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LAVOISIER

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WALLACE BROCKWAY, Executive Editor

ELEMENTS OF CHEMISTRY

BY ANTOINE LAURENT LAVOISIER

ANALYTICAL THEORY OF HEAT

BY JEAN BAPTISTE JOSEPH FOURIER

EXPERIMENTAL RESEARCHES
IN ELECTRICITY

BY MICHAEL FARADAY

\YILLIAM BENTOX, Publisher

ENCYCLOPAEDIA BRITANNICA, INC.
CHICAGO LONDON TORONTO

GENERAL CONTENTS

ELEMENTS OF CHEMISTRY, Page 1

By ANTOINE LAURENT LAVOISIER

Translated by ROBKKT KERR

ANALYTICAL THEORY OF HEAT, Page 169

By JEAN BAPTIST i: JOSEPH FOURIER

Translated by ALEXANDER FREKMAN

EXPER IMENTA L RESEARCHES

IN ELECTRICITY, Page 261

By MICHAEL FARADAY

ELEMENTS OF CHEMISTRY

BIOGRAPHICAL NOTE

ANTOINE LAVOISIER, 1743-1794

LAVOISIER was born in Paris, August 26, 1743.
His father was attorney to the Parliament of
Paris. His mother was the daughter of the sec-
retary to the Vice-Admiral of France and heir-
ess to a considerable fortune.

After completing his elementary education
Lavoisier was sent to the College Mazarin. His
early ambitions were literary rather than Sci-
entific, and in 1760 he won second prize in a
rhetorical contest. Although on leaving the
college he went on to prepare for law, and re-
ceived his Licentiate in 1764, he devoted him-
self to science, studying, with well-known
teachers of the time, mathematics, astronomy,
botany, mineralogy, geology, and chemistry.
He also began to conduct experiments arid ob-
servations of his own. One of the earliest was
in meteorology; he made barometrical obser-
vations several times daily and engaged others
in the same pursuit with the aim of discovering
the laws governing the weather. His zeal for
investigation was so great that at the age of
nineteen he decided to cut himself off from all
social activity; he gave ill-health as an excuse
and for several months lived in retirement on
a diet of milk.

His formal career as a scientist began in 1763
when he was invited by Guettard, his teacher
in geology, to collaborate in preparing the first
rnineralogical atlas of France. Lavoisier's part
of the project consisted largely of collecting
data; he kept elaborate notebooks which indi-
cate that he was not only amassing material
but analysing and developing ideas for later re-
search. While engaged in this work, he entered
the contest held by the French Academy of
Science for the best essay on methods for light-
ing the streets of a large city at night. The es-
says were divided into two groups, practical
and scientific, and while the prize was given to
entries in the first group, Lavoisier alone was
singled out from the second for special mention
and a gold medal from the King. The work with
Guettard also yielded material which Lavoisier
worked up in the form of memoires to be pre-
sented to the Academy of Science. In 1768,

after he had presented four such papers, two
on hydrometry and two on gypsum, he was
elected a member of the Academy. His youth
excited comment, and, as a friend of the family
remarked, at the age of twenty-five he had ob-
tained "a position which is usually won, with
great difficulty, by men past their fiftieth year."

Desirous of securing a larger income for re-
search, Lavoisier, shortly after his nomination
to the Academy, bought an interest in the
Ferme, an association of financiers who had the
privilege of collecting the national taxes in re-
turn for a fixed annual sum paid in advance to
the Government. His friends at the Academy
did not entirely approve of this association,
but it did provide him with the money he
sought, and it also made him acquainted with
Farmer-General Paulze, whose daughter he
married in 1771.

Lavoisier entered further into public life
when the Government took over the manufac-
ture of gunpowder. Upon his suggestion, Tur-
got, Minister of the Treasury, canceled the
private production of gunpowder and estab-
lished the Regie des poudres, a four-man admin-
istrative committee headed by Lavoisier.
With this appointment he was assigned a house
at the Arsenal, where with his own funds he
established a fully-equipped laboratory, which
he made available to all scientists interested in
his work. As his scientific fame increased, the
laboratory became a meeting place for promi-
nent scientists, and among his guests he num-
bered Priestley, Franklin, Watt, Tennant, and
Arthur Young. Lavoisier always retained an
interest in younger scientists, providing finan-
cial assistance for many and making laboratory
assistants of others, among whom was the Du-
pont who later went to America and founded
the munitions firm.

