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Title: Researches Chemical and Philosophical; Chiefly concerning
nitrous oxide

Author: Sir Humphry Davy

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*** START OF THE PROJECT GUTENBERG EBOOK RESEARCHES
CHEMICAL AND PHILOSOPHICAL; CHIEFLY CONCERNING
NITROUS OXIDE ***

RESEARCHES,
CHEMICAL and
PHILOSOPHICAL;
CHIEFLY CONCERNING
NITROUS OXIDE,
OR
DEPHLOGISTICATED NITROUS AIR,
AND ITS
RESPIRATION.

By HUMPHRY DAVY,
SUPERINTENDENT OF THE MEDICAL PNEUMATIC
INSTITUTION.

LONDON:
PRINTED FOR J. JOHNSON, ST. PAUL’S CHURCH-YARD,
BY BIGGS AND COTTLE, BRISTOL,
1800.

CONTENTS.

Introduction, xi.
RESEARCH I.
Into the analysis of Nitric Acid and Nitrous Gas, and the
production of Nitrous Oxide.
DIVISION I.
Experiments and Observations on the composition of Nitric Acid,
and on its combinations with Water and Nitrous Gas.
1. Preliminaries 1
2. Production of aëriform Nitrous Acid 3
3. Specific gravity of Gases 6
4. Experiment on the formation of Nitrous Acid 11
5. Conclusions 17
6. Experiments on the combination of Nitrous Gas with Nitric
Acid 17
7. Additional Experiments 23
8. Conclusions 29
9. Mr. Thomson’s Theory of the difference between Nitric and
Nitrous Acid 30
10. Composition of the different Nitrous Acids 36
11. Combination of Nitric Acid with Water 38
12. Of Nitrous Vapor 42
13. Comparison of the results with those of Cavendish and
Lavoisier 43

DIVISION II.

Experiments and Observations on the composition of Ammoniac
and on its combinations with Water and Nitric Acid.
1. Analysis of Ammoniac 56
2. Specific gravity of Ammoniac 62
3. Of the quantities of true Ammoniac in Ammoniacal Solutions 65
4. Composition of Nitrate of Ammoniac 71
5. Decomposition of Carbonate of Ammoniac, by Nitrous Acid 75
6. Decomposition of Sulphate of Ammoniac by Nitre 77
7. Non-existence of Ammoniacal Nitrites 79
8. Sources of error in Analysis 80
9. Loss in Solutions of Nitrate of Ammoniac during evaporation 83

DIVISION III.
Decomposition of Nitrate of Ammoniac—Preparation of respirable
Nitrous Oxide.
1. Of the heat required for the decomposition of Nitrate of
Ammoniac 84
2. Decomposition of Nitrate of Ammoniac—Production of
respirable Nitrous Oxide—its properties 86
3. Of the Gas remaining after the absorption of Nitrous Oxide
by Water 89
4. Specific Gravity of Nitrous Oxide 94
5. Analysis of Nitrous Oxide 95
6. Minute examination of the decomposition of Nitrate of
Ammoniac 101
7. Of the heat produced during the decomposition of Nitrate of
Ammoniac 108
8. Decomposition of Nitrate of Ammoniac at high temperatures 109
9. Speculations on the decompositions of Nitrate of Ammoniac 113
10. Of the preparation of Nitrous Oxide for experiments on
respiration 117

DIVISION IV.
Experiments and Observations on the composition ofNitrous Gas, and on
its absorption by different bodies.
1. Preliminaries 122
2. Analysis of Nitrous Gas by Charcoal 126
3. Analysis of Nitrous Gas by Pyrophorus 132
4. Additional observations on the composition of Nitrous Gas 134
5. Absorption of Nitrous Gas by Water 140
6. Absorption of Nitrous Gas by Water of different kinds 147
7. Absorption of Nitrous Gas by solution of pale green Sulphate
of Iron 152
8. Absorption of Nitrous Gas by solution of green muriate of
Iron 179
9. By Solution of Nitrate of Iron 187
10. By other metallic Solutions 189
11. Action of sulphurated Hydrogene on solution of green
sulphate of iron impregnated with Nitrous Gas 191
12. Additional Observations 193

DIVISION V.
Experiments and Observations on the production of Nitrous Oxide from
Nitrous Gas and Nitric Acid in different modes.
1. Preliminaries 197
2. Conversion of Nitrous Gas into Nitrous Oxide by alkaline
sulphites 199
3. By Muriate of Tin 202
4. By Sulphurated Hydrogene 203
5. Decomposition of Nitrous Gas by Nascent Hydrogene 206
6. Miscellaneous Observations 209
7. Recapitulation 211
8. Production of Nitrous Oxide from Metallic Solutions 213

9. Additional Observations relating to the production of Nitrous
Oxide 219
10. Decomposition of Aqua regia by platina, and evolution of a
gas analogous to oxygenated muriatic acid, and nitrogene 222
11. Action of the electric spark on a mixture of Nitrogene and
Nitrous gas 229
12. General remarks on the production of Nitrous Oxide 231

RESEARCH II.
Into the combinations of Nitrous Oxide, and its decomposition.
DIVISION I.
Experiments and Observations on the combinations of Nitrous
Oxide.
1. Combination of Water with Nitrous Oxide 235
2. —— of Nitrous Oxide with fluid inflammable bodies 240
3. Action of fluid Acids on Nitrous Oxide 244
4. —— of Saline Solutions 245
5. —— of Gases 248
6. Action of aëriform Nitrous Oxide on the alkalies—History of
the discovery of the combinations of Nitrous Oxide, with the
alkalies 254
7. Combination of Nitrous Oxide with Potash 262
8. Combination of Nitrous Oxide with Soda 268
9. —— —— —— with Ammoniac 269
10. Probability of forming compounds of Nitrous Oxide and the
alkaline earths 273
11. Additional Observations 274
12. The properties of Nitrous oxide resemble those of Acids 276

DIVISION II.

Decomposition of Nitrous Oxide by combustible Bodies.
1. Preliminaries 278
2. Conversion of Nitrous Oxide into Nitrous Acid and a gas
analogous to Atmospheric Air by ignition 279
3. Decomposition of Nitrous Oxide by Hydrogene 286
4. —— —— —— by Phosphorus 293
5. —— —— by Phosphorated Hydrogene 300
6. —— by Sulphur 303
7. —— by Sulphurated Hydrogene 306
8. —— by Charcoal 311
9. —— by Hydrocarbonate 313
10. Combustion of Iron in Nitrous Oxide 316
11. —— of Pyrophorus 318
12. —— of the Taper 319
13. —— of different Compound Bodies 321
14. General Conclusions relating to the decomposition of Nitrous
Oxide, and to its analysis 322
15. Observations on the combinations of Oxygene and Nitrogene 325

RESEARCH III.
Relating to the Respiration of Nitrous Oxide and other Gases.
DIVISION I.
Experiments and Observations on the effects produced upon
Animals by the respiration of Nitrous Oxide.
1. Preliminaries 333
2. On the respiration of Nitrous Oxide by warm-blooded
Animals 336
3. Effects of the respiration of Nitrous Oxide upon Animals, as
compared with those produced by their immersion in
Hydrogene and Water 343

4. Of the changes effected in the organisation of warm-blooded
Animals, by the respiration of Nitrous Oxide 347
5. Of the respiration of mixtures of Nitrous Oxide and other
Gases, by warm-blooded Animals 358
6. Recapitulation of facts relating to the respiration of Nitrous
Oxide, by warm-blooded Animals 360
7. Of the respiration of Nitrous Oxide, by amphibious Animals 362
8. Effects of Solution of Nitrous Oxide on Fishes 366
9. Effects of Nitrous Oxide on Insects 370

DIVISION II.
Of the changes effected in Nitrous Oxide and other Gases, by the
Respiration of Animals.
1. Preliminaries 373
2. Absorption of Nitrous Oxide by Venous Blood 374
3. Of the changes effected in Nitrous Oxide by Respiration 388
4. Respiration of Hydrogene 400
5. Additional Observations and Experiments on the Respiration
of Nitrous Oxide 411
6. Of the Respiration of Atmospheric Air 429
7. Respiration of Oxygene 439
8. Observations on the changes effected in the blood by
Atmospheric Air and Oxygene 445
9. Observations on the Respiration of Nitrous Oxide 449

RESEARCH IV.
Relating to the Effects produced by the Respiration of Nitrous
Oxide upon different Individuals.
DIVISION I.

History of the Discovery.—Effects produced by the Respiration of
different Gases.
1. Respirability of Nitrous Oxide 456
2. Effects of Nitrous Oxide 458
3. General Effects of Nitrous Oxide on the Health 464
4. Respiration of Hydrogene 466
5. —— of Nitrogene 467
6. Effects of Hydrocarbonate 468
7. —— of Carbonic Acid 472
8. —— of Oxygene 473
9. —— of Nitrous Gas 475
10. Most extensive action of Nitrous Oxide produces no debility 485

DIVISION II.
Details of the Effects produced by the Respiration of Nitrous Oxide
upon different Individuals, furnished by Themselves.
1. Detail of Mr. J. W. Tobin 497
2. —— of Mr. W. Clayfield 502
3. Letter from Dr. Kinglake 503
4. Detail of Mr. Southey 507
5. Letter from Dr. Roget 509
6. Letter from Mr. James Thomson 512
7. Detail of Mr. Coleridge 516
8. —— of Mr. Wedgwood 518
9. —— of Mr. G. Burnet 520
10. —— of Mr. T. Pople 521
11. —— of Mr. Hammick 522
12. —— of Dr. Blake 524
13. —— of Mr. Wanfey 525
14. —— of Mr. Rickman 526
15. —— of Mr. Lovell Edgworth 527
16. —— of Mr. G. Bedford 528

17. —— of Miss Ryland 530
18. Letter from Mr. M. M. Coates 530

DIVISION III.
Abstracts from additional Details—Observations on the effects of
Nitrous Oxide, by Dr. Beddoes—Conclusion.
1. Abstracts from additional details 533
2. Of the effects of Nitrous Oxide on delicate females 537
3. Observations on the effects of Nitrous Oxide by Dr. Beddoes 541
4. Conclusion 548

APPENDIX.
No. I. Of the effects of Nitrous Oxide on Vegetables 561
No. II. Table of the Weight and Composition of the combinations of
Nitrogene 566
No. III. Additional Observations 567
No. IV. Description of a Mercurial Airholder, and Breathing Machine,
by Mr. W. Clayfield. 573
No. V. Proposals for the Preservation of Accidental Observations in
Medicine. By Dr. Beddoes. 577

INTRODUCTION.

I
n consequence of the discovery of the respirability and extraordinary
effects of nitrous oxide, or the dephlogisticated nitrous gas of Dr.
Priestley, made in April 1799, in a manner to be particularly described
hereafter,[1] I was induced to carry on the following investigation
concerning its composition, properties, combinations, and mode of
operation on living beings.
In the course of this investigation, I have met with many difficulties;
some arising from the novel and obscure nature of the subject, and others
from a want of coincidence in the observations of different experimentalists
on the properties and mode of production of the gas. By extending my
researches to the different substances connected with nitrous oxide; nitrous
acid, nitrous gas and ammoniac; and by multiplying the comparisons of
facts, I have succeeded in removing the greater number of those difficulties,
and have been enabled to give a tolerably clear history of the combinations
of oxygene and nitrogene.
By employing both analysis and synthesis whenever these methods
were equally applicable, and comparing experiments made under different
circumstances, I have endeavoured to guard against sources of error; but I
cannot flatter myself that I have altogether avoided them. The physical
sciences are almost wholly dependant on the minute observation and
comparison of properties of things not immediately obvious to the senses;
and from the difficulty of discovering every possible mode of examination,
and from the modification of perceptions by the state of feeling, it appears
nearly impossible that all the relations of a series of phænomena can be
discovered by a single investigation, particularly when these relations are
complicated, and many of the agents unknown. Fortunately for the active
and progressive nature of the human mind, even experimental research is
only a method of approximation to truth.
In the arrangement of facts, I have been guided as much as possible by
obvious and simple analogies only. Hence I have seldom entered into

theoretical discussions, particularly concerning light, heat, and other agents,
which are known only by isolated effects.
Early experience has taught me the folly of hasty generalisation. We are
ignorant of the laws of corpuscular motion; and an immense mass of minute
observations concerning the more complicated chemical changes must be
collected, probably before we shall be able to ascertain even whether we are
capable of discovering them. Chemistry in its present state, is simply a
partial history of phænomena, consisting of many series more or less
extensive of accurately connected facts.
With the most important of these series, the arrangement of the
combinations of oxygene or the antiphlogistic theory discovered by
Lavoisier, the chemical details in this work are capable of being connected.
In the present state of science, it will be unnecessary to enter into
discussions concerning the importance of investigations relating to the
properties of physiological agents, and the changes effected in them during
their operation. By means of such investigations, we arrive nearer towards
that point from which we shall be able to view what is within the reach of
discovery, and what must for ever remain unknown to us, in the
phænomena of organic life. They are of immediate utility, by enabling us to
extend our analogies so as to investigate the properties of untried
substances, with greater accuracy and probability of success.
The first Research in this work chiefly relates to the production of
nitrous oxide and the analysis of nitrous gas and nitrous acid. In this there is
little that can be properly called mine; and if by repeating the experiments
of other chemists, I have sometimes been able to make more minute
observations concerning phænomena, and to draw different conclusions, it
is wholly owing to the use I have made of the instruments of investigation
discovered by the illustrious fathers of chemical philosophy,[2] and so
successfully applied by them to the discovery of truth.
In the second Research the combinations and composition of nitrous
oxide are investigated, and an account given of its decomposition by most
of the combustible bodies.
The third Research contains observations on the action of nitrous oxide
upon animals, and an investigation of the changes effected in it by

respiration.
In the fourth Research the history of the respirability and extraordinary
effects of nitrous oxide is given, with details of experiments on its powers
made by different individuals.
I cannot close this introduction, without acknowledging my obligations
to Dr. Beddoes. In the conception of many of the following experiments, I
have been aided by his conversation and advice. They were executed in an
Institution which owes its existence to his benevolent and philosophic
exertions.
Dowry-Square, Hotwells, Bristol.
June 25th, 1800.

RESEARCH I.
concerning the analysis of

NITRIC ACID and NITROUS GAS
and the production of

NITROUS OXIDE.

Pl. I.
MERCURIAL AIRHOLDER and BREATHING
MACHINE.

Lowry sculpᵗ.

RESEARCH I.
INTO THE PRODUCTION AND ANALYSIS OF
NITROUS OXIDE,
AND THE AËRIFORM FLUIDS RELATED TO IT.

DIVISION I.

EXPERIMENTS and OBSERVATIONS on the composition of
NITRIC ACID, and on its combinations with Water and
Nitrous Gas.
I. Though since the commencement of Pneumatic Chemistry, no
substance has been more the subject of experiment than Nitrous Acid; yet
still the greatest uncertainty exists with regard to the quantities of the
principles entering into its composition.
In comparing the experiments of the illustrious Cavendish on the
synthesis of nitrous acid, with those of Lavoisier on the decomposition of
nitre by charcoal, we find a much greater difference in the results than can
be accounted for by supposing the acid formed, and that decomposed, of
different degrees of oxygenation.
In the most accurate experiment of Cavendish, when the nitrous acid
appeared to be in a state of deoxygenation, 1 of nitrogene combined with
about 2,346 of oxygene.[3] In an earlier experiment, when the acid was
probably fully oxygenated, the nitrogene employed was to the oxygene
nearly as 1 to 2,92.[4]
Lavoisier, from his experiments on the decomposition of nitre, and
combination of nitrous gas and oxygene, concludes, that the perfectly
oxygenated, or what he calls nitric acid, is composed of nearly 1 nitrogene,
with 3,9 of oxygene; and the acid in the last state of deoxygenation, or
nitrous acid, of about 3 oxygene with 1 nitrogene.[5]

Great as the difference is between the estimations of these philosophers,
we find differences still greater in the accounts of the quantities of nitrous
gas necessary to saturate a given quantity of oxygene, as laid down by very
accurate experimentalists. On the one hand, Priestley found 1 of oxygene
condensed by 2 of nitrous gas, and Lavoisier by 1⅞. On the other,
Ingenhouz, Scherer, and De la Metherie, state the quantity necessary to be
from 3 to 5.[6] Humbolt, who has lately investigated Eudiometry with great
ingenuity, considers the mean quantity of nitrous gas necessary to saturate 1
of oxygene, as about 2,55.[7]
II. To reconcile these different results is impossible, and the immediate
connection of the subject with the production of nitrous oxide, as well as its
general importance, obliged me to search for means of accurately
determining the composition of nitrous acid in its different degrees of
oxygenation.
The first desideratum was to ascertain the nature and composition of a
fluid acid, which by being deprived of, or combined with nitrous gas, might
become a standard of comparison for all other acids.
To obtain this acid I should have preferred the immediate combination
of oxygene and nitrogene over water by the electric spark, had it been
possible to obtain in this way by a common apparatus sufficient for
extensive examination; but on carefully perusing the laborious experiments
of Cavendish, I gave up all thoughts of attempting it.
My first experiments were made on the decomposition of nitre, formed
from a known quantity of pale nitrous acid of known specific gravity, by
phosphorus, tin, and charcoal: but in those processes, unascertainable
quantities of nitrous acid, with excess of nitrous gas, always escaped
undecompounded, and from the non-coincidence of results, where different
quantities of combustible substances were employed, I had reasons for
believing that water was generally decomposed.
Before these experiments were attempted, I had analized nitrous gas and
nitrous oxide, in a manner to be particularly described hereafter; so that a
knowledge of the quantities of nitrous gas and oxygene entering into the
composition of any acid, enabled me to determine the proportions of
nitrogene and oxygene it contained. In consequence of which I attempted to
combine together oxygene and nitrous gas, in such a manner as to absorb

the nitrous acid formed by water, in an apparatus by which the quantities of
the gases employed, and the increase of weight of the water, might be
ascertained; but this process likewise failed. It was impossible to procure
the gases perfectly free from nitrogene, and during their combination, this
nitrogene made to pass into a pneumatic apparatus communicating with a
vessel containing the water carried over with it, much nitrous acid vapor, of
different composition from the acid absorbed.
After many unsuccessful trials, Dr. Priestley’s experiments on nitrous
vapor[8] induced me to suppose that oxygene and nitrous gas, made to
combine out of the contact of bodies having affinity for oxygene, would
remain permanently aëriform, and on throwing them separately into an
exhausted glass balloon, I found that this was actually the case; increase of
temperature was produced, and orange colored nitrous acid gas formed,
which after remaining for many days in the globe, at a temperature below
56°, did not in the slightest degree condense.
This fact afforded me the means not only of forming a standard acid, but
likewise of ascertaining the specific gravity of nitrous acid in its aëriform
state.
III. Previous to the experiment, for the purpose of correcting incidental
errors, I was induced to ascertain the specific gravity of the gases
employed, particularly as I was unacquainted with any process by which the
weight of nitrous gas had been accurately determined. Mr. Kirwan’s
estimation, which is generally adopted, being founded upon the comparison
of the loss of weight of a solution of copper in dilute nitrous acid, with the
quantity of gas produced.[9]
The instruments that I made use of for containing and measuring my
gases, were two mercurial airholders graduated to the cubic inch of Everard,
and furnished with stop-cocks.[10]
They were weighed in a glass globe, of the capacity of 108 cubic inches,
which with the small glass stop-cock affixed to it, was equal, when filled
with atmospheric air, to 1755 grains. The balance that I employed, when
loaded with a pound, turned with less than one eighth of a grain.
Into a mercurial airholder, of the capacity of 200 cubic inches, 160
cubic inches of nitrous gas were thrown from a solution of mercury in

nitrous acid.
70 measures of this were agitated for some minutes in a solution of
sulphate of iron,[11] till the diminution was complete. The nitrogene
remaining hardly filled a measure; and if we suppose with Humbolt[12] that
a very small portion of it was absorbed with the nitrous gas, the whole
quantity it contained may be estimated at 0,0142, or ¹/₇₀.
75 cubic inches received from the airholder into an exhausted balloon,
increased it in weight 25,5 grains; thermometer being 56°, and barometer
30,9. And allowing for the small quantity of nitrogene in the gas, 100 cubic
inches of it will weigh 34.3 grains.
One hundred and thirty cubic inches of oxygene were procured from
oxide of manganese and sulphuric acid, by heat, and received in another
mercurial airholder.
10 measures of it, mingled with 26 of the nitrous gas, gave, after the
residuum was exposed to solution of sulphate of iron, rather more than one
measure. Hence we may conclude that it contained about 0,1 nitrogene.
60 cubic inches of it weighed 20,75 grains; and accounting for the
nitrogene contained in these, 100 grains of pure oxygene will weigh 35,09
grains.
Atmospherical air was decomposed by nitrous gas in excess; and the
residuum washed with solution of sulphate of iron till the Nitrogene
remained pure; 87 cubic inches of it weighed 26,5 grains, thermometer
being 48°, barometer 30,1; 100 will consequently weigh 30,45.
90 cubic inches of the air of the laboratory not deprived of its carbonic
acid, weighed 28,75 grains; thermometer 53, barometer 30: 100 cubic
inches will consequently weigh 31,9.[13] 16 measures of this air, with 16
nitrous gas, of known composition, diminished to 19. Hence it contained
about,26 oxygene.[14]
In comparing my results with those of Lavoisier and Kirwan, the
estimation of the weights of nitrogene and oxygene is very little different,
the corrections for temperature and pressure being made, from that of those
celebrated philosophers. The first makes oxygene to weigh[15] 34,21, and
nitrogene 30,064 per cent; and the last, oxygene 34,[16] and nitrogene 30,5.

The specific gravity of nitrous gas, according to Kirwan, is to that of
common air as 1194 to 1000. Hence it should weigh about 37 grains per
cent. This difference from my estimation is not nearly so great as I expected
to have found it.[17]
IV.[18] The thermometer in the laboratory standing at 55°, and the
barometer at 30,1, I now proceeded to my experiment. The oxygene that I
employed was of the same composition as that which I had previously
weighed. The nitrous gas contained,0166 nitrogene.
For the purpose of combining the gases, a glass balloon was procured,
of the capacity of 148 cubic inches, with a glass stop-cock adapted to it,
having its upper orifice tubulated and graduated for the purpose of
containing and measuring a fluid. The whole weight of this globe and its
appendages, when filled with common air, was 2066,5 grains.
It was partially exhausted by the air-pump, and lost in weight just 32
grains. From whence we may conclude that about 15 grains of air remained
in it.
In this state of exhaustion it was immediately cemented to the stop-cock
of the mercurial airholder, and the communication being made with great
caution, 82 cubic inches of nitrous gas rushed into the globe, on the outside
of which a slight increase of temperature was perceived, while the gases on
the inside appeared of a deep orange.
Before the common temperature was restored, the communication was
stopped, and the globe removed. The increase of weight was 29,25 grains;
whence it appeared that 1,14 grains of common air, part of which had been
contained in the stop-cocks, had entered with the nitrous gas.
Whilst it was cooling, from the accidental loosening of the stopper of
the cock, 3 grains more of common air entered.[19]
The communication was now made between the globe and the mercurial
airholder containing oxygene. 64 cubic inches were slowly pressed in, when
the outside of the globe became warmer, and the color on the inside
changed to a very dark orange. As it cooled, 6 cubic inches more slowly
entered; but no new increase of temperature, or change of color took place.

The globe being now completely cold, was stopped, removed, and
weighed; it had gained 24,5 grains, from whence it appears that 0,4 grains
of common air contained in the stop-cocks, had entered with the oxygene.
[20]

To absorb the nitrous acid gas, 41 grains of water were introduced by
the tube of the stop-cock, which though closed as rapidly as possible, must
have suffered nearly,5 grains of air to enter at the same time, as the increase
of weight was 41,5 grains. The dark orange of the globe diminished rapidly;
it became warm at the bottom, and moist on the sides. After a few minutes
the color had almost wholly disappeared.
To ascertain the quantity of aëriform fluid absorbed, the globe was again
attached to the mercurial air apparatus, containing 140 cubic inches of
common air. When the communication was made, 51 cubic inches rushed
in, and it gained in weight 16,5 grains.
A quantity of fluid equal to 54 grains was now taken out of the globe.
On examination it proved to be slightly tinged with green, and occupied a
space equal to that filled by 41,5 grains of water. Its specific gravity was
consequently 1,301.
To ascertain if any unabsorbed aëriform nitrous acid remained in the
globe, 13 grains of solution of ammonia were introduced in the same
manner as the water, and after some minutes, when the white vapor had
condensed, the communication was again made with the mercurial airholder
containing common air. A minute quantity entered, which could not be
estimated at more than three fourths of an inch, and the globe was increased
in weight about 13,25 grains.[21]
Common air was now thrown into the globe till the residual gases of the
experiment were judged to be displaced; it weighed 2106,5 grains, that is,
40 grains more than it had weighed when filled with common air before the
experiment.[22]
And if from those 40 grains we take 13 for the solution of ammonia
introduced, the remainder, 27, will be the quantity of solution of nitrous
acid in water remaining in the globe, which added to 54, equals 81 grains,
the whole quantity formed; but if from this be taken 41 grains, the quantity

of water, the remainder 40 grains, will be the quantity of nitrous acid gas
absorbed in the solution.
To find the absolute quantity of nitrous acid formed, we must find the
specific gravity of that absorbed; but as during, and after its absorption, 17
grains of air, equal to 53,2 cubic inches entered, it evidently filled such a
space. 53,2 cubic inches of it consequently weigh 40 grains, and 100 cubic
inches 75,17 grains. Then,75 cubic inches weigh,56 grains, and this added
to 40, makes 40,56 grains, equal to 53,95 cubic inches, the whole quantity
of aëriform nitrous acid produced.
But the quantity of nitrous gas entering into this, allowing for the
nitrogene it contained, is 27,6 grains, equal to about 80,5 cubic inches; and
the oxygene is 40,56-27,6 = to 12,96 grains, or 36,9 cubic inches.
V. There could exist in this experiment no circumstance connected with
inaccuracy, except the impossibility of very minutely determining the
quantities of common air which entered with the gases from the stop-cocks.
But if errors have arisen from this source, they must be very inconsiderable;
as will appear from a calculation of the specific gravity of the nitrous acid
gas, founded on the volume of the gases that entered the globe.
The air that remained in the globe
after exhaustion was 15 grains = 47[23] cub. in.
The nitrous gas introduced was 82
Common air 13
Oxygene 70
Common air 1
——
Whole quantity of air thrown into the globe 213
From which subtract its capacity 148
——
The remainder is 65
And this remainder taken from 80,5 nitrous gas + 36,9 oxygene, leaves 52,4
cubic inches, which is the space occupied by the nitrous acid gas, and which
differs from 53,95 only by 1,55 cubic inches.

I ought to have observed, that before this conclusive experiment, two
similar ones had been made. In comparing the results of one of them,
performed with the assistance of my friend, Mr. Joseph Priestley, Dr.
Priestley’s eldest son, and chiefly detailed by him in the journal, I find a
coincidence greater than could be even well expected, where the processes
are so complex. According to that experiment, 41,5 grains of nitrous acid
gas fill a space equal to 53 cubic inches, and are composed of nearly 29
nitrous gas, and 12,5 oxygene.
We may then conclude, First, that 100 cubic inches of nitrous acid, such
as exists in the[24] aëriform state saturated with oxygene, at temperature
55°, and atmospheric pressure 30,1 weigh 75,17 grains.
Secondly, that 100 grains of it are composed of 68,06 nitrous gas, and
31,94 oxygene. Or assuming what will be hereafter proved, that 100 parts of
nitrous gas consist of 55,95 oxygene, and 44,05 nitrogene, of 29,9
nitrogene, and 70,1 oxygene; or taking away decimals, of 30 of the one to
70 of the other.
Thirdly, that 100 grains of pale green solution of nitrous acid in water,
of specific gravity 1,301, are composed of 50,62 water, and 49,38 acid of
the above composition.
VI. Having thus ascertained the composition of a standard acid, my next
object was to obtain it in a more condensed state, as it was otherwise
impossible to saturate it to its full extent with nitrous gas. But this I could
effect in no other way than by comparing mixtures of known quantities of
water, and acids of different specific gravities and colors, with the acid of
1,301.
For the purpose of combining my acids with water, I made use of a
cylinder about 8 inches long, and,3 inches in diameter, accurately graduated
to grain measures, and furnished with a very tight stopper.
The concentrated acid was first slowly poured into it, and the water
gradually added till the required specific gravity was produced;[25] the
cylinder being closed and agitated after each addition, so as to produce
combination without any liberation of elastic fluid.
After making a number of experiments with acids of different colors in
this advantageous way, I at length found that 90 grains of a deep yellow

acid, of specific gravity 1,5, became, when mingled at 40° with 77,5 grains
of water, of specific gravity 1,302, and of a light green tinge, as nearly as
possible resembling that of the standard acid.
Supposing, then, that these acids contain nearly the same relative
proportions of oxygene and nitrogene, 100 grains of the deep yellow acid of
1,5, are composed of 91,9 grains true nitrous acid,[26] and 8,1 grains of
water.
To ascertain the difference between the composition of this acid, and
that of the pale, or nitric acid, of the same specific gravity, I inserted 150
grains of it into a small cylindrical mattrass of the capacity of,5 cubic
inches, accurately graduated to grain measures, and connected by a curved
tube with the water apparatus. After heat had been applied to the bottom of
the mattrass for a few minutes, the color of the fluid gradually changed to a
deep red, whilst the globules of gas formed at the bottom of the acid, were
almost wholly absorbed in passing through it. In a short time deep red
vapour began to fill the tube, and being condensed by the water in the
apparatus, was converted into a bright green fluid, at the same time that
minute globules of gas were given out. As the heat applied became more
intense, a very singular phænomenon presented itself; the condensed vapor,
increased in quantity, at length filled the curvature of the tube, and when
expelled, formed itself into dark green spherules, which sunk to the bottom
of the water, rested for a moment, and then resolved themselves into nitrous
gas.[27]
When the acid was become completely pale, it was suffered to cool, and
weighed. It had lost near 15 grains, and was of specific gravity 1,491. 2
cubic inches and quarter of nitrous gas only were collected.
From this experiment evidently no conclusions could be drawn, as the
nitrous gas had carried over with it much nitrous acid (in the form of what
Dr. Priestley calls nitrous vapor) and was partially dissolved with it in the
water.[28]
To ascertain, then, the difference between the pale and yellow acids, I
was obliged to make use of synthesis, compared with analysis, carried on in
a different mode, by means of the following apparatus.

VII. To the stop-cock of the upper cylinder of the mercurial airholder, a
capillary tube was adapted, bent so as to be capable of introduction into an
orifice in the stopper of a graduated phial similar to that employed for
mingling acids with water, and sufficiently long to reach the bottom. With
another orifice in the stopper of the phial was connected a similar tube
curved, for the purpose of containing a fluid, and of increased diameter at
the extremity.[29]
50 cubic inches of pure nitrous gas[30] were thrown into the mercurial
apparatus. The graduated phial, containing 90 grains of nitric acid, of
specific gravity 1,5, was placed on the top of the airholding cylinder, and
made to communicate with it by means of the stop-cock and first tube. Into
the second tube a small quantity of solution of potash was placed. When all
the junctures were carefully cemented, by pressing on the airholder, the
nitrous gas was slowly passed into the phial, and absorbed by the nitrous
acid it contained; whilst the small quantities of nitrogene evolved, slowly
drove forward the solution in the curved tube; from the height of which, as
compared with that of the mercury in the conducing tube, the pressure on
the air in the cylinder was known.
In proportion as the nitrous gas was absorbed, the phial became warm,
and the acid changed color; it first became straw-colored, then pale yellow,
and when about 7½ cubic inches had been combined with it, bright yellow.
It had gained in weight nearly 3 grains, and was become of specific gravity
1,496.
This experiment afforded me an approximation to the real difference
between nitric and yellow nitrous acid; and learning from it that nitric acid
was diminished in specific gravity by combination with nitrous gas, I
procured a pale acid of specific gravity 1,504.[31] After this acid had been
combined in the same manner as before, with about 8 cubic inches of
nitrous gas,[32] it became nearly of specific gravity 1,5, and had gained in
weight about 3 grains.
Assuming the accuracy of this experiment as a foundation for
calculation, I endeavoured in the same manner to ascertain the differences
in the composition of the orange colored acids, and the acids containing still
larger proportions of nitrous gas.

93 grains of the bright yellow acid of 1,5 became, when 6 cubic inches
of gas had been passed through it, orange colored and fuming, whilst the
undissolved gas increased in quantity so much as to render it impossible to
confine it by the solution of potash. When 9 cubic inches had passed
through, it became dark orange. It had gained in weight 2,75 grains, and
was become of specific gravity 1,48 nearly. Hence it was evident that much
nitrous gas had passed through it undissolved. 25 cubic inches more of
nitrous gas were now slowly sent through it: it first became of a light olive,
then of a dark olive, then of a muddy green, then of a bright green, and
lastly of a blue green. After its assumption of this color, the gas appeared to
pass through it unaltered, and large globules of fluid, of a darker green than
the rest, remained at the bottom of the cylinder, and when agitated, did not
combine with it. The increase of weight was only 1 grain, and the acid was
of specific gravity 1,474 nearly.
In this experiment it was evident that the unabsorbed nitrous gas had
carried over with it a considerable quantity of nitrous acid. I endeavoured to
correct the errors resulting from this circumstance, by connecting the
curved tube first with a small water apparatus, and afterwards with a
mercurial apparatus; but when the water apparatus was used, the greater
part of the unabsorbed gas was dissolved with the nitrous acid it held in
solution, by the water; and when mercury was employed, the nitrous acid
that came over was decomposed, and the quantity of nitrous gas evolved, in
consequence increased.
As it was possible that a small deficiency of weight might arise from the
red vapor given out during the processes of weighing and examining the
acid in the last experiment, 35 cubic inches of nitrous gas were very slowly
passed through 90 grains of pale nitrous acid, of specific gravity 1,5: it
became of similar appearance to that just described, had gained in weight
6,75 grains, and was become of specific gravity 1,475.
These experiments did not afford approximations sufficiently accurate
towards the composition of deoxygenated acids, containing more nitrous
gas than the dark orange colored. To obtain them, a solution consisting of
94,25 grains of blue green, or perfectly nitrated acid, (if we may be allowed
to employ the term), of specific gravity 1,475, was inserted into a graduated
phial, and connected by a curved tube, with the mercurial airholder; in the
conductor of which a small quantity of water was inserted to absorb the

nitrous acid which might be carried over by the gas. Heat was slowly
applied to the phial, and nitrous gas given out with great rapidity. When 4
cubic inches were collected, the acid became dark olive, when 9 dark red,
when 13 bright orange, and when 18 pale. It had lost 31 grains, and when
completely cool, was of specific gravity 1,502 nearly. The water in the
apparatus was tinged of a light blue; from whence we may conclude that
some of the nitrous gas was absorbed by it with the nitrous acid: but it will
be hereafter proved that the orange colored acid is the most nitrated acid
capable of combining undecompounded with water, and that the color it
communicates to a large quantity of water, is light blue. If then we take 6,1
grains, the quantity of gas collected, from 31 the loss, the remainder is 24,9,
which reasoning from the synthetical experiment, may be supposed to
contain nearly 3 cubic inches of nitrous gas. Consequently, 94,25 grains of
dark green acid, of specific gravity 1,475, are composed of nearly 21 cubic
inches, or 7,2 grains of nitrous gas, and 87,05 grains of pale nitrous acid, of
1,504.
VIII. Comparing the different synthetical and analytical experiments,
we may conclude with tolerable accuracy, that 92,75 grains of bright
yellow, or standard acid of 1,5, are composed of 2,75 grains of nitrous gas,
and 90 grains of nitric acid of 1,504; but 92,75 grains of standard acid
contain 85,23 grains of nitrous acid, composed of about 27,23 of oxygene,
and 58, nitrous gas: now from 58, take 2,75, and the remainder 55,25, is the
quantity of nitrous gas contained in 90 grains of nitric acid of 1,504;
consequently, 100 grains of it are composed of 8,45 water, and 91,55 true
acid, containing 61,32 nitrous gas, and 30,23 oxygene; or 27,01 nitrogene,
and 64,54 oxygene: and the nitrogene in nitric acid, is to the oxygene as 1 to
2,389.
IX. My ingenious friend, Mr. James Thomson, has communicated to me
some observations relating to the composition of nitrous acid (that is, the
orange colored acid), from which he draws a conclusion which is, in my
opinion, countenanced by all the facts we are in possession of, namely, “that
it ought not to be considered as a distinct and less oxygenated state of acid,
but simply as nitric or pale acid, holding in solution, that is, loosely
combined with, nitrous gas.”[33]
It is impossible to call any substance a simple acid that is incapable of
entering undecompounded into combination with the alkalies, &c; but it

will appear hereafter that the salts called in the new nomenclature nitrites,
cannot be directly formed. If, indeed, it could be proved, that the heat
produced by the combination of nitrous acid with salifiable bases, was the
only cause of the partial decomposition of it, and that when this process was
effected in such a way as to prevent increase of temperature, no nitrous gas
was liberated, the common theory might have some foundation; but though
dilute phlogisticated nitrous acid combines[34] with alkaline solutions
without decomposition, yet no excess of nitrous gas is found in the solid
salt: it is either disengaged in proportion as the water is evaporated, or it
absorbs oxygene from the atmosphere, and becomes nitric acid.
In proportion as the nitrous acids contain more nitrous gas, so in
proportion do they more readily give it out. From the blue green acid it is
liberated slowly at the temperature of 50°, and from the green likewise on
agitation. The orange coloured and yellow acids do not require a heat above
200° to free them of their nitrous gas; and all the colored acids, when
exposed to the atmosphere absorb oxygene, and become by degrees pale.
If the nitrous vapour, i. e. such as is disengaged during the denitration
of the colored acids, was capable of combining with the alkalies, it might be
supposed a distinct acid, and called nitrous acid; and the acids of different
colors might be considered simply as compounds of this acid with nitric
acid; but it appears to be nothing more than a solution of nitric acid in
nitrous gas, incapable of condensation, undecompounded, and when
decompounded and condensed, constituting the dark green acid, which is
immiscible with water,[35] and uncombinable with the alkalies.[36]
It seems therefore reasonable, till we are in possession of new lights on
the subject, to consider, with Mr. Thomson, the deoxygenated or nitrous
acids simply as solutions of nitrous gas composed of sulphuric acid,
metallic oxides, and nitrous gas.[37]
Supposing the truth of these principles according to the logic of the
French nomenclature, there is no acid to which the term nitrous acid ought
to be applied; but as it has been used to signify the acids holding in solution
nitrous gas, it is perhaps better still to apply it to those substances, than to
invent for them new names. A nomenclature, accurately expressing their
constituent parts, would be too complex, and like all other nomenclatures
founded upon theory, liable to perpetual alterations. Their composition is

known from their specific gravity and their colors; hence it is better to
denote it by those physical properties: thus orange nitrous acid, of specific
gravity 1,480, will signify a solution of nitrous gas in nitric acid, in which
the nitric acid is to the nitrous gas, nearly as 87 to 5, and to the water as 11
to 1.
X. The estimation of the composition of the yellow and orange colored
nitrous acids given in the following table, may be considered as tolerably
accurate, being deduced from the synthetical experiments in the sixth
section, compared with the analytical ones. But as in the synthetical
experiment, when the acid became green, it was impossible to ascertain the
quantity of nitrous gas that passed through it unabsorbed, and as in the
analysis the quantity of nitrous gas dissolved by the water at different
periods of the experiment could not be ascertained, the accounts of the
composition of the green acids must be considered only as very imperfect
approximations to truth.

TABLE I.
Containing Approximations to the quantities of NITRIC
ACID, NITROUS GAS, and WATER in NITROUS
ACIDS, of different colors and specific gravities.

Specific Nitric Nitrous
100 Parts Water
Gravity Acid gas
Sol. Nitric Acid 1,504 c 91,55 8,45 ——
Yellow Nitrous[38] 1,502 o 90,5 8,3 1,2
Bright Yellow o 1,500 n 88,94 8,10 2,96
Dark Orange f 1,480 t 86,84 7,6 5,56
Light Olive‡ 1,479 a 86,00 7,55 6,45
Dark Olive‡ 1,478 i 85,4 7,5 7,1
Bright Green‡ 1,476 n 84,8 7,44 7,76
Blue Green[39] 1,475 84,6 7,4 8,00
‡ = “FOOTNOTE [38]”

TABLE II.
Binary Proportions of OXYGENE and NITROGENE in
NITRIC and NITROUS ACIDS.[40]

100 Parts Oxygene Nitrogene Nitrogene Oxygene
Nitric Acid c 70,50 29,50 1 2,389
o
Bright
yellow n 70,10 29,90 Proportions. 1 2,344
Nitrous
t Nitrogene.
Orange
a 69,63 30,37 Unity. 1 2,292
coloured
i
Dark Green n 69,08 30,92 1 2,230

XI. I have before mentioned that dilute nitric acids are incapable of
dissolving so much nitrous gas in proportion to their quantities of true acid,
as concentrated ones. During their absorption of it, they go through similar
changes of color; 330 grains of nitric acid, of specific gravity 1,36, after 50
cubic inches of gas had been passed through it, became blue green, and of
specific gravity 1,351. It had gained in weight but 3 grains; and when the
nitrous gas was driven from it by heat into a water apparatus, but 7 cubic
inches were collected.[41]
From the diminution of specific gravity of nitric acid by combination
with nitrous gas, and from the smaller attraction of nitric acid for nitrous
gas, in proportion as it is diluted, it is probable that the nitrated acids, in
their combinations with water, do not contract so much as[42] nitric acids of
the same specific gravities. The affinities resulting from the small attraction
of nitrous gas for water, and its greater attraction for nitric acid, must be
such as to lessen the affinity of nitric acid and water for each other.
Hence it would require an infinite number of experiments to ascertain
the real quantities of acid, nitrous gas, and water, contained in the different

diluted nitrous acids; and after these quantities were determined, they would
probably have no important connection with the chemical arrangement. As
yet, our instruments of experiment are not sufficiently exact to afford us the
means of ascertaining the ratio in which the attraction of nitric acid[43] for
water diminishes in its progress towards saturation.
The estimations in the following table, of the real quantities of nitric
acid in solutions of different specific gravities, were deduced from
experiments made in the manner described in section VI, except that the
phial employed was longer, narrower, and graduated to half grains. The
temperature, at the time of combination, was from 40° to 46°.

TABLE III.
Of the Quantities of True NITRIC ACID in solutions of
different SPECIFIC GRAVITIES.

100 Parts Acid
True Acid[44] Water
of specific gravity
1,5040 91,55 8,45
1,4475 c 80,39 19,61
1,4285 o 71,65 28,35
1,3906 n 62,96 37,04
1,3551 t 56,88 43,12
1,3186 a 52,03 47,97
1,3042 i 49,04 50,96
1,2831 n 46,03 53,97
1,2090 45,27 54,73

XII. The blue green spherules mentioned in section V. produced by the
condensation of nitrous vapor, and by the combination of nitric acid with
nitrous gas, may be considered as saturated solutions of nitrous gas in nitric
acid. The combinations of nitric acid and nitrous gas containing a larger
proportion of nitrous gas, are incapable of existing in the fluid state at

common temperatures; and, as appears from the first experiment, an
increase of volume takes place during their formation. They consequently
ought to be looked upon as solutions of nitric acid in nitrous gas, identical
with the nitrous vapor of Priestley.
From the researches of this great discoverer, we learn that nitrous vapor
is decomposable, both by water and mercury. Hence it is almost impossible
accurately to ascertain its composition. In one of his experiments,[45] when
more than 130 grains of strong nitrous acid were exposed for two days to
nearly 247 cubic inches of nitrous gas, over water: about half of the acid
was dissolved, and deposited with the gas in the water.[46]
XIII. In comparing the results of my fundamental experiment on the
composition of nitrous acid, with those of Cavendish, the great coincidence
between them gave me very high satisfaction, as affording additional proofs
of accuracy. If the acid formed in the last experiment of this illustrious
philosopher be supposed analogous to the light green acid formed in my
first experiment, our estimations will be almost identical.
Lavoisier’s account of the composition of the nitric and nitrous acids,
has been generally adopted. According to his estimation, these substances
contain a much larger quantity of oxygene than I have assigned to them.
The fundamental experiments of this great philosopher were made at an
early period of pneumatic chemistry,[47] on the decomposition of nitre by
charcoal; and he considered the nitrogene evolved, and the oxygene of the
carbonic acid produced in this process, as the component parts of the nitric
acid contained in the nitre.
I have before mentioned the liberation of nitrous acid, in the
decomposition of nitre by combustible bodies; and I had reasons for
suspecting that this circumstance was not the only source of inaccuracy.
That my suspicions were well founded, will appear from the following
experiments:
EXPERIMENT a. I introduced into a strong glass tube, 3 inches long,
and nearly,3 wide, a mixture of 10 grains of pulverised, well burnt charcoal,
and 60 grains of nitre. It was fired by means of touch-paper, and the tube
instantly plunged under a jar filled with dry mercury. A quantity of gas,
clouded with dense white vapor was collected. When this vapor was

precipitated, so that the surface of the mercury could be seen, it appeared
white, as if acted on by nitrous acid. On introducing a little oxygene into the
jar, copious red fumes appeared.
EXP. b. A similar mixture was fired[48] under the jar, the top of the
mercury being covered with a small quantity of red cabbage juice, rendered
green by an alkali. This juice, examined when the vapor was precipitated,
was become red, and on introducing to it a little carbonate of potash, a
slight effervescence took place.
EXP. c. Five grains of charcoal, and 20 of nitre, were now fired in the
same manner as before, the mercury being covered with a stratum of water.
After the precipitation of the vapor on the introduction of oxygene, no red
fumes were perceived.
EXP. d. 30 grains of nitre, 5 of charcoal, and five of silicious earth,[49]
were now mingled and fired. The gas received under mercury was
composed of 18 carbonic acid, and nearly 12 nitrogene.[50] A little muriatic
acid was poured on the residuum in the tube; a slight effervescence took
place.
EXP. e. The top of the mercury in the jar was now covered with a little
diluted muriatic acid, and a small glass tube filled with a mixture of 3 grains
of charcoal, and 20 nitre. After the deflagration, the tube itself with the
residuum it contained, were thrown into the jar. The carbonic acid was
quickly detached from them by the muriatic acid, and the whole quantity of
gas generated in the process, obtained; it measured 15 cubic inches.
4 cubic inches of it exposed to solution of potash, diminished to 1⁴/₁₀; 7
of the remainder, with 8 of oxygene, gave only 12.
EXP. f. 60 grains of nitre, and 9 of charcoal were fired, the top of the
mercury in the jar being covered with water. After the deflagration, the tube
that had contained them was introduced, and the carbonic acid contained by
the carbonate of potash, disengaged by muriatic acid. 30 measures of the
gases evolved were exposed to caustic potash; 20 exactly were absorbed,
the 10 remaining, with 10 of oxygene, diminished to 17.
EXP. g. A mixture of nitre and charcoal were deflagrated over a little
water in the mercurial jar: after the precipitation of the vapor, the water was

absorbed by filtrating paper. This filtrating paper, heated in a solution of
potash, gave a faint smell of ammoniac.
EXP. h. Water impregnated with the vapor produced in the deflagration,
was heated with quicklime, and presented separately to three persons
accustomed to chemical odors. Two of them instantly recognised the
ammoniacal smell, the other could not ascertain it. Paper reddened with
cabbage juice was quickly turned green by the vapor.
These experiments are sufficient to shew that the decomposition of nitre
by charcoal is a very complex process, and that the intense degree of heat
produced may effect changes in the substances employed, which we are
unable to estimate.
The products, instead of being simply carbonic acid, and nitrogene, are
carbonic acid, nitrogene, nitrous acid, probably ammonia, and sometimes
nitrous gas. The nitrous acid is disengaged from the base by the intense
heat. Concerning the formation of the ammonia, it is useless to reason till
we have obtained unequivocal testimonies of its existence; it may be
produced either by the decomposition of the water contained in the nitre, by
the combination of its oxygene with the charcoal, and of its nascent
hydrogene with the nitrogene of the nitric acid; or from some unknown
decomposition of the potash.
As neither Lavoisier nor Berthollet found nitrous gas produced in the
decomposition of nitre by charcoal, when a water apparatus was employed;
and as it was not uniformly evolved in my experiments, the most probable
supposition is, that it arises from the decomposition of a portion of the free
nitrous acid intensely heated, by the mercury.
In none of my experiments was the whole of the nitre and charcoal
decomposed, some of it was uniformly thrown with the gases into the
mercurial apparatus. The nitrogene evolved, as far as I could ascertain by
the common tests, was mingled with no inflammable gas.
If we consider experiment f as accurate, with regard to the relative
quantities of carbonic acid and nitrogene produced, they are to each other
nearly as 20 to 8; that is, allowing 2 for the nitrous gas, and consequently,
reasoning in the same manner as Lavoisier, concerning the composition of
nitric acid, it should be composed of 1 nitrogene to 3,38 oxygene. But

though the quantity of oxygene in this estimation is far short of that given in
his, yet still it is too much. From whatever source the errors arise, whether
from the evolution of phlogisticated nitrous acid, or the decomposition of
water, or the production of nitrous gas, they all tend to increase the
proportion of the carbonic acid to the nitrogene.
I am unacquainted with any experiment from which accurate opinions
concerning the different relative proportions of oxygene and nitrogene in
the nitric and nitrous acids could be deduced. Lavoisier’s calculation is
founded on his fundamental experiment, and on the combination of nitrous
gas and oxygene.
Dr. Priestley’s experiment mentioned in section 12, on the absorption of
nitrous gas by nitrous acid, from which Kirwan[51] deduces the composition
of the differently colored nitrous acids, was made over water, by which, as
is evident from a minute examination of the facts[52], the greater portion of
the nitrous gas employed was absorbed.
XIV. The opinions heretofore adopted respecting the quantities of real
or true acid in solutions of nitrous acid of different specific gravities, have
been founded on experiments made on the nitro-neutral salts, the most
accurate of which are those of Kirwan, Bergman, and Wenzel. The great
difference in the results of these celebrated men, proves the difficulty of the
investigation, and the existence of sources of error.[53] Kirwan deduces the
composition of the solutions of nitrous acid in water, from an experiment on
the formation of nitrated soda. In this experiment, 36,05 grains of soda were
saturated by 145 grains of nitrous acid, of specific gravity 1,2754. By a test
experiment, he found the quantity of salt formed to be 85,142 grains.[54]
Hence he concludes that 100 parts of nitrous acid, of specific gravity
1,5543, contain 73,54 of the strongest, or most concentrated acid.
Supposing his estimation perfectly true, 100 parts of the aëriform acid
of 55° would be composed of 74,54 of his real acid, and 25,46 water. In
examining, however, one of his later experiments,[55] we shall find reasons
for concluding, that the acid in nitrated soda cannot contain much less water
than the aëriform acid. A solution of carbonated soda, containing 125 grains
of real alkali, was saturated by 306,2 grains of nitrous acid, of specific
gravity 1,416. The evaporation was carried on in a temperature not
exceeding 120°, and the residuum exposed to a heat of 400° for six hours, at

the end of which time it weighed 308 grains. Now according to my
estimation, 306 grains of nitric acid, of 1,416, should contain 215 true acid;
and we can hardly suppose, but that during the evaporation and consequent
long exposure to heat, some of the nitrated soda was lost with the water.
Bergman estimates the quantity of water in this salt at 25, and the acid
at 43 per cent; but his real acid was not so concentrated as Kirwan’s,
consequently the nitric acid in nitrated soda should contain more water than
my true acid.
Wenzel, from an experiment on the composition of nitrated soda,
concludes that it contains 37,48 of alkali, and 62,52 of nitrous acid; and
1000 of this acid, from Kirwan’s calculation, contain 812,6 of his real acid;
consequently, 100 parts of my aëriform acid should contain 93,28 of
Wenzel’s acid, and 6,72 of water.
I saturated with potash 54 grains of solution of nitric acid, of specific
gravity 1,301. Evaporated at about 212°, it produced 66 grains of nitre. This
nitre exposed to a higher temperature, and kept in fusion for some time, was
reduced to 60 grains.
Now from the table, 54 of 1,301, should contain 26,5 of true acid. But
according to Kirwan’s estimation, 100 parts of dry nitre contain 44[56] of his
real acid, with 4 water; consequently 60 should contain 26,4.
Again, 90 grains of acid, of specific gravity 1,504, saturated with
potash, and treated in the same manner, gave 173 grains of dry nitre.
Consequently, 100 parts of it should contain 47,3 grains of true acid.
Now Lavoisier[57] allows about 51 of dry acid to 100 grains of nitre, and
Wenzel 52.
From Berthollet’s[58] experiments, 100 grains of nitre, in their
decomposition by heat, give out nearly 49 grains of gas.[59]
Hence it appears that the aëriform acid, that is, the true acid of my table,
contains rather less water than the acid supposed to exist in nitre.

