be interdependent and mutually
connected, and how they led up to a molecular theory of gases which serves
to explain them, as well as certain other gaseous phenomena to be
subsequently noted, will be shown in the second part of this work.
By the end of the period with which we are concerned—that is, the
middle of the nineteenth century—a considerable body of information had
been accumulated as to the conditions which determine the different states
of aggregation of matter—that is, the conditions which allow of the passage
of the gaseous state into that of the liquid, and of the liquid into that of the
solid. That the same substance was capable of existence in the three states
of gas, liquid, and solid was of course evident from the case of water. Even
the most primitive races must have realised that steam, dew, rain, snow,
hail, and ice were only modifications of one and the same substance. As
knowledge increased, other substances came to be known which resembled
water in their capacity for existence in various physical states. It was but
natural to assume that this was a general attribute, and that all substances
would, sooner or later, be found capable of existence in each of the different
conditions of aggregation.
Attempts were made during the first quarter of the last century to prove
that all the æriform bodies then known were simply vapours more or less
remote from their point of liquefaction, and still further removed from their
point of congelation. Monge and Clouet condensed sulphur dioxide some
time before 1800; and Northmore, in 1805, liquefied chlorine. But these
observations attracted little attention until Faraday, in 1823, independently
effected the liquefaction of chlorine, and Davy that of hydrochloric acid.
Faraday almost immediately afterwards liquefied sulphur dioxide,

sulphuretted hydrogen, carbon dioxide, euchlorine, nitrous oxide, cyanogen,
and ammonia.
Other experimenters, among whom may be mentioned Thilorier and
Natterer, greatly improved the mechanical appliances for liquefying these
gases; liquid carbonic acid and nitrous oxide were obtained in considerable
quantities, and employed in the production of cold. Certain of the gases—
hydrogen, oxygen, nitrogen, nitric oxide, carbonic oxide, etc.—resisted all
attempts to liquefy them; and hence gaseous substances came to be
classified as permanent and non-permanent, depending upon whether they
could or could not be liquefied. The division was felt to be irrational even at
the time it was made. There seemed no à priori reason why carbon dioxide
and nitrous oxide should be liquefiable, while carbonic oxide and nitric
oxide should resist all attempts to coerce them into changing their state. The
real clue to the conditions required to effect the liquefaction of a gas was
not discovered until nearly half a century later, when, as will be shown
subsequently, the arbitrary division of gases into permanent and non-
permanent was swept away.
The discovery of the law of gaseous combination by Gay Lussac, and
the recognition by Ampère and Avogadro of the relation between the
density of a gas or a vapour and its atomic weight, early led to
improvements in the methods of determining the absolute weights of gases
and vapours, especially by French chemists. Both Gay Lussac and Dumas
devised processes for determining vapour densities which were in use until
late in the century, and which, although now superseded by more
convenient and more rapid modifications afforded valuable information
concerning the molecular weights of substances and the phenomena of
gaseous dissociation.
During the first decade of the nineteenth century Dalton and Henry
discovered the simple law which connects pressure with the solubility of a
gas in any solvent upon which it exerts no specific action. Dalton further
developed the law so as to include the absorption by a solvent of the several
constituents of a gaseous mixture.
Attempts were made by Schröder, Kopp, and others, to discover
relations between the weights of unit volumes of liquids and solids and their
chemical nature; but such attempts were only partially successful, owing to

the difficulty of finding valid conditions of comparison. By comparing the
specific gravities of liquids at their boiling-points Kopp succeeded in
detecting a number of regularities among their specific volumes which
seem to indicate that a comprehensive generalisation connecting them may
yet be discovered. Kopp has also shown that regularities exist among the
boiling-points of correlated substances, and that there is an interdependence
between the temperature of their ebullition and the chemical characters of
compounds.
This short summary will suffice to show that attempts to discover
relations between the physical attributes of substances and their chemical
nature were made more or less sporadically from the time that chemistry
was pursued in the spirit of science. But it is only in recent times that any
great accession to knowledge has resulted from such efforts. The science of
physical chemistry is practically a creation of our own period. Its systematic
study may be said to date only from the last quarter of the nineteenth
century, since which time it has made extraordinary progress. Its broad
features will be dealt with in the second volume of this work.