Although occupied with many practical con-
cerns in connection with the Ferme and the
Regie des poudres, Lavoisier reserved six hours
a day, from six to nine in the morning and from
seven to ten at night, for his scientific work,
and one full day each week for experiments.

BIOGRAPHICAL NOTE

His wife, who was fourteen at the time of her
marriage, became an active partner in his re-
search. She assisted in the laboratory, learned
English so as to translate the technical works
of Priestley and Cavendish, and drew the illus-
trations for the Traitt EUmentaire de Chimie
(1789). He also engaged in many works of phil-
anthropic nature, starting a model farm to
demonstrate the advantages of scientific agri-
culture, and planning the establishment of sav-
ings banks, insurance societies, canals, and work
houses for improving the conditions of the com-
munity.

When the Revolution occurred, Lavoisier had
long been a national figure. He was Director of
the Academy of Sciences, deputy to the States-
General of 1789, and a prominent member of
the club founded to promote the cause of con-
stitutional monarchy. For some years after

1789 Lavoisier continued to work as secretary
and treasurer of the commission to secure uni-
formity of weights and measures. In 1791 he
was made a member of the commission on arts
and professions; his report for this commission,
Reflexions sur l f instruction publique (1793),
presented a detailed scheme for public free ed-
ucation. But almost from the beginning of the
Revolution, Lavoisier had been under suspi-
cion because of his association with the Fernie
and R6gie des poudres, and from early 1791 he
was subjected to vitriolic attack from Marat.
In 1794 he and the other farmers-general were
placed on trial by the Revolutionary Tribunal
and condemned to death. Lavoisier and his fa-
ther-in-law were guillotined May 8, 1794, at the
Place de la Revolution and their bodies thrown
into nameless graves in the cemetery of La
Madeleine.

CONTENTS

BIOGRAPHICAL NOTE, ix
PREFACE, 1

PART I. Of the Formation and Decomposition of
Aeriform Fluids, of the Combustion of Simple
Bodies, and the Formation of Adds

I. Of the Combinations of Caloric, and the Forma-
tion of Elastic Aeriform Fluids or Oases, 9

II. General Views Relative to the Formation and
Composition of our Atmosphere, 16

III. Analysis of Atmospheric Air, and its Division
into Two Elastic Fluids; One Fit for Respira-
tion, the Other Incapable of Being Respired, 16

IV. Nomenclature of the Several Constituent Parts
of Atmospheric Air, 21

V. Of the Decomposition of Oxygen Gas by Sul-
phur, Phosphorus, and Charcoal, and of the
Formation of Acids in General, 22

VI. Of the Nomenclature of Acids in general, and
particularly of those drawn from Nitre and Sea
Salt, 25

VII. Of the Decomposition of Oxygen Gas by means
of Metals, and the Formation of Metallic
Oxides, 28

VIII. Of the Radical Principle of Water, and of its
Decomposition by Charcoal and Iron, 29

IX. Of the Quantities of Caloric disengaged from dif-
ferent Species of Combustion, 33
SECT. i. Combustion of Phosphorus, 34
SECT. ii. Combustion of Charcoal, 34
SECT. in. Combustion of Hydrogen Gas, 34
SECT. iv. Formation of Nitric Acid, 34
SECT. v. Combustion of Wax, 35
SECT. vi. Combustion of Olive Oil, 35
X. Of the Combination of Combustible Substances
with each other, 36

XI. Observations upon Oxides and Acids with sev-
eral Bases, and upon the Composition of Ani-
mal and Vegetaole Substances, 37
XII. Of the Decomposition of Vegetable and Animal
Substances by the Action of Fire, 39

XIII. Of the Decomposition of Vegetable Oxides by
the Vinous Fermentation, 41

XIV. Of the Putrefactive Fermentation, 44
XV. Of the Acetous Fermentation, 46

XVI. Of the Formation of Neutral Salts, and of their
Bases, 46

SECT. i. Of Potash, 47
SECT. ii. Of Soda, 48
SECT. in. Of Ammonia, 48
SECT. iv. Of Lime, Magnesia, Barytes, and
Argill, 48