DIVISION II.

EXPERIMENTS and OBSERVATIONS on the composition of
AMMONIAC and on its combinations with WATER and NITRIC
ACID.

I. Analysis of AMMONIAC or VOLATILE ALKALI.

T
he formation and decomposition of volatile alkali in many processes,
was observed by Priestley, Scheele, Bergman, Kirwan, and Higgins;
but to Berthollet we owe the discovery of its constituent parts, and their
proportions to each other. These proportions this excellent philosopher
deduced from an experiment on the decomposition of aëriform ammoniac
by the electric spark:[60] a process in which no apparent source of error
exists.
Since, however, his estimations have been made, the proportions of
oxygene and hydrogene in water have been more accurately determined.
This circumstance, as well as the conviction of the impossibility of too
minutely scrutinizing facts, fundamental to a great mass of reasoning,
induced me to make the following experiments.
A porcelain tube was provided, open at both ends, and well glazed
inside and outside, its diameter being about,5 inches. To one end of this, a
glass tube was affixed, curved for the purpose of communicating with the
water apparatus. With the other end a glass retort was accurately connected,
containing a mixture of perfectly caustic slacked lime, and muriate of
ammoniac.
The water in the apparatus for receiving the gases had been previously
boiled, to expel the air it might contain, and during the experiment was yet
warm.
When the tube had been reddened in a furnace adapted to the purpose,
the flame of a spirit lamp was applied to the bottom of the retort. A great
quantity of gas was collected in the water apparatus; of this the first
portions were rejected, and the last transferred to the mercurial trough.
A small quantity examined, did not at all diminish with nitrous gas, and
burnt with a lambent white flame, in contact with common air.
2¾ of this gas, equal to 110 grain measures, were fired with 2, equal to
80, of oxygene, in a detonating tube, by the electric spark. They were

reduced to 2¼, or 90. On introducing to the remainder a solution of
strontian, it became slightly clouded on the top, and an absorption of some
grain measures took place.
It was evident, then, that in this experiment, charcoal[61] had been
somehow present in the tube; which being dissolved by the nascent
hydrogene, had rendered it slightly carbonated, and in consequence made
the results inconclusive.
A tube of thick green glass carefully made clean, was now employed,
inclosed in the porcelain tube. Every other precaution was taken to prevent
the existence of sources of error, and the experiment conducted as before.
140 grain measures of the gas produced, fired with 120 of oxygene, left,
in two experiments, nearly 110. Solution of strontian placed in contact with
the residuum, did not become clouded, and no absorption was perceived.
Now 150 measures of gas were destroyed, and if we take Lavoisier’s
and Meusnier’s estimation of the composition of water, and suppose the
weight of oxygene to be 35 grains, and that of hydrogene 2,6 the hundred
cubic inches; the oxygene employed will be to the hydrogene as 243 to 576.
Put x for the oxygene, and y for the hydrogene.
Then
x + y = 150
x : y :: 243 : 576

243y
x= ——
576

819y = 86400
y = 105 x = 45
And
140 - 105 = 35

Consequently, the nitrogene in ammoniac is to the hydrogene as 35: 105
in volume: and 13,3 grains of ammoniac are composed of 10,6 nitrogene,
(supposing that 100 cubic inches weigh 30,45 grains) and 2,7 hydrogene.
According to Berthollet, the weight of the nitrogene in ammoniac is to
that of the hydrogene as 121 to 29.[62] The difference between this
estimation and mine is so small as to be almost unworthy of notice, and
arises most probably from the slight difference between the accounts of
Lavoisier and Monge, of the composition of water, and the different weights
assigned to the gases employed.
We may then conclude, that 100 grains of ammoniac are composed of
about 80 nitrogene, and 20 hydrogene.
The decomposition of ammoniac by heat, as well as by the electric
spark, was first discovered by Priestley. In an experiment[63] when aëriform
ammoniac was sent through a heated tube from a caustic solution of
ammoniac in water, this great discoverer observed that an inflammable gas
was produced, though in no great quantity, and that a fluid blackened by
matter, probably carbonaceous, likewise came over.
In my experiments the whole of the ammoniac appeared to be
decomposed; the quantity of gas generated was immense, and not clouded,
as is usually the case with gases generated at high temperatures. It is
possible, that the larger quantity of water carried over in his experiment, by
its strong attraction for ammoniac in the aëriform state, might have, in some
measure, retarded the decomposition. It is however, more probable to
suppose, that a fissure existed in the earthen tube he employed, through
which a certain quantity of gas escaped, and coaly matter entered.
Priestley found that the metallic oxides when strongly heated,
decomposed ammoniac, the metal being revivified and water and nitrogene
produced.[64] The estimations of the composition of ammoniac that may be
deduced from his experiments on the oxide of lead, differ very little from
those already detailed.

II. Specific gravity of Ammoniac.

From the great solubility of ammoniac in water, it is difficult to
ascertain its specific gravity in the same manner as that of a gas combinable
to no great extent with that fluid. It is impossible to prevent the existence of
a small quantity of solution of ammoniac in the mercurial airholder,[65] or
apparatus containing the gas; and during the diminution of the pressure of
the atmosphere on this solution,[66] a certain quantity of gas is liberated
from it, and hence a source of error.
To ascertain, then, the weight of ammoniac, I employed an apparatus
similar to that used for the absorption of nitrous gas by nitric acid.
50 cubic inches of gas were collected in the mercurial airholder, from
the decomposition of muriate of ammoniac by lime; thermometer being 58°,
and barometer 29,6.
100 grains of diluted sulphuric acid were introduced into the small
graduated cylinder, which after being carefully weighed, was made to
communicate with the airholder, the curved tube containing a small quantity
of water. The gas was slowly passed into the fluid, and the globules wholly
absorbed before they reached the top; much increase of temperature being
consequent. When the absorption was compleat, the phial was increased in
weight exactly 9 grains.
This experiment was repeated three times. The difference of weight,
which was probably connected with alterations of temperature and pressure,
never amounted to more than one sixth of a grain.
We may then conclude, that at temperature 58°, and atmospheric
pressure 29,6, 100 cubic inches of ammoniac weigh 18 grains.
According to Kirwan, 100 cubic inches of alkaline air[67] weigh 18,16
grains; barometer 30°, thermometer 61. The difference between these
estimations, the corrections for temperature and pressure being made, is
trifling.

III. Of the quantities of true Ammoniac in Aqueous Ammoniacal
Solutions, of different specific gravities.

To ascertain the quantities of ammoniac, such as exists in the aëriform
state, saturated with moisture, in solutions of different specific gravities, I
employed the apparatus for absorption so often mentioned. Thermometer
being 52°, the mercurial airholder was filled with ammoniacal gas, and the
graduated phial, containing 50 grains of pure water, connected with it.
During the absorption of the gas, the phial became warm. When about 30
cubic inches had been passed through, it was suffered to cool, and weighed:
it had gained 5,25 grains, and the fluid filled a space equal to that occupied
by 57[68] grains of water.
Consequently, 100 grains of solution of ammoniac in water of specific
gravity,9684 contain 9,502 grains of ammoniac.
The apparatus being adjusted as before, 50 grains of pure water were
now perfectly saturated with ammoniac. They gained in weight 17 grains,
and when perfectly cool, filled a space equal to 74 of water. Consequently
100 grains of aqueous ammonial solution of specific gravity,9054 contain
25,37 grams of ammoniac.
The two solutions were mingled together; but no alteration of
temperature took place. Consequently the resulting specific gravity might
have been found by calculation.
On mingling a large quantity of caustic solution of ammoniac with ¼ of
its weight of water, of exactly the same temperature, no alteration of it was
perceptible by a sensible thermometer.—Hence the two experiments[69]
being assumed as data, the intermediate estimations in the following table,
were found by calculation.

TABLE IV.
Of approximations to the quantities of AMMONIAC,
such as exists in the aëriform state, saturated with water
at 52°, in AQUEOUS AMMONIACAL SOLUTIONS of
different specific gravities.

100
Ammoniac. Water.
Specific Gravity.
9054 25,37 74,63

100
Ammoniac. Water.
Specific Gravity.
9166 22,07 77,93
9255 19,54 80,46
9326 c 17,52 82,48
9385 o 15,88 84,12
9435 n 14,53 85,47
9476 t 13,46 86,54
9513 a 12,40 87,60
9545 i 11,56 88,44
9573 n 10,82 89,18
9597 10,17 89,83
9619 9,60 90,40
9684 9,50 90,50
9639 9,09 90,91
9713 7,17 92,83

As yet no mode has been discovered for obtaining
gases in a state of absolute dryness; consequently we are
ignorant of the different quantities of water they hold in
solution at different temperatures. As far as we are
acquainted with the combinations of ammoniac, there is
no state in which it exists so free from moisture, as when
aëriform, at low temperatures.
That no considerable source of error existed in the two experiments, is
evident from the trifling difference between the estimations of the quantities
of real ammoniac, in the solution of,9684, as found in the first experiment,
and as given by calculation from the last.
The quantity of ammoniac in a solution of specific gravity not in the
table, may be thus determined—find the difference between the two
specific gravities nearest to it in the table; d, and the difference between
their quantities of alkali, b; likewise the difference between the given
specific gravity and that nearest to it, c.

then
d : b :: c : x
and
bc
x= ——
d
Which, added to the quantity of the lower specific gravity, is the alkali
sought.
The differences in specific gravity of the solutions of ammoniac at
temperatures between 4O° and 65°[70] are so trifling as to be hardly
ascertainable, by our imperfect instruments, and consequently are unworthy
of notice.
It is possible at very low temperatures to obtain ammoniacal solutions
of less specific gravity than,9, but they are incapable of being kept for any
length of time under the common pressure of the atmosphere.

IV. Combinations of Ammoniac with Nitric Acid,
Composition of Nitrate of Ammoniac, &c.
200 grains of ammoniacal solution, of specific gravity,9056, were
saturated by 385,5 grains of nitric acid, of specific gravity 1,306. The
combination was effected in a long phial, the nitrous acid added very
slowly, and the phial closed after every addition, to prevent any evaporation
in consequence of the great increase of temperature.[71] The specific gravity
of the solution, when reduced to the common temperature, was 1,15.
Evaporated at a heat of 212°,[72] it gave 254 grains of salt of fibrous
crystalization. This salt was dissolved in 331 grains of water; the specific
gravity of the solution was 1,148 nearly.
Hence it was evident that some of the salt had been lost during the
evaporation.

To find the quantity lost, fibrous nitrate of ammoniac was dissolved in
small quantities in the solution, the specific gravity of which was examined
after every addition of 3 grains. When 16 grains had been added to it, it
became of 1,15.
Consequently, the solution composed of 200 grains of ammoniacal, and
of 385,5 of nitric acid solution, contained 262 grains of salt of fibrous
crystalization, and of this salt 8 grains were lost during the evaporation.
But the alkali in 200 grains of ammoniacal solution of,9056 = 50,5
grains. And the true nitric acid in 385,5 grains of solution of 1,306 = 190
grains.
Then 262-240,5 = 21,5, the quantity of water.
And 262 grains of fibrous crystalized nitrate of ammoniac, contain 190
grains true acid, 50,5 ammoniac, and 21,5 water. And 100 parts contain 72,5
acid. 19,3 ammoniac, and 8,2 water.
In proportion as the temperature employed for the evaporation of nitro-
ammoniacal solutions, is above or below 212°, so in proportion does the
salt produced contain more or less water than the fibrous nitrate. But
whatever may have been the temperature of evaporation, the acid and alkali
appear always to be in the same proportions to each other.
Of the salts containing different quantities of water, two varieties must
be particularly noticed. The prismatic nitrate of ammoniac, produced at the
common temperatures of the atmosphere, and containing its full quantity of
water of crystalisation; and the compact nitrate of ammoniac, either
amorphous, or composed of delicately needled crystals, formed at 300°, and
containing but little more water than exists in nitric acid and ammoniac.
To discover the composition of the prismatic nitrate of ammoniac, 200
grains of fibrous salt were dissolved in the smallest possible quantity of
water, and evaporated in a temperature not exceeding 70°. The greater part
of the salt was composed of perfectly formed tetrahædral prisms, terminated
by tetrahædral pyramids. It had gained in weight about 8,5 grains.
Consequently 100 grains of prismatic nitrate of ammoniac may be
supposed to contain 69,5 acid, 18,4 ammoniac, and 12,1 water.

To ascertain the composition of the compact nitrate of ammoniac, I
exposed in a deep porcelain cup, 400 grains of the fibrous salt, in a
temperature below 300°. It quickly became fluid, and slowly gave out its
water without any ebullition, or liberation of gas. When it was become
perfectly dry, it had lost 33 grains. I suspected, that in this experiment some
of the salt had been carried off with the water; to determine this, I
introduced into a small glass retort, 460 grains of fibrous salt; it was kept at
a heat below 320°, in communication with a mercurial apparatus, in a
regulated air-furnace, till it was perfectly dry: it had lost 23 grains. No gas,
except the common air of the retort came over, and the fluid collected had
but a faint taste of nitrate of ammoniac.
Though in this experiment I had removed all the fluid retained in the
neck of the retort, still a few drops remained in the head, and on the sides,
which I could not obtain. It was of importance to me to be accurately
acquainted with the composition of the compact salt, and for that reason I
compared these analytical experiments with a synthetical one.
I saturated 200 grains of solution of ammoniac, of,9056 with acid,
ascertained the specific gravity of the solution, evaporated it at 212°, and
fused and dried it at about 300°-260°. It gave 246 grains of salt, and a
solution made of the same specific gravity as that evaporated, indicated a
loss of 9 grains. Consequently, 255 grains of this salt contain 50,5 grains
alkali, 100 grains acid, and 14,5 grains water.
We may then conclude, that 100 parts of compact nitrate of ammoniac
contain 74,5 acid, 19,8 alkali, and 5,7 water.

V. Decomposition of Carbonate of Ammoniac by Nitric Acid.
In my first experiments on the production of nitrate of ammoniac, I
endeavoured to ascertain its composition by decompounding carbonate of
ammoniac by nitric acid; and in making for this purpose, the analysis of
carbonate of ammoniac, I discovered that there existed many varieties of
this salt, containing very different proportions of carbonic acid, alkali, and
water; the carbonic acid and water being superabundant in it, in proportion
as the temperature of its formation was low, and the alkali in proportion as
it was high: and not only that a different salt was formed at every different

temperature, but likewise that the difference in them was so great, that the
carbonate of ammoniac formed at 300° contained more than 50 per cent
alkali, whilst that produced at 60° contained only 20.[73]
I found 210 grains of carbonate of ammoniac, which from comparison
with other salts previously analised, I suspected to contain about 20 or 21
per cent alkali, saturated by 200 grains of nitric acid of 1,504. But though
the carbonate was dissolved in much water, still, from the smell of the
carbonic acid generated, I suspect that a small portion of the nitric acid was
dissolved, and carried off by it. The solution, evaporated at about 200°, and
afterwards exposed to a temperature below 300°, gave 232 grains of
compact salt. But reasoning from the quantity of acid in 200 grains of nitric
acid of 1,504, it ought to have given 245. Consequently 13 were lost by
evaporation; and this loss agrees with that in the other experiments.

VI. Decomposition of Sulphate of Ammoniac by Nitre.
As a cheap mode of obtaining nitrate of ammoniac, Dr. Beddoes
proposed to decompose nitre by sulphate of ammoniac, which is a well
known article of commerce. From synthesis of sulphate of ammoniac,
compared with analysis made in August 1799,[74] I concluded that 100
grains of prismatic salt were composed of about 18 grains ammoniac, 44
acid, and 38 water; and supposing 100 grains of nitre to contain 50 acid,
100 grains of sulphate of ammoniac will require for their decomposition
134 grains of nitre, and form 90,9 grains of compact nitrate of ammoniac.
To ascertain if the sulphate of potash and nitrate of ammoniac could be
easily separated, I added to a heated saturated solution of sulphate of
ammoniac, pulverised nitre, till the decomposition was complete. After this
decomposition, the solution contained a slight excess of sulphuric acid,
which was combined with lime, and the whole set to evaporate at a
temperature below 250°. As soon as the sulphate of potash began to
crystalise, the solution was suffered to cool, and then poured off from the
crystalised salt, which appeared to contain no nitrate of ammoniac. After a
second evaporation and crystalisation, almost the whole of the sulphate
appeared to be deposited, and the solution of nitrate of ammoniac was
obtained nearly pure: it was evaporated at 212°, and gave fibrous crystals.

VII. Non-existence of Ammoniacal Nitrites.
I attempted in different modes to combine nitrous acids with ammoniac,
so as to form the salts which have been supposed to exist, and called nitrites
of ammoniac; but without success.
I first decomposed a solution of carbonate of ammoniac by dilute olive
colored acid; but in this process, though no heat was generated, yet all the
nitrous gas appeared to be liberated with the carbonic acid.[75] I then
combined a small quantity of nitrous gas, with a solution of nitrate of
ammoniac. But after evaporating this solution at 70°-80°, I could not detect
the existence of nitrous gas in the solid salt; it was given out during the
evaporation and crystalisation, and formed into nitrous acid by the oxygene
of the atmosphere. I likewise heated nitrate of ammoniac to different
degrees, and partially decomposed it, to ascertain if in any case the acid was
phlogisticated by heat: but in no experiment could I detect the existence of
nitrous acid in the heated salt, when it had been previously perfectly
neutralised.
When nitrate of ammoniac, indeed, with excess of nitric acid, is
exposed to heat, the superabundant nitric acid becomes phlogisticated, and
is then liberated from the salt, which remains neutral.[76]
We may therefore conclude that nitrous gas has little or no affinity for
solid nitrate of ammoniac, and that no substance exists to which the name
nitrite of ammoniac can with propriety be applied.

VIII. Of the sources of error in Analysis.
To compare my synthesis of nitrate of ammoniac with analysis, I
endeavoured to separate the ammoniac and nitric acid from each other,
without decomposition. But in going through the analytical process, I soon
discovered that it was impossible to make it accurate, without many
collateral laborious experiments on the quantities of ammoniac soluble in
water at different temperatures.
At a temperature above 212°, I decomposed, by caustic slacked lime, 50
grains of compact nitrate of ammoniac in a retort communicating with the
mercurial airholder, the moisture in which had been previously saturated

with ammoniac. 22 cubic inches of gas were collected at 38°, and from the
loss of weight of the retort, it appeared that 13 grains of solution of
ammoniac in water, had been deposited by the gas.
Now evidently, this solution must have contained much more alkali in
proportion to its water than that of 55°, otherwise the quantity of ammoniac
in 50 grains of salt would hardly equal 8 grains.[77]

IX. Of the loss of Solutions of Nitrate of Ammoniac
during evaporation.
The most concentrated solution of nitrate of ammoniac capable of
existing at 60°, is of specific gravity 1,304, and contains 33 water, and 67
fibrous salt, per cent. When this solution is evaporated at temperatures
between 60° and 100, the salt is increased in weight by the addition of water
of crystalisation, and no portion of it is lost.
During the evaporation of solutions of specific gravity 1,146 and 1,15,
at temperatures below 120°, I have never detected any loss of salt. When
the temperature of evaporation is 212°, the loss is generally from 3 to 4
grains per cent; and when from 230° to the standard of their ebullition, from
4 to 6 grains.
In proportion as solutions are more diluted, their loss in evaporation at
equal temperatures is greater.

DIVISION III.

Decomposition of NITRATE of AMMONIAC: preparation of
RESPIRABLE NITROUS OXIDE; its ANALYSIS.

I. Of the heat required for the decomposition of
NITRATE of AMMONIAC.
The decomposition of nitrate of ammoniac has been supposed by
Cornette[78] to take place at temperatures below 212°, and its sublimation at
234°.

Kirwan, from the non-coincidence in the accounts of its composition,
has imagined that it is partially decomposable, even by a heat of 80°.[79]
To ascertain the changes effected by increase of temperature in this salt,
a glass retort was provided, tubulated for the purpose of introducing the
bulb of a thermometer. After it had been made to communicate with the
mercurial airholder, and placed in a furnace, the heat of which could be
easily regulated, the thermometer was introduced, and the retort filled with
the salt, and carefully luted; so that the appearances produced by different
temperatures could be accurately observed, and the products evolved
obtained.
From a number of experiments made in this manner on different salts,
the following conclusions were drawn.
1st. Compact, or dry nitrate of ammoniac, undergoes little or no change
at temperatures below 260°.
2dly. At temperatures between 275° and 300°, it slowly sublimes,
without decomposition, or without becoming fluid.
3dly. At 320° it becomes fluid, decomposes, and still slowly sublimes; it
neither assuming, or continuing in, the fluid state, without decomposition.
4thly. At temperatures between 340° and 480°, it decomposes rapidly.
5thly. The prismatic and fibrous nitrates of ammoniac become fluid at
temperatures below 300°, and undergo ebullition at temperatures between
360° and 400°, without decomposition.
6thly. They are capable of being heated to 430° without decomposition,
or sublimation, till a certain quantity of their water is evaporated.
7thly. At temperatures above 450° they undergo decomposition, without
previously losing their water of crystalisation.

II. Decomposition of Nitrate of Ammoniac; production of
respirable Nitrous Oxide; its properties.
200 grains of compact nitrate of ammoniac were introduced into a glass
retort, and decomposed slowly by the heat of a spirit lamp. The first
portions of the gas that came over were rejected, and the last received in

jars containing mercury. No luminous appearance was perceived in the
retort during the process, and almost the whole of the salt was resolved into
fluid and gas. The fluid had a faint acid taste, and contained some
undecompounded nitrate. The gas collected exhibited the following
properties.—
a. A candle burnt in it with a brilliant flame, and crackling noise. Before
its extinction, the white inner flame became surrounded with an exterior
blue one.
b. Phosphorus introduced into it in a state of inflammation, burnt with
infinitely greater vividness than before.
c. Sulphur introduced into it when burning with a feeble blue flame, was
instantly extinguished; but when in a state of active inflammation (that is,
forming sulphuric acid) it burnt with a beautiful and vivid rose-colored
flame.
d. Inflamed charcoal, deprived of hydrogene, introduced into it, burnt
with much greater vividness than in the atmosphere.
e. To some fine twisted iron wire a small piece of cork was affixed: this
was inflamed, and the whole introduced into a jar of the air. The iron burned
with great vividness, and threw out bright sparks as in oxygene.
f. 30 measures of it exposed to water previously boiled, was rapidly
absorbed; when the diminution was complete, rather more than a measure
remained.
g. Pure water saturated with it, gave it out again on ebullition, and the
gas thus produced retained all its former properties.
h. It was absorbed by red cabbage juice; but no alteration of color took
place.
i. Its taste was distinctly sweet, and its odor slight, but agreeable.
j. It underwent no diminution when mingled with oxygene or nitrous
gas.
Such were the obvious properties of the Nitrous Oxide, or the gas
produced by the decomposition of nitrate of ammoniac in a temperature not

exceeding 440°. Other properties of it will be hereafter demonstrated, and
its affinities fully investigated.

III. Of the gas remaining after the absorption of
Nitrous Oxide by Water.
In exposing nitrous oxide at different times to rain or spring water, and
water that had been lately boiled, I found that the gas remaining after the
absorption was always least when boiled water was employed, though from
the mode of production of the nitrous oxide, I had reason to believe that its
composition was generally the same.
This circumstance induced me to suppose that some of the residuum
might be gas previously contained in the water, and liberated from it in
consequence of the stronger affinity of that fluid for nitrous oxide. But the
greater part of it, I conjectured to consist of nitrogene produced in
consequence of a complete decomposition of part of the acid, by the
hydrogene. It was in endeavoring to ascertain the relative purity of nitrous
oxide produced at different periods of the process of the decomposition of
nitrate of ammoniac, that I discovered the true reason of the appearance of
residual gas.
I decomposed some pure nitrate of ammoniac in a small glass retort;
and after suffering the first portions to escape with the common air, I caught
the remainder in three separate vessels standing in the same trough, filled
with water that had been long boiled, and which at the time of the
experiment was so warm that I could scarcely bear my hands in it. The
different quantities collected gave the same intense brilliancy to the flame
of a taper.
26 measures of each of them were separately inserted into 3 graduated
cylinders, of nearly the same capacity, over the same boiled water. As the
water cooled, the gas was absorbed by agitation. When the diminution was
complete, the residuum in each cylinder filled, as nearly as possible, the
same space; about two thirds of a measure.
To each of the residuums I added two measures of nitrous gas; they
gave copious red vapor, and after the condensation filled a space rather less
than two measures.

Hence the residual gas contained more oxygene than common air.
I now introduced 26 measures of gas from one of the vessels into a
cylinder filled with unboiled spring water of the same kind.[80] After the
absorption was complete, near two measures remained. These added to two
measures of nitrous air, diminished to 2,5 nearly.
These experiments induced me to believe that the residual gas was not
produced in the decomposition of nitrate of ammoniac, but that it was
wholly liberated from the water.
To ascertain this point with precision, I distilled a small quantity of the
same kind of water, which had been near an hour in ebullition, into a
graduated cylinder containing mercury. To this I introduced about one third
of its bulk, i. e. 12 measures of nitrous oxide, which had been carefully
generated in the mercurial apparatus. After the absorption, a small globule
of gas only remained, which could hardly have equalled one fourth of a
measure. On admitting to this globule a minute quantity of nitrous gas, an
evident diminution took place.
Though this experiment proved that in proportion as the water was free
from air, the residuum was less, and though there was no reason to suppose
that the ebullition and distillation had freed the water from the whole of the
air it had held in solution, still I considered a decisive experiment wanting
to determine whether nitrous oxide was the only gas produced in the slow
decomposition of nitrate of ammoniac, or whether a minute quantity of
oxygene was not likewise evolved.
I received the middle part of the product of a decomposition of nitrate of
ammoniac, under a cylinder filled with dry mercury, and introduced to it
some strong solution of ammoniac. After the white cloud produced by the
combination of the ammoniacal vapor with the nitric acid suspended in the
nitrous oxide, had been completely precipitated, I introduced a small
quantity of nitrous gas. No white vapor was produced.
Now if any gas combinable with nitrous gas had existed in the cylinder,
the quantity of nitrous acid produced, however small, would have been
rendered perceptible by the ammoniacal fumes; for when a minute globule
of common air was admitted into the cylinder, white clouds were instantly
perceptible.

It seems therefore reasonable to conclude,
1. That the residual gas of nitrous oxide, is air previously
contained in the water, (which in no case can be perfectly
freed from it by ebullition), and liberated by the stronger
attraction of that fluid for nitrous oxide.
2. That nitrate of ammoniac, at temperatures below 440°,
is decompounded into pure nitrous oxide, and fluid.
3. That in ascertaining the purity of nitrous oxide from
its absorption by water, corrections ought to be made for the
quantity of gas dispelled from the water. This quantity in
common water distilled under mercury being about ¹/₅₀; in
water simply boiled, and used when hot, about ¹/₃₆; and in
common spring water, ¹/₁₂.

IV. Specific gravity of Nitrous Oxide.
To understand accurately the changes taking place during the
decomposition of nitrate of ammoniac, we must be acquainted with the
specific gravity and composition of nitrous oxide.
90 cubic inches of it, containing about ¹/₃₅ common air, introduced from
the mercurial airholder into an exhausted globe, increased it in weight 44,75
grains; thermometer being 51°, and atmospheric pressure 30,7.
106 cubic inches, of similar composition, weighed in like manner, gave
at the same temperature and pressure nearly 52,25 grains; and in another
experiment, when the thermometer was 41°, 53 grains.
So that accounting for the small quantity of common air contained in
the gases weighed, we may conclude, that 100 cubic inches of pure nitrous
oxide weigh 50,1 grains at temperature 50°, and atmospheric pressure 30,7.
I was a little surprised at this great specific gravity, particularly as I had
expected, from Dr. Priestley’s observations, to find it less heavy than
atmospherical air. This philosopher supposed, from some appearances
produced by the mixture of it with aëriform ammoniac, that it was even of
less specific gravity than that gas.[81]

V. Analysis of Nitrous Oxide.
The nitrous oxide may be analised, either by charcoal or hydrogene;
during the combustion of other bodies in it, small portions of nitrous acid
are generally formed, as will be fully explained hereafter.
The gas that I employed was generated from compact nitrate of
ammoniac, and was in its highest state of purity, as it left a residuum of ¹/₃₈
only, when absorbed by boiled water.
10 cubic inches of it were inserted into a jar graduated to,1 cubic inches,
containing dry mercury. Through this mercury a piece of charcoal which
had been deprived of its hydrogene by long exposure to heat, weighing
about a grain, was introduced, while yet warm. No perceptible absorption of
the gas took place.[82]
Thermometer being 46°, the focus of a lens was thrown on the charcoal,
which instantly took fire, and burnt vividly for about a minute, the gas
being increased in volume. After the vivid combustion had ceased, the focus
was again thrown on the charcoal; it continued to burn for near ten minutes,
when the process stopped.
The gas, when the original pressure and temperature were restored,
filled a space equal to 12,5 cubic inches.
On introducing to it a small quantity of strong solution of ammoniac[83],
white vapor was instantly perceived, and after a short time the reduction
was to about 10,1 cubic inches; so that apparently, 2,4 cubic inches of
carbonic acid had been formed. The 10,1 cubic inches of gas remaining
were exposed to water which had been long in ebullition, and which was
introduced whilst boiling, under mercury. After the absorption of the nitrous
oxide by the water, the gas remaining was equal to 5,3.
But on combining a cubic inch of pure nitrous oxide with some of the
same water, which had been received under mercury in a separate vessel,
nearly ¹/₂₂ remained. Consequently we may conclude, that 5,1 of a gas
unabsorbable by water, was produced in the combustion.
This gas extinguished flame, gave no diminution with oxygene, and the
slightest possible with nitrous gas. When an electric spark was passed
through it, mingled with oxygene; no inflammation, or perceptible

diminution took place.[84] We may consequently conclude that it was
nitrogene, mingled with a minute portion of common air, expelled from the
water.
The charcoal was diminished in bulk to one half nearly, but the loss of
weight could not be ascertained, as its pores were filled with mercury.
Now 5 cubic inches of nitrous oxide were absorbed by the water,
consequently 5 were decompounded by the charcoal; and these produced
5,1 cubic inches of nitrogene; and by giving their oxygene to the charcoal,
apparently 2,4 of carbonic acid.
But 5 cubic inches of nitrous oxide weigh 2,5 grains, and 5,1 cubic
inches of nitrogene 1,55; then 2,5-1,55 =,95.
So that reasoning from the relative specific gravities of nitrogene and
nitrous oxide, 2,5 grains of the last are composed of 1,55 nitrogene, and,95
oxygene.
But from many experiments made on the specific gravity of carbonic
acid, in August, 1799, I concluded that 100 cubic inches of it weighed 47,5
grains, thermometer being 60,1°, and barometer 29,5. Consequently,
making the necessary corrections, 2,4 cubic inches of it weigh 1,14 grains;
and on Lavoisier’s and Guyton’s[85] estimation of its composition, these
1,13 grains contain 8,2 of oxygene.
So that, drawing conclusions from the quantity of carbonic acid formed
in this experiment, 2,5 grains of nitrous oxide will be composed of,82
oxygene, and 1,68 nitrogene.
The difference between these estimations is considerable, and yet not
more than might have been expected, if we consider the probable sources of
error in the experiment.
1. It is likely that variable minute quantities of hydrogene remain
combined with charcoal, even after it has been long exposed to a red heat.
2. It is probable that the nitrogene and carbonic acid produced were
capable of dissolving more water than that held in solution by the nitrous
oxide; and if so, they were more condensed than if saturated with moisture,
and hence the quantity of carbonic acid under-rated.

We may consequently suppose the estimation founded on the quantity of
nitrogene evolved, most correct; and making a small allowance for the
difference, conclude, that 100 grains of nitrous oxide are composed of about
37 oxygene, and 63 nitrogene; existing in a much more condensed state
than when in their simple forms.
The tolerable accuracy of this statement will be hereafter demonstrated
by a number of experiments on the combustion of different bodies in nitrous
oxide, detailed in Research II.

VI. Minute examination of the decomposition of Nitrate of
Ammoniac.
Into a retort weighing 413,75 grains, and of the capacity of 7,5 cubic
inches, 100 grains of pulverised compact nitrate of ammoniac were
introduced. To the neck of this retort was adapted a recipient, weighing 711
grains, tubulated for the purpose of communicating with the mercurial
airholder, and of the capacity of 8,3 cubic inches.
Temperature being 50° and atmospheric pressure 30,6, the recipient was
inserted into a vessel of cold water, and made to communicate with the
airholder. The heat of a spirit lamp was then slowly applied to the retort: the
salt quickly began to decompose, and to liquify. The temperature was so
regulated, as to keep up an equable and slow decomposition.
During this decomposition, no luminous appearance was perceived in
the retort; the gas that came into the airholder was very little clouded, and
much water condensed in the receiver.
After the process was finished, the communication between the
mercurial airholder and the recipient was preserved till the common
temperature was restored to the retort.
The volume of the gas in the cylinder was 85,5 cubic inches. The
absolute quantity of nitrous oxide in those 85,5 cubic inches, it was difficult
to ascertain with great nicety, on account of the common air previously
contained in the vessels.
45 measures of it, exposed to well boiled water, diminished by agitation
to 8 measures. So that reasoning from the quantity of air, which should have

been expelled from the water by the nitrous oxide, we may conclude that
the 85,5 cubic inches were nearly pure.
The retort now weighed 419,25 grains, consequently 5,5 grains of salt
remained in it. This salt was chiefly collected about the lower part of the
neck, and contained rather more water than the compact nitrate, as in some
places it was crystalised.
The recipient with the fluid it contained, weighed 759 grains. It had
consequently gained in weight 48 grains.
Now the 85,5 cubic inches of nitrous oxide produced, weigh about 42,5
grains; and this added to 48 and 5,5, = 96 grains; so that about 4 grains of
salt and fluid were lost, probably by being carried over and deposited by the
gas.[86]
As much of the fluid as could be taken out of the recipient, weighed 46
grains, and held in solution much nitrate of ammoniac with superabundance
of acid. This acid required for its saturation, 3⅛ of carbonate of ammoniac
(containing, as well as I could guess), about 20 per cent alkali.
The whole solution evaporated, gave 18 grains of compact nitrate of
ammoniac. But reasoning from the quantity of carbonate of ammoniac
employed, the free nitric acid was equal to 2,75 grains, and this must have
formed 3,56 grains of salt. Consequently the salt pre-existing in the solution
was about 14,44 grains.
But besides the fluid taken out of the recipient, 2 grains remained in it:
let us suppose this, and the 4 grains lost, to contain 2 of salt, and,6 of free
acid.
Then the undecompounded
salt is 5,5 + 14,4 + 2 = 21,9
The free acid 2,75 + ,6 = 3,35
Gas 42,5
Water 32,25
100
Now about 78,1 grains of salt were decompounded, and formed into
42,5 grains of gas, 3,35 grains acid, and 32,25 grains water.

But there is every reason to suppose, that in this process, when the
hydrogene of the ammoniac combines with a portion of the oxygene of the
nitric acid to form water, and the nitrogene enters into union with the
nitrogene and remaining oxygene of the nitric acid, to form nitrous oxide;
that water pre-existing in nitric acid and ammoniac, such as they existed in
the aëriform state, is deposited with the water produced by the new
arrangement, and not wholly combined with the nitrous oxide formed.
Hence it is impossible to determine with great exactness, the quantity of
water which was absolutely formed in this experiment.
78,1 grains of salt are composed of 15,4 alkali, 58 acid, and 4,7 water.
And reasoning from the different affinities of water for nitric acid,
ammoniac, and nitrous oxide, it is probable that ammoniac, in its
decomposition, divides its water in such a ratio, between the nitrogene
furnished to the nitrous oxide, and the hydrogene entering into union with
the oxygene of the nitric acid, as to enable us to assume, that the hydrogene
requires for its saturation nearly the same quantity of oxygene as when in
the aëriform state; or that it certainly cannot require less.
But 15,4 alkali contain 3,08 hydrogene, and 12,32 nitrogene;[87] and
3,08 hydrogene require 17,4 of oxygene to form 20,48 of water.
Now 32,5 grains of water existed before the experiment; 4,7 grains of
water were contained by the salt decomposed, and 32,5-4,7 = 27,8: and
27,8-20,48, the quantity generated, = 7,52, the quantity existing in the nitric
acid.
But the nitric acid decomposed is 58ᵍ-3,35 = to 54,7; and 54,7-7,5 =
47,2, which entered into new combinations. These 47,2 consist of 33,2
oxygene, and 14, nitrogene. And 33,2-17,4, the quantity employed to form
the water, = 15,8, which combined with 14,0, nitrogene of the nitric acid,
and 12,32 of that of the ammoniac, to form 42,12 of nitrous oxide. And on
this estimation, 100 parts of nitrous oxide would contain 37,6 oxygene, and
62,4 nitrogene; a computation much nearer the results of the analysis than
could have been expected, particularly as so many unavoidable sources of
error existed in the process.
The experiment that I have detailed is the most accurate of four, made
on the same quantity of salt. The others were carried on at rather higher

temperatures, in consequence of which, more water and salt were sublimed
with the gas.
To Berthollet, we owe the discovery of the products evolved during the
slow decomposition of nitrate of ammoniac; but as this philosopher in his
examination of this process, chiefly designed to prove the existence of
hydrogene in ammoniac, he did not ascertain the quantity of gas produced,
or minutely examine its properties; from two of them, its absorption by
water and its capability of supporting the vivid combustion of a taper, he
inferred its identity with the dephlogisticated nitrous gas of Priestley, and
concluded that it was nitrous gas with excess of pure air.[88]

VII. Of the heat produced during the decomposition
of nitrate of ammoniac.
To ascertain whether the temperature of nitrate of ammoniac was
increased or diminished after it had been raised to the point essential to its
decomposition, during the evolution of nitrous oxide and water; that is, in
common language, whether heat was generated or absorbed in the process; I
introduced a thermometer into about 1500 grains of fibrous nitrate of
ammoniac, rendered liquid in a deep porcelain cup. During the whole of the
evaporation, the temperature was about 380°, the fire being carefully
regulated.
As soon as the decomposition took place, the thermometer began to
rise; in less than a quarter of a minute it was 410°, in two minutes it was
460°.
The cup was removed from the fire; the decomposition still went on
rapidly, and for about a minute the thermometer was stationary. It then
gradually and slowly fell; in three minutes it was 440°, in five minutes
420°, in seven minutes 405° in nine minutes 360° and in thirteen minutes
307°, when the decomposition had nearly ceased, and the salt began to
solidify.
From this experiment, it is evident that an increase of temperature is
produced by the decomposition of nitrate of ammoniac: though the capacity
of water and nitrous oxide for heat, supposing the truth of the common

doctrine, and reasoning from analogy, must be considerably greater than
that of the salt.

VIII. Of the decomposition of Nitrate of Ammoniac
at high temperatures, and production of
Nitrous gas, Nitrogene, Nitrous Acid, and Water.
At an early period of my investigation relating to the nitrous oxide, I
discovered that when a heat above 600° was applied to nitrate of ammoniac,
so that a vivid luminous appearance was produced in the retort, certain
portions of nitrous gas, and nitrogene, were evolved with the nitrous oxide.
But I was for some time ignorant of the precise nature of this
decomposition, and doubtful with regard to the possibility of effecting it in
such a manner as to prevent the production of nitrous oxide altogether.
I first attempted to decompose nitrate of ammoniac at high
temperatures, by introducing it into a well coated green glass retort, having
a wide neck, communicating with the pneumatic apparatus, and strongly
heated in an air-furnace. But though in this process a detonation always
took place, and much light was produced, yet still the greater portion of the
gas generated was nitrous oxide; the nitrous gas and nitrogene never
amounting to more than one third of the whole.
After breaking many retorts by explosions, without gaining any accurate
results, I employed a porcelain tube, curved so as to be capable of
introduction into the pneumatic apparatus, and closed at one end.
The closed end was heated red, nitrate of ammoniac introduced into it,
and all the latter portions of gas produced in the explosion, received in the
pneumatic apparatus, filled with warm water.
Three explosions were required to fill a jar of the capacity of 20 cubic
inches. The gas produced in the first, when it came over, was transparent
and dark orange, similar in its appearance to the nitrous acid gas produced
in the first experiment; but it speedily became white and clouded, whilst a
slight diminution of volume took place.
When the second portion was generated and mingled with the clouded
gas, it again became transparent and yellow for a short time, and then
assumed the same appearance as before.

The water in the trough, after this experiment, had an acid taste, and
quickly reddened cabbage juice rendered green by an alkali.
6 cubic inches of the gas produced were exposed to boiled water, but
little or no absorption took place. Hence, evidently, it contained no nitrous
oxide.
They were then exposed to solution of sulphate of iron: the solution
quickly became dark colored, and an absorption of 1,6 took place on
agitation.[89]
The gas remaining instantly extinguished the taper, and was
consequently nitrogene.
This experiment was repeated, with nearly the same results.
We may then conclude, that at high temperatures, nitrate of ammoniac is
wholly resolved into water, nitrous acid, nitrous gas, and nitrogene; whilst a
vivid luminous appearance is produced.
The transparency and orange color produced in the gas that had been
clouded, by new portions of it, doubtless arose from the solution of the
nitric acid and water forming the cloud, in the heated nitrous vapor
produced, so as to constitute an aëriform triple compound; whilst the
cloudiness and absorption subsequent were produced by the diminished
temperature, which destroyed the ternary combination, and separated the
nitrous acid and water from the nitrous gas.
From the rapidity with which the deflagration of nitrate of ammoniac
proceeds, and from the immense quantity of light produced, it is reasonable
to suppose that a very great increase of temperature takes place. The tube in
which the decomposition has been effected, is always ignited after the
process.

IX. Speculations on the decompositions of
Nitrate of Ammoniac.
All the phænomena of chemistry concur in proving, that the affinity of
one body, A, for another, B, is not destroyed by its combination with a third,
C, but only modified; either by condensation, or expansion, or by the
attraction of C for B.

On this principle, the attraction of compound bodies for each other must
be resolved into the reciprocal attractions of their constituents, and
consequently the changes produced in them by variations of temperature
explained, from the alterations produced in the attractions of those
constituents.
Thus in nitrate of ammoniac, four affinities may be supposed to exist:
1. That of hydrogene for nitrogene, producing
ammoniac.
2. That of oxygene for nitrous gas, producing nitric acid.
3. That of the hydrogene of ammoniac for the oxygene
of nitric acid.
4. That of the nitrogene of ammoniac for the nitrous gas
of nitric acid.
At temperatures below 300°, the salt, from the equilibrium between
these affinities, preserves its existence.
Now when its temperature is raised to 400°, the attractions of hydrogene
for nitrogene,[90] and of nitrous gas for oxygene,[91] are diminished; whilst
the attraction of hydrogene for oxygene[92] is increased; and perhaps that of
nitrogene for nitrous gas.
Hence the former equilibrium of affinity is destroyed, and a new one
produced.
The hydrogene of the ammoniac combines with the oxygene of the
nitric acid to generate water; and the nitrogene of the ammoniac enters into
combination with the nitrous gas to form nitrous oxide: and the water and
nitrous oxide produced, most probably exist in binary combination in the
aëriform state, at the temperature of the decomposition.
But when a heat above 800° is applied to nitrate of ammoniac, the
attractions of nitrogene and hydrogene for each other, and of oxygene for
nitrous gas,[93] are still more diminished; whilst that of nitrogene for nitrous
gas is destroyed, and that of hydrogene for oxygene increased to a great
extent: likewise a new attraction takes place; that of nitrous gas for nitric
acid, to form nitrous vapor.[94] Hence a new arrangement of principles is

rapidly produced; the nitrogene of ammoniac having no affinity for any of
the single principles at this temperature, enters into no binary compound:
the oxygene of the nitric acid forms water with the hydrogene, and the
nitrous gas combines with the nitric acid to form nitrous vapor. All these
substances most probably exist in combination at the temperature of their
production; and at a lower temperature, assume the forms of nitrous acid,
nitrous gas, nitrogene, and water.
I have avoided entering into any discussions concerning the light and
heat produced in this process; because these phænomena cannot be
reasoned upon as isolated facts, and their relation to general theory will be
treated of hereafter.