BIBLIOGRAPHY

Relating to the Period Covered by Vol. I.

Agricola, Georg. De Re Metallica.
Agricola, Georg. Vom Bergwerck XII. Bücher darinn mit schöner
Figuren, etc.
Alembic Club, Publications of the. W. Clay, Edinburgh.
Beddoes, Thomas. Chemical Essays of Scheele. Murray, London, 1786.
Berthelot, Marcellin. La Chimie des Anciens et du Moyenâge. Steinheil,
Paris, 1889.
Berthelot, Marcellin. La Révolution Chimique. Félix Alcan, Paris, 1890.
Berthollet, C. L. Essai de Statique Chimique. Firmin Didot, Paris,
1803.
Birch, Thomas. Life of Boyle. Millar, London, 1744.
Boerhaave, Hermann. New Method of Chemistry. Shaw and Chambers,
London, 1727.
Boulton, Richard. Boyle’s Works Epitomised. Phillips and Taylor,
London, 1699.
Burton, W. Life of Boerhaave. Lintot, London, 1746.
Dalton, John. A New System of Chemical Philosophy. Two Vols.
Bickerstaff, London, 1807–1810.
Davy, John. Life of Sir Humphry Davy. Longmans, London, 1836.
Davy, Humphry. Collected Works. Edited by John Davy. Smith, Elder,
and Co., London, 1839.

Figuier, Louis. L’Alchimie et les Alchimistes. Victor Lecon, Paris, 1855.
Gay Lussac and Thénard. Recherches Physico-Chimiques. Deterville,
Paris, 1811.
Gerding, Th. Geschichte der Chemie. Zweite Ausgabe. Grunow,
Leipzig, 1869.
Grimaux, Edouard. Lavoisier, 1743–1794. Félix Alcan, Paris, 1888.
Henry, William Charles. Life of Dalton. Cavendish Society, London,
1854.
Hoefer, Ferdinand. Histoire de la Chimie. Two vols., Deuxième édition.
Firmin Didot Frères, Paris, 1866.
Jones, Bence. Life and Letters of Faraday. Longmans, London, 1870.
Kopp, Hermann. Geschichte der Chemie. Four vols. Braunschweig,
1843–47.
Kopp, Hermann. Die Alchemie in älterer und neuerer Zeit. Heidelberg,
1886.
Ladenberg, Albert. History of Chemistry Since the Time of Lavoisier.
Translated by Leonard Dobbin. Alembic Club, Edinburgh, 1900.
Lavoisier. Complete Works. Edited by Dumas. Four vols. Paris, 1864.
Lemery, Nicolas. Cours de Chimie. Paris, 1675.
Meyer, Ernst v. History of Chemistry. Translated by George M’Gowan.
Macmillian and Co., London, 1891.
Nordenskiöld, A. E. Carl Wilhelm Scheele. Norsledt and Söner,
Stockholm.
Ostwald’s Klassiker der Exakten Wissenschaften.
Paris, John Ayrton. Life of Sir Humphry Davy. Colbourne and Bentley,
London, 1831.
Priestley, Joseph. Experiments and Observations on Different Kinds of
Air. Six vols. J. Johnson, London, 1775 et seq.
Roscoe, H. E., and Harden, A. A New View of the Origin of Dalton’s
Atomic Theory. Macmillian and Co., London.

Schmieder. Geschichte der Alchimie. Halle, 1832.
Schubert, E., und Sudhoff, K. Paracelsus’s Forschungen. Frankfurt,
1887–89.
Shaw, Peter. Stahl’s Chemistry. Osborn and Longman, London.
Stahl, G. E. Cheimia Rationalis (1720).
Stahl, G. E. Zymotechnia Fundamentalis, etc. (1697).
Stange, Albert. Zeitalter der Chemie. Otto Wigand, Leipzig, 1908.
Thomson, Thomas. History of Chemistry. Two vols. Colbourne and
Bentley, London, 1830.
Thorpe, T. E. Essays in Historical Chemistry. Second edition.
Macmillian and Co., London, 1902.
Thorpe, T. E. Humphry Davy, Poet and Philosopher. Cassells, London,
1895.
Thorpe, T. E. Joseph Priestley. Dent and Co., London, 1906.
Wilson, George. Life of Cavendish. Cavendish Society, London, 1851.