SECT. v. Of Metallic Bodies, 49
XVII. Continuation of the Observations upon Salifi-
able Bases, and the Formation of Neutral Salts,
49

PART II. Of the Combination of Acids with Sali-
fiable Bases, and of the Formation of Neutral Salts

INTRODUCTION, 43

TABLE of Simple Substances, 53

SECT, i Observations upon Simple Substances, 54

TABLE of Compound Oxidabls and Acidifiable Bases,

SECT. ii. Observations upon Compound Radicals, 55

TABLE of the Combinations of Oxygen with the Simple
Substances, 56

SECT. in. Observations upon the Combinations of Light
and Caloric with different Substances, 57

SECT. iv. Observations upon these Combinations, 57

TABLE of the Combinations of Oxygen with Compound
Radicals, 58

SECT. v. Observations upon these Combinations, 59

TABLE of the Combinations of Azote with the Simple
Substances, 60

SECT. vi. Observations upon these Combinations of
Azote, 60

TABLE of the Binary Combinations of Hydrogen with
Simple Substances, 61

SECT. vn. Observations upon Hydrogen, and its Com-
binations, 61

TABLE of the Binary Combinations of Sulphur with
the Simple Substances, 62

SECT. viii. Observations upon Sulphur, and its Com-
binations, 63

TABLE of the Combinations of Phosphorus with Simple
Substances, 63

SECT. ix. Observations upon Phosphorus and its Com-
binations, 63

TABLE of the Binary Combinations of Charcoal, 64

SECT. x. Observations upon Charcoal, and its Combi-
nations, 64

SECT. xi. Observations upon the Muriatic, Fluoric, and
Boracic Radicals, and their Combinations, 64

SECT. xn. Observations upon the Combinations of
Metals with each other, 65

TABLE of the Combinations of Azote, in the State of
Nitrous Acid, with the SaUfiable Bases, 65

TABLE of the Combinations of Azote, in the State of
Nitric Acid, with the SaUfiable Bases, 66

SECT. xin. Observations upon Nitrous and Nitric
Acids, and their Combinations with SaUfiable Bases,
66

TABLE of the Combinations of Sulphuric Acid with
the SaUfiable Bases, 67

SECT. xiv. Observations upon Sulphuric Acid, and its
Combinations, 68

TABLE of the Combinations of Sulphurous Acid, 68

SECT. xv. Observations upon Sulphurous Acid, and
its Combinations with SaUfiable Bases, 69

TABLE of the Combinations of Phosphorous and Phos-
phoric Acids, 69

SECT. xvi. Observations upon Phosphorous and Phos-
phoric Acids, and their Combinations with SaUfi-
able Bases, 70

TABLE of the Combinations of Carbonic Add, 70

SECT. xyn. Observations upon Carbonic Add, and its
Combinations with SaUfiable Bases, 71

TABLE of the Combinations of Oxygenated Muriatic
Acid, 71

TABLE of the Combinations of Muriatic Acid, 72

SECT. xvin. Observations upon Muriatic and Oxyge-
nated Muriatic Acid, ana their Combinations with
SaUfiable Bases, 72

TABLE of the Combinations of Nitro-Muriatic Acid, 73

SECT. xix. Observations upon Nitro-Muriatic Add,
and its Combinations with SaUfiable Bases, 73

TABLE of the Combinations of Fluoric Add, 74

SECT. xx. Observations upon Fluoric Add, and its
Combinations with Scdifiable Bases, 74

TABLE of the Combinations of Boracic Add, 74

SECT. xxi. Observations upon Boracic Add, and its
Combinations with SaUfiable Bases, 74

xii LAVOISIER

TABLE of the Combinations of Arseniac Acid, 75
SECT. xxn. Observations upon Arseniac Acid, and its

Combinations with Salifiable Bases, 75
SECT. xxni. Observations upon Molibdic Acid, and

its Combinations unth Salifiable Bases, 76
SECT. xxiv. Observations upon Tungstic Acid, and its

Combinations with Salifiable Bases, and a Table of

these in the order of their Affinity, 76
TABLE of the Combinations of Tartarous Acid, 77
SECT. xxv. Observations upon Tartarous Acid, and its