X. On the preparation of Nitrous Oxide
for experiments on Respiration.
When compact nitrate of ammoniac is slowly decomposed, the nitrous
oxide produced is almost immediately fit for respiration; but as one part of
the salt begins to decompose before the other is rendered fluid, a
considerable loss is produced by sublimation.
For the production of large quantities of nitrous oxide, fibrous nitrate of
ammoniac should be employed. This salt undergoes no decomposition till
the greater part of its water is evaporated, and in consequence at the
commencement of that process, is uniformly heated.
The gas produced from fibrous nitrate, must be suffered to rest at least
for an hour after its generation. At the end of this time it is generally fit for
respiration. If examined before, it will be found to contain more or less of a
white vapor, which has a disagreeable acidulous taste, and strongly irritates
the fauces and lungs. This vapor, most probably, consists of acid nitrate of
ammoniac and water, which were dissolved by the gas at the temperature of
its production, and afterwards slowly precipitated.
It is found in less quantity when compact nitrate is employed, because
more salt is sublimed in this process, which being rapidly precipitated,
carries with it the acid and water.
Whatever salt is employed, the last portions of gas produced, generally
contain less vapor, and may in consequence be respired sooner than the

first.
The nitrate of ammoniac should never be decomposed in a metallic
vessel,[95] nor the gas produced suffered to come in contact with any
metallic surface; for in this case the free nitric acid will be decomposed, and
in consequence, a certain quantity of nitrous gas produced.
The apparatus that has been generally employed in the medical
pneumatic institution, for the production of nitrous oxide, consists
1. Of a glass retort, of the capacity of two or three quarts,
orificed at the top, and furnished with a ground stopper.
2. Of a glass tube, conical for the purpose of receiving
the neck of the retort; about ,4 inches wide in the narrowest
part, 4 feet long, curved at the extremity, so as to be capable
of introduction into an airholder, and inclosed by tin plate to
preserve it from injury.
3. Of airholders of Mr. Watt’s invention, filled with
water saturated with nitrous oxide.
4. Of a common air-furnace, provided with dampers for
the regulation of the heat.
The retort, after the insertion of the salt, is connected with the tube,
carefully luted, and exposed to the heat of the furnace, on a convenient
stand. The temperature is never suffered to be above 500°. After the
decomposition has proceeded for about a minute, so that the gas evolved
from the tube enlarges the flame of a taper, the curved end is inserted into
the airholder, and the nitrous oxide preserved.
The water thrown out of the airholders in consequence of the
introduction of the gas, is preserved in a vessel adapted for the purpose, and
employed to fill them again; for if common water was to be employed in
every experiment, a great loss of gas would be produced from absorption.
A pound of fibrous nitrate of ammoniac, decomposed at a heat not
above 500°, produces nearly 5 cubic feet of gas; whilst from a pound of
compact nitrate of ammoniac, rarely more than 4,25 cubic feet can be
collected.

For the production of nitrous oxide in quantities not exceeding 20
quarts, a mode still more simple than that I have just described may be
employed. The salt may be decomposed by the heat of an argands lamp, or
a common fire, in a tubulated glass retort, of 20 or 30 cubic inches in
capacity, furnished with a long neck, curved at the extremity; and the gas
received in small airholders.
Thus, if the pleasurable effects, or medical properties of the nitrous
oxide, should ever make it an article of general request, it may be procured
with much less time, labor, and expence,[96] than most of the luxuries, or
even necessaries, of life.

DIVISION IV.

EXPERIMENTS and OBSERVATIONS on the COMPOSITION of
NITROUS GAS, and on its ABSORPTION by different bodies.

I. Preliminaries.

I
n my account of the composition of nitric acid, in Division I. I gave an
estimation of the quantities of oxygene and nitrogene combined in
nitrous gas: I shall now detail the experiments on which that estimation is
founded.
At an early period of my researches relating to nitrous oxide, from the
observation of the phænomena taking place during the production of this
substance, I had concluded, that the common opinion with regard to the
composition of nitrous gas, was very distant from the truth. I had indeed
analysed nitrous gas, by converting it into nitrous oxide, before I attempted
to ascertain its composition by immediately separating the constituent
principles from each other: and my first hopes of the possibility of effecting
this, were derived from Dr. Priestley’s experiments on the combustion of
pyrophorus in nitrous gas, and on the changes effected in it, by heated iron
and charcoal.
This great philosopher found, that pyrophorus placed in contact with
nitrous gas, burnt with great vividness, whilst the gas was diminished in
volume to about one half, which generally consisted of nitrogene and
nitrous oxide. He likewise found, iron heated by a lens in nitrous gas,

increased in weight, whilst the gas was diminished about ½, and converted
into nitrogene.[97]
He heated common charcoal, and charcoal of copper,[98] in nitrous gas
by a lens. When common charcoal was employed, the gas was neither
increased or diminished in bulk, but wholly converted into nitrogene; when
charcoal of copper was used, the volume was a little increased, and the gas
remaining consisted of ⁵/₇ nitrogene, and ²/₇ carbonic acid.
In his experiments on the iron and pyrophyrus, the nitrous gas was
evidently decomposed. From the great quantity of nitrogene produced in
those on the charcoal, it seems likely that both the common charcoal,[99]
and the charcoal of copper employed contained atmospherical air, which
being dispelled by the heat of the lens, was decomposed by the nitrous gas:
indeed, till I made the following experiment, I suspected that the carbonic
acid produced, when the charcoal of copper was employed, arose from a
decomposition of the nitrous acid, formed in this way.
I introduced a piece of well-burnt charcoal, which could hardly have
weighed the eighth of a grain, whilst red hot, under a cylinder filled with
mercury, and admitted to it half a cubic inch of nitrous gas. A slight
absorption took place.
The sun being very bright, I kept the charcoal in the focus of a small
lens for near a quarter of an hour. At the end of this time the gas occupied a
space nearly as before the experiment, and a very minute portion of the
charcoal had been consumed. On introducing into the cylinder a small
quantity of solution of strontian, a white precipitation was perceived, and
the gas slowly diminished to about three tenths of a cubic inch. To these
three tenths a little common air was admitted, when very slight red fumes
were perceived.
This experiment convinced me, that the attraction of charcoal for the
oxygene of nitrous gas, at high temperatures, was sufficiently strong to
effect a slow decomposition of it.
To be more accurately acquainted with this decomposition, and to learn
the quantities of carbonic acid and nitrogene produced from a known
quantity of nitrous gas, I proceeded in the following manner.

II. Analysis of Nitrous Gas by Charcoal.
A quantity of nitrous gas was procured in a water apparatus, from the
decomposition of nitrous acid by mercury. A portion of it was transferred to
the mercurial trough. After the mercury and the jar had been dried by
bibulous paper, 40 measures of this portion were agitated in a solution of
sulphate of iron. The gas remaining after the absorption was complete,
filled about a measure and half; so that the nitrous gas contained nearly ¹/₂₆
nitrogene.
Thermometer being 53°, a small piece of well-burnt charcoal, the
weight of which could hardly have equalled a quarter of a grain, was
introduced ignited, into a small cylinder filled with mercury, graduated
to,10 grain measures; to this, 16 measures, equal to 160 grain m. of nitrous
gas, were admitted. An absorption of about one measure and half took
place. When the focus of a lens was thrown on the charcoal, a slight
increase of the gas was produced, from the emission of that which had been
absorbed.
After the process had been carried on for about a half an hour, the
charcoal evidently began to fume, and to consume very slowly, though no
alteration in the volume of the gas was observed.
The sun not constantly shining, the progress of the experiment was now
and then stopped: but taking the whole time, the focus could not have been
applied to it for less than four hours. When the process was finished, the gas
was increased in bulk nearly three quarters of a measure.
A drop of water was introduced into the cylinder, by means of a small
glass tube, on the supposition that the carbonic acid, and nitrogene, might
be capable of holding in solution, more water than that contained in the
nitrous gas decomposed; but no alteration of volume took place.
When 20 grain measures of solution of pale green[100] sulphate of iron
were introduced into the cylinder, they became rather yellower than before,
but not dark at the edges, as is always the case when nitrous gas is present.
On agitation, a diminution of nearly half a measure was produced, doubtless
from the absorption of some of the carbonic acid by the solution.
A small quantity of caustic potash, much more than was sufficient to
decompose the sulphate of iron, was now introduced. A rapid diminution

took place, and the gas remaining filled about 8 measures. This gas was
agitated for some time over water, but no absorption took place. Two
measures of it were then transferred into a detonating cylinder with two
measures of oxygene. The electric spark was puffed through them, but no
diminution was produced. Hence it was nitrogene, mingled with no
ascertainable quantity of hydrogene: consequently little or no water could
have been decomposed in the process.
Now supposing, for the greater ease of calculation, each of the measures
employed, cubic inches.
16 of nitrous gas—¹/₂₆ = 15,4 were decomposed, and these weigh,
making the necessary corrections, 5,2; but 7,4 nitrogene were produced, and
these weigh about 2,2. So that reasoning from the relative specific gravities
of nitrous gas and nitrogene, 5,2 grains of nitrous gas will be composed of 3
oxygene, and 2,2 nitrogene.
But 8,7 of carbonic acid were produced, which weigh 4,1 grains, and
consist of 2,9 oxygene, and 1,2 charcoal.[101] Consequently, drawing
conclusions from the quantity of carbonic acid formed, 5,2 grains of nitrous
gas will consist of 2,9 oxygene, and 2,3 nitrogene.
The difference in these estimations is much less than could have been
expected; and taking the mean proportions, it would be inferred from them,
that 100 grains of nitrous gas, contain 56,5 oxygene, and 43,5 nitrogene.
I repeated this experiment with results not very different, except that the
increase of volume was rather greater, and that more unabsorbable gas
remained; which probably depended on the decomposition of a minute
quantity of water, that had adhered to the charcoal in passing through the
mercury.
As nitrous gas is decomposable into nitrous acid, and nitrogene, by the
electric spark; it occurred to me, that a certain quantity of nitrous acid might
have been possibly produced, in the experiments on the decomposition of
nitrous gas, by the intensely ignited charcoal. To ascertain this
circumstance, I introduced into 12 measures of nitrous gas, a small piece of
charcoal which had been just reddened. The sun being very bright, the focus
of the lens was kept on it for rather more than an hour and quarter. In the
middle of the process it began to fume and to sparkle, as if in combustion.

In three quarters of an hour, the gas was increased rather more than half a
measure; but no alteration of volume took place afterwards.
The mercury was not white on the top as is usually the case when
nitrous acid is produced. On introducing into the cylinder a little pale green
sulphate of iron, and then adding prussiate of potash, a white precipitate
only was produced. Now, if the minutest quantity of nitric acid had been
formed, it would have been decomposed by the pale green oxide of iron,
and hence, a visible quantity of prussian blue[102] produced, as will be fully
explained hereafter.

III. Analysis of Nitrous Gas by Pyrophorus.
I placed some newly made pyrophorus, about as much as would fill a
quarter of a cubic inch, in a jar filled with dry mercury, and introduced to it,
four cubic inches of nitrous gas, procured from mercury and nitric acid.
It instantly took fire and burnt with great vividness for some moments.
After the combustion had ceased, the gas was diminished about three
quarters of a cubic inch. The remainder was not examined; for the
diminution appeared to go on for some time, after; in an half hour, when it
was compleat, it was to 2 cubic inches. A taper, introduced into these, burnt
with an enlarged flame, blue at the edges; from whence it appeared, that
they were composed of nitrogene and nitrous oxide.
I now introduced about half a cubic inch of pyrophorus to two cubic
inches of nitrous gas; the combustion took place, and the gas was rapidly
diminished to one half; and on suffering it to remain five minutes to one
third nearly; which extinguished flame.
Suspecting that this great diminution was owing to the absorption of
some of the nitrogene formed, by the charcoal of the pyrophorus, I carefully
made a quantity of pyrophorus; employing more than two thirds of alumn,
to one third of sugar.
To rather more than half of a cubic inch of this, two cubic inches of
nitrous gas, which contained about ¹/₄₀ nitrogene, were admitted. After the
combustion, the gas remaining, apparently filled a space equal to 1,2 cubic
inches; but, as on account of the burnt pyrophyrus in the jar, it was
impossible to ascertain the volume with nicety, it was carefully and wholly

transferred into another jar. It filled a space equal to 1,15 cubic inches
nearly.
When water was admitted to this gas no absorption took place. It
underwent no diminution with nitrous gas, and a taper plunged into it was
instantly extinguished. We may consequently conclude that it was
nitrogene.
Now 2 cubic inches of nitrous gas weigh,686 grains, and 1,1 of
nitrogene—,05, the quantity previously contained in the gas = to 1,05, 3,19.
Hence,686 of nitrous gas would be composed of,367 oxygene, and ,319
nitrogene; and 100 grains would contain 53,4 oxygene, and 46,6 nitrogene.

IV. Additional observations on the combustion of bodies in Nitrous
Gas,
and on its Composition.
Though phosphorus may be fused, and even sublimed, in nitrous gas,
without producing the slightest luminous appearance,[103] yet when it is
introduced into it in a state of active inflammation, it burns with almost as
much vividness as in oxygene.[104] Hence it is evident, that at the heat of
ignition, phosphorus is capable of attracting the oxygene from the nitrogene
of nitrous gas.
I attempted to analise nitrous gas, by introducing into a known quantity
of it, confined by mercury, phosphorus, in a vessel containing a minute
quantity of oxygene.[105] The phosphorus was inflamed with an ignited iron
wire, by which, at the moment of the combustion, the vessel containing it
was raised from the mercury into the nitrous gas. But after making in this
way, five of six unsuccessful experiments, I desisted. When the
communication between the vessels was made before the oxygene was
nearly combined with the phosphorus, nitrous acid was formed, which
instantly destroyed the combustion; when, on the contrary, the phosphorus
was suffered to consume almost the whole of the oxygene, it was not
sufficiently ignited when introduced, to decompose the nitrous gas.
In one experiment, indeed, the phosphorus burnt for a moment in the
nitrous gas; the diminution however was slight, and not more than ¼ of it
was decomposed.

Sulphur, introduced in a state of vivid inflammation, into nitrous gas,
was instantly extinguished.
I passed a strong electric shock through equal parts of hydrogene and
nitrous gas, confined by mercury in a detonating tube; but no inflammation,
or perceptible diminution, was produced.
19,2 grain measures of hydrogene were fired by the electric shock, with
10 of nitrous oxide, and 6 of nitrous gas; the diminution was to 17; and pale
green sulphate of iron admitted to the residuum, was not discolored.
Consequently the nitrous gas was decomposed by the hydrogene, and as
will be hereafter more clearly understood, nearly as much nitrogene
furnished by it, as would have been produced from half the quantity of
nitrous oxide.
Suspecting that phosphorated hydrogene might inflame with nitrous gas,
I passed the electric spark through 1 measure of phosphorated hydrogene,
and 4 of nitrous gas; but no diminution was perceptible. I likewise passed
the electric spark through 1 of nitrous gas, with 2 of phosphorated
hydrogene, without inflammation.
Perhaps if I had tried many other different proportions of the gases, I
should have at last discovered one, in which they would have inflamed; for,
as will be seen hereafter, nitrous oxide cannot be decomposed by the
compound combustible gases, except definite quantities are employed.
From Dr. Priestley’s experiments on iron and pyrophorus, and from the
experiments I have detailed, on charcoal, phosphorus, and hydrogene, it
appears that at certain temperatures, nitrous gas is decomposable by most of
the combustible bodies: even the extinction of sulphur, when introduced
into it in a state of inflammation, depends perhaps, on the smaller quantity
of heat produced by the combustion of this body, than that of most others.
The analysis of nitrous gas by charcoal, as affording data for
determining immediately the quantities of oxygene and nitrogene, ought to
be considered as most accurate; and correcting it by mean calculations
derived from the decomposition of nitrous gas by pyrophorus and
hydrogene, and its conversion into nitrous oxide, a process to be described
hereafter, we may conclude, that 100 grains of nitrous gas are composed of

55,95 oxygene, and 44,05 nitrogene; or taking away decimals, of 56
oxygene, and 44 nitrogene.
This estimation will agree very well with the mean proportions that
would be given from Dr. Priestley’s experiments on the decomposition of
nitrous gas by iron; but as he never ascertained the purity of his nitrous gas,
[106]
and probably employed different kinds in different experiments, it is
impossible to fix on any one, from which accurate conclusions can be
drawn.
Lavoisier’s estimation of the quantities of oxygene and nitrogene
entering into the composition of nitrous gas, has been generally adopted. He
supposes 64 parts of nitrous gas to be composed of 43½ of oxygene, and
20½ of nitrogene.[107]
The difference between this account and mine is very great indeed; but I
have already, in Division 1st, pointed out sources of error in the
experiments of this great man, on the decomposition of nitre by charcoal;
which experiments were fundamental, both to his accounts of the
constitution of nitrous acid, and nitrous gas.

V. Of the absorption of Nitrous Gas by Water.
Amongst the properties of nitrous gas noticed by its great discoverer, is
that of absorbability by water.
In exposing nitrous air to distilled water, Dr. Priestley found a
diminution of the volume of gas, nearly equal to one tenth of the bulk of the
water; and by boiling the water thus impregnated, he procured again a
certain portion of the nitrous gas.
Humbolt, in his paper on eudiometry, mentions the diminution of
nitrous gas by water. This diminution, he supposes to arise from the
decomposition of a portion of the nitrous gas, by the water, and the
consequent formation of nitrate of ammoniac.[108]
I confess, that even before the following experiments were made, I was
but little inclined to adopt this opinion: the small diminution of nitrous gas
by water, and the uniform limits of this diminution, rendered it extremely
improbable.

a. To ascertain the quantity of nitrous gas absorbable by pure water, and
the limits of absorption, I introduced into a glass retort about 5 ounces of
water, which had been previously boiled for some hours. The neck of the
retort was inverted in mercury, and the water made to boil. After a third of it
had been distilled, so that no air could possibly remain in the retort, the
remainder was driven over, and condensed in an inverted jar filled with
mercury. To three cubic inches of this water,[109] confined in a cylinder
graduated to,05 cubic inches, 5 cubic inches of nitrous gas, containing
nearly one thirtieth nitrogene, were introduced.
After agitation for near an hour, rather more than ⁴/₂₀ of a cubic inch
appeared to be absorbed; but though the process was continued for near two
hours longer, no further diminution took place.
The remaining gas was introduced into a tube graduated to,02 cubic
inches. It measured ¹⁴/₅₀; hence ¹¹/₅₀ had been absorbed.
Consequently, 100 cubic inches of pure water are capable of absorbing
11,8 of nitrous gas. In the water thus impregnated with nitrous gas I could
distinguish no peculiar taste;[110] it did not at all alter the color of blue
cabbage juice.
b. To determine if the absorption of nitrous gas was owing, to a
decomposition of it by the water, as Humbolt has supposed, or to a simple
solution; I procured some nitrous gas from nitrous acid and mercury,
containing about one seventieth nitrogene. ,5 cubic inches of it, mingled
with ,25, of oxygene, from sulphuric acid and manganese left a residuum
of,03. 5 cubic inches more were introduced to 3 of water, procured in the
same manner as in the last experiment, in the same cylinder. After the
diminution was complete, the cylinder was transferred in a small vessel
containing mercury, into a water bath, and nearly covered by the water.
As the bath was heated, small globules of gas were given out from the
impregnated water, and when it began to boil, the production of gas was
still more rapid. After an hour’s ebullition, the volume of heated gas was
equal to 1,4 cubic inches nearly.
The cylinder was now taken out of the bath, and quickly rendered cool
by being placed in a water apparatus. At the common temperature the gas
occupied, as nearly as possible, the space of,5 cubic inches: these,5 mingled

with,25 of oxygene, of the same kind as that employed before, left a
residuum nearly equal to,03.
From this experiment, which was repeated with nearly the same results,
it is evident,

1. That nitrous gas is not decomposable by pure water.
2. That the diminution of volume of nitrous gas placed in
contact with water, is owing to a simple solution of it in that
fluid.
3. That at the temperature of 212°, nitrous gas is
incapable of remaining in combination with water.
Humbolt’s opinion relating to the decomposition of nitrous gas by
water, is founded upon the disengagement of vapor from distilled water
impregnated with nitrous gas, by means of lime, which became white in the
proximity of the muriatic acid. But this is a very imperfect, and fallacious
test, of the presence of ammoniac. I have this day, April 2, 1800, heated 4
cubic inches of distilled water, impregnated with nitrous gas, with caustic
lime; the vapor certainly became a little whiter when held over a vessel
containing muriatic acid; but the vapor of distilled water produced precisely
the same appearance,[111] which was owing, most likely, to the combination
of the acid with the aqueous vapor. Indeed, when I added a particle of
nitrate of ammoniac, which might have equalled one twentieth of a grain, to
the lime and impregnated water, the increased whiteness of the vapor was
but barely perceptible, though this quantity of nitrate of ammoniac is much
more considerable than that which could have been formed, even supposing
the nitrous gas decomposed.

VI. Of the absorption of Nitrous Gas by
Water of different kinds.
In agitating nitrous gas over spring water, the diminution rarely amounts
to more than one thirtieth, the volume of water being taken as unity. I at
first suspected that this great differcnce in the quantity of gas absorbed by
spring water, and pure water, depended on carbonic acid contained in the
last, diminishing the attraction of it for nitrous gas: but by long boiling a
quantity of spring water confined by mercury, I obtained from it about one
twentieth of its bulk of air, which gave nearly the same diminution with
nitrous gas, as atmospheric air.
This fact induced me to refer the difference of diminution to the
decomposition of the atmospheric air held in solution by the water, the

oxygene of which I supposed to be converted into nitric acid, by the nitrous
gas, whilst the nitrogene was liberated; and hence the increased residuum.
a. I exposed to pure water, that is, water procured by distillation under
mercury, nitrous gas, containing a known quantity of nitrogene. After the
absorption was complete, I found the same quantity of nitrogene in the
residuum, as was contained in a volume of gas equal to the whole quantity
employed.
b. Spring water boiled for some hours, and suffered to cool under
mercury, absorbed a quantity of nitrous gas equal to one thirteenth of its
bulk; which is not much less than that absorbed by pure water.
c. I exposed to spring water, 10 measures of nitrous gas; the
composition of which had been accurately ascertained; the diminution was
one twenty-eighth, the volume of water being taken as unity. On placing the
residuum in contact with solution of sulphate of iron, the nitrogene
remaining was nearly one twentieth more than had been contained by the
gas before its exposure to water.
d. Distilled water was saturated with common air, by being agitated for
some time in the atmosphere. Nitrous gas placed in contact with this water,
underwent a diminution of ¹/₁₈; the volume of water being unity. The gas
remaining after the absorption contained about one twenty-seventh
nitrogene more than before.
e. Nitrous gas exposed to water combined with about one fourth of its
volume of carbonic acid, diminished to ¹/₃₂[112] nearly. The remainder
contained little or no superabundant nitrogene.
From these observations it appears, that the different degrees of
diminution of nitrous gas by different kinds of water, may depend upon
various causes.
1. Less nitrous gas will be absorbed by water holding in solution earthy
salts, than by pure water; and in this case the diminution of the attraction of
water for nitrous gas will probably be in the ratio of the quantities of salt
combined with it. a. b.
2. The apparent diminution of nitrous gas in water, holding in solution
atmospheric air, will be less than in pure water, though the absolute

diminution will be greater; for the same portion will be absorbed, whilst
another portion is combined with the oxygene of the atmospheric air
contained in the water; and from the disengagement of the nitrogene of this
air, arises an increased residuum. c. d.
3. Probably in waters containing nitrogene, hydrogene, and other gases,
absorbable only to a slight extent, the apparent diminution will be less, on
account of the disengagement of those gases from the water, by the stronger
affinity of nitrous gas for that fluid.
4. In water containing carbonic acid, and probably some other acid
gases, the diminution will be small in proportion to the quantity of gas
contained in the water: the affinity of this fluid for nitrous gas being
diminished by its greater affinity for the substance combined with it. e.
The different diminution of nitrous gas when agitated in different kinds
of water, has been long observed by experimenters on the constituent parts
of the atmosphere, and various solutions have been given of the
phænomenon; the most singular is that of Humbolt.[113] He supposes that
the apparent diminution of nitrous gas is less in spring water than distilled
water, on account of the decomposition of the carbonate of lime contained
in the spring water, by the nitrous acid formed from the contact of nitrous
gas with the water; the carbonic acid disengaged from this decomposition
increasing the residuum.
This opinion may be confuted without even reference to my
observations. It is, indeed, altogether unworthy of a philosopher, generally
acute and ingenious. He seems to have forgotten that carbonic acid is
absorbable by water.

VII. Of the absorption of Nitrous Gas, by solution
of pale green Sulphate of Iron.
a. The discovery of the exact difference between the sulphates of iron, is
owing to Proust.[114] According to the ingenious researches of this chemist,
there exist two varieties of sulphate of iron, the green and the red. The oxide
in the green sulphate contains ²⁷/₁₀₀ oxygen. This salt, when pure, is
insoluble in spirit of wine; its solution in water is of a pale green color; it is

not altered by the gallic acid, and affords a white precipitate with alkaline
prussiates.
The red sulphate of iron is soluble in alcohol and uncrystalizable; its
oxide contains ⁴⁸/₁₀₀ oxygene. It forms a black precipitate with the gallic
acid, and with the alkaline prussiates, a blue one.
The common sulphates of iron generally consist of combinations of
these two varieties in different proportions.
The green sulphate may be converted into the red by oxygenated
muriatic acid or nitric acid. The common sulphate may be converted into
green sulphate, by agitation in contact with sulphurated hydrogene.
The green sulphate has a strong affinity for oxygene, it attracts it from
the atmosphere, from oxygenated marine acid, and nitric acid. The alkalies
precipitate from it a pale green oxide, which if exposed to the atmosphere,
rapidly becomes yellow red.
The red sulphate of iron has no affinity for oxygene, and when
decomposed by the alkalies, gives a red precipitate, which undergoes no
alteration when exposed to the atmosphere.[115]
b. The absorption of nitrous gas by a solution of sulphate of iron, was
long ago discovered by Priestley. During this absorption, he remarked a
change of color in the solution, analogous to that produced by the mixture
of it with nitric acid.
This chemical fact has been lately applied by Humbolt, to the discovery
of the nitrogene generally mingled with nitrous gas.
Vauquelin and Humbolt have published a memoir, on the causes of the
absorption[116] of nitrous gas by solution of sulphate of iron. They saturated
an ounce and half of sulphate of iron in solution, with 180 cubic inches of
nitrous gas.
Thus impregnated it strongly reddened tincture of turnsoyle; when
mingled with sulphuric acid, gave nitric acid vapor; and saturated with
potash, ammoniacal vapor.
By analysis, it produced as much ammoniac as that contained in 4
grains of ammoniacal muriate, and a quantity of nitric acid equal to that

existing in 17 grains of nitre. Hence they concluded, that the nitrous gas and
a portion of the water of the solution, had mutually decomposed each other;
the oxygene of the water combining with the oxygene and a portion of the
nitrogene of nitrous gas to form nitric acid; and its hydrogene uniting with
the remaining nitrogene, to generate ammoniac.
They have taken no notice of the nature of the sulphate of iron
employed, which was most probably the common or mixed sulphate; nor of
the attraction of the oxide of iron in this substance for oxygene.
c. Before I was acquainted with the observations of Proust, the common
facts relating to the oxygenation of vitriol of iron induced me to suppose,
that the attraction of this substance for oxygene was in some way connected
with the process of absorption. The comparison of the experiments of
Humbolt and Vauquelin, with the observations of Proust, enabled me to
discover the true nature of the process.
I procured a solution of red sulphate of iron, by passing oxygenated
muriatic acid through a solution of common sulphate of iron, till it gave
only a red precipitate, when mingled with caustic potash. To nitrous gas
confined by mercury, a small quantity of this solution was introduced. On
agitation, its color altered to muddy green; but the absorption that took
place was extremely trifling: in half an hour it did not amount to,2, the
volume of the solution being unity, when it had nearly regained the yellow
color.
I now obtained a solution of green sulphate of iron, by dissolving iron
filings in diluted sulphuric acid. The solution was agitated in contact with
sulphurated hydrogene, and afterwards boiled; when it gave a white
precipitate with prussiate of potash.
A small quantity of this solution agitated in nitrous gas, quickly became
of an olive brown, and the gas was diminished with great rapidity; in two
minutes, a quantity equal to four times the volume of the solution, had been
absorbed.
These facts convinced me that the solubility of nitrous gas in common
sulphate of iron, chiefly depended upon the pale green sulphate contained
by it; and that the attraction of one of the constituents of this substance, the

green oxide of iron, for oxygene, was one of the causes of the
phænomenon.
d. Green sulphate of iron rapidly decomposes nitric acid. It was
consequently difficult to conceive how any affinities existing between
nitrous gas, water, and green sulphate of iron, could produce the nitric acid
found in the experiments of Vauquelin and Humbolt.
To ascertain if the presence of a great quantity of water destroyed the
power of green sulphate of iron to decompose nitric acid, I introduced into a
cubic inch of solution of green sulphate of iron, two drops of concentrated
nitric acid.
The solution assumed a very light olive color; prussiate of potash
mingled with a little of it, gave a dark green precipitate. Hence the nitric
acid had been evidently decomposed. As no nitrous gas was given out,
which is always the case when nitric acid is poured on crystalised sulphate
of iron, I suspected that a compleat decomposition of the acid had taken
place; but when the solution was heated, a few minute globules of gas were
liberated, and it gradually became slightly clouded.
Having often remarked that no precipitation is ever produced during the
conversion of green sulphate of iron into red, by oxygenated muriatic acid,
or concentrated nitric acid, I could refer the cloudiness to no other cause
than to the formation of ammoniac.
To ascertain if this substance had been produced, a quantity of slacked
caustic lime was thrown into the solution. On the application of heat, the
ammoniacal smell was distinctly perceptible, and the vapor held over
orange nitrous acid, gave dense white fumes.
e. When I considered this fact of the decomposition of nitric acid and
water by the solution of green sulphate of iron, and the change of color
effected in it by the absorption of nitrous gas, exactly analogous to that
produced by the decomposition of nitric acid; I was induced to believe that
the nitric acid found in the analysis of Vauquelin and Humbolt, had been
formed by the combination of some of the nitrous gas thrown into the
solution with the oxygene of the atmosphere: and that the absorbability of
nitrous gas, by solution of green sulphate of iron, was owing to a
decomposition produced by the combination of its oxygene with the green

oxide of iron, and of its nitrogene with the hydrogene disengaged from
water, decompounded at the same time.
To ascertain this, I procured a quantity of nitrous gas: it was suffered to
remain in contact with water for some hours after its production.
Transferred to the mercurial apparatus, it gave no white vapor when placed
in contact with solution of ammoniac; and consequently held no nitric acid
in solution.
Into a graduated jar filled with mercury, a cubic inch of concentrated
solution of pure green sulphate of iron was introduced, and 7 cubic inches
of nitrous gas admitted to it. The solution immediately became dark olive at
the edges, and on agitation this color was diffused through it. In 3 minutes,
when near 5¾ cubic inches had been absorbed, the diminution ceased. The
solution was now of a bright olive brown, and transparent at the edges.
After it had rested for a quarter of an hour, no farther absorption was
observed; the color was the same, and no precipitation could be perceived.
A little of it was thrown into a small glass tube, under the mercury, and
examined in the atmosphere. Its taste was rather more astringent than that of
solution of green sulphate; it did not at all alter the color of red cabbage
juice. When a little of it was poured on the mercury, it soon lost its color, its
taste became acid, and it quickly reddened cabbage juice, even rendered
green by an alkali.
To the solution remaining in the mercurial jar, a small quantity of
prussiate of potash was introduced, to ascertain if any red sulphate of iron
had been formed; but instead of the production of either a blue, or a white
precipitate, the whole of the solution became opaque, and chocolate
colored.
Surprised at this appearance, I was at first induced to suppose, that the
ammoniac formed by the nitrogene of the nitrous gas and the hydrogene of
the water, had been sufficient to precipitate from the sulphuric acid, the red
oxide of iron produced, and that the color of the mixture was owing to this
precipitation. To dissolve any uncombined oxide that might exist in the
solution, I added a very minute quantity of diluted sulphuric acid; but little
alteration of color was produced. Hence, evidently, no red oxide had been
formed.

This unexpected result obliged me to theorise a second time, by
supposing that nitrate of ammoniac had been produced, which by
combining with the white prussiate of iron, generated a new combination.
But on mingling together green sulphate of iron, prussiate of potash, and
nitrate of ammoniac in the atmosphere, the mixture remained perfectly
white.
To ascertain if any nitric acid existed, combined with any of the bases,
in the impregnated solution, I introduced into it an equal bulk of diluted
sulphuric acid: it became rather paler; but no green or blue tinge was
produced.
That the prussic acid had not been decomposed, was evident from the
bright green produced, when less than a grain of dilute nitric acid was
admitted into the solution.
f. From these experiments it was evident, that no red sulphate of iron, or
nitric acid, and consequently no ammoniac, had been produced after the
absorption of nitrous gas by green sulphate of iron. And when I compared
them with the observations of Priestley, who had expelled by heat a minute
quantity of nitrous gas from an impregnated solution of common sulphate
of iron, and who found common air phlogisticated by standing in contact
with it, I began to suspect that nitrous gas was simply dissolved in the
solution, without undergoing decomposition.
g. To determine more accurately the nature of the process, I introduced
into a mercurial cylinder 410 grains of solution of green sulphate of iron,
occupying a space nearly equal to a cubic inch and quarter; it was saturated
with nitrous gas, by absorbing 8 cubic inches. This saturated solution
exhibited the same appearance as the last; and after remaining near an hour
untouched, had evidently deposited no oxide of iron, nor gained any acid
properties.
Into a small mattrass filled with mercury, having a tight stopper with a
curved tube adapted to it, the greater part of this solution was introduced;
judging from the capacity of the mattrass, about 50 grains of it might have
been lost. To prevent common air from coming in contact with the solution,
the stopper was introduced into the mattrass under the mercury; the curved
tube connected with a graduated cylinder filled with that substance; and the
mattrass brought over the side of the mercurial trough. But in spite of these

precautions a large globule of common air got into the top of the mattrass,
from the curvature of the tube. When the heat of a spirit lamp was applied
to the solution, it gave out gas with great rapidity, and gradually lost its
color. When 5 cubic inches were collected it became perfectly pale green,
whilst a yellow red precipitate was deposited on the bottom of the mattrass.
On pouring a little of the clear solution into prussiate of potash, it gave
only white prussiate of iron.
But on introducing a particle of sulphuric acid into the solution,
sufficient to dissolve some of the red precipitate, and then pouring a little of
it into a solution of prussiate of potash, it gave a fine blue prussiate of iron.
Hence the red precipitate was evidently red yellow oxide of iron.
I now examined the gas, suspecting that it was nitrous oxide. On
mingling a little of it with atmospheric air, it gave red vapor, and
diminished. Solution of sulphate of iron introduced to the remainder, almost
wholly absorbed it: the small residual globule of nitrogene could not equal
one thirtieth of a cubic inch.
Consequently it was nitrous gas, nearly pure.
Caustic potash was now introduced into the solution, till all the oxide of
iron was precipitated. The solution, when heated, gave a strong smell of
ammoniac, and dense white fumes when held over muriatic acid. It was
kept at the heat of ebullition till the evaporation had been nearly
compleated. Sulphuric acid poured upon the residuum gave no yellow
fumes, or nitric acid vapor in any way perceptible; even when heated and
made to boil, there was no indication of the production of any vapor, except
that of the sulphuric acid.
h. This experiment, compared with the others, seemed almost to prove,
that nitrous gas combined with solution of pale green sulphate of iron, at the
common temperature, without decomposition; and that when the
impregnated solution was heated, the greater portion of gas was disengaged,
whilst the remainder was decompounded by the green oxide of iron; which
attracted at the same time oxygene from the water and the nitrous gas;
whilst their other constituent principles, hydrogene and nitrogene, entered
into union as ammoniac.

Whilst, however, I was reasoning upon this singular chemical change,
as affording presumptive proofs in favor of the exertion of simple affinities
by the constituent parts of compound substances, a doubt concerning the
decomposition of the nitrous gas occurred to me. As near as I could guess at
the quantity of nitrous gas contained by the impregnated solution, at least ¾
of it must have been expelled undecompounded.
More than a quarter of a cubic inch of common air had been present in
the mattrass: the oxygene of this common air must have combined with the
nitrous gas, to form nitric acid. Might not this nitric acid have been
decomposed, and furnished oxygene to the red oxide of iron, and nitrogene
to the small quantity of ammoniac found in the solution, as in d?
i. I now introduced to a solution of green sulphate confined by mercury,
nitrous gas, perfectly free from nitric acid. When the solution was saturated,
a portion of it was introduced into a small mattrass filled with dry mercury,
in the mercurial trough. The curved tube was closed by a small cork at the
top, and filled with nitrous gas; it was then adapted to the mattrass, which
was raised from the trough, and the solution thus effectually preserved from
the contact of the atmosphere.
When the heat of a spirit lamp was applied to the mattrass, it began to
give out gas with great rapidity. After some time the solution lost its dark
color, and became turbid. When the production of nitrous gas had ceased, it
was suffered to cool. A copious red precipitate had fallen down; which,
examined by the same tests as in the last experiment, proved to be red oxide
of iron.
The solution treated with lime, as before, gave ammoniac; but with
sulphuric acid, not the slightest indications of nitric acid.
k. Having thus procured full evidence of the decomposition of nitrous
gas in the heated solution, in order to gain a more accurate acquaintance
with the affinities exerted, I endeavoured to ascertain the quantity of nitrous
gas decomposed by a given solution, under known circumstances.
Into a cylinder of the capacity of 20 cubic inches, inverted in mercury,
1150 grains of solution of green sulphate of iron, of specific gravity 1,4,
were introduced. Nitrous gas was admitted to it, and after some time 21
cubic inches were absorbed.

The impregnated solution was thrown into a mattrass, in the same
manner as in the last experiment, and the same precautions taken to
preserve it from the contact of atmospheric air. A quantity was lost during
the process of transferring, which, reasoning from the space occupied in the
mattrass by the remaining portion, as determined by experiment afterwards,
must have amounted nearly to 240 grains.
The curved tube from the mattrass was now made to communicate with
the mercurial airholder. By the application of heat 12,5 cubic inches of
nitrous gas were collected, after the common temperature had been restored
to the mattrass; which was suffered to remain in communication with the
conducting tube.
The solution was now pale green, that is, of its natural color, and a
considerable quantity of red oxide of iron had been deposited.
Solid caustic potash was introduced into it, till all the green oxide of
iron had been precipitated, and till the solution rendered green, red cabbage
juice.
A tube was now accurately connected with the mattrass, bent, and
introduced into a small quantity of diluted sulphuric acid. Nearly half of the
fluid in it was slowly distilled into the sulphuric acid, by the heat of a spirit
lamp. The impregnated acid evaporated at a heat above 212°, and gave a
small quantity of crystalised salt, which barely amounted to two grains and
quarter: it had every property of sulphate of ammoniac. Sulphuric acid in
excess was poured on the residuum, and the whole distilled by a heat not
exceeding 300°, into a small quantity of water. This water, after the process,
tasted strongly of sulphuric acid; it had no peculiar odor. Tin thrown into it
when heated, was not perceptibly oxydated; mingled with strontitic lime
water, it gave a copious white precipitate, and after the precipitation became
almost tasteless. Hence it evidently contained no nitric acid.
The 12,5 cubic inches of undecompounded gas that came over were
examined; and accounting for the small quantity of common air previously
contained in the airholder, must have been almost pure.
l. Now supposing 927 grains of the impregnated solution (including the
weight of the nitrous gas), to have been operated upon, this must have
contained about 16,7 cubic inches of nitrous gas. But 12,5 cubic inches

escaped undecompounded: hence 4,2 were decomposed; and these weigh
1,44 grains, and are composed of,8 oxygene, and,64 nitrogene.[117]
Consequently, the nitrous gas must have furnished,8 of oxygene to the
green oxide of iron.
But,64 of nitrogene require,15 of hydrogene to form,79 of ammoniac:
[118]
consequently 1 of water was decompounded, and this furnished,85 of
oxygene to the green oxide of iron.
The green oxide of iron contains ²⁷/₁₀₀ oxygene; the red ⁴⁸/₁₀₀. But the
whole quantity of oxygene supplied from the water and nitrous gas is 0,8 +
0,85 = 1,65; and calculating on the difference of the composition of the red
and green oxide of iron, 5,7 grains of red oxide must have been deposited,
and consequently these would saturate as much acid as,79 grains of
ammoniac, or 4,1 grains of green oxide of iron.[119]
And supposing the ammoniac in sulphate of ammoniac to be to the acid
as 1 is to 3,[120] 3.2 grains of sulphate of ammoniac must have been formed,
containing about 2,4 grains acid; and then 6,5 grains of green sulphate of
iron must have been decomposed.
Hence we gain the following equation:
6,5 green s. = 2,41 sul. acid + 4,1 gr. ox. iron.
+
1,44 nit. gas = ,64 nitrogene + ,8 oxygene.
+
1 water = ,85 oxygene, + ,15 hydrogene,

equal

3,2 sul. am. = 2,41 s. acid + ,64 nit. + ,15 hyd.
+
5,7 r. ox. iron = 4,1 gr. ox. iron + 1,6 oxyg.
Though the estimation of the quantities in this equation must not be
considered as strictly accurate, on account of the degree of uncertainty that
remains concerning the exact numerical expression of the quantities of the

constituents of water, ammoniac, and the other compound bodies employed;
yet as founded on a simple quantity, that is, the nitrous gas decomposed, it
cannot be very distant from the truth.
The sulphate of ammoniac given by experiment, is considerably less
than that which was really produced; much of it was probably carried off
during the evaporation of the superabundant acid.
The conclusions that may be drawn from this experiment, afford a
striking instance of the importance of the application of the science of
quantity to the chemical changes: for the data being one chemical fact, the
decomposition of a given quantity of nitrous gas by known agents; the
composition of nitrous gas, of water, ammoniac, the oxides of iron, and
sulphate of ammoniac; we are able not only to determine the quantities of
the simple constituents that have entered into new arrangements, but
likewise the composition of two compound bodies, the green and red
sulphates of iron.[121]
m. Though from the experiments in e it appeared that no decomposition
of nitrous gas had been produced during or even after its absorption by
solution of sulphate of iron at the common temperature; yet a suspicion that
it might take place slowly, and that indications of it might be given by
deposition, induced me to examine minutely two impregnated solutions,
one of which had been at rest, confined by mercury, for 19 hours, and the
other for 27. In neither of them could I discover any deposition, or
alteration of color, which might denote a change.
Two cubic inches of oxygene were admitted to half a cubic inch of one
of these solutions. The oxygene was slowly absorbed, and the solution
gradually lost its color.
To ascertain if during the conversion of the nitrous gas held in solution
by sulphate of iron, into nitric acid, by the oxygene of the atmosphere at the
common temperature, any water was decomposed; I suffered an
impregnated solution, weighing nearly two ounces, to remain in contact
with the atmosphere at 57°-62°, till it was become perfectly pale. It then
had a strong acid taste, effervesced with carbonate of potash, and gave a
blue precipitate with prussiate of potash.—It was saturated with quicklime,
and heated: slight indications of the presence of ammoniac were perceived.

As in this experiment the nitric acid had been most probably
decomposed by the green oxide of iron, as in f, I sent oxygenated muriatic
acid through an impregnated solution, till all the green oxide of iron was
converted into red, and all the nitrous gas into nitric acid.
This solution saturated with potash, and heated, gave no ammoniacal
smell.
From these experiments we may conclude,
1st. That solution of red sulphate of iron has little or no affinity for
nitrous gas[122]; and that solution of common sulphate absorbs nitrous gas
only in proportion as it contains green sulphate.
2dly. That solutions of green sulphate of iron dissolve nitrous gas in
quantities proportionable to their concentration, without effecting any
decomposition of it at common temperatures. And the solubility of nitrous
gas in solution of green sulphate, may be supposed to depend on an
equilibrium of affinity, produced by the following simple attractions:
1. That of green oxide of iron for the oxygene of nitrous
gas and water.
2. That of the hydrogene of the water for the nitrogene of
the nitrous gas.
3. That of the principles of the sulphuric acid, for
nitrogene and hydrogene.
3dly. That at high temperatures, that is, from 200° to 300°, the
equilibrium of affinity producing the binary combination between nitrous
gas and solution of green sulphate of iron is destroyed; the attraction of the
green oxide of iron for oxygene being increased; whilst probably that of
nitrogene for hydrogene is diminished.
Hence the nitrous gas is either liberated,[123] in consequence of the
affinity between oxygene and hydrogene, and oxygene and nitrogene not
following the same ratio of alteration on increased temperature; or
decomposed, because at a certain temperature the green oxide exerts such
affinities upon water and nitrous gas, as to attract oxygene from both of
them to form red oxide; whilst the still existing affinity between the

hydrogene of the one, and the nitrogene of the other, disposes them to
combine to form ammoniac.
4thly. That the change of color produced by introducing nitric acid to
solution of common sulphate of iron, exactly analogous to that occasioned
in it by impregnation with nitrous gas, is owing to the decomposition of the
acid, by the combination of its oxygene with the green oxide of iron, and of
its nitrous gas with the solution.
5thly. That nitrous gas in combination with solution of green sulphate of
iron, is capable of exerting a strong affinity upon free or loosely combined
oxygene, and of uniting with it to form nitric acid.
n. The products obtained from a solution of sulphate of iron saturated
with nitrous gas, by Vauquelin and Humbolt, and their consequent mistake
with regard to the nature of the process of absorption,[124] must have arisen
from exposure of their impregnated solution to the atmosphere.
Indeed, from the acidity of it, on examination, from the small portion of
ammoniac, and the large quantity of nitric acid obtained, it appears most
probable that the whole of the nitrous gas employed was converted into
nitric acid, by combining with atmospheric oxygene; for no nitric acid
could have been obtained in the mode in which they operated, unless the
green oxide of iron in the solution had been previously converted into red.

VIII. On the absorption of Nitrous Gas by
solution of green Muriate of Iron.
a. The analogy between the affinities of the constituents of the muriate
and sulphate of iron, induced me to conjecture that they possessed similar
powers of absorbing nitrous gas; and I soon found that this was actually the
case; for on agitating half a cubic inch of solution of muriated iron,
procured by dissolving iron filings in muriatic acid, in nitrous gas, the gas
was absorbed with great rapidity, whilst the solution assumed a deep and
bright brown tinge.
b. Proust,[125] who as I have before mentioned, supposes the existence
of two oxides of iron only, one containing ²⁷/₁₀₀ oxygene, the other ⁴⁸/₁₀₀,
has assumed, that the muriatic acid, and most other acids as well as the
sulphuric, are capable of combining with these oxides, and of forming with

each of them a distinct salt. He has, however, detailed no experiments on
the muriates of iron.
As these salts are still more distinct from each other in their properties
than the sulphates, and as these properties are connected with the
phænomenon of the absorption and decomposition of nitrous gas, I shall
detail the observations I have been able to make upon them.
c. When iron filings have been dissolved in pure muriatic acid, and the
solution preserved from the contact of air, it is of a pale green color, and
gives a white precipitate with alkaline prussiates. The alkalies throw down
from it a light green oxide of iron.
When evaporated, it gives crystals almost white, which are extremely
soluble in water; but insoluble in alcohol.
The solution of green muriate of iron has a great affinity for oxygene,
and attracts it from the atmosphere, from nitric acid, and probably from
oxygenated muriatic acid.
When red oxide of iron is dissolved in muriatic acid, or when nitric acid
is decomposed by solution of green muriate of iron; the red muriate of iron
is produced. The solution of this salt is of a deep brown red, its odor is
peculiar, and its taste, even in a very diluted state, highly astringent. It acts
upon animal and vegetable matters in a manner somewhat analogous to the
oxygenated muriatic acid, rendering them yellowish white, or yellow.[126]
Sulphuric acid poured upon it, produces a smell resembling that of
oxygenated muriatic acid. Evaporated at a low temperature, it gives an
uncrystalisable dark, orange colored salt, which is soluble in alcohol, and
when decomposed by the alkalies, gives a red precipitate. With prussiate of
potash it gives prussian blue.
The common muriate of iron consists of different proportions of these
two salts. It may be converted into red muriate by concentrated nitric acid,
or into green by sulphurated hydrogene.
d. To ascertain if solution of red muriate of iron was capable of
absorbing nitrous gas, I introduced into a jar filled with mercury, a cubic
inch of nitrous gas, and admitted to it nearly half a cubic inch of solution of
red muriate of iron. No discoloration took place. By much agitation,

however, an absorption of nearly,2 was produced, and the solution became
of a muddy green. But this change of color, and probably the absorption,
was in consequence of the oxydation of either the mercury, or some
imperfect metals combined with it, by the oxygene of the red muriate. For I
afterwards found, that precisely the same change of color was produced
when a solution was agitated over mercury.
e. I introduced to a cubic inch of concentrated solution of green muriate
of iron, 7 cubic inches of nitrous gas, free from nitric acid; the solution
instantly became colored at the edges, and on agitation absorbed the gas
with much greater rapidity than even sulphate of iron; in a minute, only a
quarter of a cubic inch remained.
The solution appeared of a very dark brown, but evidently no
precipitation had taken place in it, and the edges, when viewed against the
light, were transparent and puce colored.
Five cubic inches more of nitrous gas were now dissolved in the
solution. The intensity of the color increased, and after an hour no
deposition had taken place. A little of it was then examined in the
atmosphere; it had a much more astringent taste than the unimpregnated
solution, and effected no change in red cabbage juice. When prussiate of
potash was introduced into it, its color changed to olive brown. A few drops
of the solution, that had accidentally fallen on the mercury, soon became
colorless, and then effervesced with carbonate of potash, and tasted strongly
acid.
The remainder of the impregnated solution, which must have nearly
equalled,75 cubic inches, was introduced into a mattrass, having a stopper
and curved tube, as in the experiments on the solution of sulphate of iron;
great care being taken to preserve it from the contact of air.
The mattrass was heated by a spirit lamp, the curved tube being in
communication with a mercurial cylinder. Near 8 cubic inches of nitrous
gas were collected, when the solution became of a muddy yellow. It was
suffered to cool, and examined. A small quantity of yellow precipitate
covered the bottom of the mattrass; the fluid was pellucid, and light green.
A little of it thrown on prussiate of potash, gave a white precipitate, colored
by streaks of light blue. When the yellow precipitate was partly dissolved

by sulphuric acid, a drop of the solution, mingled with prussiate of potash,
gave a deep blue green.
Hence, evidently, the precipitate was red oxide of iron.
Caustic potash in excess was introduced into the remainder of the
solution, and it was heated. It gave an evident smell of ammoniac, and
dense white fumes, when held over strong phlogisticated nitrous acid.
When half of it was evaporated, sulphuric acid in excess was poured on
the remainder; muriatic acid was liberated, not perceptibly combined with
any nitric acid.
f. In an experiment that I made to ascertain the quantity of nitrous gas
capable of combining with solution of green muriate of iron; I found that,75
cubic inches of saturated solution absorbed about 18 of nitrous gas, which is
nearly double the quantity combinable with an equal portion of the
strongest solution of sulphate of iron. A part of this impregnated solution,
heated slowly, gave out more gas in proportion to the quantity it contained,
than the last, and consequently produced less precipitate; so that I am
inclined to suppose it probable, that at a certain temperature, all the
dissolved nitrous gas may be dispelled from a solution.
From these experiments we may conclude,
1st. That the solution of green muriate of iron absorbs nitrous gas in
consequence of nearly the same affinities as solution of green sulphate of
iron; its capability of absorbing larger quantities depending most probably
on its greater concentration (that is, on the greater solubility of the muriate
of iron), and perhaps, in some measure, on a new combining affinity, that of
muriatic acid for oxygene.
2dly. That at certain temperatures nitrous gas is either liberated from
solution of green muriate, or decomposed, by the combination of its
oxygene with green oxide of iron, and of its nitrogene with hydrogene,
produced from water decompounded by the oxide at the same time.