INDEX

Æneas Garæus, 35
Agricola, Georg, 66
Aidoneous, god of earth, 22
Albertus Magnus, 40, 47
Alchemy, 28
and astrology, 36
its character, 39
Alkahest, 51
Anastatius the Sinaite, 35
Anaxagoras, 26
Anaximenes, 21
Aqua regia, 39
Arabian learning, influence on Western Europe, 25
Archæus, 59
Argentarium, 10
Argentum vivum, 11
Aristotle, his doctrine of “elements”, 23
his character as a man of science, 24
Arnoldus Villanovanus (Arnaud de Villeneuve), 42, 47, 48, 51
Arvidson, 155
Arrenichon, 13
Ars Transmutatoria, 46
Artephius, 49
Astrology and alchemy, 36
Atoms, ancient theories of, 26
Atramentum, 14
Aurichalcum, 9
Auri pigmentum (orpiment), 13

Averroes, 25, 38
Avicenna, 38
Avogadro, 181

Bacon, Roger, 40, 41
Bacon, Lord, 55
Baldwin’s phosphorus, 80
Bartoletti, Fabrizio, 155
Basil Valentine, 43, 47, 49, 156
Bathurst, Ralph, 74
Becher, John Joachim, 81, 156
Benther, David, alchemist, 53
Bergman, 94, 107, 124, 158, 160
Berigard de Pisa, 48
Berthollet, Claude-Louis, 116 et seq., 156, 160, 164
Berthelot, 37
Berzelius, Jöns Jakob, 133, 156, 159, 160, 164
Black, Joseph, 98 et seq., 171
Bochart, 4
Boerhaave, 3–20, 35, 42, 49, 51, 106
his life and work, 84 et seq.
Bolim, 160
Borri, 53
Botryitis, 12
Bouillon-Lagrange, 158
Boullay, 162, 167
Boyle, Robert 20, 72 et seq., 107, 113, 155, 157, 159, 175, 177
Bragadino, alchemist, 53
Brooke Taylor, 171
Brugnatelli, 158, 161

Cadmia, 12

Cœruleum, 12
Caligula, 34
Carbunculus, 48
Cardan, 110
Cavendish, 94, 102 et seq., 107, 171
Caventou, 162
Cerium, its discovery, 121
Cerussa, 10
usta, 12
Chalcantum (copper sulphate), 12
Charles, 178
Chalybes, smelters of iron, 11
Chemistry of the ancients, 1
Chenevix, 157
Chevreul, 54, 162
Chlorine, discovery of, 107
Chromium, discovery of, 120
Chrysocolla, 12
Cinnabar, use as pigment, 13
Clouet, 180
Clytemius, John, 54
Cobalt, discovered by Brandt, 107
Combining proportion, 129
Conservation of matter, 113
Conringius, Hermann, 51
Copper, Egyptian, 8
Roman, 9
Cordus Valerius, 69
Crawford, 107, 172
Croll, Oswald, 65
Cronstedt, 107
Cyanogen, discovery of, 151

Dalton, 125 et seq., 178, 181
Davy, 29, 141
Dee, John, 53
Delambre, 116
Demokritos, 26
De Re Metallica, 66
Derosne, 157
Dickinson, 50
Diodorus Siculus, 7
Dioscorides, 156, 160
Döbereiner, 155, 162, 167
Dorn, 60
Duchesne, 61
Duhamel, 98, 157
Dumas, 162, 167, 168, 181
Dulong, 158, 173, 174
Dyeing by the Egyptians, 14

Egypt, birthplace of chemistry, 1
Electrum, 8
Elementa Chemia, 87
“Elements,” Aristotelian, qualities of, 23
Elephantinum, 14
Elixir, 32
Eller, 94
Empedokles, 23
Erastius, Thomas, 51
Equivalent, 129