Combinations with Salifiable Bases, 77
SECT. xxvi. Observations upon Malic Acid, and its

Combinations with Salifiable Bases, 77
TABLE of the Combinations of Citric Acid, 78
SECT, xxvii. Observations upon Citric Acid, and its

Combinations with Salifiable Bases, 78
TABLE of the Combinations of Pyro-lignous Acid, 78
SECT, xxvin. Observations upon Pyro-lignous Acid,

and its Combinations with Salifiable Bases, 78
SECT. xxix. Observations upon Pyro-tartarous Add,

and its Combinations with Salifiable Bases, 79
TABLE of the Combinations of Pyro-mucous Acid, 79
SECT. xxx. Observations upon Pyro-mucou* Acid, and

its Combinations with Salifiable Bases, 79
SECT. xxxi. Observations upon Oxalic Acid, and its

Combinations with Salifiable Bases, 79
TABLE of the Combinations of Oxalic Acid, 79
TABLE of the Combinations of Acetous Acid

80
SECT, xxxii. Observations upon Acetous Acid, and its

Combinations with the Salifiable Bases, 81
TABLE of the Combinations of Acetic Acid, 81
SECT, xxxiii. Observations upon Acetic Acid, and its

Combinations with Salifiable Bases, 82
TABLE of the Combinations of Succinic Add, 82
SECT, xxxiv. Observations upon Sucdnic Add, and

its Combinations with Salifiable Bases, 82
SECT. xxxv. Observations upon Benstoic Add, and its

Combinations with Salifiable Bases, 82
SECT, xxxvi. Observations upon Camphoric Add, and

its Combinations with Salifiable Bases, 83
SECT. XXXVII, Observations upon Gallic Add, and its

Combinations with Salifiable Bases, 83
SECT, xxxyin. Observations upon Lactic Add, and

its Combinations with Salifiable Bases, 83
TABLE of the Combinations of Saccho-Lactic Add, 83
SECT, xxxix. Observations upon Saccho4actic Add,

and its Combinations with Salifiable Bases, 84
TABLE of the Combinations of Formic Add, 84
SECT. XL. Observations upon Formic Add, and its

Combinations with the Salifiable Bases, 84
SECT. XLI. Observations upon the Bombic Add, and

Us Combinations with the Salifiable Bases, 84
TABLE of the Combinations of the Sebadc Add, 84
SECT. XLII. Observations upon the Sebadc Add, and

its Combinations with the Salifiable Bases, 85
SECT. XLIII. Observations upon the Lithic Add, and

its Combinations with the Salifiable Bases, 85
TABLE of the Combinations of the Prussic Add, 85
SECT. XLIV. Observations upon the Prussic Add, and

its Combinations with the Salifiable Bases, 85

PART III. Description of the Instruments and
Operations of Chemistry

INTRODUCTION, 87

I. Of the Instruments necessary for determining
the Absolute and Specific Gravities of Solid and
Liquid Bodies, 87

II. Of Gazometry, or the Measurement of the
Weight and Volume of Aeriform Substances, 90
SECT. i. Of the Pneumato-chemical Apparatus,
90

SECT. ii. Of the Gazometer, 91
i SECT. in. Some other methods for Measuring
the Volume of Gasses, 94

SECT. iv. Of the method of Separating the differ-
ent Gasses from each other, 95
SECT. v. Of the necessary Corrections of the
volume of Uases, according to the Pressure of
the Atmosphere, 96

SECT. vi. Of the Correction relative to the De-
grees of the Thermometer, 98
SECT. vn. Example for Calculating the Correc-
tions relative to the Variations of Pressure and
Temperature, 98

SECT. yiii. Method of determining the Weight
of the different Gasses, 99

III. Description of the Calorimeter, or Apparatus
for measuring Caloric, 99

IV. Of the Mechanical Operations for Division of
Bodies, 103

SECT. i. Of Trituration, Levigation, and Pul-
verization, 103
SECT. ii. Of Sifting and Washing Powdered