IX. Absorption of Nitrous Gas by
Solution of Nitrate of Iron.

a. As well as two sulphates and two muriates of iron, there exist two
nitrates.[127] When concentrated nitric acid is made to act upon iron, nitrous
gas is disengaged with great rapidity, and with great increase of
temperature: the solution assumes a yellowish tinge, and as the process goes
on, a yellow red oxide is precipitated.
Nitrate of iron made in this way, gives a bright blue mingled with
prussiate of potash, and decomposed by the alkalies, a red precipitate. Its
solution has little or no affinity for nitrous gas.
b. When very dilute nitric acid, that is, such as of specific gravity 1,16,
is made to oxydate iron, without the assistance of heat, the solution gives
out no gas for some time, and becomes dark olive brown: when neutralised
it gives, decomposed by the alkalies, a light green precipitate; and mingled
with prussiate of potash, pale green prussiate of iron.
It owes its color to the nitrous gas it holds in solution. By exposure to
the atmosphere it becomes pale, the nitrous gas combined with it being
converted into nitric acid.
It is then capable of absorbing nitrous gas, and consists of pale nitrate of
iron, mingled with red nitrate.
I have not yet obtained a nitrate of iron giving only a white precipitate
with prussiate of potash, that is, such as contains only oxide of iron at its
minimum of oxydation; for when pure green oxide of iron is dissolved by
very dilute nitric acid, a small quantity of the acid is generally decomposed,
which is likewise the case in the decomposition of nitre by green sulphate
of iron. The solutions of nitrate of iron, however, procured in both of these
modes, absorb nitrous gas with rapidity, and by sulphurated hydrogene
might probably be converted into pale nitrate.
As it is impossible to obtain concentrated solutions of pale nitrate of
iron, chiefly containing green oxide, its powers of absorbing nitrous gas
cannot be compared with the muriatic and sulphuric solutions, unless they
are made of nearly the same specific gravity.
Nitrous gas is disengaged by heat from the impregnated solution of
nitrate of iron, at the same time that much red oxide of iron is precipitated.
Whether any nitrous gas is decomposed, I have not yet ascertained; for
when unimpregnated pale nitrate of iron is heated, a part of the acid, and of

the water of the solution, is decomposed by the green oxide of iron;[128] and
in consequence ammoniac, and red nitrate of iron formed, whilst red oxide
is precipitated.

X. Absorption of Nitrous Gas by other
Metallic Solutions.
a. White prussiate of iron in contact with water absorbs nitrous gas to a
great extent, and becomes dark chocolate.[129]
b. Concentrated solution of sulphate of tin, probably at its minimum of
oxydation, absorbs one eighth of its bulk of nitrous gas, and becomes
brown, without deposition.
c. Solution of sulphate of zinc absorbs about one tenth of its volume of
nitrous gas, and becomes green.
d. Solution of muriate of zinc[130] absorbs nearly the same quantity, and
becomes orange brown.
e. These are all the metallic substances on which I have experimented. It
is more than probable that there exist others possessing similar powers of
absorbing nitrous gas.
Whenever the metals capable of decomposing water exist in solutions at
their minimum of oxydation, the affinities exerted by them on nitrous gas
and water, will be such as to produce combination. The powers of metallic
solutions to combine with nitrous gas at common temperatures, as well as to
decompose it at higher temperatures, will probably be in the ratio of the
affinity of the metallic oxides they contain, for oxygene.

XI. The action of Sulphurated Hydrogene on solution of
Green Sulphate of Iron, impregnated with Nitrous Gas.
a. In an experiment on the absorption of nitrous gas by solution of green
sulphate of iron, I introduced an unboiled solution of common sulphate,
deprived of red oxide of iron by sulphurated hydrogene, into a jar filled
with nitrous gas; the absorption took place as usual, and nearly six of gas
entered into combination, the volume of the solution being unity. On
applying heat to a part of this impregnated solution, the whole of the nitrous

gas it contained (as nearly as I could guess), was expelled
undecompounded, and no yellow precipitate produced. Prussiate of potash
poured into it gave only white prussiate of iron; and when it was heated
with lime, no ammoniacal smell was perceptible.
I could refer this phænomenon to no other cause than to the existence of
a small quantity of sulphurated hydrogene in the solution. That this was the
real cause I found from the following experiment.
b. One part of a solution of green sulphate of iron, formed by the
agitation of common sulphate of iron in contact with sulphurated
hydrogene, was boiled for some minutes to expel the small quantity of gas
retained by it undecompounded. It had then no peculiar smell, and gave a
white prussiate of iron with prussiate of potash; the other part had a faint
odor of sulphurated hydrogene, and gave a dirty white precipitate with
prussiate of potash. Nearly equal quantities of each were saturated with
nitrous gas, and heated. The unboiled impregnated solution gave out all its
nitrous gas undecompounded; whilst in the boiled solution it was partly
decomposed, yellow precipitate and ammoniac being formed.
c. This singular phænomenon of the power of a minute quantity of
sulphurated hydrogene, in preventing the decomposition of nitrous gas and
water, by green oxide of iron, will most probably take place in other
impregnated solutions. It seems to depend on the strong affinity of the
hydrogene of sulphurated hydrogene for oxygene.

XII. Additional Observations.
a. For separating nitrous gas from gases absorbable to no great extent by
water; a well boiled solution of green muriate of iron should be employed.
Nitrous gas agitated in this is rapidly absorbed, and it has no affinity for, or
action on, nitrogene, hydrogene, or hydrocarbonate.
b. Nitrous gas carefully obtained from mercury and nitric acid, when
received under mercury, or boiled water, and absorbed by solution of green
muriate, or sulphate of iron, rarely leaves a residuum of ¹/₂₀₀ of its volume:
preserved over common water, and absorbed, the remainder is generally
from ¹/₄₀ to ¹/₉₀, from the nitrogene disengaged by the decomposition of the
common air contained in the water.

c. The nitrous gas carefully obtained from the decomposition of nitric
acid of 1,26, by copper, I have hardly ever found to contain more than from
¹/₃₀ to ¹/₅₀ nitrogene, when received through common water: when boiled
water is employed, the residuum is nearly the same as that of nitrous gas
obtained from mercury.
d. Consequently the gas from those two solutions may be used in
common. It is more than probable, that the small quantities of nitrogene
generally mingled with nitrous gas from copper and mercury, arise either
from the common air of the vessels in which it was produced, or that of the
water over which it was received. There is no reason for supposing that it is
generated by a complete decomposition of a portion of the acid.[131]
e. Whenever nitrous oxide is mingled with nitrous gas and nitrogene, it
must be separated by well boiled water; and after the corrections are made
for the quantity of air disengaged from the water, the nitrous gas absorbed
by the muriatic solution.

DIVISION V.

EXPERIMENTS and OBSERVATIONS on the production of
NITROUS OXIDE from NITROUS GAS and NITRIC ACID, in
different modes.
I. Preliminaries.
a.

T
[132]
he opinions of Priestley and Kirwan,[133] relating to the causes of
the conversion of nitrous gas into nitrous oxide, were founded on the
theory of phlogiston. The first of these philosophers obtained nitrous oxide
by placing nitrous gas in contact with moistened iron filings, or the alkaline
sulphures. The last by exposing it to sulphurated hydrogene.
The Dutch chemists,[134] the latest experimentalists on nitrous oxide,
have supposed that the production of this substance depends upon the
simple abstraction of a portion of the oxygene of nitrous gas. They obtained
nitrous oxide by exposing nitrous gas to muriate of tin, to copper in solution
of ammoniac, and likewise by passing it over heated sulphur.

The diminution of volume sustained by nitrous gas during its
conversion into nitrous oxide, has never been accurately ascertained; it has
generally been supposed to be from two thirds to eight tenths.
b. Nitrous gas may be converted into nitrous oxide in two modes.
First, by the simple abstraction of a portion of its oxygene, by bodies
possessing a strong affinity for that principle, such as alkaline sulphites,
muriate of tin, and dry sulphures.
Second, by the combination of a body with a portion both of its oxygene
and nitrogene, such as hydrogene, when either in a nascent form, or a
peculiar state of combination.
c. Each of these modes will be distinctly treated of; and to prevent
unnecessary repetitions, I shall give an account of the general manner in
which the following experiments on the conversion of nitrous gas into
nitrous oxide, have been conduced.
Nitrous gas, the purity of which has been accurately ascertained by
solution of muriate of iron, is introduced into a graduated jar filled with dry
mercury. If a fluid substance is designed for the conversion of the gas into
nitrous oxide, it is heated, to expel any loosely combined air which might
be liberated during the process; and then carefully introduced into the jar,
by means of a small phial. After the process is finished, and the diminution
accurately noted, the nitrous oxide formed is absorbed by pure water. If any
nitrous gas remains, it is condensed by solution of muriate of iron; other
residual gases are examined by the common tests. The quantity of nitrous
oxide dissolved by the fluid is determined by a comparative experiment;
and the corrections for temperature and pressure being guessed at, the
conclusions drawn.
If a solid substance is used, rather more nitrous gas than that designed
for the conversion, is introduced into the jar. The substance is brought in
contact with the gas, by being carried under the mercury; and as a little
common air generally adheres to it, a small portion of the nitrous gas is
transferred into a graduated tube, after the insertion, and its purity
ascertained. In other respects the process is conducted as mentioned above.

II. Of the conversion of Nitrous gas into Nitrous Oxide,
by Alkaline Sulphites.
The alkaline sulphites, particularly the sulphite of potash, convert
nitrous gas into nitrous oxide, with much greater rapidity than any other
bodies.
At temperature 46°, 16 cubic inches of nitrous gas were converted, in
less than an hour, into 7,8 of nitrous oxide, by about 100 grains of
pulverised sulphite of potash, containing its water of crystalisation. No
sensible increase of temperature was produced during the process, no water
was decomposed, and the quantity of nitrogene remaining after the
experiment, was exactly equal to that previously contained in the nitrous
gas.
The nitrous oxide produced from nitrous gas by sulphite of potash, has
all the properties of that generated from the decomposition of nitrate of
ammoniac. It gives, as will be seen hereafter, the same products by analysis.
Phosphorus, the taper, sulphur, and charcoal, burn in it with vivid light. It is
absorbable by water, and capable of expulsion from it unaltered, by heat.
Nitrous gas is converted into nitrous oxide by the alkaline sulphites with
the same readiness, whether exposed to the light, or deprived of its
influence.
The solid sulphites act upon nitrous gas much more readily than their
concentrated solutions; they should however always be suffered to retain
their water of crystalisation, or otherwise they attract moisture from the gas,
and render it drier, and in consequence more condensed than it would
otherwise be. In case perfectly dry sulphites are employed, the gas should
be always saturated with moisture after the experiment, by introducing into
the cylinder a drop of water.
The sulphites, after exposure to nitrous gas, are either found wholly, or
partially, converted into sulphates. Consequently the conversion of nitrous
gas into nitrous oxide by these bodies, simply depends on the abstraction of
a portion of its oxygene; the nitrogene and remaining oxygene assuming a
more condensed state of existence.
If we reason from the different specific gravities of nitrous oxide and
nitrous gas, as compared with the diminution of volume of nitrous gas,

during its conversion into nitrous oxide, 100 parts of nitrous gas, supposing
the former estimation of the composition of nitrous oxide given in Division
III, accurate, would consist of 54 oxygene, and 46 nitrogene; which is not
far from the true estimation. Or assuming the composition of nitrous gas, as
given in Division IV, it would appear from the diminution, that 100 parts of
nitrous oxide consisted of 38 oxygene, and 62 nitrogene.

III. Conversion of Nitrous Gas into Nitrous Oxide,
by Muriate of Tin, and dry Sulphures.
a. Nitrous gas exposed to dry muriate of tin, is slowly converted into
nitrous oxide: during this process the apparent diminution is to about one
half; but if the products are nicely examined, and the necessary corrections
made, the real diminution of nitrous gas by muriate of tin, will be the same
as by the sulphites; that is, 100 parts of it will be converted into 48 of
nitrous oxide.
During this conversion, no water is decomposed, and no nitrogene
evolved. Solution of muriate of tin converts nitrous gas into nitrous oxide;
but with much less rapidity than the solid salt.
b. Nitrous gas exposed to dry and perfectly well made sulphures,
particularly such as are produced from crystalised alumn[135] and charcoal
not sufficiently inflammable to burn in the atmosphere, is converted into
nitrous oxide by the simple abstraction of a portion of its oxygene, and
consequently undergoes a diminution of ⁵²/₁₀₀.
It is probable, that all the bodies having strong affinity for oxygene will,
at certain temperatures, convert nitrous gas into nitrous oxide. Priestley, and
the Dutch chemists, effected the change by heated sulphur. Perhaps nitrous
gas sent through a tube heated, but not ignited, with phosphorus, would be
converted into nitrous oxide.

IV. Decomposition of Nitrous Gas, by Sulphurated Hydrogene.
a. When nitrous gas and sulphurated hydrogene are mingled together, a
decomposition of them slowly takes place. The gases are diminished,
sulphur deposited, nitrous oxide formed, and signs of the production of
ammoniac[136] and water perceived.

In this process no sulphuric, or sulphureous acid is produced;
consequently none of the sulphur is oxydated, and of course the changes
depend upon the combination of the hydrogene of the sulphurated
hydrogene, with different portions of the oxygene and nitrogene of the
nitrous gas, to form water and ammoniac, the remaining oxygene and
nitrogene assuming the form of nitrous oxide.
This singular exertion of attractions by a simple body, appears highly
improbable a priori, nor did I admit it, till the formation of ammoniac, and
the non-oxygenation of the sulphur, were made evident by many
experiments.
In those experiments, the diminution of the nitrous gas was not
uniformly the same. It varied from ¹¹/₂₀ to ¹⁴/₂₀. In the most accurate of
them, 5 cubic inches of nitrous gas were converted into 2.2 of nitrous oxide.
Consequently the quantity of ammoniac formed was,047 grains.
In experiments on the conversion of nitrous gas into nitrous oxide, by
sulphurated hydrogene, the gases should be rendered as dry as possible. The
presence of water considerably retards the decomposition.
b. The sulphures[137] dissolved in water convert nitrous gas into nitrous
oxide. This decomposition is not, however, produced by the simple
abstraction of oxygene from the nitrous gas to form sulphuric acid. It
depends as well on the decomposition of the sulphurated hydrogene
dissolved in the solution, or liberated from it. In this process sulphur is
deposited on the surface of the fluid, sulphuric acid is formed, and the
diminution, making the necessary corrections, is nearly the same as when
free sulphurated hydrogene is employed.
It is extremely probable that sulphurated hydrogene, in combination
with the alkalies, as well as with water, is capable of being slowly
decomposed by nitrous gas.

V. Decomposition of Nitrous Gas by Nascent Hydrogene.
a. When nitrous gas, is exposed to wetted iron filings, a diminution of
its volume slowly takes place; and after a certain time, it is found converted
into nitrous oxide.
In this process ammoniac[138] is formed, and the iron partially oxydated.

The water in contact with the iron is decomposed by the combination of
its oxygene with that substance, and of its hydrogene with a portion of the
oxygene and nitrogene of the nitrous gas, to form water and ammoniac.
That the iron is not oxydated at the expence of the oxygene of the
nitrous gas, appears very probable from the analogy between this process,
and the mutual decomposition of nitrous gas and sulphurated hydrogene.
Besides, dry iron filings effect no change whatever in nitrous gas, at
common temperatures.
I have generally found about 12 of nitrous gas converted into 5 of
nitrous oxide in this process; which is not very different from the
diminution by sulphurated hydrogene. It takes place equally well in light
and darkness; but more rapidly in warm weather than in cold.
b. Nitrous gas exposed to a large surface of zinc, in contact with water,
is slowly converted into nitrous oxide; at the same time that ammoniac is
generated, and white oxide of zinc formed. This process appears to depend,
like the last, upon the decomposition of water by the affinities of part of the
oxygene and nitrogene of nitrous gas, for its hydrogene, to form ammoniac
and water; and by that of zinc for its oxygene. Zinc placed in contact with
water, and confined by mercury,[139] decomposes it at the common
temperature. Zinc, when perfectly dry, does not in the slightest degree act
upon nitrous gas.
I have not been able to determine exactly the diminution of volume of
nitrous gas, during its conversion into nitrous oxide by zinc. In one
experiment 20 measures of nitrous gas, containing about,03 nitrogene, were
diminished to 9, after an exposure of eight days to wetted zinc; but from an
accident, I was not able to ascertain the exact quantity of nitrous oxide
formed.
c. It is probable that most of the imperfect metals will be found capable
of oxydation, by the decomposition of water, when its hydrogene is
attracted by the oxygene and nitrogene of nitrous gas. I have this day (April
14, 1800), examined two portions of nitrous gas, one of which had been
exposed to copper filings, and the other to powder of tin, for twenty-three
days.

The gas that had been exposed to copper was diminished nearly two
fifths. The taper burnt in it with an enlarged flame, blue at the edges. Hence
it evidently contained nitrous oxide.
The nitrous gas in contact with tin had undergone a diminution of one
fourth only, and did not support flame.

VI. Miscellaneous Observations on the conversion
of Nitrous Gas into Nitrous Oxide.
a. Dr. Priestley found nitrous gas exposed to a mixture of iron filings
and sulphur, with water, converted after a certain time, into nitrous oxide.
Sulphurated hydrogene is always produced during the combination of iron
and sulphur, when they are in contact with water; and by the hydrogene of
this in the nascent state, the nitrous gas is most probably decomposed.
b. Green oxide of iron moistened with water, exposed to nitrous gas,
slowly gains an orange tinge, whilst the gas is diminished. Most likely it is
converted into nitrous oxide; but this I have not ascertained.
c. I exposed nitrous gas, to the following bodies over mercury for many
days, without any diminution, or apparent change in its properties. Alcohol,
saccharine matter, hydrocarbonate, sulphureous acid, and phosphorus.
d. Crystalised sulphate, and muriate of iron, absorb a small quantity of
nitrous gas, and become dark colored on the outside; but after this
absorption, (which probably depends on their water of crystalisation,) has
taken place, no change is effected in the gas remaining.
e. The power of iron to decompose water being much increased by
increase of temperature, nitrous gas is converted into nitrous oxide much
more rapidly when placed in contact with a surface of heated iron, than
when exposed to it at common temperatures. During the decomposition of
nitrous gas in this way, ammoniac[140] is formed.
f. The curious experiments of Rouppe,[141] on the absorption of gases by
charcoal, compared with the phænomena noticed in this Division, render it
probable that hydrogene in a state of loose combination with charcoal, will
be found to convert nitrous gas into nitrous oxide.

VII. Recapitulation of conclusions concerning the
conversion of Nitrous Gas into Nitrous Oxide.
a. Certain bodies having a strong affinity for oxygene, as the sulphites,
dry sulphures, muriate of tin, &c. convert nitrous gas into nitrous oxide, by
simply attracting a portion of its oxygene; whilst the remaining oxygene
enters into combination with the nitrogene, and they assume a more
condensed state of existence.
b. Nitrous gas is converted into nitrous oxide by hydrogene, in a
peculiar state of existence, as in sulphurated hydrogene; and that by a series
of very complex affinities. Both oxygene and nitrogene are attracted from
the nitrous gas by the hydrogene, in such proportions as to form water and
ammoniac, whilst the remaining oxygene and nitrogene[142] assume the
form of nitrous oxide.
c. Nitrous gas placed in contact with bodies, such as iron and zinc
decomposing water, is converted into nitrous oxide, at the same time that
ammoniac is formed. It is difficult to ascertain the exact rationale of this
process. For either the nascent hydrogene produced by the decomposition of
the water by the metallic substance may combine with portions of both the
oxygene and nitrogene of the nitrous gas; and thus by forming water and
ammoniac, convert it into nitrous oxide. Or the metallic substance may
attract at the same time oxygene from the water and nitrous gas, whilst the
nascent hydrogene of the water seizes upon a portion of the nitrogene of the
nitrous gas to form ammoniac.
The degree of diminution, and the analogy between this process and the
decomposition of nitrous gas by sulphurated hydrogene, render the first
opinion most probable.

VIII. The production of Nitrous Oxide during the
oxydation of Tin, Zinc, and Iron, in Nitric Acid.
a. Dr. Priestley discovered, that during the solution of tin, zinc, and iron,
in nitric acid, certain portions of nitrous oxide were produced, mingled with
quantities of nitrous gas, and nitrogene, varying in proportion as the acid
employed was more or less concentrated.

It has long been known that ammoniac is formed during the solution of
tin, zinc, and iron, in diluted nitric acid. Consequently, in these processes
water is decomposed.
I had designed to investigate minutely these phænomena, so as to
ascertain the quantities of water and acid decompounded, and of the new
products generated. But after going through some experiments on the
oxydation of tin without gaining conclusive results, the labor, and sacrifice
of time they demanded, obliged me to desist from pursuing the subject, till I
had completed more important investigations.
I shall detail the few observations which have occurred to me, relating
to the production of nitrous oxide from metallic solutions.
b. When tin is dissolved in concentrated nitric acid, such as of 1.4,
nitrous oxide is produced, mingled with generally more than twice its bulk
of nitrous gas. In this process but little free nitrogene is evolved, and the tin
is chiefly precipitated in the form of a white powder. If the solution, after
the generation of these products, is saturated with lime, and heated, the
ammoniacal smell is distinct.
When nitric acid of specific gravity 1.24, is made to act upon tin; in the
beginning of the process, nearly equal parts of nitrous gas and nitrous oxide
are produced; as it advances, the proportion of nitrous oxide to the nitrous
gas increases: the largest quantity of nitrous oxide that I have found in the
gas procured from tin is ¾, the remainder being nitrous gas and nitrogene.
When tin is oxydated in an acid of less specific gravity than 1.09, the
quantities of gas disengaged are very small, and consist of nitrogene,
mingled with minute portions of nitrous oxide, and nitrous gas.
Whenever I have saturated solutions of tin in nitric acid of different
specific gravities, with lime, and afterwards heated them, the ammoniacal
smell has been uniformly perceptible, and generally most distinct when
diluted acids have been employed.
c. When zinc is dissolved in nitric acid, whatever is its specific gravity,
certain quantities of nitrous oxide are produced.
Nitric acids of greater specific gravity than 1.2, act upon zinc with great
rapidity, and great increase of temperature. The gases disengaged from

these solutions consist of nitrous gas, nitrous oxide, and nitrogene; the
nitrous oxide rarely equals one third of the whole.
When nitric acid of 1,104 is made to dissolve zinc, the gas obtained in
the middle of the process consists chiefly of nitrous oxide. From such a
solution I obtained gas which gave a residuum of one sixth only when
absorbed by water. The taper burnt in it with a brilliant flame, and sulphur
with a vivid rose-colored light.
100 grains of granulated zinc, during their solution in 300 grains of
nitric acid, of 1,43, diluted with 14 times its weight of water, produced 26
cubic inches of gas. Of this gas ⁷/₃₆ were nitrous, ¹⁷/₃₆36 nitrous oxide, and
the remainder nitrogene. The solution saturated with lime and heated, gave
a distinct smell of ammoniac.
d. During the solution of iron in concentrated nitric acid, the gas given
out is chiefly nitrous; it is however generally mingled with minute
quantities of nitrous oxide. When very dilute nitric acids are made to act
upon iron, by the assistance of heat, nitrous oxide is produced in
considerable quantities, mingled with nitrous gas and nitrogene; the
proportions of which are smaller as the process advances.[143] The fluid
remaining after the oxydation and solution of iron in nitric acid, always
contains ammoniac.
e. As during the solution of tin, zinc, and iron, in nitric acid, the quantity
of acid is diminished in proportion as the process advances, it is reasonable
to suppose that the relative quantities of the gases evolved are perpetually
varying. In the beginning of a dissolution, the nitrous gas generally
predominates, in the middle nitrous oxide, and at the end nitrogene.
f. During the generation of nitrous gas, nitrous oxide, and ammoniac,
from the decomposition of solution of nitric acid in water, by tin, zinc, and
iron, very complex attractions must exist between the constituents of the
substances employed. The acid and the water are decomposed at the same
time, and in proportions different as the solution is more concentrated, by
the combination of their oxygene with the metallic body.
The nitrous gas is produced by the combination of the metal with ³²/₁₀₀
of the oxygene of the acid. The nitrous oxide is most probably generated by
the decomposition of a portion of the nitrous gas disengaged, by the nascent

hydrogene of the water decompounded; some of it may be possibly formed
from a more complete decomposition of the acid.
The production of ammoniac may arise, probably from two causes;
from the decomposition of the nitrous gas by the combination of the nascent
hydrogene of the water, with portions of its oxygene and nitrogene at the
same time; and from the union of hydrogene with nascent nitrogene
liberated in consequence of a complete decomposition of part of the acid.

IX. Additional Observations on the production
of Nitrous Oxide.
a. When nitric acid is combined with muriatic acid, or sulphuric acid,
[144]
the quantities of nitrous oxide produced from its decomposition by tin,
zinc, and iron, are rather increased than diminished. The nitrous oxide
obtained from these solutions is, however, never sufficiently pure for
physiological experiments. It is always mingled with either nitrous gas,
nitrogene, or hydrogene, and sometimes with all of them.
b. From the solutions of bismuth, nickel, lead, and copper, in diluted
nitric acid, I have never obtained any perceptible quantity of nitrous oxide:
the gas produced is nitrous, mingled with different portions of nitrogene.
Antimony and mercury, during their solution in aqua regia, give out only
nitrous gas.
Probably none of the metallic bodies, except those that decompose
water at temperatures below ignition, will generate nitrous oxide from nitric
acid. On cobalt and manganese I have never had an opportunity of
experimenting: manganese will probably produce nitrous oxide.
c. During the solution of vegetable matters[145] in nitric acid, by heat,
very minute portions of nitrous oxide are sometimes produced, always
however mingled with large quantities of nitrous gas, and carbonic acid.
When nitric acid is decompounded by ether, fixed oils, volatile oils, or
alcohol, towards the end of the process small quantities of nitrous oxide are
produced, and sometimes sufficiently pure to support the flame of the taper.
[146]

d. When green oxide of iron is dissolved in nitric acid, nitrous oxide is
produced, mingled with nitrogene and nitrous gas.
e. During the conversion of green sulphate, or green muriate of iron into
red, by the decomposition of dilute nitric acid, nitrous oxide is formed,
mingled with different proportions of nitrous gas and nitrogene.
f. When solution of green nitrate of iron is heated, a part of the acid is
decomposed, red oxide is precipitated, red nitrate formed, and impure
nitrous oxide evolved.
g. When iron is introduced into a solution of nitrate of copper, the
copper is precipitated in its metallic state, whilst nitrous oxide, mingled
with small portions of nitrogene, is produced.[147]
Both zinc and tin precipitate copper in its metallic form from solution in
the nitric acid. During these precipitations, certain quantities of nitrous
oxide are generated, mingled however with larger quantities of nitrogene
than that produced from decomposition by iron. In all these processes
ammoniac is formed, and water consequently decomposed.
The decomposition of water and nitric acid, during the precipitation of
copper from solution of nitrate of copper, by tin, zinc, and iron, depends
upon the strong affinity of those metals for oxygene, and their powers of
combining with a larger quantity of it than copper.

X. Decomposition of Aqua Regia by Platina, and
evolution of a Gas analogous to Oxygenated
Muriatic Acid, and Nitrogene.
a. De la Metherie, in his essay on different airs, has asserted that the gas
produced by the solution of platina in nitro-muriatic acid, is identical with
the dephlogisticated nitrous gas of Priestly. He calls it nitrous gas with
excess of pure air, and affirms that it diminishes, both with nitrous gas and
common air.
b. I introduced into a vessel containing 30 grains of platina, 2050 grains
of aqua regia, composed of equal parts, by weight, of concentrated nitric
acid of 1,43, and muriatic acid of 1,16. At the common temperature, that is,
49°, no action between the acid and platina appeared to take place. On the

application of the heat of a spirit lamp, the solution gradually became
yellow red, and gas was given out with rapidity. Some of this gas received
in a jar filled with warm water, appeared of a bright yellow color. On
agitation, the greater part of it was absorbed by the water, and the remainder
extinguished flame. When it was received over mercury, it acted upon it
with great rapidity, and formed on the surface a white crust.
As the process of solution advanced, the color of the acid changed to
dark red, at the same time that the production of gas was much increased;
more than 40 cubic inches were soon collected in the water apparatus.
Different portions of the gas were examined, it exhibited the following
properties:
1. Its color was orange red,[148] and its smell exactly
resembled that of oxygenated muriatic acid.
2. When agitated in boiled water, it was rapidly
absorbed, leaving a residuum of rather more than one
twelfth.
3. The taper burnt in it with increased brilliancy, the
flame being long, and deep red at the edges.
4. Iron introduced into it ignited, burnt with a dull red
light.
5. Green vegetables exposed to it were instantly rendered
white.
6. It underwent no diminution, mingled with atmospheric
air.
7. When mingled with nitrous gas, it gave dense red
vapor, and rapid diminution.
c. From the exhibition of these properties, it was evident that the gas
produced during the solution of platina in aqua regia, chiefly consisted of
oxygenated muriatic acid, or of a gas highly analogous to it. It was,
however, difficult to conceive how a body, by combining with a portion of
the oxygene of nitro-muriatic acid, could produce from it oxygenated
muriatic acid, apparently mingled with very small portions of any other gas.

d. To ascertain whether any permanent gas was produced during the
ebullition of aqua regia, of the same composition as that used for the
solution of the platina; I kept a large quantity of it boiling for some time, in
communication with the water apparatus; the gas generated appeared to be
wholly nitro-muriatic, and was absorbed as fast as produced, by the water.
e. To determine whether any nitrous oxide was mingled with the
peculiar gas, as well as the nature and quantity of the unabsorbable gas,
nitrous gas was gradually added to 21 cubic inches of the gas produced
from a new solution, till the diminution was complete: the gas remaining
equalled 2,3 cubic inches; it was unabsorbable by water, and extinguished
flame.
In another experiment, when the last portions of gas from a solution
were carefully received in water previously boiled, 12 cubic inches agitated
in water left a residuum of 1.3; whilst the same quantity decomposed by
nitrous gas, containing,02 nitrogene, left about 1.5.
Hence it appeared that the aëriform products of the solution consisted of
the peculiar gas analogous to oxygenated muriatic acid, and of a small
quantity of nitrogene.
f. Consequently a portion of the nitric acid of the aqua regia had been
decomposed; but if it had given oxygene both to the platina and muriatic
acid, the quantity of nitrogene evolved ought to have been much more
considerable.
g. To ascertain if any water had been decomposed, and the nitrogene
condensed in the solution by its hydrogene, to form ammoniac, I saturated a
solution with lime, and heated it, but no ammoniacal smell was perceived.
h. To determine if any nitrogene had entered into chemical combination
with muriatic acid and oxygene, so as to form an aëriform triple compound,
analogous in its properties to oxygenated muriatic acid, I exposed some of
the gas to mercury, expecting that this substance, by combining with its
oxygene, would effect a complete decomposition; and this was actually the
case: for the gas was at first rapidly diminished, and the mercury became
oxydated; its volume, however, soon increased; and the residual gas
appeared to be nitrous, mingled with much nitrogene. The exact proportions
of each, from an accident, I could not determine.

This experiment was inconclusive, because the nitro-muriatic acid
suspended in the peculiar gas, from which it can probably be never
perfectly freed, acted in common with it upon the mercury, and produced
nitrous gas: and this nitrous gas, at the moment of its production, formed
nitrous acid by combining with the oxygene of the peculiar gas; and the
nitrous acid generated[149] was again decomposed by the mercury; and
hence nitrous gas evolved, and possibly some nitrogene.
i. Peculiar circumstances prevented me at this time from completely
investigating the subject. It remains doubtful whether the gas consists
simply of highly oxygenated muriatic acid and nitrogene,[150] produced by
the decomposition of nitric acid from the coalescing affinities of platina and
muriatic acid for oxygene; or whether it is composed of a peculiar gas,
analogous to oxygenated muriatic acid, and nitrogene, generated from some
unknown affinities.[151]

XI. On the action of the Electric Spark on a mixture
of Nitrogene and Nitrous Gas.
Thinking it possible that nitrous gas and nitrogene might be made to
combine by the action of the electric spark, so as to form nitrous oxide, I
introduced 20 grain measures of each of them into a small detonating tube,
graduated to grains, standing over mercury, and containing a very small
quantity of cabbage juice rendered green by an alkali. After electric sparks
had been passed through the gases for an hour and half, they were
diminished to about 32, and the cabbage juice was slightly reddened. On
introducing about 10 measures of hydrogene, and passing the electric spark
through the whole, no inflammation or diminution was perceptible. Hence
the condensation most probably arose wholly from the formation of nitrous
acid,[152] by the more intimate union of the oxygene of nitrous gas with
some of its nitrogene, as in the experiments of Priestley.
As the nascent nitrogene, in the decomposition of nitrate of ammoniac,
combines with a portion of oxygene and nitrogene, to form nitrous oxide; it
is probable that nitrous oxide may be produced during the passage of
nitrous gas and ammoniac through a heated tube.

XII. General Remarks.

There are no reasons for supposing that nitrous oxide is formed in any
of the processes of nature; and the nice equilibrium of affinity by which it is
constituted, forbids us to hope for the power of composing it from its
simple principles. We must be content to produce it, either directly or
indirectly, from the decomposition of nitric acid. And as in the
decomposition of nitrate of ammoniac, not only all the nitrogene of the
nitric acid enters into the composition of the nitrous oxide produced, but
likewise that of the ammoniac, this process is by far the cheapest, as well as
the most expeditious. A mode of producing ammoniac at little expence, has
been proposed by Mr. Watt. Condensed in the sulphuric acid, it can be
easily made to combine with nitric acid, from the decomposition of nitre by
double affinity. And thus, if the hopes which the experiments at the end of
those researches induce us to indulge, do not prove fallacious, a substance
which has been heretofore almost exclusively appropriated to the
destruction of mankind, may become, in the hands of philosophy, a means
of producing health and pleasurable sensation.

RESEARCH II.
INTO THE COMBINATIONS OF NITROUS OXIDE,
AND ITS DECOMPOSITION BY
COMBUSTIBLE BODIES.

DIVISION I.

EXPERIMENTS and OBSERVATIONS on the COMBINATIONS of
NITROUS OXIDE.
I. Combination of Water with Nitrous Oxide.
a. The discoverer of nitrous oxide first observed its solubility in water;
and it has since been noticed by different experimentalists.
Dr. Priestley found that water dissolved about one half of its bulk of
nitrous oxide, and that at the temperature of ebullition, this substance was
incapable of remaining in combination with it.[153]
b. I introduced to 9 cubic inches of pure water, i. e. water distilled under
mercury, 7 cubic inches of nitrous oxide, which had been obtained over
mercury, from the decomposition of nitrate of ammoniac, and in
consequence was perfectly pure. After they had remained together for 11
hours, temperature being 46°, during which time they were frequently
agitated, the gas remaining was 2,3; consequently 4,7 cubic inches had been
absorbed. And then, 100 cubic inches, = 25300 grains of water, will absorb
54 cubic inches, = 27 grains, of nitrous oxide.
c. The taste of water impregnated with nitrous oxide, is distinctly
sweetish; it is softer than common water, and, in my opinion, much more
agreeable to the palate. It produces no alteration in vegetable blues, and
effects no change of color in metallic solutions.
d. Thinking that water impregnated with nitrous oxide might probably
produce some effects when taken into the stomach, by giving out its gas, I

drank, in June, 1799, about 3 ounces of it, but without perceiving any
effects.
A few days ago, considering this quantity as inadequate, I took at two
draughts nearly a pint, fully saturated; and at this time Mr. Joseph Priestley
drank the same quantity.
We neither of us perceived any remarkable effects.
Since that time I have drank near three pints of it in the course of a day.
In this instance it appeared to act as a diuretic, and I imagined that it
expedited digestion. As a matter of taste, I should always prefer it to
common water.
e. Two cubic inches of pure water, that had been made to absorb about
1,1 cubic inches of nitrous oxide; when kept for some time in ebullition,
and then rapidly cooled, produced nearly 1 of gas. Sulphur burnt in this gas
with a vivid rose-colored flame.
In another experiment, in which the gas was expelled by heat from
impregnated water, and absorbed again after much agitation on cooling; the
residuum was hardly perceptible, and most likely depended upon some gas
which had adhered to the mercury, and was liberated during the ebullition.
Hence it appears that nitrous oxide is expelled unaltered from its aqueous
solution by heat.
f. I have before mentioned, Division III, that nitrous oxide, during its
combination with spring water, expels the common air dissolved in it. This
common air generally amounts to one sixteenth, the volume of the water
being unity. A correction on account of this circumstance must be made for
the apparent deficiency of diminution, and for the common air mingled in
consequence, with nitrous oxide during its absorption by common water.
g. Water impregnated with nitrous gas absorbed nitrous oxide; but the
residual gas was much greater than that of common water, and gave red
fumes with atmospheric air. Nitrous gas agitated for a long while over water
highly impregnated with nitrous oxide, was not in the slightest degree
diminished, in one experiment indeed it was rather increased; doubtless
from the liberation of some nitrous oxide from the water by the agitation.
h. Nitrous oxide kept in contact with aqueous solution of sulphurated
hydrogene and often agitated, was not in the slightest degree diminished.

Sulphurated hydrogene, introduced into a solution of nitrous oxide, was
rapidly absorbed, and as the process advanced, the nitrous oxide was given
out.
i. Water impregnated with carbonic acid, possessed no action upon
nitrous oxide, and did not in the slightest degree absorb it. When carbonic
acid was introduced to an aqueous solution of nitrous oxide; the aëriform
acid was absorbed, and the nitrous oxide liberated.
k. From these observations it appears that nitrous oxide has less affinity
for water, than even the weaker acids, sulphurated hydrogene and carbonic
acid; as indeed one might have conjectured a priori from its degree of
solubility: likewise that it has a stronger attraction for water than the gases
not possessed of acid or alkaline properties; it expelling from water nitrous
gas, oxygene, and common air; probably hydrocarbonate, hydrogene, and
nitrogene.

II. Combinations of Nitrous Oxide with
Fluid Inflammable Bodies.
a. Vitriolic ether absorbs nitrous oxide in much larger quantities than
water.
A cubic inch of ether, at temperature 52°, combined with a cubic inch
and seven tenths of nitrous oxide.
Ether thus impregnated was not at all altered in its appearance; its smell
was precisely the same, but the taste appeared less pungent, and more
agreeable. Nitrous oxide is liberated unaltered from ether at a very low
temperature, that is, at about the boiling point of this fluid.
For expelling nitrous oxide from impregnated ether, and for ascertaining
in general the quantity of gases combined with fluids, I have lately made
use of a very simple method, which it may not be amiss to describe.
The impregnated fluid is introduced into a small thin tube, graduated
to,05 cubic inches, through mercury. The quantity of fluid should never
equal more than a fifth or sixth of the capacity of the tube.
The lower part of the tube is adapted to an orifice in the shelf of the
mercurial apparatus, so as to make an angle of about 40° with the surface of

the mercury.
The flame of a small spirit lamp is then applied to that part of the tube
containing the fluid; and after the expulsion of the gas from it, the heat is
raised so as to drive out the fluid through the orifice of the tube. Thus the
liberated gas is preserved in a state proper for accurate examination.
Impregnated ether, during its combination with water, gives out the
greater part of its nitrous oxide. During the liberation of nitrous oxide from
ether, by its combination with water, a very curious phænomenon takes
place.
If the water employed is colored, so that it may be seen in a stratum
distinct from the impregnated ether, at the point of contact a number of
small spherules of fluid will be perceived, apparently repulsive both to
water and ether; these spherules become gradually covered with minute
globules of gas, and as this gas is liberated from their surfaces, they
gradually disappear.
b. Alcohol dissolves considerable quantities of nitrous oxide.
2 cubic inches of alcohol, at 52°, combined with 2,4 cubic inches of
nitrous oxide. The alcohol thus impregnated had a taste rather sweeter than
before, but in other physical properties was not perceptibly altered.
Nitrous oxide is incapable of remaining in combination with this fluid at
the temperature of ebullition; it is liberated from it unaltered by heat.
Impregnated alcohol, during its combination with water, gives out the
greater part of its combined nitrous oxide: on mingling the two fluids
together, at the point of contact the alcohol becomes covered with an
infinite number of small globules of gas, which continue to be generated
during the whole of the combination, and in passing through the fluid
render it almost opaque.
c. The essential oils absorb nitrous oxide to a greater extent than either
alcohol or ether.
,5 cubic inches of oil of carui combined with 1,2 cubic inches of nitrous
oxide at 51°. The color of the oil thus impregnated was rather paler than
before.

Nitrous oxide is expelled unaltered from impregnated oil of carui, by
heat.
1 of oil of turpentine absorbed nearly 2 of nitrous oxide, at 57°. Its
properties were not sensibly altered from this combination, and the gas was
expelled from it undecompounded, by heat.
d. As well as the essential oils, the fixed oils dissolve nitrous oxide at
low temperatures, whilst at high temperatures they do not remain in
combination.
1 of olive oil absorbed, at 61°, 1,2 of nitrous oxide, but without
undergoing any apparent physical change.

III. Action of Fluid Acids on Nitrous Oxide.
a. Nitrous oxide exposed to concentrated sulphuric acid, undergoes no
change, and suffers no diminution, that may not be accounted for from the
abstraction of a portion of its water by the acid.
b. Nitrous oxide is scarcely at all soluble in nitrous acid, and exposed to
that substance, undergoes no alteration.
c. Muriatic acid, of specific gravity 1,14 absorbs about a third of its bulk
of nitrous oxide. It suffers no apparent change in its properties from being
thus impregnated, and the gas is again given out from it on the application
of heat.
d. Acetic acid absorbs nearly one third of its bulk of nitrous oxide.
e. Aqua regia, that is, the nitro-muriatic acid, absorbs a very minute
portion of nitrous oxide.
f. Nitrous oxide was exposed to a new compound acid, consisting of
oxygenated muriatic acid, and sulphuric acid, which I discovered in July,
1799, and of which an account will be shortly published; but it was neither
absorbed or altered.
I have before mentioned that the aqueous solutions of sulphurated
hydrogene and carbonic acid, neither dissolve or alter nitrous oxide.

IV. Action of Saline Solutions, and other Substances,
on Nitrous Oxide.
a. Nitrous oxide exposed to concentrated solution of green sulphate of
iron, at 58°, underwent no perceptible diminution; not even after it had been
suffered to remain in contact with it for half an hour.
b. It underwent diminution of nearly,2 when agitated in contact with a
solution of red sulphate of iron, the volume of the solution being unity.
c. Solution of green sulphate of iron, fully impregnated with nitrous gas,
did not in the slightest degree absorb nitrous oxide, and appeared to have no
action upon it.
d. Solution of green muriate of iron, whether impregnated with nitrous
gas, or unimpregnated, has no affinity for, or action upon, nitrous oxide.
e. Solution of red muriate of iron in alcohol, absorbed nearly one fifth of
its bulk, of nitrous oxide.
f. Solution of prussiate of potash absorbed nearly one third of its
volume, of nitrous oxide, which was again expelled from it by heat.
g. Solution of nitrate of copper appeared to have no affinity for nitrous
oxide.
h. Concentrated solution of nitrate of ammoniac, at 58°, absorbed one
eighth of its bulk of nitrous oxide.
i. Solutions of alkaline sulphures absorb nitrous oxide in quantities
proportionable to the water they contain; it is expelled from them unaltered
by heat. None of the hydro-sulphures dissolve more than half their bulk of
nitrous oxide.
k. Concentrated solutions of the sulphites possess little or no action on
nitrous oxide; diluted solutions absorb it in small quantities.
l. Concentrated solution of muriate of tin absorbs about one eighth of
nitrous oxide; more dilute solutions absorb larger quantities.
From these observations we learn, that neutro-saline solutions in
general, have very feeble attractions for nitrous oxide; and as solutions of
green muriate, and sulphate of iron, whether free from nitrous gas, or

impregnated with it, possess no action upon nitrous oxide, nitrous gas may
be separated from this substance by those solutions with greater facility
than nitrous oxide can be separated from nitrous gas, by water or alcohol.
Charcoal absorbs nitrous oxide as well as all other gases; and it is
disengaged from it by heat.
I have as yet found no other solid body, not possessed of alkaline
properties, capable of absorbing nitrous oxide in any state of existence.
The bodies possessing the strongest affinity for oxygene, the dry
sulphites, muriate of tin, the common sulphures, white prussiate of potash,
and green oxide of iron, do not in the slightest degree act on nitrous oxide at
common temperatures.