Fæx vini, 137
Fischer, G. E., 124
Flos æris, 12

Fourcroy, 112, 118, 155, 158, 161, 162
Frankland, 168

Gahn, 108
Gas sylvestre, 63
Gay Lussac, 150, 155, 161, 164, 167, 178, 181
Geber, 36
theory of metals, 37, 156
Generation of metals, 33
Geoffroy, 106
Gerhardt, 168
Glass, known to the ancients, 15
Glauber, Johann Rudolf, 68
Glucinum, its discovery, 120
Gmelin, L. 161
Gold, extraction by ancients, 7
Goulard, 157
Gomes, 161
Göttling, 156
Graham, Thomas, 178
Gresham College, 74
Gualdo, 49
Guyton de Morveau, 112, 160

Hæmatinon, 15
Hales, Stephen, 89
“Harmonics,” Paracelsian, 61
Hauy, 176
Hellot, 108
Helmont, John Baptist van, 63
Helvetius, 48
Hennel, 155

Henry, 181
Herakleitos, 21
Here, god of air, 22
Hermbstädt, 158
Hermes Trismegistus, 4, 33
“Hermes of Germany, the”, 52
Hoffmann, 106
Homberg, William, 84
Houton-Labillardière, 158
Howard, 161
Hyalos, use of, for kindling fire, 15
Hydrargyrum, 11

Iatro-chemistry, 57
Ink of the ancients, 14
Ingenhousz, 21
Invisible College, the, 74
Iron, use of, by the ancients, 10
Irvine, 172
Isaac of Holland, 49
Isomerism, 165
Isomorphism, discovery of, 176

“Kalid,” his philosopher’s stone, 48
Key of Wisdom, 53
Kircher, 51
Kirchhoff, 162
Kirwan, 113
Klaproth, 120, 160
Klettenberg, Hector de, 54
Kopp, 181
Krohnemann, William de, 53

Kunkel, John, 51, 79

Laboratorium Chymicum, 80
Lac Virginis, 157
Lagrange, 116
Laplace, 172
Latent heat, 99, 172
Lauraquais, 155
Laurent, 168
Lavoisier, 20, 22, 109
antiphlogistic theory, 112, 116, 156, 164, 166, 173
Law of Dulong and Petit, 173, 174
Law of electrolytic action, 153
Lead, known to the ancients, 10
Leblanc, 108
Lehmann, 159
Lemery, Nicolas, 83, 154, 156
Leo Africanus, 36
Leukippos, 26
Libavius, Andreas (Libau), 62, 155, 157
Lieber, Thomas, 65
Liebig, 155, 156, 159, 164, 167
Löwiz, 156
Lucretius, 26, 27
Lully, Raymund, 41, 47, 49

Macquer, 98
Magistery, grand, 48
small, 48
Magnesia alba, nature of, 107
Manganese, discovery of, 107
Marggraf, 95, 107, 108, 157

Marie Ziglerin burnt, 53
Martian preparations, 37
Marriotte, 178
Maternus, Julius Firmicus, 35
Mayerne, Turquet de, 65
Mayow, John, 82 et seq.
Medicine and Astrology, 58
Melinum, 13–14
Menethes Sibonita, 3
“Mercury,” as “element”, 31
Mercury, receipt for fixing, 50
Metallurgy of the ancients, 7
Metals of the phlogistians, 104
Minderer, Raymond, 157
Minium, 12
Mitscherlich, 159, 175, 176, 177
Molybdena, 12
Monge, 180
Monro, Donald, 159
Mordants, Egyptian, 15
Mundamus, 43
Mynsicht, Adrian van, 65, 158

Narcotine, 161
Natron, used as a detergent, 16
Natterer, 180
Nestis, god of water, 22
Neumann, 94, 175
New System of Chemical Philosophy, Dalton’s, 129
Nickel, discovery of, 107
Nitrogen, discovery of, 107
Northmore, 180

Œrugo, 12
Oil of wine, 155
Okeanos, 19
Oleus Borrichius, 33
Olimpiodorus, 35
Onychitis, 12
Operinus, 60
Ostracitis, 12
Oxides, metallic, used by ancients to colour glass 15
Oxygen, its discovery, 105
influence of, on chemistry, 105