Substances, 104
SECT. iii. Of Filtration, 104
SECT. iv. Of Decantation, 105
V. Of Chemical means for Separating the Particles
of Bodies from each other without Decomposi-
tion, and for Uniting them again, 105
SECT. i. Of the Solution of Salts, 106
SECT. ii. Of Lixiviation r 107
SECT. in. Of Evaporation, 107
SECT. iv. Of Crystallization, 108
SECT. v. Of Simple Distillation, 110
SECT. vi. Of Sublimation, 111
VI. Of Pneumato-chemical Distillations, Metallic
Dissolutions, and some other operations which
require very complicated instruments, 111
SECT. i. Of Compound and Pneumato-chemical
Distillations 111

SECT. ii. Of Metallic Dissolutions, 113
SECT. iii. Apparatus necessary in Experiments
upon Vinous and Putrefactive Fermentations,
114

SECT. iv. Apparatus for the Decomposition of
Water, 114

VII. Of the Composition and Use of Lutes, 115
VIII. Of Operations upon Combustion and Deflagra-
tion, 117

SECT. i. Of Combustion in general, 117
SECT. n. Of the Combustion of Phosphorus, 118
SECT. in. Of the Combustion of Charcoal, 119
SECT. iv. Of the Combustion of Oils, 120
SECT. v. Of the Combustion of Alcohol, 122
SECT. vi. Of the Combustion of Ether, }22
SECT. vn. Of the Combustion of Hydrogen
Gas, and the Formation of Water, 123
SECT. vin. Of the Oxidation of Metals, 124
IX. Of Deflagration, 126

X. Of the Instruments necessary for Operating
upon Bodies in very high Temperatures, 128
SECT. i. Of Fusion, 128
SECT. n. Of Furnaces, 129
SECT. in. Of increasing the Action of Fire, by
using Oxygen Gaa instead of Atmospheric
Air, 132

PLATES I XIII, 135

PREFACE

WHEN I began the following work, my only
object was to extend and explain more fully the
memoir which I read at the public meeting of
the Academy of Sciences in the month of April,
1787, on the necessity of reforming and com-
pleting the nomenclature of chemistry. While
engaged in this employment, I perceived, bet-
ter than I had ever done before, the justice of
the following maxims of the Abb de Condillac,
in his Logic, and some other of his works.

"We think only through the medium of
words. Languages are true analytical meth-
ods. Algebra, which is adapted to its purpose
in every species of expression, in the most sim-
ple, most exact, and best manner possible, is at
the same time a language and an analytical
method. The art of reasoning is nothing more
than a language well arranged."

Thus, while I thought myself employed only
in forming a nomenclature, and while I propos-
ed to myself nothing more than to improve the
chemical language, my work transformed itself
by degrees, without my being able to prevent it,
into a treatise upon the elements of chemistry.

The impossibility of separating the nomen-
clature of a science from the science itself is
owing to this, that every branch of physical
science must consist of three things : the series
of facts which are the objects of the science,
the ideas which represent these facts, and the
words by which these ideas are expressed. Like
three impressions of the same seal, the word
ought to produce the idea, and the idea to be a
picture of the fact. And, as ideas are preserved
and communicated by means of words, it nec-
essarily follows that we cannot improve the
language of any science without at the same
time improving the science itself; neither can
we, on the other hand, improve a science with-
out improving the language or nomenclature
which belongs to it. However certain the facts
of any science may be and however just the
ideas we may have formed of these facts, we

can only communicate false impressions to
others while we want words by which these
may be properly expressed.

To those who will consider it with attention,
the first part of this treatise will afford frequent
proofs of the truth of the above observations.
But as, in the conduct of my work, I have been
obliged to observe an order of arrangement es-
sentially differing from what has been adopted
in any other chemical work yet published, it is
proper that I should explain the motives which
have led me to do so.

It is a maxim universally admitted in geom-
etry, and indeed in every branch of knowledge,
that, in the progress of investigation, we should
proceed from known facts to what is unknown.
In early infancy, our ideas spring from our
wants; the sensation of want excites the idea of
the object by which it is to be gratified. In this
manner, from a series of sensations, observa-
tions, and analyses, a successive train of ideas
arises, so linked together that an attentive ob-
server may trace back to a certain point the
order and connection of the whole sum of hu-
man knowledge.