V. Action of different Gases on Nitrous Oxide.
a. 12 measures of muriatic acid gas were mingled with 7 measures of
nitrous oxide at 56°. After remaining together for a minute, they filled a
space equal to 19½ measures. When water was introduced to them, the
muriatic acid was absorbed much more slowly than if it had been
unmingled.
In another experiment, when the gases were saturated with water, 9
measures of each of them, when mingled and suffered to remain in contact
for a quarter of an hour, filled a space nearly equal to 19; and after the
muriatic acid had been absorbed by potash, the nitrous oxide remained
unaltered in its properties.
From the expansion, it appears most probable that aëriform muriatic
acid, and nitrous oxide, have a certain affinity for each other, and that they
combine when mingled together; for in the last experiment, the increase of
volume cannot be accounted for by supposing that nitrous oxide undergoes
less change of volume than muriatic acid, by aëriform combination with
water, and that the expansion depended upon the solution of some of its
combined water by the muriatic acid. That muriatic acid and nitrous oxide
have a slight affinity for each other, likewise appears from the absorption of
nitrous oxide by aqueous solution of muriatic acid.
Thinking that nitrous oxide might attract muriatic acid from its solution
in water, I exposed a minute quantity of fluid muriatic acid to nitrous oxide;

but no alteration of volume took place in the gas.
b. 6 measures of nitrous oxide were mingled with 11 measures of
sulphureous acid, saturated with water; after remaining at rest for six
minutes, they filled a space nearly equal to 18 measures. Exposed to water,
the sulphureous acid was absorbed, but not nearly so rapidly as when in a
free state. Sulphur burnt with a vivid flame in the residual nitrous oxide. 7
measures of sulphureous acid were now mingled with 8 of nitrous oxide.
They filled a space nearly equal to 15¾, and no farther expansion took
place afterwards.
From these experiments it appears probable that sulphureous acid, and
nitrous oxide, have some affinity for each other.
c. 11 measures of carbonic acid were mingled with 8 of nitrous oxide;
they filled a space nearly equal to 19 measures. On exposing the mixture to
caustic potash, the carbonic acid was absorbed, and the nitrous oxide
remained pure. Hence it appears that carbonic acid and nitrous oxide do not
combine with each other.
d. Oxygenated muriatic acid, and nitrous oxide, were mingled in a water
apparatus: there was a slight appearance of condensation; but this was most
probably owing to absorption by the water; on agitation, the oxygenated
muriatic acid was absorbed, and the greater part of the nitrous oxide
remained unaltered.
e. Sulphurated hydrogene and nitrous oxide, mingled together, neither
expanded or contracted; exposed to solution of potash, the acid[154] only
was absorbed.
f. 10 measures of nitrous gas were admitted to 12 of nitrous oxide at
59°. They filled a space equal to 22, and after remaining together for an
hour, had undergone no change. Solution of muriate of iron absorbed the
nitrous gas without affecting the nitrous oxide.
g. Nitrous oxide was successively mingled with oxygene, atmospheric
air, hydrocarbonate, phosphorated hydrogene, hydrogene, and nitrogene, at
57°; it appeared to possess no action on any of them, and was separated by
water, the gases remaining unaltered.

h. As nitrous oxide was soluble in ether, alcohol, and the other
inflammable fluids, it was reasonable to suppose that its affinity for those
bodies would enable them to unite with it in the aëriform state. At the
suggestion of Dr. Beddoes I made the following experiment:
To 12 measures of nitrous oxide, at 54°, I introduced a single drop of
ether; the gas immediately began to expand, and in four minutes filled a
space equal to sixteen measures and a quarter. When an inflamed taper was
plunged into the gas thus holding ether in solution, a light blue flame slowly
passed through it.
A considerable diminution of temperature is most probably produced,
from the great expansion of nitrous oxide during its combination with ether.
A drop of alcohol was admitted to 14 measures of nitrous oxide. In five
minutes, the gas filled a space equal to fifteen and a third; but no farther
diminution took place afterwards.
A minute quantity of oil of turpentine was introduced to 14 measures of
nitrous oxide; it filled, in 4 minutes, a space rather less than 14; and no
farther change took place afterwards. Most likely this contraction arose
from the precipitation of the water dissolved in the gas by the stronger
affinity of the oil for nitrous oxide. To ascertain with certainty if any oil had
been dissolved by the gas, I introduced into it a small quantity of
ammoniac. It immediately became slightly clouded, most probably from the
formation of soap, by the combination of the dissolved oil with the
ammoniac.
From these experiments we learn, that when nitrous oxide is mingled
with either carbonic acid, oxygene, common air, hydrocarbonate,
sulphurated hydrogene, hydrogene, or nitrogene, they may be separated
from each other without making any allowance for contraction or
expansion; but if a mixture of either muriatic acid, or sulphureous acid gas,
with nitrous oxide, is experimented upon; in the absorption of the acid by
alkalies, the apparent volume of gas condensed will be less than the real
one, by a quantity equal to the sum of expansion from combination.
Consequently a correction must be made on account of this circumstance.
Though alcohol, ether, essential oils, and the fluid inflammable bodies
in general, dissolve nitrous oxide with much greater rapidity than water, yet

as we are not perfectly acquainted with their action on unabsorbable gases,
it is better to employ water for separating nitrous oxide from these
substances; particularly as that fluid is more or less combined with all
gases, and as we are acquainted with the extent of its action upon them.
By pursuing the subject of the solution of essential oils in gases, we
may probably discover a mode of obtaining them in a state of absolute
dryness. For if other gases as well as nitrous oxide, have a stronger affinity
for oils than for water, water most probably will be precipitated from them
during their solution of oils; and after their saturation with oil, it is likely
that they are capable of being deprived of that substance by ammoniac.

VI. Action of aëriform Nitrous Oxide in the Alkalies.
History of the discovery of the combinations
of Nitrous Oxide with the Alkalies.
a. When nitrous oxide in a free state is exposed to the solid caustic
alkalies and alkaline earths, at common temperatures, it is neither absorbed
nor acted upon; when it is placed in contact with solutions of them in water,
a small quantity is dissolved; but this combination appears to depend on the
water of the solution, for the gas can be expelled unaltered, at the
temperature of ebullition.
b. Caustic potash was exposed to nitrous oxide for 13 hours: the
diminution was not to one fiftieth, and this slight condensation most
probably depended upon its combination with the water of the gas.
Concentrated solution of potash absorbed a fourth of its bulk of nitrous
oxide. When the impregnated solution was heated, globules of gas were
given out from it rapidly; but the quantity collected was too small to
examine.
Soda, whether solid or in solution, exhibited exactly the same
phænomena with nitrous oxide. The solution of soda absorbed near a
quarter of its bulk of gas.
c. 11 measures of ammoniacal gas were mingled with 8 measures of
nitrous oxide over dry mercury, both of the gases being saturated with
water. No change of appearance was produced by the mixture, and they
filled, after two minutes, a space equal to 19. On the introduction of a little

water, the ammoniac was absorbed, and the nitrous oxide remained
unaltered, for it was dissolved by water as rapidly as if it had never been
mingled with ammoniac.[155]
7 measures of nitrous oxide, exposed to 6 measures of solution of
ammoniac in water, was in an hour diminished to 4½ nearly. When the
solution was heated over mercury, permanent gas was produced, which was
unabsorbable by a minute quantity of water, and soluble in a large quantity;
consequently it was nitrous oxide.
d. Nitrous oxide was exposed to dry caustic strontian; it underwent a
diminution of nearly one fortieth, which most likely was owing to the
combination of the strontian with its water.
11 measures of nitrous oxide were agitated in contact with 8 of strontian
lime water: nearly 4 measures were absorbed. The impregnated solution
exposed to heat, rapidly gave out its gas; 3 measures were soon collected,
which mingled with a small quantity of hydrogene, and inflamed by the
taper, gave a smart detonation.
e. Nitrous oxide exposed to lime and argil, both wet and dry, was not in
the slightest degree acted upon.
From these experiments it is evident that nitrous oxide in the aëriform
state cannot be combined either with the alkalies, or the alkaline earths.
That a combination may be effected between nitrous oxide and these
substances, it must be presented to them, in the nascent state.
The salts composed of the alkalies and nitrous oxide, are not analogous
to any other compound substances, being possessed of very singular
properties. Before these properties are detailed, it may not be amiss to give
an account of the accidental way in which I discovered the mode of
combination.
In December, 1799, designing to make a very delicate experiment, with
a view to ascertain if any water was decomposed during the conversion of
nitrous gas into nitrous oxide, by sulphite of potash, I exposed 200 grains of
crystalised sulphite of potash, containing great superabundance of alkali, to
14 cubic inches of nitrous gas, containing one eighteenth nitrogene. The
alkali was employed to preserve any ammoniac that might be formed, in the
free state, as it would otherwise combine with sulphureous acid.[156]

The volume of gas diminished with great rapidity; in two hours and ten
minutes it was reduced to 6⁴/₅, which I considered as the limit of
diminution. Accidentally, however, suffering it to remain for three hours
longer, I was much surprised by finding that not quite 2 cubic inches
remained, which consisted of nitrous oxide, mingled with the nitrogene that
existed before the experiment.
In accounting theoretically for this phænomenon, different suppositions
necessarily presented themselves.
1st, It was possible, that though sulphite of potash, and potash,
separately possessed no action on free nitrous oxide, yet in combination
they might exert such affinities upon it as either to absorb it, or make it
enter into new combinations.
2dly. It was more probable that the caustic potash, though incapable of
condensing aëriform nitrous oxide, was yet possessed of a strong affinity
for it when in the nascent state, and that the nitrous oxide condensed in the
experiment had been combined in this state with the free alkali.
To ascertain if the compound of potash and sulphite of potash with
sulphate, was capable of acting upon nitrous oxide, I suffered a quantity of
this substance to remain in contact with the gas for near a day: no change
whatever took place.
To determine whether the diminution of nitrous oxide depended upon its
absorption in the nascent state, by the peculiar compound of potash and
sulphite of potash, or if it was simply owing to the alkali.
I mingled a solution of sulphite of potash with caustic soda; the salt,
after being evaporated at a low temperature, was exposed to nitrous gas.
The nitrous oxide formed was absorbed, but in rather less quantities than
when alkaline sulphite of potash was employed.
Hence it was evident that the alkali was the agent that had condensed
the nitrous oxide in those experiments, for soda is incapable of combining
either with sulphate, or sulphite of potash.
To ascertain whether any change in the constitution of the nitrous oxide
had been produced by the condensation, I introduced a small quantity of
sulphite of potash, with excess of alkali, that had absorbed nitrous oxide,
into a long and thin cylindrical tube filled with mercury; and inclining it at

an angle of 35° with the plane of the mercury, applied the heat of a spirit
lamp to that part of the tube containing the salts; when the glass became
very hot, gas was given out with rapidity; in less than a minute the tube was
full. This gas was transfered into another tube, and examined; it proved to
be nitrous oxide in its highest state of purity;[157] for a portion of it absorbed
by common water, left no more than a residuum of ¹/₁₅, and sulphur burnt in
it with a vivid rose-colored flame.
Being now satisfied that the alkalies were capable of combining with
nitrous oxide; to investigate with precision the nature of these new
compounds, I proceeded in the following manner.

VII. Combination of Nitrous Oxide with Potash.
a. Into a solution of sulphite of potash, which had been made by passing
sulphureous acid gas from a mercurial airholder into caustic potash
dissolved in water, I introduced 17 grains of dry potash. The whole
evaporated at a low temperature, gave 143 grains of salt. This salt was not
wholly composed of sulphite of potash and potash; it contained as well, a
minute quantity of carbonate, and sulphate of potash, formed during the
evaporation.[158]
120 grains of it finely pulverised, and retaining the water of
crystalisation, were exposed to 15 cubic inches of nitrous gas, over
mercury. The nitrous gas diminished with great rapidity, and in three hours
a cubic inch and nine tenths only remained, which consisted of nearly one
third nitrous oxide, and two thirds nitrogene that had pre-existed in the
nitrous gas. The increase of weight of the salt could not be determined, as
some of it was lost by adhering to the vessel in which the combination was
effected, and to the mercury. It presented no distinct series of
crystalisations, even when examined by the magnifier; rendered green
vegetable blues, and its taste was very different from that of the remaining
quantity of salt that had been exposed to the atmosphere. A portion of it
strongly heated over mercury, gave out gas with great rapidity, which had
all the properties of the purest nitrous oxide.
When water was poured upon some of it, no gas was given out, and the
whole was equably and gradually dissolved. Alcohol, as well as ether,
appeared incapable of dissolving any part of it.

When muriatic acid was introduced into it, confined by mercury, a rapid
effervescence took place. Part of the gas disengaged was sulphureous acid,
and carbonic acid; the remainder was nitrous oxide.
b. I made a number of experiments upon salts procured in the manner I
have just described, with a view to obtain the compound of nitrous oxide
and potash, free from admixture of other salts.
When the mixed salt was boiled in alcohol or ether, no part of it
appeared to be dissolved. Finding that little or no gas was given out during
the ebullition of concentrated solutions of the mixed salts, I attempted to
separate the sulphate, sulphite, and carbonate of potash, from the
combination of nitrous oxide and potash, by successive evaporations and
crystalisations. But though in this way it was nearly freed from sulphate of
potash, yet the extreme and nearly equal solubility of the other salts,
prevented me from completely separating them from each other.
By exposing, however, very finely pulverised sulphite of potash,
mingled with alkali, for a great length of time to nitrous gas, it was almost
wholly converted into sulphate; and after the separation of this solution,
evaporation, and crystalisation, at a low temperature, I obtained the new
combination, mingled with very little carbonate of potash, and still less of
sulphite.
The minute quantity of sulphite chiefly appeared in very small crystals;
distinct from the mass of salt, which possessed no regular crystalisation,
and was almost wholly composed of the new compound, intimated mingled
with a little carbonate. The new compound, as nearly as I could estimate
from the quantity of nitrous oxide absorbed, consisted of about 3 alkali, to 1
of nitrous oxide, by weight.
It exhibited the following properties:
1. Its taste was caustic, and possessed of a pungency
different from either potash or carbonate of potash.
2. It rendered vegetable blues green, which might
possibly depend upon the carbonate of potash mixed with it.
3. Pulverised charcoal mingled with a few grains of it,
and inflamed, burnt with flight scintillations. Projected into
zinc in a state of fusion, a slight inflammation was produced.

4. When either sulphuric, muriatic, or nitric acid was
introduced to it under mercury, it gave out nitrous oxide,
mingled with a little carbonic acid.
5. Thrown into a solution of sulphurated hydrogene, gas
was disengaged from it, but in quantities too minute to be
examined.
6. When carbonic acid was thrown into a solution of it in
water, gas was disengaged; on examination it proved to be
nitrous oxide.
7. A concentrated solution of it kept in ebullition in a
cylinder, confined by mercury, gave out a few globules of
gas, which were too minute to be examined, and probably
consisted of common air previously contained in the water.
c. In the experiments made to ascertain these properties all the salt was
expended, otherwise I should have endeavoured to ascertain what quantity
of gas would have been liberated by heat from a given weight; and likewise
what would have been the effects of admixture of it with oil. When some of
the mixed salt was mingled with oil of turpentine, part of it was dissolved,
and the fluid became white; but no gas was given out. On this coarse
experiment, however, I cannot place much dependance. If the combination
of nitrous oxide and potash is capable of combining with oil without
decomposition, barytes and strontian[159] will probably separate the oil from
it, and thus it may possibly be obtained in a state of purity.
In a rough experiment made on the conversion of nitrous gas into
nitrous oxide, by concentrated solution of sulphite of potash with excess of
alkali, very little of the nitrous oxide was absorbed. Hence it is probable
that water lessens the affinity of potash for nascent nitrous oxide.

VIII. Combination of Nitrous Oxide with Soda.
The union of nitrous oxide with soda is effected in the same manner as
with potash. The alkali, mingled by solution and evaporation, with either
sulphite of soda, or of potash, is exposed to nitrous gas; the nitrous oxide is
condensed by it at the moment of generation, and the combination effected.

As far as I have been able to observe, nitrous oxide is not absorbed to so
great an extent by soda, as potash.
I have not yet been able to obtain the combination of nitrous oxide with
soda in its pure state. To the attainment of this end, difficulties identical
with those noticed in the last section present themselves. It is extremely
difficult to procure the soda perfectly free from carbonic acid, and though
by using sulphite of potash the sulphate formed is easily separated, yet still
evaporation and crystalisation will not disengage the sulphite and carbonate
from the new compound.
The compound of soda and nitrous oxide, mingled with a little sulphite
and carbonate of soda, was rapidly soluble, both in warm and cold water,
without effervescence. Its solution, heated to ebullition, gave out no gas.
The taste of the solid salt was caustic, and more acrid than that of the
mixture of carbonate and sulphite of soda. When cast upon zinc in fusion, it
burnt with a white flame. When heated to 400° or 500°, it gave out nitrous
oxide with rapidity. Nitrous oxide was expelled from it by the sulphuric,
muriatic, and carbonic acids, I believe, by sulphurated hydrogene.[160]

IX. Combination of Nitrous Oxide with Ammoniac.
I attempted to effect this combination by converting nitrous gas into
nitrous oxide, by sulphite of ammoniac, wetted with strong solution of
caustic ammoniac; but without success; for the whole of the nitrous oxide
produced remained in a free state.
When I exposed sulphite of potash, mingled by solution and evaporation
with highly alkaline carbonate of ammoniac,[161] to nitrous gas, the
diminution was nearly one fourth more than if pure sulphite of potash had
been employed. Hence it appears most likely that ammoniac is capable of
combination with nitrous oxide in the nascent state.
In the experiments on the conversion of nitrous gas into nitrous oxide,
by nascent hydrogene, and by sulphurated hydrogene, Res. I. Divis. V.
probably the water formed at the same time with the ammoniac and nitrous
oxide, prevented them from entering into combination; possibly the peculiar
compound was formed, but in quantities so minute as not to be

distinguished from simple ammoniac;[162] for even the existence of
ammoniac in these processes, is but barely perceptible.
If it should be proved by future experiments, that in the decomposition
of nitrous gas by nascent hydrogene, a peculiar compound of nitrous oxide,
water and ammoniac, is formed, it will afford proofs in favor of the doctrine
of predisposing affinity;[163] for then this decomposition might be supposed
to depend upon the disposition of oxygene, hydrogene and nitrogene to
assume the states of combination in which they might form a triple
compound, of water, nitrous oxide, and ammoniac.
Nitrous oxide might probably be made to combine with ammoniac by
exposing a mixture of nitrous gas and aëriform ammoniac, to the sulphites.
It is probable that nitrous oxide may be combined with ammoniac, by
means of double affinity. Perhaps sulphate of ammoniac and the
combination of potash with nitrous oxide mingled together in solution,
would be converted into sulphate of potash and the compound of nitrous
oxide, and ammoniac.

X. Probability of forming Compounds of Nitrous Oxide
and the Alkaline Earths.
I attempted to combine nitrous oxide with lime and strontian, by
exposing sulphites of lime and strontian with excess of earth, to nitrous gas;
but this process did not succeed: the diminution took place so slowly as to
destroy all hopes of gaining any results in a definite time. Sulphite of potash
is decomposable by barytes, strontian, and lime;[164] consequently it was
impossible to employ this substance to effect the combination.
As the dry sulphures, when well made, convert nitrous gas into nitrous
oxide, it is probable that the union of the earths with nascent nitrous oxide
may be effected by exposing nitrous gas to their sulphures, containing an
excess of earth.
Perhaps the combination of nitrous oxide with strontian may be effected
by introducing the combination of potash and nitrous oxide into strontian
lime water.

It is probable that nitrous oxide may be combined with clay and
magnesia, by exposing these bodies, mingled with sulphite of potash or
soda, to nitrous gas.

XI. Additional Observations on the combinations
of Nitrous Oxide with the Alkalies.
A desire to complete physiological investigations relating to nitrous
oxide, has hitherto prevented me from pursuing to a greater extent, the
experiments on the combination of this substance with the alkalies, &c. As
soon as an opportunity occurs, I purpose to resume the subject.
The observations detailed in the foregoing sections are sufficient to
show that nitrous oxide is capable of entering into intimate union with the
fixed alkalies: and as the compounds formed by this union are insoluble in
alcohol, decomposable by the acids, and heat, and possessed of peculiar
properties, they ought to be considered as a new class of saline substances.
If it is thought proper, on a farther investigation of their properties, to
signify them by specific names, they may, according to the usually adopted
fashion of nomenclature, be called nitroxis: thus the nitroxi of potash would
signify the salt formed by the combination of nitrous oxide with potash.
Future experiments must determine the different affinities of nitrous
oxide for the alkalies, and alkaline earths.
With regard to the uses of these new compounds it is difficult to form a
guess. When they are obtained pure, and fully saturated with nitrous oxide,
on account of the low temperature at which their gas is liberated, they will
probably constitute detonating compounds. From their facility of
decomposition by the weaker acids, they may possibly be used medicinally,
if ever the evolution of nitrous oxide in the stomach should be found
beneficial in diseases.

XII. The properties of Nitrous Oxide resemble those of Acids.
If we were inclined to generalise, and to place nitrous oxide among a
known class of bodies, its properties would certainly induce us to consider
it as more analogous to the acids than to any other substances; for it is
capable of uniting with water and the alkalies, and is insoluble in most of

the acids. It differs, however, from the stronger acids, in not possessing the
sour taste,[165] and the power of reddening vegetable blues: and from both
the stronger and weaker acids, in not being combinable when in a perfectly
free state, at common temperatures, with the alkalies. If it should be proved
by future experiments, that condensation by cold gave it the capability of
immediately forming neutro-saline compounds with the alkalies; it ought to
be considered as the weakest of the acids. Till those experiments are made,
its extraordinary chemical and physiological properties are sufficient to
induce us to consider it as a body sui generis.
It is a singular fact that nitrous gas, which contains in its composition a
quantity of oxygene so much greater than nitrous oxide, should nevertheless
possess no acid properties. It is uncombinable with alkalies, very little
soluble in water, and absorbable by the acids.

DIVISION II.

On the DECOMPOSITION of NITROUS OXIDE by
COMBUSTIBLE BODIES. Its ANALYSIS. OBSERVATIONS on
the different combinations of OXYGENE and NITROGENE.
I. Preliminaries.

F
[166]
rom the phænomena mentioned in Res. I. Divis. III. it appears that
the combustible bodies burn in nitrous oxide at certain temperatures.
The experiments in this Division were instituted for the purpose of
investigating the precise nature of these combustions, with a view of
ascertaining exactly the composition of nitrous oxide.
It will be seen hereafter that very high temperatures are required for the
decomposition of nitrous oxide, by most of the combustible bodies, and that
in this process heat and light are produced to a very great extent. These
agents alone are possessed of a considerable power of action on nitrous
oxide; of which it is necessary to give an account, that we may be able to
understand the phænomena in the following sections.

II. Conversion of Nitrous Oxide into Nitrous Acid,
and a Gas analogous to Atmospheric Air, by Ignition.

a. Dr. Priestley asserts, that nitrous oxide exposed for a certain time to
the action of the electric spark, is rendered immiscible with water, and
capable of diminution with nitrous gas, without suffering any alteration of
volume; and likewise that the same changes are effected in it by exposure to
ignited incombustible bodies.[167]
The Dutch chemists state, that the electric spark passed through nitrous
oxide, occasions a small diminution of its volume, and that the gas
remaining is analogous to common air.[168] They conclude that this change
depends on the separation of its constituent parts, oxygene and nitrogene,
from each other.
None of these chemists have suspected the production of nitrous acid in
this process.
b. Nitrous oxide undergoes no change whatever from the simple action
of light. I exposed some of it, confined by mercury, for many days to this
agent, often passing through it concentrated rays by means of a small lens.
When examined it appeared, as well as I could estimate, of the same degree
of purity as at the beginning of the experiment.
c. A temperature below that of ignition effects no alteration in the
constitution of nitrous oxide. I passed nitrous oxide from a retort containing
decomposing nitrate of ammoniac, through a green glass tube, strongly
heated in an air-furnace, but not suffered to undergo ignition. The gas,
received in a water apparatus exhibited the same properties as the purest
nitrous oxide; some of it absorbed by water, left a residuum of not quite one
thirteenth.
d. The action of the electric spark for a long while continued, converts
nitrous oxide into a gas analogous to atmospheric air, and nitrous acid.
I passed about 150 strong shocks from a small Leyden phial, through 7
ten grain measures of pure nitrous oxide. After this it filled a space rather
less than six measures: the mercury was rendered white on the top, as if it
had been acted on by nitric acid. Six measures of nitrous gas mingled with
the residual gas of the experiment, over mercury covered by a little water,
gave red fumes, and rapid diminution. In five minutes the volume of the
gases nearly equalled ten. Thermometer in this experiment was 58°.

Electric sparks were passed for an hour and half through 7 ten grain
measures of nitrous oxide over mercury covered with a little red cabbage
juice, previously saturated with nitrous oxide, and rendered green by an
alkali. After the process the gas filled a space equal to rather more than six
measures and half, and the juice was become of a pale red. The gas was
introduced into a small tube filled with pure water, and agitated; no
absorption was perceptible: 7 measures of nitrous gas added to it gave red
fumes, and after six minutes a diminution to 9¼ nearly. 6½ measures of
common air from the garden, with 7 of nitrous gas, gave exactly 9.
In this experiment it was evident that nitrous oxide was converted into a
gas analogous to atmospheric air, at the same time that an acid was formed.
There could be little doubt but that this was the nitrous acid. To ascertain it,
however, with greater certainty, the electric spark was passed through 6
measures of nitrous oxide, over a little solution of green sulphate of iron,
confined by mercury. As the process went on, the color of the solution
became rather darker. When the diminution was complete, a little prussiate
of iron was added to the solution. A precipitate of pale blue prussiate of
potash was produced.
c. Nitrous oxide was passed from decomposing nitrate of ammoniac,
through a porcelain tube well glazed inside and outside, strongly ignited in
an air-furnace, and communicating with the water apparatus. The gas
collected was rendered opaque by dense red vapor. It appeared wholly
unabsorbable by water. After the precipitation of its vapor, a candle burnt in
it with nearly the same brilliancy as in atmospheric air. 20 measures of it
that had been agitated in water immediately after its production, mingled
with 40 measures of nitrous gas, diminished to about 47.5; whereas 20
measures that had remained unagitated for some time after their generation,
introduced to the same quantity of nitrous gas, gave nearly 49. 20 measures
of atmospheric air, with 40 of the same nitrous gas, were condensed to 46.
The water with which the gas had been in contact, was strongly acid. A
little of it poured into a solution of green sulphate of iron, and then mingled
with prussian alkali, produced a green precipitate. Hence the acid it
contained was evidently nitrous.
That no source of error could have existed in this experiment from
fissure in the tube, I proved, by sending water through it whilst ignited,

after the process, from the same retort in which the nitrate of ammoniac had
been decomposed; a few globules of air only were produced, not equal to
one tenth of the volume of the water boiled, and which were doubtless
previously contained in it.
I have repeated this experiment two or three times, with similar results;
whenever the air was agitated in water immediately after its production, it
gave almost the same diminution with nitrous gas as common air; when, on
the contrary, it has been suffered to remain for some time in contact with
the phlogisticated nitrous acid suspended in it, the condensation has been
less with nitrous gas by five or six hundred parts. Hence I am inclined to
believe, that if it were possible to condense all the nitrous acid formed,
immediately after its generation, so as to prevent it from absorbing oxygene
from the permanent gas, this gas would be found identical with the air of
the atmosphere.
The changes effected by fire on nitrous oxide are not analogous to those
produced by it in other bodies; for the power of this agent seems generally
uniform, either in wholly separating the constituent principles of bodies
from each other, or in making them enter into more intimate union.[169]
It is a singular phænomenon, that whilst it condenses one part of the
oxygene and nitrogene of nitrous oxide, in the form of nitrous acid; it
should cause the remainder to expand, in the state of atmospheric air. Does
not this fact afford an inference in favor of the chemical composition of
atmospheric air?

III. Decomposition of Nitrous Oxide by Hydrogene,
at the temperature of Ignition.
In the following experiments on the decomposition of nitrous oxide by
hydrogene, the gases were carefully generated in the mercurial apparatus,
and their purity ascertained by the tests mentioned in Research I. They were
measured in small tubes graduated to grains, and then transferred into the
detonating tube, which was eight tenths of an inch in diameter, and
graduated to ten grain measures.
The space occupied by the gases being noted after the inflammation by
the electric shock, green muriate of iron, and prussiate of potash, were

successively introduced, to ascertain if any nitrous acid had been formed.
The absorption, if any took place, was marked, and the gases transferred
into a narrow grain measure tube, and their bulk and composition accurately
ascertained.
b. The hydrogene employed was procured from water by means of zinc
and sulphuric acid. 50 grain measures of it fired by the electric spark, with
30 grain measures of oxygene containing one eleventh nitrogene, gave a
residuum of about 4. Nitrous gas mingled with those 4, indicated the
presence of rather less than 1 of unconsumed oxygene. In another
experiment 23 of it, with 20 of the same oxygene left rather more than 6
residuum.
The nitrous oxide was apparently pure, for it left a remainder of about
,05 only, when absorbed by common water.
c. 30 of hydrogene were fired with 40 of nitrous oxide; the concussion
was very great, and the light given out bright red; no perceptible quantity of
nitrous acid was formed; the residual gas filled a space equal to 52. No part
of it was absorbable by water, it gave no diminution with nitrous gas, when
it was mingled with a little oxygene, and again acted on by the electric
spark, an inflammation and slight diminution was produced.
d. 33 of hydrogene were fired with 35 of nitrous oxide: nitrous acid was
produced in very minute quantity; the gas that remained was not absorbable
by water, and filled a space equal to 37 grains. Nitrous gas mingled with
these, underwent a very slight diminution.
e. 46 hydrogene were fired with 46 nitrous oxide. The quantity of
nitrous acid formed was just sufficient to tinge the white prussiate of
potash. The gases filled a space equal to 49, gave no perceptible diminution
with nitrous gas, and did not inflame with oxygene.
f. 40 hydrogene were fired with 39 nitrous oxide; no perceptible
quantity of nitrous acid was formed. The residual gas filled a space equal to
41; was unabsorbable by water, underwent no diminution when mingled
with nitrous gas; or when acted on by the electric spark in contact with
oxygene.
g. 20 hydrogene were fired with 64 nitrous oxide; after detonation the
expansion of the gases was greater in this experiment than any of the

preceding ones; dense white fumes were observed in the cylinder, and a
slow contraction of volume took place. After a little green muriate of iron
had been admitted, the gases filled a space equal to 73: prussiate of potash
mingled with the muriate, gave a deeper blue than in any of the preceding
experiments. The residual gas was unabsorbable by water: 65 of it, mingled
with 65 of nitrous gas, diminished to 93; whilst 65 of common air, with 65
of nitrous gas, gave 84.
h. 8 of hydrogene were fired with 54 of nitrous oxide; the same
phænomena as were observed in the last experiment took place; nitrous acid
was formed; after the absorption of which the residual gas filled a space
equal to 55. 50 of this, with an equal quantity of nitrous gas, diminished to
76. In these processes the temperatures were from 56° to 61°.
These experiments are selected as the most accurate of nearly fifty,
made on the inflammation of different quantities of nitrous oxide and
hydrogene.
As Mr. Keir found muriatic acid in the fluid, produced by the
inflammation of oxygene and hydrogene in closed vessels, in Dr. Priestley’s
experiments, I preserved the residual gas of about 3 cubic inches of nitrous
oxide, that had been detonated at different times with less than a cubic inch
and half of hydrogene; but solution of nitrate of silver was not clouded
when agitated in this gas, nor when introduced into the detonating tube in
which the inflammation had been made.
From these experiments we learn that nitrous oxide is decomposable at
the heat of ignition, by hydrogene, in a variety of proportions.
When the quantity of hydrogene very little exceeds that of the nitrous
oxide, both of the gates disappear, water is produced, no nitrous acid is
formed, and the volume of nitrogene evolved is rather greater than that of
the nitrous oxide decomposed.
When the quantity of hydrogene is less than that of the nitrous oxide,
water, nitrous acid, oxygene and nitrogene, are generated in different
proportions; one part of the nitrous oxide is most probably wholly
decomposed by the hydrogene, and the other part converted into nitrous
acid and atmospheric air, in consequence of the ignition.

From experiments c, d, and e, the composition of nitrous oxide may be
deduced. In experiment d, 39 of nitrous oxide were decomposed by 40 of
hydrogene, and converted into 41 of nitrogene.
Now from b it appears that 40 of hydrogene require for their
condensation about 20.8 of oxygene in volume; so that founding the
estimation upon the quantity of hydrogene consumed, 100 parts of nitrous
oxide would consist nearly of 63.1 of nitrogene, and 36.9 of oxygene. But
41 of nitrogene weigh 12.4, Res. I. Div. I. Consequently, deducing the
composition of nitrous oxide from the quantity of nitrogene evolved, 100
parts of it would consist of 63.5 nitrogene, and 36.5 oxygene.
These estimations are very little different from those which may be
deduced from the other experiments, and the coincidence is in favor of their
accuracy.
From the following experiment it appears that the temperature required
for the decomposition of nitrous oxide by hydrogene must be higher than
that which is necessary to produce the inflammation of hydrogene with
oxygene. I introduced into small tubes filled with equal parts of nitrous
oxide and hydrogene, standing on a surface of mercury, iron wires ignited
to different degrees, from the dull red to the vivid white heat. The gases
were always inflamed by the white and vivid red heats; but never by the
dull red heat, though the last uniformly inflamed mixtures of oxygene and
hydrogene, and atmospheric air and hydrogene.
Dr. Priestley[170] first detonated together nitrous oxide and hydrogene;
his experiment was repeated by the Dutch chemists, who found that when a
small quantity of hydrogene was employed, the nitrous oxide was partially
converted into a gas analogous to common air. Their estimation of its
composition, which is not far removed from the truth, was founded on this
phænomenon.[171]

IV. Decomposition of Nitrous Oxide by Phosphorus.
a. Phosphorus introduced into pure nitrous oxide at common
temperatures, is not at all luminous. It is capable of being fused, and even
sublimed in it, without undergoing acidification, and without effecting any
alteration in its composition.

About 2 grains of phosphorus were fused, and gradually sublimed, in 2
cubic inches of pure nitrous oxide, over mercury, by the heat of a burning
lens. No alteration was produced in the volume of gas, and a portion of it
absorbed by water, left a residuum of one twelfth only.
Phosphorus was sublimed in pure nitrous oxide over mercury, in a dark
room, by an iron heated nearly to ignition; but no luminous appearance was
perceptible, nor was any gas decomposed.
b. Phosphorus decomposes nitrous oxide at the temperature of ignition,
with greater or less rapidity, according to the degree of heat. We have
already seen, that when phosphorus in active inflammation is introduced
into nitrous oxide, it burns with intensely vivid light.
Phosphorus was sublimed by a heated wire in a jar filled with nitrous
oxide, standing over warm mercury. In this state of sublimation an iron
heated dull red was introduced to it by being rapidly passed through the
mercury; a light blue flame surrounded the wire, and disappeared as soon as
it ceased to be red.
To phosphorus sublimed as before, in nitrous oxide, over warm
mercury, a thick wire ignited to whiteness was introduced; a terrible
detonation took place, and the jar was shattered in pieces.
By employing thick conical jars,[172] containing only a small quantity of
nitrous oxide, I effected the detonation several times with safety; but on
account of the great expansion of the elastic products, the jar was generally
either raised from the mercury, or portions of gas were thrown out of it.
Hence I was unable to ascertain the exact changes produced by this mode of
decomposition.
c. As my first attempts to ascertain the constitution of nitrous oxide
were made on its decomposition by phosphorus, I employed many different
modes of partially igniting this substance in it over mercury, so as to
produce a combustion without explosion.
The first method adopted was inflammation by means of oxygenated
muriate of potash. A small particle of oxygenated muriate of potash was
inserted into the phosphorus to be burnt. On the application of a wire,
moderately hot, to the point of insertion, the salt was decomposed by the
phosphorus, and sufficient fire generated and partially applied by the slight

explosion, to produce the combustion of the phosphorus, without the
previous sublimation of any part of it.
The second way employed was the ignition of a part of the phosphorus,
by means of the combustion of a small portion of tinder of cotton,[173] or
paper, in contact with it, by the burning glass.
The third, and most successful mode, was by introducing into the
graduated jar containing the nitrous oxide, the phosphorus in a small tube
containing oxygene, so balanced as to swim on the surface of the mercury,
without communicating with the nitrous oxide. The phosphorus was fired in
the oxygene with an ignited iron wire, by which at the moment of
combustion, the tube containing it was raised into the nitrous oxide, and
thus the inflammation continued.
d. In different experiments, made with accuracy, I found that the whole
of a quantity of nitrous oxide was never decomposable by ignited
phosphorus; the combustion always stopped when the nitrous oxide
remaining was to the nitrogene evolved as about 1 to 5; likewise that the
volume of nitrogene produced was rather less than that of the nitrous oxide
decomposed, and that this deficiency arose from the formation of nitrous
acid by the intense ignition produced during the process.
Of one experiment I shall give a detail.
Temperature being 48°, two cubic inches of pure nitrous oxide, which
had been generated over mercury, were introduced into a jar of the capacity
of 9 cubic inches, graduated to,1 cubic inches, and much enlarged at the
base. A grain of phosphorus was inserted into a small vessel about one third
of an inch long, and half an inch in diameter, containing about 15 grain
measures of very pure oxygene; this vessel, which swam on the surface of
the mercury, was carefully introduced into the jar containing the nitrous
oxide. The phosphorus was fired by means of a heated wire, and before the
oxygene was wholly consumed, the vessel containing it elevated into the
nitrous oxide. The combustion was extremely vivid and rapid. After the
atmospheric temperature was restored, the gas was rendered opaque by
dense white vapor. When this had been precipitated, and the small vessel
removed from the jar, the gas filled a space nearly equal to 1.9 cubic inches.
On introducing to it a little solution of green muriate of iron, and prussiate

of potash, green prussiate of iron was produced: hence, evidently, nitrous
acid had been formed.
On the admission of pure water, an absorption of rather more than,3
took place.
The 16 measures remaining underwent no perceptible diminution with
nitrous gas; the taper plunged into them was instantly extinguished.
To ascertain if the phosphoric acid produced in the experiments made
under mercury did not in some measure prevent the decomposition of the
whole of the nitrous oxide by the phosphorus, I introduced into a mixture of
5 nitrogene and 1 nitrous oxide, ignited phosphorus: but it was immediately
extinguished.[174]
The Dutch Chemists found that phosphorus might be fused in nitrous
oxide without being luminous. They assert that phosphorus in a state of
inflammation, introduced into this gas, was immediately extinguished;
though when taken out into the atmosphere, it again burnt of its own accord.
[175]
It is difficult to account for their mistake.

V. Decomposition of Nitrous Oxide by
Phosphorated Hydrogene.
a. It has been mentioned in Res. II. Div. I. that phosphorated hydrogene
and nitrous oxide posses no action on each other, at atmospheric
temperatures.
Phosphorated hydrogene mingled with nitrous oxide, is capable of being
inflamed by the electric spark, or by ignition.
b. E. 1. 10 grain measures of phosphorated hydrogene, carefully
produced by means of phosphorus and solution of caustic alkali, were
mingled with 52 measures of nitrous oxide. The electric spark passed
through them, produced a vivid inflammation. The elastic products were
clouded with dense white vapor, and after some minutes filled a space
nearly equal to 60. On the introduction of water, no absorption took place.
When 43 of nitrous gas were admitted, the whole diminished to 70.
E. 2. 25 of nitrous oxide were fired with 10 of phosphorated hydrogene,
by the electric spark. After detonation[176] they filled a space exactly equal

to 25. On the admission of solution of green sulphate of iron, and prussiate
of potash, no blue or green precipitate was produced. On the introduction of
water, no diminution was perceived. 25 of nitrous gas mingled with them,
gave exactly 50.
E. 3. 10 of nitrous oxide, mingled with 20 of phosphorated hydrogene,
could not be inflamed.
25 of nitrous oxide, with 20 phosphorated hydrogene, inflamed. The gas
after detonation, was rendered opaque by dense white vapor, and filled a
space nearly equal to 45. No absorption took place when water was
introduced. On admitting a little oxygene no white fumes, or diminution,
was perceived. The electric spark passed through the mixture, produced an
explosion, with great diminution.
c. From E. 1 it appears, that when a small quantity of phosphorated
hydrogene is inflamed with nitrous oxide, both the phosphorus and
hydrogene are consumed; whilst the superabundant nitrous oxide, is
converted into nitrous acid and atmospheric air, by the ignition; or a certain
quantity is partially decomposed into atmospheric air by the combination of
a portion of its oxygene with the combustible gas.
From E. 2 we learn, that when the phosphorated hydrogene and nitrous
oxide are to each other as 25 to 10 nearly, they both disappear, whilst
nitrogene is evolved, and water and phosphoric acid produced. Reasoning
concerning the composition of nitrous oxide from this experiment, we
should conclude that it was composed of about 38 oxygene, and 62
nitrogene.
The result of E. 3 is interesting; we are taught from it that the affinity of
phosphorus for the oxygene of nitrous oxide is stronger than that of
hydrogene, at the temperature of ignition; so that when phosphorated
hydrogene is mingled with a quantity of nitrous oxide, not containing
sufficient oxygene to burn both its constituent parts, the phosphorus only is
consumed, whilst the hydrogene is liberated.
In repeating the experiments with phosphorated hydrogene that had
remained for some hours in the mercurial apparatus, I did not gain exactly
the same results; for a larger quantity of it was required to decompose the
nitrous oxide, than in the former experiments; doubtless from its having

deposited a portion of its phosphorus. They confirm, however, the above
mentioned conclusions.
In the course of experimenting, I passed the electric spark, for a quarter
of an hour, through about 60 measures of phosphorated hydrogene. It
underwent no alteration of volume. Phosphorus was apparently precipitated
from it, and it had wholly lost its power of inflaming, in contact with
common air.

VI. Decomposition of Nitrous Oxide by Sulphur.
From the phænomena before mentioned,[177] relating to the combustion
of sulphur in nitrous oxide, it was evident that this gas was only
decomposable by it, at a much higher temperature than common air.
I introduced into sulphur in contact with nitrous oxide, over mercury
heated to 112°-114°, a wire intensely ignited. It lost much of its heat in
passing through the mercury, but still appeared red in the vessel. The
sulphur rapidly fused, and sublimed without being at all luminous. This
experiment was repeated five or six times, but in no instance could the
combustion of sulphur, by means of the ignited wire, be effected.
I inflamed sulphur in nitrous oxide in the same manner as phosphorus;
namely, by introducing it into the small vessel filled with oxygene, and
igniting it by means of the heated wire. In these experiments the sulphur
burnt with a vivid rose-colored light, and much sulphuric, with a little
sulphureous acid, was formed.
Experimenting in this way I was never, however, able to decompose
more than one third of the quantity of nitrous oxide employed; not only the
nitrogene evolved, but likewise the sulphuric and sulphureous acids
produced, stopping the combustion.
I found that sulphur in a state of vivid inflammation, when introduced
into a mixture of one fourth nitrogene, and three fourths nitrous oxide, burnt
with a flame very much enlarged, and of a vivid rose color. In one third
nitrogene, and two thirds nitrous oxide, it burnt feebly with a yellow flame.
In equal parts of nitrous oxide and nitrogene, it was instantly extinguished.
Sulphur burnt feebly, with a light yellow flame, when introduced ignited
into a mixture of 5 nitrous gas, and 6 nitrous oxide. In one third nitrous

oxide, and two thirds nitrous gas, it was instantly extinguished. From many
circumstances, I am inclined to believe that sulphur is incapable, at any
temperature, of slowly decomposing nitrous oxide, so as to burn in it with a
blue flame, forming sulphureous acid alone. It appears to attract oxygene
from it only when intensely ignited, so as to form chiefly sulphuric acid,
and that with great rapidity, and vivid inflammation.

VII. Decomposition of Nitrous Oxide by
Sulphurated Hydrogene.
a. Though nitrous oxide and sulphurated hydrogene do not act upon
each other at common temperatures, yet they undergo a mutual
decomposition when mingled together in certain proportions, and ignited by
the electric spark.
From more than twenty experiments made on the inflammation of
sulphurated hydrogene in nitrous oxide, I select the following as the most
conclusive and accurate. The temperature at which they were made was
from 41° to 49°.
b. E. 1. About 35 measures of nitrous oxide were fired with 10 of
sulphurated hydrogene; the expansion during inflammation was very great,
and the flame sky-blue. Immediately after, the gases filled a space equal to
48 nearly. White fumes were then formed, and they gradually contracted to
40. On the admission of a little strontian lime water, a slight absorption took
place, with white precipitation; and the volume occupied by the residual gas
nearly equalled 37. On admitting nitrous gas to these, no perceptible
diminution took place.
E. 2. 20 sulphurated hydrogene, with 25 nitrous oxide, could not be
inflamed.
30 nitrous oxide, with 22 sulphurated hydrogene, could not be inflamed.
35 nitrous oxide, with 20 sulphurated hydrogene, inflamed with vivid
blue light, and great expansion. After the explosion, the gases filled exactly
the same space as before the experiment; no white fumes were perceived,
and no farther contraction occurred. On the addition of strontian lime water,
a copious precipitation, with diminution, took place; and the residual gas
filled a space nearly equal to 35½.

E. 3. 47 nitrous oxide, and 14 sulphurated hydrogene, inflamed. After
the explosion, the gases filled a space nearly equal to 65; then white fumes
formed, and they gradually diminished to 52. On the introduction of muriate
of strontian, a copious white precipitate was produced; and on the addition
of water, no further absorption took place. To the residual 52, about 20 of
nitrous gas were added; they filled together a space equal to about 67.
c. In none of the experiments made on the inflammation of sulphurated
hydrogene and nitrous oxide, could I ascertain with certainty the
precipitation of sulphur. In one or two processes the detonating tube was
rendered a little white at the points of contact with the mercury; but this was
most probably owing to the oxydation of the mercury, either by the heated
sulphuric acid formed, or from nitrous acid produced by the ignition. The
presence of nitrous acid I could not ascertain in these processes by my usual
tests, because the combustion of sulphur over white prussiate of iron,
converts it into light green.
When I introduced an inflamed taper into about 3 parts of sulphurated
hydrogene, and 2 parts of nitrous oxide, in which proportions they could not
have been fired by the electric spark, a blue flame passed through them, and
much sulphur was deposited on the sides of the vessel. But this sulphur
most probably owed its formation to the decomposition of a portion of
sulphurated hydrogene not burnt, by the sulphureous acid formed from the
combustion of the other portion.
We may then conclude with probability, that sulphurated hydrogene and
nitrous oxide will not decompose each other, when acted on by the electric
spark, unless their proportions are such as to enable the whole of the
sulphurated hydrogene to be decomposed, so that both of its constituents
may become oxygenated, by attracting oxygene from the nitrous oxide:
likewise, that when the sulphurated hydrogene is at its maximum of
inflammation, the hydrogene and sulphur form with the whole of the
oxygene of nitrous oxide, water and sulphureous acid; E. 2: whereas at its
minimum they produce water, and chiefly, perhaps wholly, sulphuric acid;
at the same time that the nitrous oxide partially decomposed, is converted
into nitrogene, and a gas analogous to atmospheric air, or into nitrogene,
nitrous acid, and atmospheric air. E. 1. E. 3.

By pursuing those experiments, and using larger quantities of gas, we
may probably be able to ascertain from them with accuracy, the
composition of sulphuric and sulphureous acids.
I own I was disappointed in the results, for I expected to have been able
to ascertain from them, the relative affinities of sulphur, and hydrogene for
the oxygene of nitrous oxide, at the temperature of ignition. I conjectured
that nitrous oxide, mingled with excess of sulphurated hydrogene, would
have been decomposed, and one of the principles of it evolved unaltered, as
was the case with phosphorated hydrogene.
If we estimate the composition of nitrous oxide from the quantity of
nitrogene produced in E. 2, it is composed of about 61 nitrogene, and 39
oxygene.

VIII. Decomposition of Nitrous Oxide by Charcoal.
An account of the analysis of nitrous oxide by charcoal is given in Res.
I. Div. III. I have lately made two experiments on the combustion of
charcoal in nitrous oxide, in which every precaution was taken to prevent
the existence of sources of error. Of one of these I shall give a detail.
E. Temperature being 51°, about a grain of charcoal, which had been
exposed for some hours to a red heat, was introduced whilst ignited, under
mercury, and transferred into a graduated jar, containing 3 cubic inches of
pure nitrous oxide, standing over dry mercury.
The focus of a burning lens was thrown on the charcoal; it instantly
inflamed, and burnt with great vividness for near a minute, the gas being
much expanded. The focus was continually applied to it for ten minutes,
when the process appeared at an end. The gases, when the common
temperature and pressure were restored, filled a space equal to 4,2 cubic
inches.
On introducing into them a few grain measures of solution of green
muriate of iron, for the double purpose of saturating them with moisture,
and ascertaining if any nitrous acid had been formed, no change of volume
took place; and prussiate of potash gave with the muriate a white precipitate
only.

On the admission of a small quantity of concentrated solution of caustic
potash, a diminution of the gas slowly took place; when it was complete the
volume equalled about 3.05 cubic inches. By agitation in well boiled water,
about,9 of these were absorbed; the remainder appeared to be pure
nitrogene.
The difference between the estimation founded upon the nitrogene
evolved, and that deduced from the carbonic acid generated in this
experiment, is not nearly so great as in that Res. I. Div. III. Taking about the
mean proportions, we should conclude that nitrous oxide was composed of
about 38 oxygene, and 62 nitrogene.
Charcoal burnt with greater vividness than in common air, in a mixture
of one third nitrogene and two thirds nitrous oxide. In equal parts of nitrous
oxide and nitrogene, its light was barely perceptible. In one third nitrous
oxide, and two thirds nitrogene, it was almost immediately extinguished.
As charcoal burns vividly in nitrous gas, when it has been previously
ignited to whiteness, I introduced it into a mixture of equal parts of nitrous
oxide and nitrous gas; it burnt with a deep and bright red.