Palissy, Bernard, 67
Paracelsus, 40, 48, 57
Paratonium, 13
Pelletier, 162
Peligot, 162
Peripatetic philosophy, influence on science, 24
Petit, Alexis Therese, 173, 175
Pherekides, 21
Philosophia Orientalis, 38
Philosopher’s Stone, 32, 46, 49
Philosophical egg, 33
Phlogistonism, 95 et seq.
Phosphorus, discovery of, 80, 107
Placitis, 12
Platinum, discovery of, 107
Plato’s doctrine of “elements”, 23
Pliny, 156
Plumbum album, 10
nigrum, 10
Pope John XXII., alchemist, 46

Porret, 160
Pott, 94, 95, 159
Price, James of Guildford, 54
Priestley, Joseph, 20, 22
his life and work, 99 et seq.
Proust, Joseph Louis, 121
Purple of Cassius, 81
Purpurissum, 13

Quintessence of philosophers, 32

Raquetaillade, Jean de, 43
Realgar, 13
Reaumur, 108
Rey, 110
Rhazes, 38
Richter, Jeremiah Benjamin, 124
Ripley, George, 43
Robiquet, 161, 167
Roebuck, 108
Romé de L’Isle, 176
Rose, Gustav, 177
Rosenkreutz, Christian, 55
Rouelle, 94, 106, 159
Royal Society, foundation of, 74
Rubrica, 13
Rupecissa, Johannes de, 43

Saccharum plumbi quintessentiale, 157
Sala, Angelus, 65
Sal Armoniacum, 44
Sal Duplicatum, 81

Sal mirabile, 68
Sandarach, 13
Saturnine solutions, 37
Savary, 155
Sceptical Chemist, The, 70
Scheele, 96 et seq., 107, 155, 158, 159, 160, 166
Schroeder, 181
Scoria æris, 12
Sefström, 135
Seguin, 159
Seignette, Peter, 157
Selenium, its discovery, 135
Sennert, Daniel, 65
Sertürner, 161
Severinus, 61
Silver, known to the ancients, 7
Sinopis, 13
Soap, manufacture by Gauls, 15
Specific heat, discovery of, 99
Spiritus igno-aëreus, 82
Stahl, George Ernst, 92, 156
Stannum, 10
Statical Essays of Hales, 89
Statique Chimique, 117
Stephanus, 35
Stibium, 13
Stimmi, 13
Strontia, discovery of, 107
Suidas, 34
“Sulphur,” as “element”, 31
Sulzbach, 110
Sun worship, 22

Sylvius, Francis de le Boë, 64
Syncellus, 35

Tachenius, 69
Tartarus, doctrine of, 59, 157
Tellurium, discovery of, 121
Terra pinguis of Becher, 92
Tertiarium, 10
Tertullian, 19
Thales of Miletus, 19
Thénard, 152, 164
Theophrastus, 156
The Tincture, 32
Thilorier, 180
Thomson, Thomas, 129
Thorium, its discovery, 135
Thurneysser, Leonard, 53, 60
Tin, known to the Egyptians, 9
Transmutation, 28, 30
Trommsdorff, 157
Tubal Cain (Tuval-Cain), 7
Turquet de Mayerne, 158
Tyrian purple, 14

Valentine, Basil, 43, 47, 49, 156
Van Helmont, 20, 48, 63
Vasa murrhina, 15
Vauquelin, 119, 155, 158, 161, 162
Verdigris, 56
Vincent de Beauvais, 50
Von Ittner, 160

Wallis, John, 74
Ward, Seth, 74
“White” gold, 7
Wilcke, 172
Willis, Thomas, 64, 74
Wöhler, 161, 163, 167
Wollaston, 144, 176
Woodward, 160
Wray, 159
Wren, Christopher, 74

Zacharias, Daniel, 49
Zozimus the Panopolite, 4

Transcriber’s Notes
Punctuation and spelling were made consistent when
a predominant preference was found in this book;
otherwise they were not changed.
Simple typographical errors were corrected;
occasional unbalanced quotation marks retained.
Ambiguous hyphens at the ends of lines were
retained; occurrences of inconsistent hyphenation have
not been changed.
Index not checked for proper alphabetization or
correct page references.
Page 16: “jeunesse d’oreé” was printed that way, but
should be “_jeunesse dorée_”.
Page 183: “Moyenâge” was printed that way, but
should be “Moyen Âge”.

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