When we begin the study of any science, we
are in a situation, respecting that science, simi-
lar to that of children; and the course by which
we have to advance is precisely the same which
nature follows in the formation of their ideas.
In a child, the idea is merely an effect produced
by a sensation; and, in the same manner, in
commencing the study of a physical science,
we ought to form no idea but what is a neces-
sary consequence, and immediate effect, of an
experiment or observation. Besides, he that en-
ters upon the career of science is in a less ad-
vantageous situation than a child who is ac-
quiring his first ideas. To the child, nature
gives various means of rectifying any mistakes
he may commit respecting the salutary or hurt-
ful qualities of the objects which surround him.
On every occasion his judgments are corrected

LAVOISIER

by experience; want and pain are the necessary
consequences arising from false judgment ; grat-
ification and pleasure are produced by judging
aright. Under such masters, we cannot fail to
become well informed; and we soon learn to
reason justly, when want and pain are the
necessary consequences of a contrary conduct.
. In the study and practice of the sciences it is
quite different; the false judgments we form
neither affect our existence nor our welfare;
and we are not forced by any physical neces-
sity to correct them. Imagination, on the con-
trary, which is ever wandering beyond the
bounds of truth, joined to self-love and that
self-confidence we are so apt to indulge, prompts
us to draw conclusions which are not immedi-
ately derived from facts; so that we become in
some measure interested in deceiving ourselves.
Hence, it is by no means to be wondered that, in
the science of physics in general, men have
often made suppositions instead of forming
conclusions. These suppositions, handed down
from one age to another, acquire additional
weight from the authorities by which they are
supported, till at last they are received, even
by men of genius, as fundamental truths.

The only method of preventing such errors
from taking place, and of correcting them when
formed, is to restrain and simplify our reason-
ing as much as possible. This depends entirely
upon ourselves, and the neglect of it is the only
source of our mistakes. We must trust to noth-
ing but facts : these are presented to us by na-
ture and cannot deceive. We ought, in every
instance, to submit our reasoning to the test of
experiment and never to search for truth but
by the natural road of experiment and observa-
tion. Thus mathematicians obtain the solution
of a problem by the mere arrangement of data
and by reducing their reasoning to such simple
steps, to conclusions so very obvious, as never
to lose sight of the evidence which guides them.

Thoroughly convinced of these truths, I have
imposed upon myself, as a law, never to ad-
vance but from what is known to what is un-
known; never to form any conclusion which is
not an immediate consequence necessarily
flowing from observation and experiment; and
always to arrange the facts, and the conclu-
sions which are drawn from them, in such an
order as shall render it most easy for beginners

in the study of chemistry thoroughly to under-
stand them. Hence, I have been obliged to de-
part from the usual order of courses of lectures
and of treatises upon chemistry, which always
assume the first principles of the science as
known, when the pupil or the reader should
never be supposed to know them till they have
been explained in subsequent lessons. In al-
most every instance, these begin by treating of
the elements of matter and by explaining the
table of affinities, without considering that, in
so doing, they must bring the principal phe-
nomena of chemistry into view at the very out-
set: they make use of terms which have not
been defined and suppose the science to be un-
derstood by the very persons they are only be-
ginning to teach. It ought likewise to be con-
sidered that very little of chemistry can be
learned in a first course, which is hardly suffi-
cient to make the language of the science famil-
iar to the ears or the apparatus familiar to
the eyes. It is almost 4 impossible to become a
chemist in less than three or four years of con-
stant application.

These inconveniences are occasioned not so
much by the nature of the subject as by the
method of teaching it; and, to avoid them, I
was chiefly induced to adopt a new arrange-
ment of chemistry, which appeared to me more
consonant to the order of nature. I acknowl-
edge, however, that in thus endeavouring to
avoid difficulties of one kind I have found my-
self involved in others of a different species,
some of which I have not been able to remove;
but I am persuaded that such as remain do not
arise from the nature of the order I have
adopted, but are rather consequences of the
imperfection under which chemistry still la-
bours. This science still has many chasms,
which interrupt the series of facts and often
render it extremely difficult to reconcile them
with each other: it has not, like the elements
of geometry, the advantage of being a com-
plete science, the parts of which are all closely
connected together: its actual progress, how-
ever, is so rapid, and the facts, under the mod-
ern doctrine, have assumed so happy an ar-
rangement that we have ground to hope, even
in our own times, to see it approach near to the
highest state of perfection of which it is sus-
ceptible.