IX. Decomposition of Nitrous Oxide
by Hydrocarbonate.
Nitrous oxide, and hydrocarbonate, possess no action on each other,
except at high temperatures. When mingled in certain proportions, and
exposed to the electric shock, a new arrangement of their principles takes
place.
E. 1. Temperature being 53°, 35 of nitrous oxide, mingled with 15 of
hydrocarbonate, were fired by the electric spark; the inflammation was very
vivid, and the light produced, bright red. After the explosion, the space
occupied by the gases equalled about 60. On the admission of solution of
strontian, a copious white precipitate was produced, and the gas diminished
by agitation, to rather more than 35. When 36 of nitrous gas were added to
these, white fumes appeared and the whole diminished to 62. When a little
muriatic acid was poured on the white precipitate from the solution of
strontian, gas was evolved from it, and it was gradually dissolved.

E. 2. 22 nitrous oxide were inflamed with 20 hydrocarbonate; after the
explosion, they filled a space equal to 45; when strontian lime water was
introduced, white precipitation took place, and the diminution was to 31.
To these 31, 14 of nitrous oxide were admitted, and the electric spark
passed through them; an inflammation took place: carbonic acid was
formed, after the absorption of which, the gas remaining filled a space equal
to 43, and did not diminish with nitrous gas.
The hydrocarbonate employed in these experiments, was procured from
alcohol by means of sulphuric acid. In another set of experiments made
with less accuracy, the same general results were obtained. Whenever
hydrocarbonate inflamed with nitrous oxide, both its constituents were
oxygenated; in all cases carbonic acid was formed, and in no instance free
hydrogene evolved, or charcoal precipitated.
In the decomposition of nitrous oxide by hydrocarbonate, the residual
nitrogene is less than in other combustions. This circumstance I am unable
to explain.
Reasoning from analogy, there can be little doubt, but that when
hydrocarbonate is inflamed with excess of nitrous oxide, it will be only
partially decompounded, or converted into nitrogene, nitrous acid, and
atmospheric air.
The Dutch Chemists have asserted, that charcoal does not burn in
nitrous oxide, except in consequence of the previous decomposition of the
gas by the hydrogene always contained in this substance; and likewise, that
when hydrocarbonate and nitrous oxide were mingled together, and fired by
the electric spark, the hydrogene only was burnt, whilst the charcoal was
precipitated.
It is difficult to account for these numerous mistakes. Their theory of
the non-respirability of nitrous oxide was founded upon them. They
supposed that the chief use of respiration was to deprive the blood of its
superabundant carbon, by the combination of atmospheric oxygene with
that principle; and that nitrous oxide was highly fatal to life, because it was
incapable of de-carbonating the blood[178]!!

X. Combustion of Iron in Nitrous Oxide.

I introduced into a jar of the capacity of 20 cubic inches, containing 11
cubic inches of nitrous oxide, over mercury, a small quantity of fine iron
wire twisted together, and having affixed to it a particle of cork. On
throwing the focus of a burning glass on the cork, it instantly inflamed, and
the fire was communicated to the wire, which burnt with great vividness for
some moments, projecting brilliant white sparks. After it had ceased to burn
the gas was increased in volume rather more than three tenths of an inch.
The nitrous acid tests were introduced, but no acid appeared to have been
formed. On exposing the gas to water, near 4,2 cubic inches were absorbed:
the 7,1 remaining appeared to be pure nitrogene.
From this experiment it is evident that iron at the temperature of
ignition, is capable of decomposing nitrous oxide; likewise that it is
incapable of burning in it when it contains more than three fifths nitrogene.
I attempted to inflame zinc in nitrous oxide, in the same way as iron; but
without success. By keeping the focus of a burning glass upon some zinc
filings, in a small quantity of nitrous oxide, I converted a little of the zinc
into white oxide, and consequently decomposed a portion of the gas.

XI. Combustion of Pyrophorus in Nitrous Oxide.
Pyrophorus, which inflames in nitrous gas, and atmospheric air, at or
even below 40°, requires for its combustion in nitrous oxide a much higher
temperature. It will not burn in it, or alter it, even at 212°.
I have often inflamed pyrophorus in nitrous oxide over mercury, by
means of a wire strongly heated, but not ignited. The light produced by the
ignition of pyrophorus in nitrous oxide is white, like that produced by it in
oxygene: in nitrous gas it is red.
When pyrophorus burns out in nitrous oxide, a little increase of the
volume of gas is produced. Strontian lime water agitated in this gas
becomes clouded; but the quantity of carbonic acid formed is extremely
minute. I have never made any delicate experiments on the combustion of
pyrophorus in nitrous oxide.

XII. Combustion of the Taper in Nitrous Oxide.

It has been noticed by different experimentalists, that the taper burns
with a flame considerably enlarged in nitrous oxide: sometimes with a vivid
light and crackling noise, as in oxygene; at other times with a white central
flame, surrounded by a feeble blue one.
My experiments on the combustion of the taper in nitrous oxide, were
chiefly made with a view to ascertain the cause of the double flame.
When the inflamed taper is introduced into pure nitrous oxide, it burns
at first with a brilliant white light, and sparkles as in oxygene. As the
combustion goes on, the brilliancy of the flame diminishes; it gradually
lengthens, and becomes surrounded with a pale blue cone of light, from the
apex of which much unburnt charcoal is thrown off, in the form of smoke.
The flame continues double to the end of the process.
When the residual gases are examined after combustion, much nitrous
acid is found suspended in them; and they are composed of carbonic acid,
nitrogene, and about one fourth of undecompounded nitrous oxide.
The double flame depends upon the nitrous acid formed by the ignition;
for it can be produced by plunging the taper into common air containing
nitrous acid vapor, or into a mixture of nitrous oxide and nitrogene, through
which nitrous acid has been diffused. It is never perceived in the
combustion of the taper, till much nitrous acid is formed.
In attempting to respire some residual gas of nitrous oxide, in which a
taper had burnt out, I found it so highly impregnated with nitrous acid, as to
disable me from even taking it into my mouth.
The taper burns in a mixture of equal parts nitrous oxide and nitrogene,
at first with a flame nearly the same as that of a candle in common air;
white. Before its extinction the interior white flame, and exterior blue
flame, are perceived.
The taper is instantly extinguished in a mixture of one fourth nitrous
oxide, and three fourths nitrogene.
In a mixture of equal parts nitrous oxide and nitrous gas, the taper burns
at first with nearly as much brilliancy as in pure nitrous oxide; gradually the
double and feeble flame is produced.

XIII. On the Combustion of different
Compound Bodies in Nitrous Oxide.
All the solid and fluid compound inflammable bodies on which I have
experimented, burn in nitrous oxide, at high temperatures. Wood, cotton,
and paper, are easily inflamed in it by the burning glass. During their
combustion, nitrous acid is always formed, carbonic acid, and water
produced, and nitrogene evolved, rather less in bulk than the nitrous oxide
decomposed.
I have already mentioned that alcohol and ether are soluble in nitrous
oxide. When an ignited body is introduced into the solution of alcohol, or
ether in nitrous oxide, a slight explosion takes place.

XIV. General Conclusions relating to the Decomposition
of Nitrous Oxide, and to its Analysis.
From what has been said in the preceding sections, it appears that the
inflammable bodies, in general, require for their combustion in nitrous
oxide, much higher temperatures than those at which they burn in
atmospheric air, or oxygene.
When intensely heated they decompose it, with the production of much
heat and light, and become oxygenated.
During the combustion of solid or fluid bodies, producing flame, in
nitrous oxide, nitrous acid is generated, most probably from a new
arrangement of principles, analogous to those observed in Sect. II, by the
ignition of that part of the gas not in contact with the burning substance.
Likewise when nitrous oxide in excess is decomcomposed by inflammable
gases, nitrous acid, and sometimes a gas analogous to common air, is
produced, doubtless from the same cause.
Pyrophorus is the only body that inflames in nitrous oxide, below the
temperature of ignition.
Phosphorus burns in it with the blue flame, probably forming with its
oxygene only phosphoreous acid at the dull red heat, and with the intensely
vivid flame, producing phosphoric acid at the white heat.

Hydrogene, charcoal, sulphur, iron, and the compound inflammable
bodies, decompose it only at heats equal to, or above, that of ignition:
probably each a different temperature.
From the phænomena in Sect. V. it appears, that at the temperature of
intense ignition, phosphorus has a stronger affinity for the oxygene of
nitrous oxide than hydrogene; and reasoning from the different degrees of
combustibility of the inflammable bodies, in mixtures of nitrous oxide and
nitrogene, and from other phænomena, we may conclude with probability,
that at about the white heat, the affinity of the combustible bodies for
oxygene takes place in the following order. Phosphorus, hydrogene,
charcoal,[179] iron, sulphur, &c.
This order of attraction is very different from that obtaining at the red
heat; in which temperature charcoal and iron have a much stronger affinity
for oxygene than either phosphorus or hydrogene.[180]
The smallest quantity of oxygene given in the different analyses of
nitrous oxide just detailed, is thirty five hundred parts; the greatest
proportion is thirty-nine.
Taking the mean estimations from the most accurate experiments, we
may conclude that 100 grains of the known ponderable matter of nitrous
oxide, consist of about 36,7 oxygene, and 63,3 nitrogene; or taking away
decimals, of 37 oxygene to 63 nitrogene; which is identical with the
estimation given in Research I.

XV. Observations on the combinations of
Oxygene and Nitrogene.
During the decompositions of the combinations of oxygene and
nitrogene by combustible bodies, a considerable momentary expansion of
the acting substances, and the bodies in contact with them is generally
produced, connected with increased temperature; whilst light is often
generated to a great extent.
Of the causes of these phænomena we are at present ignorant. Our
knowledge of them must depend upon the discovery of the precise nature of
heat and light, and of the laws by which they are governed. The application
of general hypotheses to isolated facts can be of little utility; for this reason

I shall at present forbear to enter into any discussions concerning those
agents, which are imperceptible to the senses, and known only by solitary
effects.
Analysis and synthesis clearly prove that oxygene and nitrogene
constitute the known ponderable matter of atmospheric air, nitrous oxide,
nitrous gas, and nitric acid.
That the oxygene and nitrogene of atmospheric air exist in chemical
union, appears almost demonstrable from the following evidences.
1st. The equable diffusion of oxygene and nitrogene through every part
of the atmosphere, which can hardly be supposed to depend on any other
cause than an affinity between these principles.[181]
2dly. The difference between the specific gravity of atmospheric air, and
a mixture of 27 parts oxygene and 73 nitrogene, as found by calculation; a
difference apparently owing to expansion in consequence of combination.
3dly. The conversion of nitrous oxide into nitrous acid, and a gas
analogous to common air, by ignition.
4thly. The solubility of atmospheric air undecompounded in water.
Atmospheric Air, then, may be considered as the least intimate of the
combinations of nitrogene and oxygene.
It is an elastic fluid, permanent at all known temperatures, consisting
of,73 nitrogene, and,27 oxygene. It is decomposable at certain
temperatures, by most of the bodies possessing affinity for oxygene. It is
soluble in about thirty times its bulk of water, and as far as we are
acquainted with its affinities, incapable of combining with most of the
simple and compound substances. 100 cubic inches of it weigh about 31
grains at 55° temperature, and 30 atmospheric pressure.
Nitrous Oxide is a gas unalterable in its constitution, at temperatures
below ignition. It is composed of oxygene and nitrogene, existing perhaps
in the most intimate union which those substances are capable of assuming.
[182]
Its properties approach to those of acids. It is decomposable by the
combustible bodies at very high temperatures, is soluble in double its
volume of water, and in half its bulk of most of the inflammable fluids. It is
combinable with the alkalies, and capable of forming with them peculiar

salts. 100 grains of it are composed of about 63 nitrogene, and 37 oxygene.
100 cubic inches of it weigh 50 grains, at 55° temperature, and 30
atmospheric pressure.
Nitrous Gas is composed of about,56 oxygene, and,44 nitrogene, in
intimate union. It is soluble in twelve times its bulk of water, and is
combinable with the acids, and certain metallic solutions; it is possessed of
no acid properties, and is decomposable by most of the bodies that attract
oxygene strongly, at high temperatures. 100 cubic inches of it weigh about
34 grains, at the mean temperature and pressure.
Nitric Acid is a substance permanently aëriform at common
temperatures, composed of about 1 nitrogene, to 2,3 oxygene. It is soluble
to a great extent in water, and combinable with the alkalies, and nitrous gas.
It is decomposable by most of the combustible bodies, at certain
temperatures. 100 cubic inches of it weigh, at the mean temperature and
pressure, nearly 76 grains.

RESEARCH III.
RELATING TO THE RESPIRATION OF NITROUS OXIDE,
AND OTHER GASES.

DIVISION I.

EXPERIMENTS and OBSERVATIONS on the EFFECTS produced
upon ANIMALS by the RESPIRATION of NITROUS OXIDE.
I. Preliminaries.

T
he term respirable, in its physiological application, has been differently
employed. Some times by the respirability of a gas has been meant, its
power of supporting life for a great length of time, when repeatedly
applied to the blood in the lungs. At other times all gases have been
considered as respirable, which were capable of introduction into the lungs
by voluntary efforts, without any relation to their vitality.
In the last sense the word respirable is most properly employed. In this
sense it is used in the following sections.
Non-respirable gases are those, which when applied to the external
organs of respiration, stimulate the muscles of the epiglottis in inch a way
as to keep it perfectly close on the glottis; thus preventing the smallest
particle of gas from entering into the bronchia, in spite of voluntary
exertions; such are carbonic acid, and acid gases in general.[183]
Of respirable gases, or those which are capable of being taken into the
lungs by voluntary efforts.
One only has the power of uniformly supporting life;—atmospheric air.
Other gases, when respired, sooner or later produce death; but in different
modes.
Some, as nitrogene and hydrogene, effect no positive change in the
venous blood. Animals immersed in these gases die of a disease produced

by privation of atmospheric air, analogous to that occasioned by their
submersion in water, or non-respirable gases.
Others, as the different varieties of hydrocarbonate, destroy life by
producing some positive change[184] in the blood, which probably
immediately renders it incapable of supplying the nervous and muscular
fibres with principles essential to sensibility and irritability.
Oxygene, which is capable of being respired for a much greater length
of time than any other gas, except common air, finally destroys life; first
producing changes in the blood, connected with new living action.[185]
After experiments, to be detailed hereafter, made upon myself and
others, had proved that nitrous oxide was respirable, and capable of
supporting life for a longer time than any of the gases, except atmospheric
air and oxygene, I was anxious to ascertain the effects of it upon animals, in
cases where its action could be carried to a full extent; and to compare the
changes occasioned by it in their organs, with those produced by other
powers.

II. On the respiration of Nitrous Oxide
by warm-blooded Animals.
The nitrous oxide employed in the following experiments, was procured
from nitrate of ammoniac, and received in large jars, filled with water
previously saturated with the gas. The animal was introduced into the jar,
by being carried under the water; after its introduction, the jar was made to
rest on a shelf, about half an inch below the surface of the water; and the
animal carefully supported, so as to prevent his mouth from resting in the
water.
This mode of experimenting, either under water or mercury, is
absolutely necessary, to ascertain with accuracy the effects of pure gases on
living beings. In some experiments that I made on the respiration of nitrous
oxide, by animals that were plunged into jars of it opened in the
atmosphere, and immediately closed after their introduction, the unknown
quantities of common air carried in, were always sufficient to render the
results perfectly inaccurate.
Animals suffer little or nothing by being passed through water.

That the phænomena in these experiments might be more accurately
observed, two or three persons were always present at the time of their
execution, and an account of them was noted down immediately after.
a. A stout and healthy young cat, of four or five months old, was
introduced into a large jar of nitrous oxide. For ten or twelve moments he
remained perfectly quiet, and then began to make violent motions, throwing
himself round the jar in every direction. In two minutes he appeared quite
exhausted, and sunk quietly to the bottom of the jar. On applying my hand
to the thorax, I found that the heart beat with extreme violence; on feeling
about the neck, I could distinctly perceive a strong and quick pulsation of
the carotids. In about three minutes the animal revived, and panted very
much; but still continued to lie on his side. His inspirations then became
longer and deeper, and he sometimes uttered very feeble cries. In four
minutes the pulsations of the heart appeared quicker and feebler. His
inspirations were at long intervals, and very irregular; in five minutes the
pulse was hardly perceptible; he made no motions, and appeared wholly
senseless. After five minutes and quarter he was taken out, and exposed to
the atmosphere before a warm fire. In a few seconds he began to move, and
to take deep inspirations. In five minutes he attempted to rise on his legs;
but soon fell again, the extremities being slightly convulsed. In eight or nine
minutes he was able to walk, but his motions were staggering and unequal,
the right leg being convulsed, whilst the other was apparently stiff and
immoveable; in about half an hour he was almost completely recovered.
b. A healthy kitten, of about six weeks old, was introduced into nitrous
oxide. She very soon began to make violent exertions, and in less than a
minute fell to the bottom of the receiver, as if apoplectic. At this moment,
applying my hand to her side, I felt the heart beating with great violence.
She continued gasping, with long inspirations, for three minutes and half; at
the end of five minutes and half she was taken out completely dead.
c. Another kitten of the same breed was introduced into nitrous oxide,
the day after. She exhibited the same phænomena, and died in it in about
five minutes and half.
d. A small dog that had accidentally met with a dislocation of the
vertebræ of the loins, and was in great pain, as manifested by his moaning
and whining, was introduced into a large jar of nitrous oxide. He

immediately became quiet, and lay on his side in the jar, breathing very
deeply. In four minutes his respiration became noisy, and his eyes sparkled
very much. I was not able to apply my hand to the thorax. In five minutes
he appeared senseless, and in seven minutes was perfectly dead.
e. A strong rabbit, of ten or twelve months old, was introduced into
nitrous oxide. He immediately began to struggle very much, and in a minute
fell down senseless: in two minutes the legs became convulsed, and his
inspirations were deep and noisy: in less than five minutes he appeared
perfectly dead.
f. A rabbit of a month old introduced into nitrous oxide, became
senseless in less than a minute; the pulsations of the heart were very strong
at this moment: they gradually became weaker, and in three minutes and
half the animal was dead.
g. Another rabbit of the same breed, after being rendered senseless in
nitrous oxide in a minute and half, was taken out. He soon became
convulsed; in a minute began to breathe quickly; in two minutes attempted
to rise, but staggered, and fell again on his side. His hinder legs were
paralytic for near five minutes. In twenty he had almost recovered.
h. A middle sized guinea-pig was much convulsed, after being in nitrous
oxide for a minute. In two minutes and half he was senseless. Taken out at
this period, he remained for some minutes by the side of a warm fire,
without moving; his fore legs then became convulsed; his hind legs were
perfectly paralytic. In this state he continued, without attempting to rise or
move, for near an hour, when he died.
i. A large and old guinea-pig died in nitrous oxide, exhibiting the same
phænomena as the other animals, in about five minutes and quarter. A
young one was killed in three minutes and half.
j. A small guinea-pig, after breathing nitrous oxide for a minute and
half, was taken out, and placed before a warm fire. He was for a few
minutes a little convulsed; but in a quarter of an hour got quite well, and did
not relapse.
k. A large mouse introduced into nitrous oxide, was for a few seconds
very active. In half a minute he fell down senseless; in a minute and quarter
he appeared perfectly dead.

l. A mouse taken out of nitrous oxide, after being in it for half a minute,
continued convulsed for some minutes, but finally recovered.
m. A young hen was introduced into a vessel filled with nitrous oxide.
She immediately began to struggle very much; fell on her breast in less than
half a minute, and in two minutes was quite dead.
n. A goldfinch died in nitrous oxide in less than a minute.
In each of these experiments a certain absorption of the gas was always
perceived, the water rising in the jar during the respiration of the animal.
From them we learn
1st. That nitrous oxide is destructive when respired for a certain time to
the warm-blooded animals, apparently previously exciting them to a great
extent.
2dly. That when its operation is stopped before compleat exhaustion is
brought on, the healthy living action is capable of being gradually
reproduced, by enabling the animal to respire atmospheric air.
3dly. That exhaustion and death is produced in the small animals by
nitrous oxide sooner than in the larger ones, and in young animals of the
same species, in a shorter time than in old ones, as indeed Dr. Beddoes had
conjectured a priori would be the case.
Most of the animals destroyed in these experiments were examined after
death; the appearances in their organs were peculiar. To prevent
unnecessary repetitions, an account of them will be given in the fourth
section.

III. Effects of the respiration of Nitrous Oxide upon animals,
as compared with those produced by their immersion
in Hydrogene and Water.
Before the following experiments were made, a number of
circumstances had convinced me that nitrous oxide acted on animals by
producing some positive change in their blood, connected with new living
action of the irritable and sensitive organs, and terminating in their death.
To ascertain however, the difference between the effects of this gas and
those of hydrogene and non-respirable gases, I proceeded in the following

way.
a. Of two healthy rabbits of about two months old, of the same breed,
and nearly of the same size.
One was introduced into nitrous oxide. In a half a minute, it had fallen
down apparently senseless. On applying my hand to the thorax, the action
of the heart appeared at first, very quick and strong, it gradually became
weaker, and in two minutes and half, the animal was taken out quite dead.
The other was introduced into a jar of pure hydrogene through water. He
immediately began to struggle very much, and in a quarter of a minute fell
on his side. On feeling the thorax, the pulsations of the heart appeared very
quick and feeble, they gradually diminished; his breathing became
momentarily shorter, and in rather more than three quarters of a minute, he
was taken out dead. Dr. Kinglake was present at this experiment, and
afterwards dissected both of the animals.
b. Of two similar rabbits of the same breed, nearly three months old.
One was introduced into nitrous oxide, and after being rendered senseless
by the respiration of it for nearly a minute and half, was exposed to the
atmosphere, before a warm fire. He recovered gradually, but was
occasionally convulsed, and had a paralysis of one of his hinder legs for
some minutes: in an hour he was able to walk. The other, after being
immerged in hydrogene for near half a minute, was restored to the
atmosphere apparently inanimate. In less than a minute he began to breathe,
and to utter a feeble noise; in two minutes was able to walk, and in less than
three minutes appeared perfectly recovered.
c. A kitten of about two months old, was introduced into a jar of nitrous
oxide, at the same time that another of the same breed was plunged under a
jar of water. They both struggled very much. The animal in the nitrous
oxide fell senseless before that under water had ceased to struggle, and to
throw out air from its lungs. In two minutes and three quarters, the animal
under water was quite dead: it was taken out and exposed to heat and air,
but did not shew the slightest signs of life. At the end of three minutes and
half, the animal in nitrous oxide began to gasp, breathing very slowly; at
four minutes and three quarters it was yet alive; at the end of five minutes
and quarter it appeared perfectly dead. It was taken out, and did not recover.

From these experiments it was evident, that animals lived at least twice
as long in nitrous oxide as in hydrogene or water. Consequently from this
circumstance alone, there was every reason to suppose that their death in
nitrous oxide could not depend on the simple privation of atmospheric air;
but that it was owing to some peculiar changes effected in the blood by the
gas.

IV. Of the changes effected in the Organisation of
warm-blooded Animals, by the respiration
of Nitrous Oxide.
The external appearance of animals that have been destroyed in nitrous
oxide, is very little different from that of those killed by privation of
atmospheric air. The fauces and tongue appear of a dark red, and the eyes
are dull, and a little protruded. Their internal organs, however, exhibit a
very peculiar change. The lungs are pale brown red, and covered here and
there with purple spots; the liver is of a very bright red, and the muscular
fibre in general dark. Both the auricles and ventricles of the heart are filled
with blood. The auricles contract for minutes after the death of the animal.
The blood in the left ventricle, and the aorta, is of a tinge between purple
and red, whilst that in the right ventricle is of a dark color, rather more
purple than the venous blood. But these appearances, and their causes, will
be better understood after the following comparative observations are read.
a. Of two similar rabbits, about eight months old, one A, was killed by
exposure for near six minutes to nitrous oxide, the other, B, was destroyed
by a blow on the head.
They were both opened as speedily as possible. The lungs of B were
pale, and uniform in their appearance; this organ in A was redder, and every
where marked with purple spots. The liver of A was of a dark and bright
red, that of B of a pale red brown. The diaphragm of B, when cut, was
strongly irritable; that of A rather darker, and scarce at all contractile. All
the cavities of the heart contracted for more than 50 minutes in B. The
auricles contracted for near 25 minutes with force and velocity in A: but the
ventricles were almost inactive. The vena cava, and the right auricle, in A,
were filled with blood, apparently a shade darker than in B. The blood in

the left auricle, and the aorta, appeared in A of a purple, a shade brighter
than that of the venous blood. In the left auricle of B it was red.
I opened the head of each, but not without injuring the brains, so that I
was unable to make any accurate comparison. The color of the brain in A
appeared rather darker than in B.
b. Two rabbits, C and D, were destroyed, C by immersion in nitrous
oxide, D in hydrogene: they were both dissected by Dr. Kinglake. The
blood in the pulmonary vein and the left auricle of C was of a different
tinge, from that in D more inclined to purple red. The membrane of the
lungs in C was covered with purple spots, that of D was pale and uniform in
its appearance. The brain in C was rather darker than in D; but there was no
perceptible effusion of blood into the ventricles either in D or C. The liver
in C was of a brighter red than in health, that in D rather paler.
c. In the last experiment, the comparative irritability of the ventricles
and auricles of the heart and the muscular fibre in the two animals, had not
been examined. That these circumstances might be noticed, two rabbits, E
and F were killed; E under water in about a minute, and F in nitrous oxide
in three minutes. They were immediately opened, and after a minute, the
appearance of the heart, and organs of respiration observed.
Both the right and left ventricles of the heart in F contracted but very
feebly; the auricles regularly and quickly contracted; the aorta appeared
perfectly full of blood. In E, a feeble contraction of the left sinus venosus
and auricle was observed; the left ventricle did not contract: the right
contracted, but more slowly than in F. In a few minutes, the contractions of
the ventricles in F had ceased, whilst the auricles contracted as strongly and
quickly as before. The blood in the pulmonary veins of F was rather of a
redder purple than in E; the difference of the blood in the vena cava was
hardly perceptible, perhaps it was a little more purple in F. The
membranous substance of the lungs in F was spotted with purple as from
extravasated blood, whilst that in E was pale. The brain in F was darker
than in E. On opening the ventricles no extravasation of blood was
perceptible. The auricles of the heart in F contracted strongly for near
twenty minutes, and then gradually their motion became less frequent; in
twenty-eight minutes it had wholly ceased. The right auricle and ventricle in
E, occasionally contracted for half an hour. The livers of both animals were

similar when they were first opened, of a dark red; that of F preserved its
color for some time when exposed to the atmosphere; whilst that of E
almost immediately became paler under the same circumstances.
The peristaltic motion continued for nearly an equal time in both
animals.
d. The sternum of a young rabbit was removed so that the heart and
lungs could be perceived, and he was introduced into a vessel filled with
nitrous oxide; the blood in the pulmonary veins gradually became more
purple, and the heart appeared to beat quicker than before, all the muscles
contracting with great force. After he had been in about a minute, spots
began to appear on the lungs, though the contractions of the heart became
quicker and weaker; in three minutes and half he was quite dead; after death
the ventricles contracted very feebly, though the contractions of the auricles
were as strong almost after the end of five minutes as at first. This animal
was passed through water saturated with nitrous oxide; possibly this fluid
had some effect on his organs.
Besides these animals, many others, as guinea-pigs, mice and birds,
were dissected after being destroyed in nitrous oxide; in all of them the
same general appearance was observed. Their muscular fibre almost always
appeared less irritable than that of animals destroyed, by organic læsion of
part of the nervous system, in the atmosphere. The ventricles of the heart in
general, contracted feebly and for a very short time; whilst the auricles
continued to act for a great length of time. The lungs were dark in their
appearance, and always suffused here and there with purple; the blood in
the pulmonary veins when slightly observed, appeared dark, like venous
blood, but when minutely examined, was evidently much more purple. The
blood in the vena cava, was darker than that in the pulmonary veins. The
cerebrum was dark.
In a late experiment, I thought I perceived a slight extravasation of
blood in one of the ventricles of the brain in a rabbit destroyed in nitrous
oxide; but as this appearance had not occurred in the animals I had
examined before, or in those dissected by Dr. Kinglake, and Mr. King,
Surgeon, I am inclined to refer it to an accidental cause. At my request, Mr.
Smith, Surgeon, examined the brain of a young rabbit that had been killed

in his presence in nitrous oxide; he was of opinion that no effusion of blood
into the ventricles had taken place.
In comparing the external appearance of the crural nerves in two rabbits
that had been dissected by Dr. Kinglake, having been destroyed one in
hydrogene, the other in nitrous oxide, we could perceive no perceptible
difference.
It deserves to be noticed, that whenever the gall bladder and the urinary
bladder have been examined in animals destroyed in nitrous oxide, they
have been always distended with fluid; which is hardly ever the case in
animals killed by privation of atmospheric air.
In the infancy of my experiments on the action of nitrous oxide upon
animals, I thought that it rendered the venous blood less coagulable; but this
I now find to be a mistake. The blood from the pulmonary veins of animals
killed in nitrous oxide, does not sensibly differ in this respect from the
arterial blood of those destroyed in hydrogene, and both become vermilion
nearly in the same time when exposed to the atmosphere.
In describing the various shades of color of the blood in the preceding
observations on the different dissected animals, the poverty of the language
of color, has obliged me to adopt terms, which I fear will hardly convey to
the mind of the reader, distinct notions of the differences observable by
minute examination in the venous and arterial blood of animals that die of
privation of atmospheric air, and of those destroyed by the action of nitrous
oxide. This difference can only be observed in the vessels by means of a
strong light; it may however be easily noticed in the fluid blood by the
introduction of it from the arteries or veins at the moment of their incision,
between two polished surfaces of white glass,[186] so closely adapted to
each other, as to prevent the blood from coming in contact with the
atmosphere.
Having four or five times had an opportunity of bleeding people in the
arm for trifling complaints, I have always received the blood in phials,
filled with various gases, in a mode to be described hereafter. Venous blood
agitated in nitrous oxide, compared with similar blood in common air,
hydrogene, and nitrogene, was always darker and more purple than the first,
and much brighter and more florid than the two last, which were not
different in their color from venous blood, received between two surfaces of

glass. It will be seen hereafter, that the coagulum of venous blood is
rendered more purple when exposed to nitrous oxide, whilst the gas is
absorbed; likewise that blood altered by nitrous oxide, is capable of being
again rendered vermilion, by exposure to the air.
The appearances noticed in the above mentioned experiments, in the
lungs of animals destroyed in nitrous oxide, are similar to those observed by
Dr. Beddoes, in animals that had been made to breathe oxygene for a great
length of time.
There were many reasons for supposing that the large purple spots in the
lungs of animals destroyed in nitrous oxide, were owing to extravasation of
venous blood from the capillary vessels; their coats being broken by the
highly increased arterial action. To ascertain whether these phænomena
existed at a period of the action of nitrous oxide, when the animal was
recoverable by exposure to the atmosphere.
I introduced a rabbit of six months old, into a vessel of nitrous oxide,
and after a minute, when it had fallen down apparently apoplectic, plunged
him wholly under water; he immediately began to struggle, and what
surprised me very much, died in less than a minute after submersion. On
opening the thorax, the blood in the pulmonary veins was nearly of the
color of that in animals that have been simply drowned. The lungs were
here and there, marked with a few points; but there were no large purple
spots, as in animals that have been wholly destroyed in nitrous oxide: the
right side of the heart only contracted. In this experiment, the excitement
from the action of the gas was probably carried to such an extent, as to
produce indirect debility. There are reasons for supposing, that animals after
having been excited to but a small extent by the respiration of nitrous oxide,
will live under water for a greater length of time, than animals previously
made to breathe common air.

V. Of the respiration of mixtures of Nitrous Oxide,
and other gases, by warm-blooded Animals.
a. A rabbit of near two months old, was introduced into a mixture of
equal parts hydrogene and nitrous oxide through water. He immediately
began to struggle; in a minute fell on his side; in three minutes gasped, and
made long inspirations; and in four minutes and half, was dead. On

dissection, he exhibited the same appearances as animals destroyed in
nitrous oxide.
b. A large and strong mouse was introduced into a mixture of three parts
hydrogene to one part nitrous oxide. He immediately began to struggle very
much, in half a minute, became convulsed, and in about a minute, was quite
dead.
c. Into a mixture of one oxygene, and three nitrous oxide, a small
guinea-pig was introduced. He immediately began to struggle, and in two
minutes reposed on his side, breathing very deeply. He made afterwards no
violent muscular motion; but lived quietly for near fourteen minutes: at the
end of which time, his legs were much convulsed. He was taken out, and
recovered.
d. A mouse lived apparently without suffering, for near ten minutes, in a
mixture of 1 atmospheric air, and 3 nitrous oxide, at the end of eleven
minutes he began to struggle, and in thirteen minutes became much
convulsed.
e. A cat of three months old, lived for seventeen minutes, in a very large
quantity of a mixture of 1 atmospheric air, and 12 nitrous oxide. On her first
introduction she was very much agitated and convulsed, in a minute and
half she fell down as if apoplectic, and continued breathing very deeply
during the remainder of the time, sometimes uttering very feeble cries.
When taken out, she appeared almost inanimate, but on being laid before
the fire, gradually began to breathe and move; being for some time, like
most of the animals that have recovered after breathing nitrous oxide,
convulsed on one side, and paralytic the other.
f. A goldfinch lived for near five minutes in a mixture of equal parts
nitrous oxide and oxygene, without apparently suffering. Taken out, he
appeared faint and languid, but finally recovered.[187]

VI. Recapitulation of facts relating to
the respiration of Nitrous Oxide,
by warm-blooded Animals.
1. Warm-blooded animals die in nitrous oxide infinitely sooner than in
common air or oxygene; but not nearly in so short a time as in gases

incapable of effecting positive changes in the venous blood, or in non-
respirable gases.
2. The larger animals live longer in nitrous oxide than the smaller ones,
and young animals die in it sooner than old ones of the same species.
3. When animals, after breathing nitrous oxide, are removed from it
before compleat exhaustion has taken place, they are capable of being
restored to health under the action of atmospheric air.
4. Peculiar changes are effected in the organs of animals by the
respiration of nitrous oxide. In animals destroyed by it, the arterial blood is
purple red, the lungs are covered with purple spots, both the hollow and
compact muscles are apparently very inirritable, and the brain is dark
colored.
5. Animals are destroyed by the respiration of mixtures of nitrous oxide
and hydrogene nearly in the same time as by pure nitrous oxide; they are
capable of living for a great length of time in nitrous oxide mingled with
very minute quantities of oxygene or common air.
These facts will be reasoned upon in the next division.

VII. Of the respiration of Nitrous Oxide
by amphibious Animals.
As from the foregoing experiments, it appeared that the nitrous oxide
destroyed warm-blooded animals by increasing the living action of their
organs to such an extent, as finally to exhaust their irritability and
sensibility; it was reasonable to conjecture that the cold-blooded animals,
possessed of voluntary power over respiration, would so regulate the
quantity of nitrous oxide applied to the blood in their lungs as to bear its
action for a great length of time. This conjecture was put to the test of
experiment; the following facts will prove its error.
a. Of two middle sized water-lizards, one was introduced into a small
jar filled with nitrous oxide, over moist mercury, by being passed through
the mercury; the other was made to breathe hydrogene, by being carried
into it in the same manner.

The lizard in nitrous oxide, in two or three minutes, began to make
violent motions, appeared very uneasy, and rolled about the jar in every
direction, sometimes attempting to climb to the top of it. The animal in
hydrogene was all this time very quiet, and crawled about the vessel
without being apparently much affected. At the end of twelve minutes, the
lizard in nitrous oxide was lying on his back seemingly dead; but on
agitating the jar he moved a little; at the end of fifteen minutes he did not
move on agitation, and his paws were resting on his belly. He was now
taken out stiff and apparently lifeless, but after being exposed to the
atmosphere for three or four minutes, took an inspiration, and moved his
head a little; he then raised the end of his tail, though the middle of it was
still stiff and did not bend when touched. His four legs remained close to his
side, and were apparently useless; but on pricking them with the point of a
lancet, they became convulsed. After being introduced into shallow water,
he was able to crawl in a quarter of an hour, though his motions were very
irregular. In an hour he was quite well. The animal in hydrogene appeared
to have suffered very little in three quarters of an hour, and had raised
himself against the side of the jar. At the end of an hour he was taken out,
and very soon recovered.
b. Some hours after, the same lizards were again experimented upon.
That which had been inserted into hydrogene in the last experiment, being
now inserted into nitrous oxide.
This lizard was apparently lifeless in fourteen minutes, having tumbled
and writhed himself very much during the first ten minutes. Taken out after
being in twenty-five minutes, he did not recover. The other lizard lived in
hydrogene for near an hour and quarter, taken out after an hour and twenty
minutes, he was dead.
These animals were both opened, but the viscera of the nitrous oxide
lizard were so much injured by the knife, that no accurate comparison of
them with those of the other could be made, I thought that the lungs
appeared rather redder.
c. Of two similar large water-lizards, one was introduced into a vessel
standing over mercury, wholly filled with water that had been long boiled
and suffered to cool under mercury.

The animal very often rose to the top of the jar as, if in search of air,
during the first half hour; but shewed no other signs of uneasiness. At the
end of three quarters of an hour, he became very weak, and appeared
scarcely able to swim in the water. Taken out at the end of fifty minutes, he
recovered.
The other was inserted into nitrous oxide. After much struggling, he
became senseless in about fifteen minutes, and lay on his back. Taken out at
the end of twenty minutes, he remained for a long time motionless and stiff,
but in a quarter of an hour, began to move some of his limbs.
From these experiments, we may conclude, that water-lizards, and most
probably the other amphibious animals, die in nitrous oxide in a much
shorter time than in hydrogene or pure water; consequently their death in it
cannot depend on the simple privation of atmospheric air.
At the season of the year in which this investigation was carried on, I
was unable to procure frogs or toads. This I regret very much.
Supposing that cold-blooded animals die in nitrous oxide from positive
changes effected in their blood by the gas, it would be extremely interesting
to notice the apparent alterations taking place in their organs of respiration
and circulation during its action, which could easily be done, the
membranous substance of their lungs being transparent. The increase or
diminution of the irritability of their muscular fibre, might be determined by
comparative galvanic experiments.

VIII. Effects of solution of nitrous oxide
in water on Fishes.
a. A small flounder was introduced into a vessel filled with solution of
nitrous oxide in water over mercury. He remained at rest for ten minutes
and then began to move about the jar in different directions. In a half an
hour he was apparently dying, lying on his side in the water. He was now
taken out, and introduced into a vessel filled with water saturated with
common air, he very soon recovered.
b. Of two large thornbacks,[188] equally brisk and lively. One, A, was
introduced into a jar containing nearly 3 cubic inches of water, saturated
with nitrous oxide, and which previous to its impregnation had been long

boiled; the other, B, was introduced into an equal quantity of water which
had been deprived of air by distillation through mercury.
A, appeared very quiet for two or three minutes, and then began to
move up and down in the jar, as if agitated. In eight minutes his motions
became very irregular, and he darted obliquely from one side of the jar to
the other. In twelve minutes, he became still, and moved his gills very
slowly. In fifteen minutes he appeared dead. After sixteen minutes he was
taken out, but shewed no signs of life.
B was very quiet for four minutes and half. He then began to move
about the jar. In seven minutes he had fallen on his back, but still continued
to move his gills. In eleven minutes he was motionless; taken out after
thirteen minutes, he did not recover.
c. Of two thornbacks, one, C was introduced into about an ounce of
boiled water in contact with hydrogene, standing over mercury. The other,
D, was introduced into well boiled water saturated with nitrous oxide, and
standing in contact with it over mercury. C lived near thirteen minutes, and
died without being previously much agitated. D was apparently motionless,
after having the same affections as A in the last experiment, in sixteen
minutes. At the end of this time he was taken out and introduced into
common water. He soon began to move his gills, and in less than a quarter
of an hour was so far recovered as to be able to swim.
The last experiment was repeated on two smaller thornbacks; that in the
aqueous solution of nitrous oxide lived near seventeen minutes, that in the
water in contact with hydrogene, about fifteen and half.
The experiments in Res. I. Div. 3, prove the difficulty, and indeed
almost impossibility of driving from water by boiling, the whole of the
atmospheric air held in solution by it; they likewise show that nitrous oxide
by its strong affinity for water, is capable of expelling air from that fluid
after no more can be procured from it by ebullition.
Hence, if water saturated with nitrous oxide had no positive effects upon
fishes; they ought to die in it much sooner than in water deprived of air by
ebullition. From their living in it rather longer;[189] we may conclude, that
they are destroyed not by privation of atmospheric air, but from some
positive change effected in their blood by the gas.

A long while ago, from observing that the gills of fish became rather of
a lighter red during their death, in the atmosphere; I conjectured that the
disease of which they died, was probably hyperoxygenation of the blood
connected with highly increased animal heat. For not only is oxygene
presented to their blood in much larger quantities in atmospheric air than in
its aqueous solution; but likewise, to use common language, in a state in
which it contains much more latent heat. Without however laying any stress
on this supposition, I had the curiosity to try whether thornbacks would live
longest in atmospheric air or nitrous oxide. In one experiment, they
appeared to die in them nearly in the same time. In another, the fish in
nitrous oxide lived nearly half as long again as that in atmospheric air.

IX. Effects of Nitrous Oxide on Insects.
The winged insects furnished with breathing holes, become motionless
in nitrous oxide very speedily; being however possessed of a certain
voluntary power over respiration, they sometimes recover, after having been
exposed to it for some minutes, under the action of atmospheric air.
A butterfly was introduced into a small jar, filled with pure nitrous
oxide, over mercury, He struggled a little during the first two or three
seconds; in about seven seconds, his legs became convulsed, and his wings
were wrapt round his body; in about half a minute he was senseless; taken
out after six minutes, he did not recover.
Another butterfly introduced into hydrogene, became convulsed in
about a quarter of a minute, was senseless in twenty seconds, and taken out
after five minutes, did not revive.
A large drone, after being in nitrous oxide for a minute and a quarter,
was taken out senseless. After being for some time exposed to the
atmosphere, he began to move, and at last rose on his wings. For some time,
however, he was unable to fly in a straight line; and often after describing
circles in the air, fell to the ground as if giddy.
A large fly, became motionless in nitrous oxide after being convulsed, in
about half a minute. Another was rendered senseless in hydrogene, in less
than a quarter of a minute.

A fly introduced into hydrocarbonate, dropt immediately senseless;
taken out after about a quarter of a minute, he recovered; but like the fly
that had lived after exposure to nitrous oxide, was for some time
vertiginous.
Flies live much longer under water, alcohol, or oil, than in non-
respirable gases, or gases incapable of supporting life. A certain quantity of
air always continues attached in the fluid to the fine hairs surrounding their
breathing holes, sufficient to support life for a short time.
Snails and earth-worms, live in nitrous oxide a long while, they die in it
however, much sooner than in water or hydrogene; probably from the same
causes as the amphibious animals.

DIVISION II.

Of the CHANGES effected in NITROUS OXIDE, and other GASES,
by the RESPIRATION of ANIMALS.
I. Preliminaries.

A s soon as I had discovered that nitrous oxide was respirable, and
possessed of extraordinary powers of action on living beings, I was
anxious to be acquainted with the changes effected in it by the venous
blood. To investigate these changes, appeared at first a simple problem; I
soon however found that it involved much preliminary knowledge of the
chemical properties and affinities of nitrous oxide. After I had ascertained
by experiments detailed in the preceding Researches, the composition of
this gas its combinations, and the physical changes effected by it in living
beings, I began my enquiry relating to the mode of its operation.
Finding that the residual gas of nitrous oxide after it had been breathed
for some time in silk bags, was chiefly nitrogene, I at first conjectured that
nitrous oxide was decomposed in respiration in the same manner as
atmospheric air, and its oxygene only combined with the venous blood; the
following experiments soon however convinced me of my error.

II. Absorption of Nitrous Oxide by venous blood.
Changes effected in the blood by different Gases.

a. Though the laws of the coagulability of the blood are unknown, yet
we are certain that at the moment of coagulation, a perfectly new
arrangement of its principles takes place; consequently, their powers of
combination must be newly modified. The affinities of living blood can
only be ascertained during its circulation in the vessels of animals. At the
moment of effusion from those vessels, it begins to pass through a series of
changes, which first produce coagulation, and finally its compleat
decomposition.
Consequently, the action of fluid blood upon gates out of the vessels,
will be more analogous to that of circulating blood in proportion as it is
more speedily placed in contact with them.
b. To ascertain the changes effected in nitrous oxide by fluid venous
blood.
A jar, six inches long and half an inch wide, graduated to,05 cubic
inches, having a tight stopper adapted to it, was filled with nitrogene, which
is a gas incapable of combining with, and possessing no power of a action
upon venous blood. A large orifice was made in the vein of a tolerably
healthy man, and the stopper removed from the jar, which was brought in
contact with the arm so as to receive the blood, and pressed close against
the skin, in such a way as to leave an orifice just sufficient for the escape of
the nitrogene, as the blood flowed in. When the jar was full, it was closed,
and carried to the pneumatic apparatus, the mercury of which had been
previously a little warmed. A small quantity of the blood was transferred
into another jar to make room for the gas. The remaining quantity equalled
exactly two cubic inches; to this was introduced as speedily as possible,
eleven measures equal to,55 cubic inches of nitrous oxide, which left a
residuum of ¹/₃₂ only, when absorbed by boiled water, and was
consequently, perfectly pure. On agitation, a rapid diminution of the gas
took place.
In the mass of blood which was opaque, but little change of color could
be perceived; but that portion of it diffused over the sides of the jar, was
evidently of a brighter purple than the venous blood.
It was agitated for two or three minutes, and then suffered to rest; in
eight minutes it had wholly coagulated; a small quantity of serum had
separated, and was diffused over the coagulum. This coagulum was dark;

but evidently of a more purple tinge than that of venous blood; no gas had
apparently been liberated during its formation.
The nitrous oxide remaining, was not quite equal to seven measures;
hence, at least four measures of it had been absorbed.
To ascertain the nature of the residuum, it was necessary to transfer it
into another vessel, but this I found very difficult to accomplish, on account
of the coagulated blood. By piercing through the coagulum and removing
part of it by means of curved iron forceps, I at last contrived to introduce
about 4½ measures of the gas into a small cylinder, graduated to,25 cubic
inches, in which it occupied of course, nearly 9 measures; when a little
solution of strontian was admitted to these, it became very slightly clouded;
but the absorption that took place did not more than equal half its bulk.
Consequently, the quantity of carbonic acid evolved from the blood, or
formed, must have been extremely minute.
On the introduction of pure water, a rapid absorption of the gas took
place, and after agitation, not quite 3 measures remained. These did not
perceptibly diminish with nitrous gas; their quantity was too small to be
examined by any other test; but there is reason to suppose that they were
chiefly composed of nitrogene.
From this experiment, it appeared that nitrous oxide is absorbed when
placed in contact with venous blood; at the same time, that a very minute
quantity of carbonic acid and probably nitrogene is produced.
c. In another similar experiment when nearly half a cubic inch of nitrous
oxide was absorbed by about a cubic inch and three quarters of fluid blood,
the residual gas did not equal more than ⅛, the quantity absorbed being
taken as unity. This fact induced me to suppose that the absorption of
nitrous oxide by venous blood, was owing to a simple solution of the gas in
that fluid, analogous to its solution in water or alcohol.
To ascertain if nitrous oxide could be expelled from blood impregnated
with it, by heat; I introduced to 2 cubic inches of fluid blood taken from the
medial vein, about,6 cubic inches of nitrous oxide. After agitation, in seven
minutes nearly,4 were absorbed. In ten minutes, after the blood had
completely coagulated, the cylinder containing it, was transferred in contact
with mercury, into a vessel of solution of salt in water; this solution was

heated and made to boil. During its ebullition, the whole of the blood
became either white or pale brown, and formed a solid coherent mass;
whilst small globules of gas were given out from it. In a few minutes,
about,25 of gas had collected. After the vessel had cooled, I attempted to
transfer this gas into a small graduated jar in the mercurial apparatus, but in
vain; the mass in the jar was so solid and tough, that I could not remove it.
By transferring it to the water apparatus, I succeeded in displacing enough
of the coagulum to suffer the water to come in contact with the gas; an
absorption of nearly half of it took place; hence, I conjecture, that nitrous
oxide had been given out by the impregnated blood.
d. Some fresh dark coagulum of venous blood, was exposed to nitrous
oxide. A very slight alteration of color took place at the surface of the
blood, perceptible only in a strong light, and a minute quantity of gas was
absorbed. A taper burnt in the remaining gas as brilliantly as before, hence,
it had apparently suffered no alteration.
e. To compare the physical changes effected in the venous blood by
nitrous oxide, with those produced by other gases, I made the following
experiments.—I filled a large phial, containing near 14 cubic inches, with
blood from the vein of the arm of a man, and immediately transferred it to
the mercurial apparatus. Different portions of it were thrown into small
graduated cylinders, filled with the following gases: nitrogene, nitrous gas,
common air, oxygene, nitrous oxide, carbonic acid, and hydrocarbonate.
The blood in each of them was successively agitated till it began to
coagulate; and making allowances for the different periods of agitation,
there was no marked difference in the times of coagulation.
The color of the coagulum in every part of the cylinder, containing
nitrogene, was the same very dark red. When it was agitated so as to tinge
the sides of the jar, it appeared exactly of the color of venous blood received
between two surfaces of glass; no perceptible absorption of the gas had
taken place.
The blood in nitrous gas was dark, and much more purple on the top
than that in nitrogene. When agitated so as to adhere to the jar as a thin
surface, this purple was evidently deep and bright. An absorption of rather
more than ⅛ of the volume of gas had taken place.

The blood in oxygene and atmospheric air, were of a much brighter
tinge than that in any of the other gases. On the top, the color was
vermilion, but no perceptible absorption had taken place.
The coagulum in nitrous oxide, when examined in the mass was dark,
and hardly distinguishable in its color from venous blood; but when
minutely noticed at the surface where it was covered with serum, and in its
diffusion over the sides of the jar, it appeared of a fine purple red, a tinge
brighter than the blood in nitrous gas. An absorption had taken place in this
cylinder, more considerable than in any of the others.
In carbonic acid, the coagulum was of a brown red, much darker than
the venous blood, and a slight diminution of gas had taken place.
In the hydrocarbonate,[190] the blood was red, a shade darker than the
oxygenated blood, and a very slight diminution of the gas[191] was
perceptible.
f. To human blood that had been saturated with nitrous oxide whilst
warm and constantly agitated for four or five minutes, to prevent its
uniform coagulation, oxygene was introduced; the red purple on the surface
of it, immediately changed to vermilion; and on agitation, this color was
diffused through it. On comparing the tinge with that of oxygenated blood,
no perceptible difference could be observed. No change of volume of the
oxygene introduced, had taken place; and consequently, no nitrous oxide
had been evolved from the blood.
g. Blood, impregnated with nitrous gas, was exposed to oxygene; but
after agitation in it for many minutes, no change of its dark purple tinge
could be observed, though a slight diminution of the oxygene appeared to
take place.
h. Blood that had been rendered vermilion in every part by long
agitation in atmospheric air, the coagulum of which was broken and
diffused with the coagulable lymph through the serum, was exposed to
nitrous oxide; for some minutes no perceptible change of color took place;
but by agitation for two or three hours, it evidently affirmed a purple tinge,
whilst a a slight absorption of gas took place. It never however, became
nearly so dark as venous blood that had been exposed to nitrous oxide.

i. Blood, oxygenated in the same manner as in the last experiment, the
coagulum of which had been broken, was exposed to nitrous gas. The
surface of it immediately became purple, and by agitation for a few
minutes, this color was diffused through it. A slight diminution of the gas
was observed. On comparing the tinge with that of venous blood that had
been previously exposed to nitrous gas, there was no perceptible difference.
k. Blood exposed to oxygenated muriatic acid is wholly altered in its
constitution and physical properties, as has been often noticed; the
coagulum becomes black in some parts, and brown and white in others.
Venous blood, after agitation in hydrogene or nitrogene, oxygenates when
exposed to the atmosphere in the same manner as simple venous blood. I
had the curiosity to try whether venous blood exposed to hydrogene, would
retain its power of being oxygenated longer than blood saturated with
nitrous oxide: for this purpose some similar black coagulum was agitated
for some time in two phials, one filled with hydrogene, the other with
nitrous oxide. They were then suffered to rest for three days at a
temperature from about 56° to 63°. After being opened, no offensive smell
was perceived in either of them, the blood in hydrogene was rather darker
than at the time of their exposure, whilst that in nitrous oxide was of a
brighter purple. On being agitated for some time in the atmosphere, the
blood in nitrous oxide became red, but not of so bright a tinge as
oxygenated venous blood. The color of the blood in hydrogene did not at all
alter.
l. To ascertain whether impregnation with nitrous oxide accelerated or
retarded the putrefaction of the blood; I exposed venous blood in four
phials, the first filled with hydrocarbonate, the second with hydrogene; the
third with atmospheric air, and the fourth with nitrous oxide. Examined
after a fortnight, the blood in hydrogene and common air were both black,
and stunk very much; that in hydrocarbonate was red, and perfectly sweet;
that in nitrous oxide appeared purple and had no disagreeable smell.
In a second experiment, when blood was exposed for three weeks to
hydrocarbonate and nitrous oxide, that in nitrous oxide was darker than
before and stunk a little; that in hydrocarbonate was still perfectly sweet.
The power of hydrocarbonate to prevent the putrefaction of animal matters,
was long ago noticed by Mr. Watt.

m. Having accidentally cut one of my fingers so as to lay bare a little
muscular fibre, I introduced it whilst bleeding into a bottle of nitrous oxide;
the blood that trickled from the wound evidently became much more
purple; but the pain was neither alleviated or increased. When however, the
finger was taken out of the nitrous oxide and exposed to the atmosphere, the
wound smarted more than it had done before. After it had ceased to bleed, I
inserted it through water into a vessel of nitrous gas; but it did not become
more painful than before.
From all these observations, we may conclude,
1st. That when nitrous oxide is agitated in fluid venous
blood, a certain portion of the gas is absorbed; whilst the
color of the blood changes from dark red to red purple.
2dly. That during the absorption of nitrous oxide by the
venous blood, minute portions of nitrogene and carbonic
acid are produced, either by evolution from the blood, or
from a decomposition of part of the nitrous oxide.
3dly. That venous blood impregnated with nitrous oxide
is capable of oxygenation; and vice versa; that oxygenated
blood may be combined with nitrous oxide.
When blood separated into coagulum and serum, is exposed to nitrous
oxide, it is most probable that the gas is chiefly absorbed by the serum. That
nitrous oxide however is capable of acting upon the coagulum, is evident
from d. In the fluid blood, as we shall see hereafter, nitrous oxide is
absorbed by the attractions of the whole compound.

III. Of the changes effected in Nitrous Oxide
by Respiration.
To ascertain whether the changes effected in nitrous oxide by the
circulating blood acting through the moist coats of the pulmonary veins of
living animals, were highly analogous to those produced in it by fluid
venous blood removed from the vessels, I found extremely difficult.
I have before observed, that when animals are made to respire nitrous
oxide, a certain absorption of the gas always takes place; but the smaller
animals, the only ones that can be experimented upon in the mercurial

apparatus, die in nitrous oxide so speedily and occasion so slight a
diminution of gas, that I judged it useless to attempt to analise the residuum
of their respiration, which supports flame as well as pure nitrous oxide, and
is chiefly absorbable by water.
In the infancy of my researches, I often respired nitrous oxide in a large
glass bell, furnished with a breathing tube and stop-cock, and poised in
water saturated with the gas.
In two or three experiments in which the nostrils being closed after the
exhaustion of the lungs, the gas was inspired from the bell and respired into
it, a considerable diminution was perceived, and by the test of lime water
some carbonic acid appeared to have been formed; but on account of the
absorption of this carbonic acid by the impregnated water, and the liberation
of nitrous oxide from it, it was impossible to determine with the least
accuracy, the quantities of products after respiration.
About this time likewise, I often examined the residuum of nitrous
oxide, after it had been respired in silk bags. In these experiments when the
gas had been breathed for a long time, a considerable diminution of it was
observed, and the remainder extinguished flame and gave a very slight
diminution with nitrous gas. But the great quantity of this remainder as well
as other phænomena, convinced me that though the oiled silk was
apparently air-tight when dry, under slight pressure, yet during the action of
respiration, the moist and warm gas expired, penetrated through it, whilst
common air entered through the wetted surface.
To ascertain accurately, the changes effected in nitrous oxide by
respiration, I was obliged to make use of the large mercurial airholder
mentioned in Research I. of the capacity of 200 cubic inches. The upper
cylinder of it was accurately balanced so as to be constantly under the
pressure of the atmosphere. To an aperture in it, a stop-cock having a very
large orifice was adapted, curved and flattened at its upper extremity, so as
to form an air-tight mouth-piece.
By accurately closing the nose, and bringing the lips tight on the mouth-
piece, after a few trials I was able to breathe oxygene or common air in this
machine for two minutes or two minutes and half, without any other uneasy
feeling than that produced by the inclination of the neck and chest towards
the cylinder. The power of uniformly exhausting the lungs and fauces to the

same extent, I did not acquire till after many experiments. At last, by
preserving exactly the same posture after exhaustion of the lungs before the
inspiration of the gas to be experimented upon, and during its compleat
expiration, I found that I could always retain nearly the same quantity of
gas in the bronchial vessels and fauces; the difference in the volume expired
at different times, never amounting to a cubic inch and half.
By connecting the conducting pipe of the mercurial airholder, during the
respiration of the gas, with a small trough of mercury by means of a curved
tube, it became a perfect and excellent breathing machine. For by exerting a
certain pressure on the airholding cylinder, it was easy to throw a quantity
of gas after every inspiration or expiration, into tubes filled with mercury
standing in the trough. In these tubes it could be accurately analised, and
thus the changes taking place at different periods of the process ascertained.
Whenever I breathed pure nitrous oxide in the mercurial airholder, after
a compleat voluntary exhaustion of my lungs, the pleasurable delirium was
very rapidly produced, and being obliged to stoop on the cylinder, the
determination of blood to my head from the increased arterial action in less
than a minute became so great, as often to deprive me of voluntary power
over the muscles of the mouth. Hence, I could never rely on the accuracy of
any experiment, in which the gas had been respired for more than three
quarters of a minute.
I was able to respire the gas with great accuracy for more than half a
minute; it at first, rather increasing than diminishing the power of volition;
but even in this short time, very strong sensations were always produced,
with sense of fulness about the head, somewhat alarming; a feeling which
hardly ever occurs to me when the gas is breathed in the natural posture.
In all the numerous experiments that I made on the respiration of nitrous
oxide in this way, a very considerable diminution of gas always took place;
and the diminution was generally apparently greater to the eye during the
first four or five inspirations.
The residual gas of an experiment was always examined in the
following manner. After being transferred through mercury into a graduated
cylinder, a small quantity of concentrated solution of caustic potash was
introduced to it, and suffered to remain in contact with it for some hours;
the diminution was then noted, and the quantity of gas absorbed by the

potash, judged to be carbonic acid. To the remainder, twice its bulk of pure
water was admitted. After agitation and rest for four or five hours, the
absorption by this was noticed, and the gas absorbed considered as nitrous
oxide. The residual unabsorbable gas was mingled over water with twice its
bulk of nitrous gas; and by this means, its composition, whether it consisted
wholly of nitrogene, or of nitrogene mingled with small quantities of
oxygene, ascertained.
From a number of experiments made at different times on the
respiration of nitrous oxide, I select the following as the most accurate.
E. 1. At temperature 54°, I breathed 102 cubic inches of nitrous oxide,
which contained near ¹/₅₀ common air, for about half a minute, seven
inspirations and seven expirations being made. After every expiration, an
evident diminution of gas was perceived; and when the last full expiration
was made, it filled a space equal to 62 cubic inches.
These 62 cubic inches analised, were found to consist of
Carbonic acid 3,2
Nitrous oxide 29,0
Oxygene 4,1
Nitrogene 25,7
62,0
Hence, accounting for the two cubic inches of common air previously
mingled with the nitrous oxide, 71 cubic inches had disappeared in this
experiment.
In the last respirations, the quantity of gas was so much diminished, as
to prevent the full expansion of the lungs; and hence the apparent
diminution was very much less after the first four inspirations.
E. 2. At temperature 47°, I breathed 182 cubic inches of nitrous oxide,
mingled with 2½ cubic inches of atmospheric air, which previously existed
in the airholder, for near 40 seconds; having in this time made 8
respirations. The diminution after the first full inspiration, appeared to a by-
stander nearly uniform. When the last compleat expiration was made, the

gas filled a space equal to 128 cubic inches, the common temperature being
restored. These 128 cubic inches analised, were found to consist of
Carbonic acid 5,25
Nitrous oxide 88,75
Oxygene 5,00
Nitrogene 29,00
Consequently, in this experiment, 93,25 cubic inches of nitrous oxide
had disappeared.
In each of these experiments, the cylinder was covered with condensed
watry vapor exactly in the same manner as if common air had been breathed
in it. It ought to be observed that, E. 1. was made in the morning, four hours
and half after a moderate breakfast; whereas, E. 2. was made but an hour
and quarter after a plentiful dinner; at which near three fourths of a pint of
table-beer had been drank.
From these experiments we learn, that nitrous oxide is rapidly absorbed
by the venous blood, through the moist coats of the pulmonary veins. But as
after a compleat voluntary exhaustion of the lungs, much residual air must
remain in the bronchial vessels and fauces, as appears from their
incapability of compleatly collapsing, it is evident that the gas expired after
every inspiration of nitrous oxide mast be mingled with different quantities
of the residual gas of the lungs;[192] whilst after a complete expiration,
much of the unabsorbed nitrous oxide must remain as residual gas in the
lungs. Now when a complete expiration is made after the breathing of
atmospheric air, it is evident that the residual gas of the lungs consists of
nitrogene,[193] mingled with small portions of oxygene and carbonic acid.
And these are the only products found after the respiration of nitrous oxide.
To ascertain whether these products were partially produced, during the
process of respiration, as I was inclined to believe from the experiments in
the last section, or whether they were wholly the residual gases of the lungs,
I found extremely difficult.
I at first thought of breathing nitrous oxide immediately after my lungs
had been filled with oxygene; and to compare the products remaining after
the full expiration, with those produced after a full expiration of pure

oxygene; but on the supposition that oxygene and nitrous oxide, when
applied together to the venous blood, must effect changes in it different
from either of them separately, the idea was relinquished.
I attempted to inspire nitrous oxide, after having made two inspirations
and a complete expiration of hydrogene; but in this experiment the effects
of the hydrogene were so debilitating, and the consequent stimulation by
the nitrous oxide so great, as to deprive me of sense. After the first three
inspirations, I lost all power of standing, and fell on my back, carrying in
my lips the mouth-piece separated from the cylinder, to the great alarm of
Mr. Patrick Dwyer, who was noting the periods of inspiration.
Though experiments on successive inspirations of pure nitrous oxide
might go far to determine whether or no any nitrogene, carbonic acid and
oxygene were products of respiration, yet I distinctly saw that it was
impossible in this way to ascertain their quantities, supposing them
produced, unless I could first determine the capacity of my lungs; and the
different proportions of the gases remaining in the bronchial vessels after a
compleat expiration, when atmospheric air had been respired.
In some experiments (that I made on the respiration of hydrogene, with
a view to determine whether carbonic acid was produced by the
combination of carbon loosely combined in the venous blood, with the
oxygene respired, or whether it was simply given out as excrementitious by
this blood) I found, without however being able to solve the problem I had
proposed to myself, that in the respiration of pure hydrogene, little or no
alteration of volume took place; and that the residual gas was mingled with
some nitrogene, and a little oxygene and carbonic acid.
From the comparison of these facts with those noticed in the last section
and in R. III. Div. I. there was every reason to suppose that hydrogene was
not absorbed or altered when respired: but only mingled with the residual
gases of the lungs. Hence, by making a full expiration of atmospheric air,
and afterwards taking six or seven respirations of hydrogene in the
mercurial airholder, and then making a compleat expiration, I conjectured
that the residual gas and the hydrogene would be so mingled, as that nearly
the same proportions should remain in the bronchial vessels, as in the
airholder. By ascertaining these proportions and calculating from them, I
hoped to be able to ascertain with tolerable exactness, the capacity of my

fauces and bronchia, as well as the composition of the gas remaining in
them, after a complete expiration of common air.

IV. Respiration of Hydrogene.
The hydrogene that I employed, was procured from the decomposition
of water by means of clean iron filings and diluted sulphuric and muriatic
acids. It was breathed in the same manner as nitrous oxide, in the large
mercurial airholder.
After a compleat voluntary exhaustion of my lungs in the usual posture,
I found great difficulty in breathing hydrogene for so long as half a minute,
so as to make a compleat expiration of it. It produced uneasy feelings in the
chest, momentary loss of muscular power, and sometimes a transient
giddiness.
In some of the experiments that I made; on account of the giddiness, the
results were rendered inconclusive, by my removing my mouth from the
mouth-piece after expiration, before the assistant could turn the stop-cock.
The purity of the hydrogene was ascertained immediately before the
experiment by the test of nitrous gas, and by detonation with oxygene or
atmospheric air; generally 12 measures of atmospheric air were fired with 4
of the hydrogene, and if the diminution was to ten or a little more, the gas
was judged to be pure.
After the experiment, when the compleat expiration had been made and
the common temperature restored; the volume of the gas was noticed, and
then a small quantity of it thrown into the mercurial apparatus by means of
the conducting tube, to be examined. The carbonic acid was separated by
from it by means of solution of potash or strontian; the quantity of oxygene
it contained, was ascertained by means of nitrous gas of known
composition; the superabundant nitrous gas was absorbed by solution of
muriate of iron; and the proportions of hydrogene and nitrogene in the
remaining gas, discovered by inflammation with atmospheric air or
oxygene in the detonating tube by the electric spark.
a. The two following experiments made upon quantities of hydrogene,
equal to those of the nitrous oxide respired in the experiments in the last
section, are given as the most accurate of five.

E. 1. I respired at 59° 102 cubic inches of hydrogene apparently pure,
for rather less than half a minute, making in this time seven quick
respirations.
After the complete expiration, when the common temperature was
restored, the gas occupied a space equal to 103 cubic inches nearly. These
analised were found to consist of
Carbonic acid 4,0
Oxygene 3,7
Nitrogene 17,3
Hydrogene 78,0
103,0
Now as in this experiment, the gas was increased in bulk only a cubic
inch; supposing that after the compleat expiration the gas in the lungs,
bronchia and fauces was of nearly similar composition with that in the
airholder, and that no hydrogene had been absorbed by the blood, it would
follow that 24 cubic inches of hydrogene remained in the internal organs of
respiration, and consequently, by the rule of proportion, about 7,8 of the
mixed residual gas of the common air. And then the whole quantity of
residual gas of the lungs, supposing the temperature 59°, would have been
31,8 cubic inches; but as its temperature was nearly that of the internal parts
of the body, 98°, it must have filled a greater space; calculating from the
experiments of Guyton and Vernois,[194] about 37,5[195] cubic inches.
From the increase of volume, it would appear that a minute quantity of
gas had been generated during the respiration, and this was, as we shall see
hereafter, most probably carbonic acid.[196] Likewise there is reason to
suppose, that a little of the residual oxygene must have been absorbed.
Making allowances for those circumstances, it would follow, that the 37,5
cubic inches of gas remaining in my lungs, after a compleat expiration of
atmospheric air at animal heat 98°, equal to 31,8 cubic inches at 59°, were
composed of
Nitrogene 21,9
Carbonic acid 4,9

Oxygene 5,0
31,8
E. 2. I respired for near a half a minute in the mercurial airholder at 61°,
182 cubic inches of hydrogene; having made during this time, six long
inspirations. After the last expiration, the gas filled a space nearly equal to
184 cubic inches, and analised, was found to consist of
Carbonic acid 4,8
Oxygene 4,6
Nitrogene 21,0
Hydrogene 153,6
184,0
Now in this experiment, reasoning in the same manner as before, 28,4
cubic inches of hydrogene must have remained in the lungs, and likewise
5,5 of the atmospheric residual gas. Consequently, the whole residual gas
was nearly equal to 34 cubic inches at 61°, which at 98° would become
about 40,4 cubic inches. And reasoning as before, it would appear from this
experiment, that the quantity of gas remaining in my lungs after a compleat
voluntary respiration, equalled at 98, about 40 cubic inches, and at 61°, 34
nearly: making the necessary corrections; that after common air had been
breathed, these 34 cubic inches consisted of
Carbonic acid 4,1
Oxygene 5,5
Nitrogene 24,4
b. It would have been possible to prove the truth of the postulate on
which the experiments were founded, by respiring common air or oxygene
after the compleat expiration of the hydrogene, for the same time as the
hydrogene was respired and in equal quantities.
For if portions of hydrogene were found in the airholder equal to those
of the residual gases in the two experiments, it would prove that a uniform
mixture of residual gas with the gas inspired, was produced by the
respiration. That this mixture must have taken place, appeared, however, so

evident from analogous facts, that I judged the experimental proof
unnecessary.
Indeed, as most gases, though of different specific gravities, when
brought in contact with each other, assume some sort of union, it is more
than probable, that gas inspired into the lungs, from being placed in contact
with the residual gas on such an extensive surface, must instantly mingle
with it. Hence, possibly one deep inspiration and compleat expiration of the
whole of a quantity of hydrogene, will be sufficient to determine the
capacity of the lungs after compleat voluntary exhaustion, and the nature of
the residual air.
That two inspirations are sufficient, appears probable from the
following experiment.
E. 3. After a compleat voluntary expiration of common air, I made two
deep inspirations of 141 cubic inches of hydrogene. After the compleat
expiration, they filled a space equal to rather more than 142 cubic inches,
and analised, were found to consist of
Carbonic acid 3,1
Oxygene 4,5
Nitrogene 18,8
Hydrogene 115,6
142,0
Now calculating on the exhausted capacity of my lungs from this
experiment, supposing uniform mixture, they would contain after expiration
of common air, about 30,7 cubic inches at 58°, equal to 36 at 98°, composed
of about
Nitrogene 20,9
Oxygene 5,8
Carbonic acid 4,0
30,7
One should suppose a priori that in this experiment much less of the
residual oxygene of the lungs must have been absorbed, than in Expts. 1
and 2; yet there is no very marked difference in the portions evolved. That a

tolerably accurate mixture took place, appears from the quantity of
nitrogene. The smaller quantity of carbonic acid is an evidence in favour of
its evolution from the venous blood.
c. It is reasonable to suppose that the pressure upon the residual gas of
the exhausted lungs, must be nearly equal to that of the atmosphere. But as
aqueous vapour is perpetually given out by the exhalents, and perhaps
evolved from the moist coats of the pulmonary vessels, it is likely that the
residual gas is not only fully saturated with moisture at 98°, but likewise
impregnated with uncombined vapor; and hence its volume enlarged
beyond the increment of expansion of temperature.
Considering all these circumstances, and calculating from the mean of
the three experiments on the composition of the residual gas, I concluded,
1st. That the exhausted capacity of my lungs was equal to about 41
cubic inches.
2dly. That the gas contained in my bronchial vessels and fauces, after a
compleat expiration of atmospheric air, was equal to about 32 cubic inches,
its temperature being reduced to 55°.
3dly. That these 32 cubic inches were composed of about
Nitrogene 23,0
Carbonic acid 4,1
Oxygene 4,9
d. In many experiments made in the mercurial airholder on the capacity
of my lungs under different circumstances, I found that I threw out of my
lungs by a full forced expiration at temperatures from 58° to 62°
cub. in. cub. in.
After a full voluntary inspiration, from 189 to 191
After a natural inspiration, from 78 to 79
After a natural expiration, from 67 to 68
So that making the corrections for temperature, it would appear, that my
lungs in a state of voluntary inspiration, contained about 254 cubic inches;

in a state of natural inspiration about 135; in a state of natural expiration,
about 118; and in a state of forced expiration 41.[197]
As the exhausted capacity as well as impleted capacity of the internal
organs of respiration must be different in different individuals, according as
the forms and size of their thorax, fauces, and bronchia are different, it
would be almost useless to endeavour to ascertain a standard capacity. It is
however probable, that a ratio exists between the quantities of air inspired
in the natural and forced inspiration, those expired in the natural and forced
expiration, and the whole capacity of the lungs. If this ratio were
ascertained, a single experiment on the natural inspiration and expiration of
common air, would enable us to ascertain the quantity of residual gas in the
lungs of any individual after a compleat forced expiration.[198]

V. Additional observations and experiments
on the Respiration of Nitrous Oxide.
a. Having thus ascertained the capacity of my lungs, and the
composition of the residual gas of expiration, I proceeded to reason
concerning the experiments in section III, on the respiration of nitrous
oxide.
In Exp. I. nearly 100 cubic inches of nitrous oxide, making the
corrections on account of the common air, were respired for half a minute.
In this time, they were reduced to 62 cubic inches, which consisted of 3,2
carbonic acid, 29 nitrous oxide, 4,1 oxygene, and 25,7 nitrogene.
But, as appears from the last section, there existed in the lungs before
the inspiration of the nitrous oxide, about 32 cubic inches of gas, consisting
of 23 nitrogene, 4,1 carbonic acid, and 4,9 oxygene, temperature being
reduced to 59°. This gas must have been perfectly mingled with the nitrous
oxide during the experiment; and consequently, the residual gas in the lungs
after the experiment, was of the same composition as that in the airholder.
Supposing it as before, to be about 32 cubic inches: from the rule of
proportion, they will be composed of
Nitrous oxide 14,7
Nitrogene 13,3

Carbonic acid 1,9
Oxygene 2,1
And the whole quantity of gas in the lungs and the airholder, supposing
the temperature 59°, will equal 94 cubic inches, which are composed of
Nitrous oxide 43,7
Nitrogene 39,0
Carbonic acid 5,2
Oxygene 6,1
94
But before the experiment, the gas in the lungs and airholder equalled
134 cubic inches, and these, reckoning for the common air, were composed
of
Nitrous oxide 100
Nitrogene, 24,3
Carbonic acid 4,1
Oxygene 5,6
Hence, it appears, that 56,3 cubic inches of nitrous oxide were absorbed
in this experiment, and 13,7 of nitrogene produced, either by evolution from
the blood, or decomposition of the nitrous oxide. The quantities of carbonic
acid and oxygene approach so near to those existing after the respiration of
hydrogene, that there is every reason to believe that no portion of them was
produced in consequence of the absorption, or decomposition of the nitrous
oxide.
b. In Exp. 2, calculating in the same manner, before the first inspiration,
a quantity of gas equal to 216,5 cubic inches at 47°, existed in the lungs and
airholder, and these 216,5 cubic inches were composed of
Nitrous oxide, 182,0
Nitrogene 24,9
Carbonic acid 4,1
Oxygene 5,5

216,5
After the compleat expiration, 160 cubic inches remained in the lungs
and airholder, which was composed of
Nitrous oxide 110,6
Nitrogene 36,3
Carbonic acid 6,8
Oxygene 6,3
Hence, it appears, that 71,4 cubic inches of nitrous oxide were absorbed
in this experiment, and about 12 of nitrogene produced. The quantity of
carbonic acid and oxygene is rather greater than that which existed in the
experiments on hydrogene.
c. From these estimations, I learned that a small quantity of nitrogene
was produced during the absorption of nitrous oxide in respiration. It
remained to determine, whether this nitrogene owed its production to
evolution from the blood, or to the decomposition of a portion of the nitrous
oxide.
Analogical evidences were not in favour of the hypothesis of
decomposition. It was difficult to suppose that a body requiring the
temperature of ignition for its decomposition by the most inflammable
bodies, should be partially absorbed and partially decompounded at 98°, by
a fluid apparently possessed of uniform attractions.
It was more easy to believe, that from the immense quantity of
nitrogene taken into the blood in nitrous oxide; the system soon became
overcharged with this principle, which not being wholly expended in new
combinations during living action, was liberated in the aëriform state by the
exhalents, or through the moist coats of the veins.
Now if the last rationale were true, it would follow, that the quantity of
nitrogene produced in respiration, ought to be increased in proportion as a
greater quantity of nitrous oxide entered into combination with the blood.
d. To ascertain whether this was the case, I made after full voluntary
exhaustion of my lungs, one full voluntary inspiration and expiration of 108
cubic inches of nitrous oxide. After this, it filled a space nearly equal to 99

cubic inches. The quantities of carbonic acid and oxygene in these were not
determined; but by the test of absorption by water, they appeared to contain
only 18 nitrogene; which is very little more than should have been given
from the residual gas of the lungs.
In a second experiment, I made two respirations of 108 cubic inches of
nitrous oxide nearly pure. The diminution was to 95. On analysing these 95,
I found to my great surprise, that they contained only 17 nitrogene. Hence, I
could not but suspect some source of error in the process.
I now introduced into a strong new silk bag, the sides of which were in
perfect contact, about 8 quarts of nitrous oxide. From the mode of
introduction, this nitrous oxide must have been mingled with a little
common air, not however sufficient to disturb the results.
I then adapted a cork cemented to a long curved tube to my right nostril;
the tube was made to communicate with the water apparatus; and the left
nostril being accurately closed, and the mouth-piece of the silk bag tightly
adapted to the lips, I made a full expiration of the common air of my lungs,
inspired nitrous oxide from the bag, and by carefully closing the mouth-
piece with my tongue, expired it through the curved tube into the water
apparatus. In this way, I made nine respirations of nitrous oxide. The
expired gas of the first respiration was not preserved; but part of the gas of
the second, third, fifth, seventh and ninth, were caught in seperate graduated
cylinders. The second, analised by absorption, consisted of about 29
absorbable gas, which must have been chiefly nitrous oxide; and 17
unabsorbable gas, which must have been chiefly nitrogene; and the third of
22 absorbable gas, and 8 unabsorbable. The fifth was composed of 27 to 6;
the seventh of 23 to 7, and the ninth of 26 to 11.
e. Though the results of these experiments were not so conclusive as
could be wished; yet, comparing them with those of the experiments in
section III. it seemed reasonable to conclude, that the production of
nitrogene was increased, in proportion as the blood became more fully
impregnated with nitrous oxide.
From this conclusion, compared with the phænomenon noticed in
section 2, and in Div. I. section 4, I am induced to believe that the
production of nitrogene during the respiration of nitrous oxide, is not owing
to the decomposition of part of the nitrous oxide, in the aëriform state

immediately by the attraction of the red particles of venous blood for its
oxygene; but that it is rather owing to a new arrangement produced in the
principles of the impregnated blood, during circulation; from which,
becoming supersaturated with nitrogene, it gives it out through the moist
coats of the vessels.
For if any portion of nitrous oxide were decomposed immediately by
the red particles of the blood, one should conjecture, that the quantity of
nitrogene produced, ought to be greater during the first inspirations, before
these particles became fully combined with condensed oxygene. If on the
contrary, the whole of the nitrogene and oxygene of the nitrous oxide were
both combined with the blood, and carried through the pulmonary veins and
left chamber of the heart to the arteries; then, supposing the oxygene chiefly
expended in living action, whilst the nitrogene was only partially consumed
in new combinations, it would follow, that the venous blood of animals
made to breathe nitrous oxide, hyper-saturated with nitrogene, must be
different from common venous blood; and this we have reason to believe
from the phænomena in Div. I. section 4, is actually the case.
f. Besides the nitrogene generated during the respiration of nitrous
oxide, we have noticed the evolution of other products, carbonic acid,[199]
and water.
Now as nearly equal quantities of carbonic acid are produced, whether
hydrogene or nitrous oxide is respired, provided the process is carried on
for the same time; there is every reason to believe, as we have said before,
that no part of the carbonic acid produced, is generated from the immediate
decomposition of nitrous oxide by carbon existing in the blood.
Consequently, in these experiments, it must be either evolved from the
venous blood; or formed, by the slow combination of the oxygene of the
residual air of respiration with the charcoal of the blood.
But if it was produced by the decomposition of residual atmospheric air,
it would follow, that its volume must be much less than that of the oxygene
of the residual air, which had disappeared; for some of this oxygene must
have been absorbed by the blood, and during the conversion of oxygene
into carbonic acid by charcoal, a slight diminution of volume is produced.

In the experiments when nitrous oxide and hydrogene were respired for
about half a minute, the medium quantity of carbonic acid produced, was
5,6 cubic inches nearly.
Now we will assume, that the quantity of carbonic acid produced, is in
the ratio of the oxygene diminished; and there is every reason to believe,
that in the expiration of atmospheric air, the expired air and the residual air
are nearly of the same composition.
Hence, no more carbonic acid can remain in the lungs or be produced
from the residual gas after the compleat expiration of common air, than that
which can be generated from a volume of atmospheric air equal to the
residual gas of the lungs.
The residual gas of the lungs, after compleat expiration, equals at 55°,
32 cubic inches, and 32 cubic inches of common air contain 8.6 cubic
inches of oxygene.
But in the experiments on the respiration of hydrogene, not only 5.6
cubic inches of carbonic acid were produced, but more than 4 of residual
oxygene remained unabsorbed.
Hence it appears impossible that all the carbonic acid evolved from the
lungs during the respiration of nitrous oxide or hydrogene could have been
produced by the combination of charcoal in the venous blood with residual
atmospheric oxygene: there is consequently every reason to believe that it is
wholly or partially liberated from the venous blood through the moist coats
of the vessels.
g. The water carried out of the lungs in solution by the expired gas of
nitrous oxide, could neither have been wholly or partially formed by the
decomposition of nitrous oxide. The coats of the vessels in the lungs, and
indeed in the whole internal surface of the body, are always covered with
moisture, and the solution of part of this moisture by the inspired heated
gas, and its deposition by the expired gas, are sufficient causes for the
appearance of the phænomenon.
There are no reasons for supposing that any of the residual atmospheric
oxygene is immediately combined with fixed or nascent hydrogene, or
hydrocarbonate, in the venous blood at 98°, by slow combustion, and

consequently none for supposing that water is immediately formed in
respiration.
The evolution of water from the vessels in the lungs, is almost certain
from numerous analogies.
h. As from the experiments in section II. it appeared that nitrous oxide
was capable of being combined with oxygenated blood, and vice versa,
blood impregnated with nitrous oxide capable of oxygenation; I was curious
to ascertain what changes would be effected in nitrous oxide when it was
respired, mingled with atmospheric air or oxygene. For this purpose,
without making a very delicate experiment, I breathed in the large mercurial
airholder about 112 cubic inches of nitrous oxide, mingled with 44 of
common air, for near half a minute, in the usual mode. The gas, after
expiration, filled a space nearly equal to 119. I did not exactly ascertain the
composition of the residual gas; it supported flame rather better than
common air, and after the nitrous oxide was absorbed, gave much less
diminution with nitrous gas than atmospheric air.
i. I breathed a mixture of four quarts of nitrous oxide with three quarts
of hydrogene, in a dry silk bag, for near a minute; an evident diminution
was produced; but on account of the mode of experimenting it was
impossible to determine the quantity of nitrous oxide absorbed, or the exact
nature of the products. When a taper was introduced into a little of the
residual gas, it inflamed with a very feeble explosion. Now a mixture of 4
parts nitrous oxide and 3 hydrogene, detonates when inflamed with very
great violence.
k. Nitrous oxide can be respired without danger by the human animal
for a much longer time than that required for the death of the smaller
quadrupeds in it.
I have breathed it two or three times in a considerable state of purity, in
a dry silk bag, for four minutes and quarter and four minutes and half: some
diseased individuals have respired it for upwards of five minutes.
In the infancy of my experiments, from general appearances, I thought
that the proportion of nitrous oxide absorbed in respiration was greater in
the first inspirations than the last; but this I have since found to be a
mistake. In the last respirations the apparent absorption is indeed less; but

this is on account of the increased evolution of nitrogene from the blood.
When nitrous oxide is respired for a long time, the last inspirations are
always fuller and quicker than the first; but the consumption by the same
individual is nearly in the ratio of the time of respiration. Three quarts, i. e.
about 174 cubic inches, are consumed so as to be unfit for respiration, by an
healthy individual with lungs of moderate capacity, in about a minute and
quarter; six quarts, or 348 cubic inches, last generally for two minutes and
half or two minutes and three quarters; eight quarts, or 464 cubic inches, for
more than three minutes and half; and twelve, or 696 cubic inches, for
nearly five.
The quantities of nitrous oxide absorbed by the same individual, will, as
there is every reason to suppose, be different under different circumstances,
and will probably be governed in some measure by the state of the health. It
is reasonable to suppose, that the velocity of the circulation must have a
considerable influence on the absorption of nitrous oxide; probably in
proportion as it is greater a larger quantity of gas will be consumed in equal
times.
I am inclined from two or three experiments, to believe that nitrous
oxide is absorbed more rapidly after hearty meals or during stimulation
from wine or spirits, than at other times. As its absorption appears to depend
on a simple solution in the venous blood; probably diminution of
temperature will increase its capability of being absorbed.
l. The quantities of nitrous oxide absorbed by different individuals, will
probably be governed in some measure by the size of their lungs and the
surface of the blood vessels, all other circumstances being the same.
From the observations that I have been able to make on the absorption
of nitrous oxide, as compared with the capacity of the lungs, the range of
the consumption of different individuals does not extend to more than a
pint, or 30 cubic inches at the maximum dose.
We may therefore conclude, that the medium consumption of nitrous
oxide by the respiration of different individuals, is not far from two cubic
inches, or about a grain every second, or 120 cubic inches, or 60 grains
every minute.

m. When nitrous oxide is breathed in tight silk bags, towards the end of
the experiment as the internal surface becomes moist, as I have before
mentioned, a certain quantity of common air penetrates through it and
becomes mixed with the residual gas of the experiment; but this quantity is
always too small to destroy any of the effects of the nitrous oxide. The
residual gas of the common air, the nitrogene and carbonic acid produced in
the process, and the residuum of the admitted atmospheric air, hardly ever
amount after the experiment, to one half of the volume of the nitrous oxide
absorbed. There is consequently, a perfect propriety in successively
inspiring and expiring the whole of a given quantity of nitrous oxide, till it
is nearly consumed. In the respiration of nitrous oxide as the gas is
absorbed and not decomposed, little will be gained in effect, by perpetually
inspiring and expiring new portions, whilst an immense quantity of gas will
be idly wasted, and this circumstance, considering the expence of the
substance, is of importance.

VI. On the respiration of Atmospheric Air.
Having thus ascertained the absorption of nitrous oxide in respiration,
and the evolution of nitrogene and carbonic acid from the lungs during its
absorption: considering atmospheric air as a compound in which principles
identical with those in nitrous oxide existed, though in different quantities
and looser combination, I was anxious to compare the changes effected in
this gas by respiration, with those produced in nitrous oxide and oxygene;
particularly as they are connected with the health and life of animals.
The ingenious experiments of Lavoisier and Goodwyn, prove the
consumption of oxygene in respiration, and the production of carbonic acid.
From many experiments on the respiration of common air, Dr. Priestly
suspected that a certain portion of nitrogene, as well as oxygene, was
absorbed by the venous blood.
b. In the following experiments on the respiration of atmospheric air in
the mercurial airholder; the composition of the gas before inspiration and
after expiration, was ascertained in the following manner.
Forty measures of it were agitated over mercury in solution of caustic
potash, and suffered to remain in contact with it for two or three hours. The
diminution was noted, and the gas absorbed judged to be carbonic acid.

Twenty measures of the gas, freed from carbonic acid, were mingled with
thirty of nitrous gas, in a tube of,5 inches diameter; they were not agitated,
[200]
but suffered to rest for an hour or an hour and half, when the volume
occupied by them was noticed: and 50-m the volume occupied, divided by 3
considered as the oxygene x, and 20-x considered as the nitrogene.
c. To ascertain the changes effected in atmospheric air by single
inspirations,
I made, after a compleat voluntary exhaustion of my lungs, at
temperature 61°, one inspiration and expiration of 141 cubic inches of
atmospheric air. After expiration, they filled a space equal to 139 cubic
inches nearly. These 139 cubic inches analised were found to consist of
Nitrogene 101
Oxygene 32
Carbonic acid 6
The 141 cubic inches before inspiration, were composed of 103
nitrogene, 1 carbonic acid and 37 oxygene. The time taken to perform the
inspiration and full expiration, was nearly a quarter of a minute.
I repeated this experiment seven or eight times, and the quantity of
oxygene absorbed was generally from 5 to 6 cubic inches, the carbonic acid
formed from 5 to 5,5, and the quantity of nitrogene apparently diminished
by from 1 to 3 cubic inches.
E. 2. I made, after a voluntary expiration of common air, one inspiration
and full expiration of 100 cubic inches of atmospheric air. It was diminished
nearly to 98¾ or 99 cubic inches, and analised, was found to consist of
Nitrogene 71,7
Oxygene 22,5
Carbonic acid 4,5
This experiment I likewise repeated four or five times, with very little
difference of result, and there always seemed to be a small diminution of
nitrogene. I made no corrections on account of the residual air of the lungs
in these processes, because there was every reason to suppose that it was
always of similar composition.

c. Before I could ascertain whether similar changes were effected in
atmospheric air, by natural inspirations as by forced ones, I was obliged to
practise respiration in the mercurial airholder, by differing the conducting
tube to communicate with the atmosphere till I had attained the power of
breathing in it naturally, without labor or attention; I then found by a
number of experiments, that I took into my lungs at every natural
inspiration, about 13 cubic inches of air, and that I threw out of my lungs at
every expiration,[201] rather less than this quantity; about 12¾ cubic inches.
The mean composition of the 13 cubic inches of air inspired, was
cub. in.
Nitrogene 9,5
Oxygene 3,4
Carbonic acid 0,1
That of the 12,7 of air expired
Nitrogene 9,3
Oxygene 2,2
Carbonic acid 1,2
These results I gained from more than 20 experiments, so that I could
not possibly entertain any doubt of this accuracy.
I found, by making a person observe my respirations when I was
inattentive to the process, that I made about 26 or 27 natural inspirations in
a minute. So that calculating from the above estimations, it would follow,
that 31,6 cubic inches of oxygene were consumed, and 5,2 inches of
nitrogene lost in respiration every minute, whilst 26,6 cubic inches of
carbonic acid were produced.
To collect the products of a great number of natural expirations so as to
ascertain whether their composition corresponded with the above accounts,
I proceeded in the following manner.
I fastened my lips tight on the mouth-piece of the exhausted airholder,
and suffering my nostrils to remain open, inspired naturally through them,
throwing the expired air through my mouth into the airholder.

In many experiments, I found that in about a half a minute, I made in
this way 14 or 15 expirations. The mean quantity of air collected was 171
cubic inches, and consisted of
cub. in.
Nitrogene 128
Oxygene 29
Carbonic acid 14
Comparing these results with the former ones, we find the mean
quantities of air respired in equal terms rather less; but the proportions of
carbonic acid, nitrogene and oxygene in the respired air, nearly identical.
e. To ascertain the changes effected in a given quantity of atmospheric
air by continued respirations, I breathed after a compleat expiration, at
temperature 63°, 161 cubic inches of air for near a minute, making in this
time, 19 deep inspirations. After the compleat expiration, which was very
carefully made, the gas filled a space nearly equal to 152 cubic inches, so
that 9 cubic inches of gas had disappeared.
The 152 cubic inches analised, were found to consist of
cub. in.
Nitrogene 111,6
Oxygene 23,
Carbonic acid, 17,4
The 161 cubic inches before inspiration, were composed of
cub. in.
Nitrogene 117,0
Oxygene 42,4
Carbonic acid 1,6
But the residual gas in the lungs before the experiment, was of different
composition from that remaining in the lungs after the experiment. Making
corrections on account of this circumstance, as in section IV. it appears that

about 5,1 of nitrogene were absorbed in respiration, 23,9 of oxygene
consumed, and 12 of carbonic acid produced.
I repeated this experiment three times; in each experiment the
diminution after respiration, was nearly the same; and the residual gas
making the necessary allowances, of similar composition. So that supposing
the existence of no source of error in the experiments from which the
quantity and composition of the residual gas of the lungs were estimated in
section IV. the absorption of nitrogene by the venous blood, appears almost
demonstrated.
f. To compare the changes effected in atmospheric air by respiration of
the smaller quadrupeds, with those in the experiments just detailed, I
introduced into a jar of the capacity of 20 cubic inches filled with mercury
in the mercurial trough, 15 cubic inches of atmospheric air which had been
deprived of its carbonic acid by long exposure, to solution of potash.
Temperature being 64°, a healthy small mouse was quickly passed
under the mercury into the jar, and suffered to rest on a very thin bit of
cheese, which was admitted immediately after.
He continued for near 40 minutes without apparently suffering,
occasionally raising himself on his hind legs. At the end of 50 minutes, he
was lying on his side, and in 55 minutes was apparently dying. He was now
carefully taken out through the mercury by the tail, and exposed before the
fire, where he soon recovered. After the cheese had been carefully removed,
the gas in the jar filled a space nearly equal to 14 cubic inches; so that a
diminution of a cubic inch had taken place. These 14 cubic inches analised,
were found to consist of
cub. in.
Carbonic acid 2,0
Oxygene 1,4
Nitrogene 10,6
The 15 cubic inches before the experiment, consisted of
cub. in.
Oxygene 4

Nitrogene 11
Hence it appeared, that 2,6 cubic inches of oxygene had been
consumed, 2 cubic inches of carbonic acid produced, and about 0,4 of
nitrogene lost.
The relation between the quantities of oxygene consumed in this
experiment, and the carbonic acid produced, are nearly the same as that of
those in the experiments just detailed; but the quantity of nitrogene lost is
much smaller.

VII. Respiration of Oxygene.
The gases before and after respiration, were analised in these
experiments in the manner described in the last section, except that 3 of
nitrous gas were always employed to one of oxygene.
E. I. At temperature 53°, after a full forced respiration, I respired in the
mercurial airholder, for half a minute, 102 cubic inches of oxygene, making
seven very long and deep inspirations. After the compleat expiration, the
gases filled a space equal to 93 cubic inches; these 93 cubic inches analised,
were found to consist of
cub. in.
Carbonic acid 5,9
Nitrogene 33,8
Oxygene 53,3
The 102 cubic inches before the experiment, were composed of
cub. in.
Oxygene 78
Nitrogene 24
The residual gas in the lungs before the experiment, was 32 cubic
inches, and composed of about 23 nitrogene, 4,1 carbonic acid, and 4,9
oxygene, Section IV. The residual gas after expiration, was composed of
18,2 oxygene, 2 carbonic acid, and 11,8 nitrogene.

Hence the whole of the gas in the lungs and airholder before inspiration,
was 134 cubic inches, composed of
cub. in.
Oxygene 82,9
Nitrogene 47,0
Carbonic acid 4,1
And after respiration, 125 cubic inches, consisting of
cub. in.
Oxygene 71,5
Nitrogene 45,6
Carbonic acid 7,9
So that comparing the quantities, it appears, that 11,4 of oxygene and
1,4 of nitrogene, were consumed in this experiment, and 3,8 of carbonic
acid produced.
I was much surprised at the small quantity of oxygene that had been
consumed in this experiment. This quantity was less than that expended
during the respiration of atmospheric air for half a minute: the portion of
carbonic acid evolved was likewise smaller. I could detect no source of
inaccuracy, and it was difficult to suppose that the greater depth and fulness
of the inspirations could make any difference.
E. 2. I now respired at the same temperature, after a full expiration, 162
cubic inches of gas, composed of 133 oxygene and 20 nitrogene for two
minutes, imitating as much as possible, the natural respiration. After the
experiment, they filled a space equal to 123 cubic inches. And when the
analysis and calculations had been made as in the last experiment, it
appeared that 57 cubic inches of oxygene, and 2 of nitrogene had been
absorbed, whilst 21 cubic inches of carbonic acid had been formed.
Now from the estimations in the last section, it appears that 63 cubic
inches of oxygene are consumed, and about 52 cubic inches of carbonic
acid produced every two minutes during the natural respiration of common
air. So that supposing the experiment accurate, 6 cubic inches of oxygene
less are absorbed, and 30 cubic inches less of carbonic acid produced every

minute, when oxygene nearly pure is respired, than when atmospheric air is
respired.
Both these experiments were made in the morning, at a time when I was
in perfect health; so that there could be apparently no source of error from
accidental circumstances.
The uncommon and unexpected nature of the results, made me however,
very sceptical concerning them; and before I would draw any inferences, I
resolved to ascertain the comparative consumption of atmospheric air and
oxygene by the smaller quadrupeds, for which purpose, I made the
following experiment.
E. 3. Of two strong and healthy small mice, apparently of the same
breed, and exactly similar.
One was introduced into a jar containing 10 cubic inches and half of
oxygene, and 3 cubic inches of nitrogene, and made to rest on a bit of
cheese.
The other was introduced into a jar containing fifteen cubic inches and
half of atmospheric air, and made to rest in the same manner on cheese.
The mouse in oxygene began apparently to suffer in about half an hour,
and occasionally panted very much; in about an hour he lay down on his
side as if dying. The jars were often agitated, that the gases might be well
mingled.
The mouse in atmospheric air became very feeble in 40 minutes, and at
the end of 50 minutes was taken out through the mercury alive, but unable
to stand.
The mouse in oxygene was taken out in the same manner after an hour
and quarter, alive, but motionless, and breathing very deeply.
The gas in the jars was examined. That in the oxygene jar filled a space
exactly equal to 12,7 cubic inches, and analised, was found to consist of 1,7
carbonic acid, 2,6 of nitrogene, and 8,4 of oxygene. So that absolutely, 2,1
cubic inches of oxygene and,4 of nitrogene had been consumed, and 1,7 of
carbonic acid produced.
The gas in the atmospheric air jar was diminished nearly to 14,4, and
consisted of 2,1 carbonic acid, 1,4 oxygene; and 10,9 nitrogene. So that 2,7

of oxygene and,5 of nitrogene, had been consumed by the mouse; and 2,1
of carbonic acid produced.
Hence it appears, that the mouse in atmospheric air consumed nearly
one third more oxygene and produced nearly one fourth more carbonic acid
in respiration in 55 minutes, than the other in an hour and quarter in
oxygene. And if we consider the perpetual diminution of the oxygene of the
atmospheric air; from which at last it became almost incapable of
supporting the life of the animal; we may conclude, that the quantity of
oxygene consumed by it, had the air been perpetually renovated, would
have been much more considerable.
I design very shortly, to repeat these experiments, and to make others on
the comparative consumption of oxygene and atmospheric air, by the larger
quadrupeds. Whatever may be the results, I hope to be able to ascertain
from them, why pure oxygene is incapable of supporting life.
VIII. Observations on the changes effected in the blood, by
atmospheric air and oxygene.
From the experiments of Mr. Cigna and Dr. Priestley,[202] it appears that
the coagulum of the venous blood becomes florid at its surface when
exposed to the atmosphere, though covered and defended from the
immediate contact of air by a very thick stratum of serum.
Hence it is evident, that serum is capable of dissolving either the whole
compound atmospheric air, or the oxygene of it.
Supposing what indeed is most probable from numerous analogies, that
it dissolves the whole compound; it would follow, that the coloring of the
coagulum of blood under serum, depended upon the decomposition of the
atmospheric air condensed in the serum, the oxygene[203] of it combining
with the red particles, and the nitrogene either remaining dissolved in the
fluid, or being liberated through it into the atmosphere.
Now the circulating blood consists of red particles, floating in and
diffused through serum and coagulable lymph.
In natural respiration, the red particles are rendered of a brighter tinge
during the passage of the blood through the pulmonary veins. And as we
have seen in the last sections, during respiration atmospheric air is

decomposed; all the oxygene of it consumed, apparently a small portion of
the nitrogene lost, and a considerable quantity of carbonic acid produced.
It seems therefore reasonable to suppose, that the whole compound
atmospheric air passing through the moist coats of the vessels is first
dissolved by the serum of the venous blood, and in its condensed state,
decomposed by the affinity of the red particles for its oxygene; the greater
part of the nitrogene being liberated unaltered; but a minute portion of it
possibly remaining condensed in the serum and coagulable lymph, and
passing with them into the left chamber of the heart.
From the experiments on the respiration of nitrous oxide and hydrogene,
it appears that a certain portion of the carbonic acid produced in respiration,
is evolved from the venous blood; but as a much greater quantity is
generated during the respiration of common air and oxygene, than during
that of hydrogene in equal times, it is not impossible but that some portion
of it may be formed by the combination of charcoal in the red particles with
the oxygene dissolved in the serum; but this can only be determined by
farther experiments.
Supposing that no part of the water evolved in solution by the expired
gas of common air is formed immediately in respiration, it will follow that a
very considerable quantity of oxygene must be constantly combined with
the red particles, even allowing the consumption of a certain portion of it to
form carbonic acid; for the carbonic acid evolved, rarely amounts to more
than three fourths of the volume of the oxygene consumed.
Perhaps the serum of the blood is capable of dissolving a larger quantity
of atmospheric air than of pure oxygene. On this supposition, it would be
easy to explain the smaller consumption of oxygene in the experiments in
the last section.

IX. Observations on the respiration
of Nitrous Oxide.
The experiments in the first Division of this Research, prove that nitrous
oxide when respired by animals, produces peculiar changes in their blood
and in their organs, first connected with increased living action; but
terminating in death.

From the experiments in this Division, it appears, that nitrous oxide is
rapidly absorbed by the circulating venous blood, and of course its
condensed oxygene and nitrogene distributed in the blood over the whole of
the system.
Concerning the changes effected in the principles of the impregnated
blood during circulation and its action upon the nervous and muscular fibre;
it is useless to reason in the present state of our knowledge.
It would be easy to form theories referring the action of blood
impregnated with nitrous oxide, to its power of supplying the nervous and
muscular fibre with such proportions of condensed nitrogene, oxygene and
light or etherial fluid, as enabled them more rapidly to pass through those
changes which constitute their life: but such theories would be only
collections of terms derived from known phænomena and applied by loose
analogies of language to unknown things.
We are unacquainted with the composition of dead organised matter;
and new instruments of experiment and new modes of research must be
found, before we can ascertain even our capabilities of discovering the laws
of life.

RESEARCH IV.
RELATING TO THE EFFECTS PRODUCED BY
THE RESPIRATION OF NITROUS OXIDE.

DIVISION I.

HISTORY of the DISCOVERY.—Effects produced by the
RESPIRATION of different GASES.

A short time after I began the study of Chemistry, in March 1798, my
attention was directed to the dephlogisticated nitrous gas of Priestley,
by Dr. Mitchill’s Theory of Contagion.[204]
The fallacy of this Theory was soon demonstrated, by a few coarse
experiments made on small quantities of the gas procured from zinc and
diluted nitrous acid. Wounds were exposed to its action, the bodies of
animals were immersed in it without injury; and I breathed it mingled in
small quantities with common air, without remarkable effects. An inability
to procure it in sufficient quantities, prevented me at this time, from
pursuing the experiments to any greater extent. I communicated an account
of them to Dr. Beddoes.
In 1799, my situation in the Medical Pneumatic Institution, made it my
duty to investigate the physiological effects of the aëriform fluids, the
properties of which presented a chance of useful agency. At this period I
recommenced the investigation.
A considerable time elapsed before I was able to procure the gas in a
state of purity, and my first experiments were made on the mixtures of
nitrous oxide, nitrogene and nitrous gas, which are produced during
metallic solutions.
In the beginning of March, I prepared a large quantity of impure nitrous
oxide from the nitrous solution of zinc. Of this I often breathed the
quantities of a quart and two quarts generally mingled with more than equal

parts of oxygene or common air. In the most decisive of those trials, its
effects appeared to be depressing, and I imagined that it produced a
tendency to fainting: the pulse was certainly rendered slower under its
operation.
At this time, Mr. Southey respired it in an highly diluted state; it
occasioned a slight degree of giddiness, and considerably diminished the
quickness of his pulse.
Mr. C. Coates likewise respired it highly diluted, with similar effects.
In April, I obtained nitrous oxide in a state of purity, and ascertained
many of its chemical properties. Reflections upon these properties and upon
the former trials, made me resolve to endeavour to inspire it in its pure
form, for I saw no other way in which its respirability, or powers could be
determined.[205]
I was aware of the danger of this experiment. It certainly would never
have been made if the hypothesis of Dr. Mitchill had in the least influenced
my mind. I thought that the effects might be possibly depressing and
painful, but there were many reasons which induced me to believe that a
single inspiration of a gas apparently possessing no immediate action on the
irritable fibre, could neither destroy or materially injure the powers of life.
On April 11th, I made the first inspiration of pure nitrous oxide; it
passed through the bronchia without stimulating the glottis, and produced
no uneasy feeling in the lungs.
The result of this experiment, proved that the gas was respirable, and
induced me to believe that a farther trial of its effects might be made
without danger.
On April 16th, Dr. Kinglake being accidentally present, I breathed three
quarts of nitrous oxide from and into a silk bag for more than half a minute,
without previously closing my nose or exhausting my lungs.
The first inspirations occasioned a slight degree of giddiness. This was
succeeded by an uncommon sense of fulness of the head, accompanied with
loss of distinct sensation and voluntary power, a feeling analogous to that
produced in the first stage of intoxication; but unattended by pleasurable

sensation. Dr. Kinglake, who felt my pulse, informed me that it was
rendered quicker and fuller.
This trial did not satisfy me with regard to its powers; comparing it with
the former ones I was unable to determine whether the operation was
stimulant or depressing.
I communicated the result to Dr. Beddoes, and on April the 17th, he was
present, when the following experiment was made.
Having previously closed my nostrils and exhausted my lungs, I
breathed four quarts of nitrous oxide from and into a silk bag. The first
feelings were similar to those produced in the last experiment; but in less
than half a minute, the respiration being continued, they diminished
gradually, and were succeeded by a sensation analogous to gentle pressure
on all the muscles, attended by an highly pleasurable thrilling, particularly
in the chest and the extremities. The objects around me became dazzling
and my hearing more acute. Towards the last inspirations, the thrilling
increased, the sense of muscular power became greater, and at last an
irresistible propensity to action was indulged in; I recollect but indistinctly
what followed; I know that my motions were various and violent.
These effects very soon ceased after respiration. In ten minutes, I had
recovered my natural state of mind. The thrilling in the extremities,
continued longer than the other sensations.[206]
This experiment was made in the morning; no languor or exhaustion
was consequent, my feelings throughout the day were as usual, and I passed
the night in undisturbed repose.
The next morning the recollections of the effects of the gas were very
indistinct, and had not remarks written immediately after the experiment
recalled them to my mind, I should have even doubted of their reality. I was
willing indeed to attribute some of the strong emotion to the enthusiasm,
which I supposed must have been necessarily connected with the perception
of agreeable feelings, when I was prepared to experience painful sensations.
Two experiments however, made in the course of this day, with sceptism,
convinced me that the effects were solely owing to the specific operation of
the gas.

In each of them I breathed five quarts of nitrous oxide for rather a
longer time than before. The sensations produced were similar, perhaps not
quite so pleasurable; the muscular motions were much less violent.
Having thus ascertained the powers of the gas, I made many
experiments to ascertain the length of time for which it might be breathed
with safety, its effects on the pulse, and its general effects on the health
when often respired.
I found that I could breathe nine quarts of nitrous oxide for three
minutes, and twelve quarts for rather more than four. I could never breathe
it in any quantity, so long as five minutes. Whenever its operation was
carried to the highest extent, the pleasurable thrilling at its height about the
middle of the experiment, gradually diminished, the sense of pressure on
the muscles was lost; impressions ceased to be perceived; vivid ideas
passed rapidly through the mind, and voluntary power was altogether
destroyed, so that the mouth-piece generally dropt from my unclosed lips.
Whenever the gas was in a high state of purity, it tasted distinctly sweet
to the tongue and palate, and had an agreeable odor. I often thought that it
produced a feeling somewhat analogous to taste, in its application to my
lungs. In one or two experiments, I perceived a distinct sense of warmth in
my chest.
I never felt from it any thing like oppressive respiration: my inspirations
became deep in proportion as I breathed it longer; but this phænomenon
arose from increased energy of the muscles of respiration, and from a desire
of increasing the pleasurable feelings.
Generally when I breathed from six to seven quarts, muscular motions
were produced to a certain extent; sometimes I manifested my pleasure by
stamping or laughing only; at other times, by dancing round the room and
vociferating.
After the respiration of small doses, the exhilaration generally lasted for
five or six minutes only. In one or two experiments when ten quarts had
been breathed for near four minutes, an exhilaration and a sense of slight
intoxication lasted for two or three hours.
On May 3d. To ascertain whether the gas would accelerate or retard the
progress of sleep, I breathed at about 8 o’clock in the evening, 25 quarts of

nitrous oxide, in quantities of six at a time, allowing but short intervals
between each dose. The feelings were much less pleasurable than usual, and
during the consumption of the two last doses, almost indifferent; indeed the
gas was breathed rather too soon after its production and contained some
suspended acid vapour which stimulated the lungs so as to induce coughing.
After the experiments, for the first time I was somewhat depressed and
debilitated; my propensity to sleep however, came on at the usual hour, and
as usual was indulged in, my repose was sound and unbroken.
Between May and July, I habitually breathed the gas, occasionally three
or four times a day for a week together; at other periods, four or five times a
week only.
The doses were generally from six to nine quarts; their effects appeared
undiminished by habit, and were hardly ever exactly similar. Sometimes I
had the feelings of intense intoxication, attended with but little pleasure; at
other times, sublime emotions connected with highly vivid ideas; my pulse
was generally increased in fulness, but rarely in velocity.
The general effects of its operation upon my health and state of mind,
are extremely difficult of description; nor can I well discriminate between
its agency and that of other physical and moral causes.
I slept much less than usual, and previous to sleep, my mind was long
occupied by visible imagery. I had a constant desire of action, a
restlessness, and an uneasy feeling about the præcordia analogous to the
sickness of hope.
But perhaps these phænomena in some measure depended on the
interest and labour connected with the experimental investigation relating to
the production of nitrous oxide, by which I was at this time incessantly
occupied.
My appetite was as usual, and my pulse not materially altered.
Sometimes for an hour after the inspiration of the gas, I experienced a
species of mental indolence[207] pleasing rather than otherwise, and never
ending in listlessness.
During the last week in which I breathed it uniformly, I imagined that I
had increased sensibility of touch: my fingers were pained by any thing

rough, and the tooth edge produced from slighter causes than usual. I was
certainly more irritable, and felt more acutely from trifling circumstances.
My bodily strength was rather diminished than increased.
At the end of July, I left off my habitual course of respiration; but I
continued occasionally to breathe the gas, either for the sake of enjoyment,
or with a view of ascertaining its operation under particular circumstances.
In one instance, when I had head-ache from indigestion, it was
immediately removed by the effects of a large dose of gas; though it
afterwards returned, but with much less violence. In a second instance, a
slighter degree of head-ache was wholly removed by two doses of gas.
The power of the immediate operation of the gas in removing intense
physical pain, I had a very good opportunity of ascertaining.
In cutting one of the unlucky teeth called dentes sapientiæ, I
experienced an extensive inflammation of the gum, accompanied with great
pain, which equally destroyed the power of repose, and of consistent action.
On the day when the inflammation was most troublesome, I breathed
three large doses of nitrous oxide. The pain always diminished after the first
four or five inspirations; the thrilling came on as usual, and uneasiness was
for a few minutes, swallowed up in pleasure. As the former state of mind
however returned, the state of organ returned with it; and I once imagined
that the pain was more severe after the experiment than before.
In August, I made many experiments with a view of ascertaining
whether any analogy existed between the sensible effects of the different
gases which are sooner or later fatal to life when respired, and those of
nitrous oxide.
I respired four quarts of Hydrogene[208] nearly pure produced from zinc
and muriatic acid, for near a minute, my lungs being previously exhausted
and my nostrils carefully closed. The first six or seven inspirations
produced no sensations whatever; in half a minute, I perceived a
disagreeable oppression of the chest, which obliged me to respire very
quickly; this oppression gradually increased, till at last the pain of
suffocation compelled me to leave off breathing. I felt no giddiness during
or after the experiment; my pulse was rendered feebler and quicker; and a
by-stander informed me that towards the last, my cheeks became purple.

In a second experiment, when the hydrogene was procured from iron
and diluted sulphuric acid, I was unable to respire it for so long as three
quarters of a minute; a transient giddiness and muscular debility were
produced, the pulse was rendered very feeble, and the pain of suffocation
was greater than before.
I breathed three quarts of Nitrogene mingled with a very small portion
of carbonic acid, for near a minute. It produced no alteration in my
sensations for the first twenty seconds; then the painful sense of suffocation
gradually came on, and increased rapidly in the last quarter of the minute,
so as to oblige me to desist from the experiment. My pulse was rendered
feebler and quicker. I felt no affection whatever in the head.
Mr. Watt’s observations on the respiration of diluted Hydrocarbonate by
men, and Dr. Beddoes’s experiments on the destruction of animals by pure
hydrocarbonate, proved that its effects were highly deleterious.
As it destroyed life apparently by rendering the muscular fibre
inirritable without producing any previous excitement, I was anxious to
compare its sensible effects with those of nitrous oxide, which at this time I
believed to destroy life by producing the highest possible excitement,
ending in læsion of organisation.
In the first experiment, I breathed for near a minute, three quarts of
hydrocarbonate mingled with nearly two quarts of atmospheric air.[209] It
produced a slight giddiness and pain in the head, and a momentary loss of
voluntary power: my pulse was rendered much quicker and feebler. These
effects however, went off in five minutes, and I had no return of giddiness.
Emboldened by this trial, in which the feelings were not unlike those I
experienced in the first experiments on nitrous oxide, I resolved to breathe
pure hydrocarbonate.
For this purpose, I introduced into a silk bag, four quarts of gas nearly
pure, which was carefully produced from the decomposition of water by
charcoal an hour before, and which had a very strong and disagreeable
smell.
My friend, Mr. James Tobin, Junr. being present, after a forced
exhaustion of my lungs, the nose being accurately closed, I made three
inspirations and expirations of the hydrocarbonate. The first inspiration

produced a sort of numbness and loss of feeling in the chest and about the
pectoral muscles. After the second inspiration, I lost all power of perceiving
external things, and had no distinct sensation except a terrible oppression on
the chest. During the third expiration, this feeling disappeared, I seemed
sinking into annihilation, and had just power enough to drop the mouth-
piece from my unclosed lips. A short interval must have passed during
which I respired common air, before the objects about me were
distinguishable. On recollecting myself, I faintly articulated, “I do not think
I shall die.” Putting my finger on the wrist, I found my pulse thread-like
and beating with excessive quickness.
In less than a minute, I was able to walk, and the painful oppression on
the chest directed me to the open air.
After making a few steps which carried me to the garden, my head
became giddy, my knees trembled, and I had just sufficient voluntary power
to throw myself on the grass. Here the painful feeling of the chest increased
with such violence as to threaten suffocation. At this moment, I asked for
some nitrous oxide. Mr. Dwyer brought me a mixture of oxygene and
nitrous oxide. I breathed this for a minute, and believed myself relieved. In
five minutes, the painful feelings began gradually to diminish. In an hour
they had nearly disappeared, and I felt only excessive weakness and a slight
swimming of the head. My voice was very feeble and indistinct. This was at
two o’clock in the afternoon.
I afterwards walked slowly for about half an hour, with Mr. Tobin, Junr.
and on my return, was so much stronger and better, as to believe that the
effects of the gas had disappeared; though my pulse was 120 and very
feeble. I continued without pain for near three quarters of an hour; when the
giddiness returned with such violence as to oblige me to lie on the bed; it
was accompanied with nausea, loss of memory, and deficient sensation. In
about an hour and half, the giddiness went off, and was succeeded by an
excruciating pain in the forehead and between the eyes, with transient pains
in the chest and extremities. Towards night these affections gradually
diminished. At ten,[210] no disagreeable feeling except weakness remained. I
slept sound, and awoke in the morning very feeble and very hungry. No
recurrence of the symptoms took place, and I had nearly recovered my
strength by the evening.

I have been minute in the account of this experiment because it proves,
that hydrocarbonate acts as a sedative, i. e. that it produces diminution of
vital action, and debility, without previously exciting. There is every reason
to believe, that if I had taken four or five inspirations instead of three, they
would have destroyed life immediately without producing any painful
sensation. Perhaps most of the uneasy feelings after the experiment, were
connected with the return of the healthy condition of organs.[211]
About a week after this experiment, I attempted to respire Carbonic
acid, not being at the time acquainted with the experiments of Rosier.
I introduced into a silk bag four quarts of well washed carbonic acid
produced from carbonate of ammoniac[212] by heat, and after a compleat
voluntary exhaustion of my lungs, attempted to inspire it. It tasted strongly
acid in the mouth and fauces, and produced a sense of burning at the top of
the uvula. In vain I made powerful voluntary efforts to draw it into the
windpipe; at the moment that the epiglottis was raised a little, a painful
stimulation was induced, so as to close it spasmodically on the glottis; and
thus in repeated trials I was prevented from taking a single particle of
carbonic acid into my lungs.
I tried to breathe a mixture of two quarts of common air and three of
carbonic acid, without success; it stimulated the epiglottis nearly in the
same manner as pure carbonic acid, and was perfectly non-respirable.
I found that a mixture of three quarts of carbonic acid with seven of
common air was respirable, I breathed it for near a minute. At the time, it
produced a slight degree of giddiness, and an inclination to sleep. These
effects however, very rapidly disappeared after I had ceased to breathe,[213]
and no other affections followed.
During the course of experiments on nitrous oxide, I several times
breathed Oxygene procured from manganese by heat, for from three to five
minutes.
In respiring eight or ten quarts; for the first two or three minutes I could
perceive no effects. Towards the end, even when I breathed very slowly, my
respiration became oppressed, and I felt a sensation analogous to that
produced by the want of fresh air; though but little of the oxygene had been
consumed.

In one experiment when I breathed from and into a bag containing 20
quarts of oxygene for near six minutes; Dr. Kinglake felt my pulse, and
found it not altered in velocity, but rather harder than before. I perceived no
effects but those of oppression on the chest[214].
Having observed in my experiments upon venous blood, that Nitrous
gas rendered that fluid of a purple tinge, very like the color generated in it
by nitrous oxide; and finding no painful effects produced by the application
of nitrous gas to the bare muscular fibre, I began to imagine that this gas
might be breathed with impunity, provided it were possible in any way to
free the lungs of common air before inspiration, so as to prevent the
formation of nitrous acid.
On this supposition, during a fit of enthusiasm produced by the
respiration of nitrous oxide, I resolved to endeavour to breathe Nitrous gas.
114 cubic inches of nitrous gas were introduced into the large mercurial
airholder; two small silk bags of the capacity of seven quarts were filled
with nitrous oxide.
After a forced exhaustion of my lungs, my nose being accurately closed,
I made three inspirations and expirations of nitrous oxide in one of the bags,
to free my lungs as much as possible from atmospheric oxygene; then, after
a full expiration of the nitrous oxide, I transferred my mouth from the
mouth-piece of the bag to that of the airholder, and turning the stop-cock,
attempted to inspire the nitrous gas.—In passing through my mouth and
fauces, it tasted astringent and highly disagreeable; it occasioned a sense of
burning in the throat, and produced a spasm of the epiglottis so painful as to
oblige me to desist instantly from attempts to inspire it. After moving my
lips from the mouth-piece, when I opened them to inspire common air,
aëriform nitrous acid was instantly formed in my mouth, which burnt the
tongue and palate, injured the teeth, and produced an inflammation of the
mucous membrane which lasted for some hours.
As after the respiration of nitrous oxide in the experiments in the last
Research, a small portion of the residual atmospheric air remained in the
lungs, mingled with the gas, after forced expiration; it is most probable that
a minute portion of nitrous acid was formed in this experiment, when the
nitrous gas was taken into the mouth and fauces, which might produce its
stimulating properties. If so, perhaps I owe my life to the circumstance; for

supposing I had taken an inspiration of nitrous gas, and even that it had
produced no positive effects, it is highly improbable, that by breathing
nitrous oxide, I should have freed my lungs from it, so as to have prevented
the formation of nitrous acid when I again inspired common air. I never
design again to attempt so rash an experiment.
In the beginning of September I often respired nitrous oxide mingled
with different proportions of common air or oxygene. The effects produced
by the diluted gas were much less violent than those produced by pure
nitrous oxide. They were generally pleasant: the thrilling was not often
perceived, but a sense of exhilaration was almost constant.
Between September and the end of October, I made but few
experiments on respiration, almost the whole of my time being devoted to
chemical experiments on the production and analysis of nitrous oxide.
At this period my health being somewhat injured by the constant labour
of experimenting, and the perpetual inhalation of the acid vapours of the
laboratory, I went into Cornwall; where new associations of ideas and
feelings, common exercise, a pure atmosphere, luxurious diet and moderate
indulgence in wine, in a month restored me to health and vigor.
Nov. 27th. Immediately after my return, being fatigued by a long
journey, I respired nine quarts of nitrous oxide, having been precisely thirty-
three days without breathing any. The feelings were different from those I
had experienced in former experiments. After the first six or seven
inspirations, I gradually began to lose the perception of external things, and
a vivid and intense recollection of some former experiments passed through
my mind, so that I called out “what an amazing concatenation of ideas!” I
had no pleasurable feeling whatever, I used no muscular motion, nor did I
feel any disposition to it; after a minute, when I made the note of the
experiment, all the uncommon sensations had vanished; they were
succeeded by a slight soreness in one of the arms and in the leg: in three
minutes these affections likewise disappeared.
From this experiment I was inclined to suppose that my newly acquired
health had diminished my susceptibility to the effects of the gas. About ten
days after, however, I had an opportunity of proving the fallacy of this
supposition.

Immediately after a journey of 126 miles, in which I had no sleep the
preceding night, being much exhausted, I respired seven quarts of gas for
near three minutes. It produced the usual pleasurable effects, and slight
muscular motion. I continued exhilarated for some minutes afterwards: but
in half an hour found myself neither more or less exhausted than before the
experiment. I had a great propensity to sleep.
I repeated the experiment four or five times in the following week, with
similar effects. My susceptibility was certainly not diminished. I even
thought that I was more affected than formerly by equal doses.
Though, except in one instance, when indeed the gas was impure, I had
experienced no decisive exhaustion after the excitement from nitrous oxide,
yet still I was far from being satisfied that it was unanalogous to stimulants
in general.—No experiment had been made in which the excitement from
nitrous oxide had been kept up for so great a length of time and carried to
so great an extent as that in which it is uniformly succeeded by excessive
debility under the agency of other powers.
It occurred to me, that supposing nitrous oxide to be a stimulant of the
common class, it would follow that the debility produced in consequence of
excessive stimulation by a known agent, ought to be increased after
excitement from nitrous oxide.[215]
To ascertain whether this was the case, I made on December 23d, at four
P. M. the following experiment. I drank a bottle of wine in large draughts in
less than eight minutes. Whilst I was drinking, I perceived a sense of
fulness in the head, and throbbing of the arteries, not unanalogous to that
produced in the first stage of nitrous oxide excitement. After I had finished
the bottle, this fulness increased, the objects around me became dazzling,
the power of distinct articulation was lost, and I was unable to walk
steadily. At this moment the sensations were rather pleasurable than
otherwise, the sense of fulness in the head soon however increased so as to
become painful, and in less than an hour I sunk into a state of insensibility.
[216]

In this situation I must have remained for two hours or two hours and
half.

I was awakened by head-ache and painful nausea. The nausea continued
even after the contents of the stomach had been ejected. The pain in the
head every minute increased; I was neither feverish or thirsty; my bodily
and mental debility were excessive, and the pulse feeble and quick.
In this state I breathed for near a minute and half five quarts of gas,
which was brought to me by the operator for nitrous oxide; but as it
produced no sensations whatever, and apparently rather increased my
debility, I am almost convinced that it was from some accident, either
common air, or very impure nitrous oxide.
Immediately after this trial, I respired 12 quarts of oxygene for near four
minutes. It produced no alteration in my sensations at the time; but
immediately after I imagined that I was a little exhilarated.
The head-ache and debility still however continuing with violence, I
examined some nitrous oxide which had been prepared in the morning, and
finding it very pure, respired seven quarts of it for two minutes and half.
I was unconscious of head-ache after the third inspiration; the usual
pleasurable thrilling was produced, voluntary power was destroyed, and
vivid ideas rapidly passed through my mind; I made strides across the room,
and continued for some minutes much exhilarated. Immediately after the
exhilaration had disappeared, I felt a slight return of the head-ache; it was
connected with transient nausea. After two minutes, when a small quantity
of acidified wine had been thrown from the stomach, both the nausea and
head-ache disappeared; but languor and depression not very different in
degree from those existing before the experiment, succeeded. They
however, gradually went off before bed time. I slept sound the whole of the
night except for a few minutes, during which I was kept awake by a trifling
head-ache. In the morning, I had no longer any debility. No head-ache or
giddiness came on after I had arisen, and my appetite was very great.
This experiment proved, that debility from intoxication was not
increased by excitement from nitrous oxide. The head-ache and depression,
it is probable, would have continued longer if it had not been administered.
Is it not likely that the slight nausea following the effects of the gas was
produced by new excitability given to the stomach?

To ascertain with certainty, whether the most extensive action of nitrous
oxide compatible with life, was capable of producing debility, I resolved to
breathe the gas for such a time and in such quantities, as to produce
excitement equal in duration and superior in intensity to that occasioned by
high intoxication from opium or alcohol.
To habituate myself to the excitement, and to carry it on gradually.
On December 26th, I was inclosed in an air-tight breathing-box,[217] of
the capacity of about 9 cubic feet and half, in the presence of Dr. Kinglake.
After I had taken a situation in which I could by means of a curved
thermometer inserted under the arm, and a stop-watch, ascertain the
alterations in my pulse and animal heat, 20 quarts of nitrous oxide were
thrown into the box.
For three minutes I experienced no alteration in my sensations, though
immediately after the introduction of the nitrous oxide the smell and taste of
it were very evident.[218]
In four minutes I began to feel a slight glow in the cheeks, and a
generally diffused warmth over the chest, though the temperature of the box
was not quite 50°. I had neglected to feel my pulse before I went in; at this
time it was 104 and hard, the animal heat was 98°. In ten minutes the
animal heat was near 99°, in a quarter of an hour 99.5°, when the pulse was
102, and fuller than before.
At this period 20 quarts more of nitrous oxide were thrown into the box,
and well-mingled with the mass of air by agitation.
In 25 minutes the animal heat was 100°, pulse 124. In 30 minutes, 20
quarts more of gas were introduced.
My sensations were now pleasant; I had a generally diffused warmth
without the slightest moisture of the skin, a sense of exhilaration similar to
that produced by a small dose of wine, and a disposition to muscular motion
and to merriment.
In three quarters of an hour the pulse was 104, and animal heat not
99,5°, the temperature of the chamber was 64°. The pleasurable feelings
continued to increase, the pulse became fuller and slower, till in about an
hour it was 88, when the animal heat was 99°.

20 quarts more of air were admitted. I had now a great disposition to
laugh, luminous points seemed frequently to pass before my eyes, my
hearing was certainly more acute and I felt a pleasant lightness and power
of exertion in my muscles. In a short time the symptoms became stationary;
breathing was rather oppressed, and on account of the great desire of action,
rest was painful.
I now came out of the box, having been in precisely an hour and quarter.
The moment after, I began to respire 20 quarts of unmingled nitrous
oxide. A thrilling extending from the chest to the extremities was almost
immediately produced. I felt a sense of tangible extension highly
pleasurable in every limb; my visible impressions were dazzling and
apparently magnified, I heard distinctly every sound in the room of my
situation.[219] By degrees as the pleasurable and was perfectly aware
sensations increased, I lost all connection with external things; trains of
vivid visible images rapidly passed through my mind and were connected
with words in such a manner, as to produce perceptions perfectly novel. I
existed in a world of newly connected and newly modified ideas. I
theorised; I imagined that I made discoveries. When I was awakened from
this semi-delirious trance by Dr. Kinglake, who took the bag from my
mouth, Indignation and pride were the first feelings produced by the sight
of the persons about me. My emotions were enthusiastic and sublime; and
for a minute I walked round the room perfectly regardless of what was said
to me. As I recovered my former state of mind, I felt an inclination to
communicate the discoveries I had made during the experiment. I
endeavoured to recall the ideas, they were feeble and indistinct; one
collection of terms, however, presented itself: and with the most intense
belief and prophetic manner, I exclaimed to Dr. Kinglake, “Nothing exists
but thoughts!—the universe is composed of impressions, ideas, pleasures
and pains!”
About three minutes and half only, had elapsed during this experiment,
though the time as measured by the relative vividness of the recollected
ideas, appeared to me much longer.
Not more than half of the nitrous oxide was consumed. After a minute,
before the thrilling of the extremities had disappeared, I breathed the
remainder. Similar sensations were again produced; I was quickly thrown

into the pleasurable trance, and continued in it longer than before. For many
minutes after the experiment, I experienced the thrilling in the extremities,
the exhilaration continued nearly two hours. For a much longer time I
experienced the mild enjoyment before described connected with indolence;
no depression or feebleness followed. I ate my dinner with great appetite
and found myself lively and disposed to action immediately after. I passed
the evening in executing experiments. At night I found myself unusually
cheerful and active; and the hours between eleven and two, were spent in
copying the foregoing detail from the common-place book and in arranging
the experiments. In bed I enjoyed profound repose. When I awoke in the
morning, it was with consciousness of pleasurable existence, and this
consciousness more or less, continued through the day.
Since December, I have very often breathed nitrous oxide. My
susceptibility to its power is rather increased than diminished. I find six
quarts a full dose, and I am rarely able to respire it in any quantity for more
than two minutes and half.
The mode of its operation is somewhat altered. It is indeed very
different at different times.
I am scarcely ever excited into violent muscular action, the emotions are
generally much less intense and sublime than in the former experiments,
and not often connected with thrilling in the extremities.
When troubled with indigestion, I have been two or three times
unpleasantly affected after the excitement of the gas. Cardialgia, eructations
and unpleasant fulness of the head were produced.
I have often felt very great pleasure when breathing it alone, in darkness
and silence, occupied only by ideal existence. In two or three instances
when I have breathed it amidst noise, the sense of hearing has been
painfully affected even by moderate intensity of sound. The light of the sun
has sometimes been disagreeably dazzling. I have once or twice felt an
uneasy sense of tension in the cheeks and transient pains in the teeth.
Whenever I have breathed the gas after excitement from moral or
physical causes, the delight has been often intense and sublime.
On May 5th, at night, after walking for an hour amidst the scenery of
the Avon, at this period rendered exquisitely beautiful by bright moonshine;

my mind being in a state of agreeable feeling, I respired six quarts of newly
prepared nitrous oxide.
The thrilling was very rapidly produced. The objects around me were
perfectly distinct, and the light of the candle not as usual dazzling. The
pleasurable sensation was at first local and perceived in the lips and about
the cheeks. It gradually however, diffused itself over the whole body, and in
the middle of the experiment was for a moment so intense and pure as to
absorb existence. At this moment, and not before, I lost consciousness; it
was however, quickly restored, and I endeavoured to make a by-stander
acquainted with the pleasure I experienced by laughing and stamping. I had
no vivid ideas. The thrilling and the pleasurable feeling continued for many
minutes; I felt two hours afterwards, a slight recurrence of them, in the
intermediate state between sleeping and waking; and I had during the whole
of the night, vivid and agreeable dreams. I awoke in the morning with the
feeling of restless energy, or that desire of action connected with no definite
object, which I had often experienced in the course of experiments in 1799.
I have two or three times since respired nitrous oxide under similar
circumstances; but never with equal pleasure.
During the last fortnight, I have breathed it very often; the effects have
been powerful and the sensations uncommon; but pleasurable only in a
slight degree.
I ought to have observed that a desire to breathe the gas is always
awakened in me by the sight of a person breathing, or even by that of an air-
bag or an airholder.
I have this day, June 5th, respired four large doses of gas. The first two
taken in the morning acted very powerfully; but produced no thrilling or
other pleasurable feelings. The effects of the third breathed immediately
after a hearty dinner were pleasant, but neither intense or intoxicating. The
fourth was respired at night in darkness and silence after the occurrence of a
circumstance which had produced some anxiety. This dose affected me
powerfully and pleasantly; a slight thrilling in the extremities was
produced; an exhiliration continued for some time, and I have had but little
return of uneasiness. 11 P. M.

From the nature of the language of feeling, the preceding detail contains
many imperfections; I have endeavoured to give as accurate an account as
possible of the strange effects of nitrous oxide, by making use of terms
standing for the most similar common feelings.
We are incapable of recollecting pleasures and pains of sense.[220] It is
impossible to reason concerning them, except by means of terms which
have been associated with them at the moment of their existence, and which
are afterwards called up amidst trains of concomitant ideas.
When pleasures and pains are new or connected with new ideas, they
can never be intelligibly detailed unless associated during their existence
with terms standing for analogous feelings.
I have sometimes experienced from nitrous oxide, sensations similar to
no others, and they have consequently been indescribable. This has been
likewise often the case with other persons. Of two paralytic patients who
were asked what they felt after breathing nitrous oxide, the first answered,
“I do not know how, but very queer.” The second said, “I felt like the sound
of a harp.” Probably in the one case, no analogous feelings had ever
occurred. In the other, the pleasurable thrillings were similar to the
sensations produced by music; and hence, they were connected with terms
formerly applied to music.

DIVISION II.

DETAILS of the EFFECTS produced by the RESPIRATION of
NITROUS OXIDE upon different INDIVIDUALS furnished by
THEMSELVES.

T heexperiments related in the following details, were made in the
Medical Pneumatic Institution.
Abstracts from many of them have been published by Dr. Beddoes.[221]

I. Detail of Mr. J. W. Tobin.
Having seen the remarkable effects produced on Mr.
Davy, by breathing nitrous oxide, the 18th of April; I
became desirous of taking some.

A day or two after I breathed 2 quarts of this gas,
returning it back again into the same bag, after two or
three in inspirations, breathing became difficult, and I
occasionally admitted common air into my lungs. While
the respiration was continued, my sensations became
more pleasant. On taking the bag from my mouth, I
staggered a little, but felt no other effect.
On the second time of making the experiment, I took
nearly four quarts, but still found it difficult to continue
breathing long, though the air which was left in the bag
was far from being impure.
The effects however, in this case, were more striking
than in the former. Increased muscular action was
accompanied by very pleasurable feelings, and a strong
desire to continue the inspiration. On removing the bag
from my mouth, I laughed, staggered, and attempted to
speak, but stammered exceedingly, and was utterly
unable to pronounce some words. My usual state of
mind, however, soon returned.
On the 29th, I again breathed four quarts. The
pleasant feelings produced at first, urged me to continue
the inspiration with great eagerness. These feelings
however, went off towards the end of the experiment,
and no other effects followed. The gas had probably
been breathed too long, as it would not support flame. I
then proposed to Mr. Davy, to inhale the air by the
mouth from one bag, and to expire it from the nose into
another. This method was pursued with less than three
quarts, but the effects were so powerful as to oblige me
to take in a little common air occasionally. I soon found
my nervous system agitated by the highest sensations of
pleasure, which are difficult of description; my muscular
powers were very much increased, and I went on
breathing with great vehemence, not from a difficulty of
inspiration, but from an eager avidity for more air. When
the bags were exhausted and taken from me, I continued

breathing with the same violence, then suddenly starting
from the chair, and vociferating with pleasure, I made
towards those that were present, as I wished they should
participate in my feelings. I struck gently at Mr. Davy
and a stranger entering the room at the moment, I made
towards him, and gave him several blows, but more in
the spirit of good humour than of anger. I then ran
through different rooms in the house, and at last returned
to the laboratory somewhat more composed; my spirits
continued much elevated for some hours after the
experiment, and I felt no consequent depression either in
the evening or the day following, but slept as soundly as
usual.
On the 5th of May, I again attempted to breathe
nitrous oxide, but it happened to contain suspended
nitrous vapour which rendered it non-respirable.
On the 7th, I inspired 7 quarts of pure gas mingled
with an equal quantity of common air, the sensations
were pleasant, and my muscular power much increased.
On the 8th, I inspired five quarts without any mixture
of common air, but the effects were not equal to those
produced the day before; Indeed there were reasons for
supposing that the gas was impure.
On the 18th, I breathed nearly six quarts of the pure
nitrous oxide. It is not easy to describe my sensations;
they were superior to any thing I ever before
experienced. My step was firm, and all my muscular
powers increased. My senses were more alive to every
surrounding impression; I threw myself into several
theatrical attitudes, and traversed the laboratory with a
quick step; my mind was elevated to a most sublime
height. It is giving but a faint idea of the feelings to say,
that they resembled those produced by a representation
of an heroic scene on the stage, or by reading a sublime
passage in poetry when circumstances contribute to

awaken the finest sympathies of the soul. In a few
minutes the usual state of mind returned. I continued in
good spirits for the rest of the day, and slept soundly.
Since the 18th of May, I have very often breathed
nitrous oxide. In the first experiments when pure, its
effects were generally similar to those just described.
Lately I have seldom experienced vivid sensations.
The pleasure produced by it is slight and tranquil, I
rarely feel sublime emotions or increased muscular
power.

J. W. Tobin.
October, 1799.

II. Detail of Mr. Wm. Clayfield.
The first time that I breathed the nitrous oxide, it
produced feelings analogous to those of intoxication. I
was for some time unconscious of existence, but at no
period of the experiment experienced agreeable
sensations, a momentary nausea followed it; but
unconnected with languor or head-ache.
After this I several times respired the gas, but on
account of the fulness in the head and apparent
throbbing of the arteries in the brain,[222] always desisted
to breathe before the full effects were produced. In two
experiments however, when by powerful voluntary
efforts I succeeded in breathing a large quantity of gas
for some minutes, I had highly pleasurable thrillings in
the extremities, and such increase of muscular power, as
to be obliged to exert my limbs with violence. After
these experiments, no languor or depression followed.

William Clayfield.

III. Letter from Dr. Kinglake.

In compliance with your desire, I will endeavour to
give you a faithful detail of the effects produced on my
sensations by the inhalation of nitrous oxide.
My first inspiration of it was limited to four quarts,
diluted with an equal quantity of atmospheric air. After a
few inspirations, a sense of additional freedom and
power (call it energy if you please) agreeably pervaded
the region of the lungs; this was quickly succeeded by an
almost delirious but highly pleasurable sensation in the
brain, which was soon diffused over the whole frame,
imparting to the muscular power at once an encreased
disposition and tone for action; but the mental effect of
the excitement was such as to absorb in a sort of
intoxicating placidity, and delight, volition, or rather the
power of voluntary motion. These effects were in a
greater or less degree protracted during about five
minutes, when the former state returned, with the
difference however of feeling more cheerful and alert,
for several hours after.
It seemed also to have had the further effect of
reviving rheumatic irritations in the shoulder and knee-
joints, which had not been previously felt for many
months. No perceptible change was induced in the pulse
either at or subsequent to the time of inhaling the gas.
The effects produced by a second trial of its powers,
were more extensive, and concentrated on the brain. In
this instance, nearly six quarts undiluted, were
accurately and fully inhaled. As on the former occasion,
it immediately proved agreeably respirable, but before
the whole quantity was quite exhausted, its agency was
exerted so strongly on the brain, as progressively to
suspend the senses of seeing, hearing, feeling, and
ultimately the power of volition itself. At this period, the
pulse was much augmented both in force and frequency;
slight convulsive twitches of the muscles of the arms
were also induced; no painful sensation, nausea, or

languor, however, either preceded, accompanied, or
followed this state, nor did a minute elapse before the
brain rallied, and resumed its wonted faculties, when a
sense of glowing warmth extending over the system, was
speedily succeeded by a re-instatement of the
equilibrium of health.
The more permanent effects were (as in the first
experiment) an invigorated feel of vital power, improved
spirits, transient irritations in different parts, but not so
characteristically rheumatic as in the former instance.
Among the circumstances most worthy of regard in
considering the properties and administration of this
powerful aërial agent, may be ranked, the fact of its
being (contrary to the prevailing opinion[223]) both
highly respirable, and salutary, that it impresses the brain
and system at large with a more or less strong and
durable degree of pleasurable sensation, that unlike the
effect of other violently exciting agents, no sensible
exhaustion or diminution of vital power accrues from the
exertions of its stimulant property, that its most
excessive operation even, is neither permanently nor
transiently debilitating; and finally, that it fairly promises
under judicious application, to prove an extremely
efficient remedy, as well in the vast tribe of diseases
originating from deficient irritability and sensibility, as
in those proceeding from morbid associations, and
modifications, of those vital principles.
If you should deem any thing contained in this
cursory narrative capable of subserving in any degree the
practical advantages likely to result from your scientific
and valuable investigation of the genuine properties of
the nitrous oxide, it is perfectly at your disposal.

I am
Your sincere friend,
Robert Kinglake.

Bristol, June 14th, 1799.
To Mr. Davy.

IV. Detail of Mr. Southey.
In breathing the nitrous oxide, I could not distinguish
between the first feelings it occasioned and an
apprehension of which I was unable to divest myself.
My first definite sensation was a dizziness, a fulness in
the head, such as to induce a fear of falling. This was
momentary. When I took the bag from my mouth, I
immediately laughed. The laugh was involuntary but
highly pleasurable, accompanied by a thrill all through
me; and a tingling in my toes and fingers, a sensation
perfectly new and delightful. I felt a fulness in my chest
afterwards; and during the remainder of the day,
imagined that my taste and hearing were more than
commonly quick. Certain I am that I felt myself more
than usually strong and chearful.
In a second trial, by continuing the inhalation longer,
I felt a thrill in my teeth; and breathing still longer the
third time, became so full of strength as to be compelled
to exercise my arms and feet.
Now after an interval of some months, during which
my health has been materially impaired, the nitrous
oxide produces an effect upon me totally different. Half
the quantity affects me, and its operation is more violent;
a slight laughter is first induced,[224] and a desire to
continue the inhalation, which is counteracted by fear
from the rapidity of respiration; indeed my breath
becomes so short and quick, that I have no doubt but the
quantity which I formerly breathed, would now destroy
me. The sensation is not painful, neither is it in the
slightest degree pleasurable.

Robert Southey.

V. Letter from Dr. Roget.
The effect of the first inspirations of the nitrous
oxide was that of making me vertiginous, and producing
a tingling sensation in my hands and feet: as these
feelings increased, I seemed to lose the sense of my own
weight, and imagined I was sinking into the ground. I
then felt a drowsiness gradually steal upon me, and a
disinclination to motion; even the actions of inspiring
and expiring were not performed without effort: and it
also required some attention of mind to keep my nostrils
closed with my fingers. I was gradually roused from this
torpor by a kind of delirium, which came on so rapidly
that the air-bag dropt from my hands. This sensation
increased for about a minute after I had ceased to
breathe, to a much greater degree than before, and I
suddenly lost sight of all the objects around me, they
being apparently obscured by clouds, in which were
many luminous points, similar to what is often
experienced on rising suddenly and stretching out the
arms, after sitting long in one position.
I felt myself totally incapable of speaking, and for
some time lost all consciousness of where I was, or who
was near me. My whole frame felt as if violently
agitated: I thought I panted violently: my heart seemed
to palpitate, and every artery to throb with violence; I
felt a singing in my ears; all the vital motions seemed to
be irresistibly hurried on, as if their equilibrium had been
destroyed, and every thing was running headlong into
confusion. My ideas succeeded one another with
extreme rapidity, thoughts rushed like a torrent through
my mind, as if their velocity had been suddenly
accelerated by the bursting of a barrier which had before
retained them in their natural and equable course. This
state of extreme hurry, agitation, and tumult, was but
transient. Every unnatural sensation gradually subsided;
and in about a quarter of an hour after I had ceased to

breathe the gas, I was nearly in the same state in which I
had been at the commencement of the experiment.
I cannot remember that I experienced the least
pleasure from any of these sensations. I can however,
easily conceive, that by frequent repetition I might
reconcile myself to them, and possibly even receive
pleasure from the same sensations which were then
unpleasant.
I am sensible that the account I have been able to
give of my feelings is very imperfect. For however
calculated their violence and novelty were to leave a
lasting impression on the memory, these circumstances
were for that very reason unfavourable to accuracy of
comparison with sensations already familiar.
The nature of the sensations themselves, which bore
greater resemblance to a half delirious dream than to any
distinct state of mind capable of being accurately
remembered, contributes very much to increase the
difficulty. And as it is above two months since I made
the experiment, many of the minuter circumstances have
probably escaped me.

I remain,
Yours, &c.
P. Roget.
To Mr. Davy.

VI. Letter from Mr. James Thomson.
The first time I respired nitrous oxide, the
experiment was made under a strong impression of fear,
and the quantity I breathed not sufficient, as you
informed me, to produce the usual effect. I did not note
very accurately my sensations. I remember I experienced
a slight degree of vertigo after the third or fourth
inspiration; and breathed with increased vigor, my

inspirations being much deeper and more vehement than
ordinary. I was enabled the next time I made the
experiment, to attend more accurately to my sensations,
and you have the observations I made on them at the
time.
After the fourth inspiration, I experienced the same
increased action of the lungs, as in the former case. My
inspirations became uncommonly full and strong,
attended with a thrilling sensation about the chest, highly
pleasurable, which increased to such a degree as to
induce a fit of involuntary laughter, which I in vain
endeavoured to repress. I felt a slight giddiness which
lasted for a few moments only. My inspirations now
became more vehement and frequent; and I inhaled the
air with an avidity strongly indicative of the pleasure I
received. That peculiar thrill which I had at first
experienced at the chest, now pervaded my whole frame;
and during the two or three last inspirations, was
attended with a remarkable tingling in my fingers and
toes. My feelings at this moment are not to be described:
I felt a high, an extraordinary degree of pleasure,
different from that produced by wine, being divested of
all its gross accompaniments, and yet approaching nearer
to it than to any other sensation I am acquainted with.
I am certain that my muscular strength was for a time
much increased. My disposition to exert it was such as I
could not repress, and the satisfaction I felt in any
violent exertion of my legs and arms is hardly to be
conceived. These vivid sensations were not of long
duration; they diminished insensibly, and in little more
than a quarter of an hour I could perceive no difference
between the state I was then in, and that previous to the
respiration of the air.
The observations I made on repeating the
experiment, do not differ from the preceding, except in
the circumstance of the involuntary laughter, which I