PREFACE

The rigorous law from which I have never
deviated, of forming no conclusions which are
not fully warranted by experiment, and of nev-
er supplying the absence of facts, has prevent-
ed me from comprehending in this work the
branch of chemistry which treats of affinities,
although it is perhaps the best calculated of
any part of chemistry for being reduced into a
completely systematic- foody. MM. Geoffrey,
Gellert, Bergman, Scheele, de Morveau, Kir-
wan, and many others, have collected a num-
ber of particular facts upon this subject, which
only wait for a proper arrangement; but the
principal data are still wanting, or, at least,
those we have are either not sufficiently de-
fined or not sufficiently proved to become the
foundation upon which to build so very impor-
tant a branch of chemistry. This science of af-
finities, or elective attractions, holds the same
place with regard to the other branches of
chemistry as the higher or transcendental ge-
ometry does with respect to the simpler and
elementary part; and I thought it improper
to involve those simple and plain elements,
which I flatter myself the greatest part of my
readers will easily understand, in the obscurities
and difficulties which still attend that other
very useful and necessary branch of chemical
science.

Perhaps a sentiment of self-love may, with-
out my perceiving it, have given additional
force to these reflections. Mr. de Morveau is at
present engaged in publishing the article Affin-
ity in the Methodical Encyclopedia and I had
more reasons than one to decline entering upon
a work in which he is employed.

It will, no doubt, be a matter of surprise,
that in a treatise upon the elements of chem-
istry there should be no chapter on the con-
stituent and elementary parts of matter; but I
shall take occasion, in this place, to remark
that the fondness for reducing all the bodies in
nature to three or four elements proceeds from
a prejudice which has descended to us from the
Greek philosophers. The notion of four ele-
ments, which, by the variety of their propor-
tions, compose all the known substances in na-
ture, is a mere hypothesis, assumed long before
the first principles of experimental philosophy
or of chemistry had any existence. In those
days, without possessing facts, they framed

systems; while we, who have collected facts,
seem determined to reject them when they do
not agree with our prejudices. The authority
of these fathers of human philosophy still carry
great weight, and there is reason to fear that it
will even bear hard upon generations yet to
come.

It is very remarkable that, notwithstanding
the number of philosophical chemists who have
supported the doctrine of the four elements,
there is not one who has not been led by the
evidence of facts to admit a greater number of
elements into their theory. The first chemists
that wrote after the revival of letters consid-
ered sulphur and salt elementary substances
entering into the composition of a great num-
ber of substances; hence, instead of four, they
admitted the existence of six elements. Beccher
assumes the existence of three kinds of earth,
from the combination of which, in different
proportions, he supposed all the varieties of
metallic substances to be produced. Stahl gave
a new modification to this system; and suc-
ceeding chemists have taken the liberty to
make or to imagine changes and additions of a
similar nature. All these chemists were carried
along by the influence of the genius of the age
in which they lived, which contented itself with
assertions without proofs; or, at least, often ad-
mitted as proofs the slightest degrees of prob-
ability, unsupported by that strictly rigorous
analysis required by modern philosophy.

All that can be said upon the number and na-
ture of elements is, in my opinion, confined to
discussions entirely of a metaphysical nature.
The subject only furnishes us with indefinite
problems, which may be solved in a thousand
different ways, not one of which, in ail proba-
bility, is consistent with nature. I shall there-
fore only add upon this subject that if by the
term elements we mean to express those simple
and indivisible atoms of which matter is com-
posed, it is extremely probable we know noth-
ing at all about them; but, if we apply the term
elements, or principles of bodies, to express our
idea of the last point which analysis is capable
of reaching, we must admit, as elements, all the
substances into which we are capable, by any
means, to reduce bodies by decomposition. Not
that we are entitled to affirm that these sub-
stances we consider as simple may not be com-

LAVOISIER

pounded of two, or even of a greater number of
principles; but, since these principles cannot be
separated, or rather since we have not hitherto
discovered the means of separating them, they
act with regard to us as simple substances, and
we ought never to suppose them compounded
until experiment and observation has proved
them to be so.

The foregoing reflections upon the progress
of chemical ideas naturally apply to the words
by which these ideas are to be expressed. Guid-
ed by the work which, in the year 1787, Messrs.
de Morveau, Berthoiiet, de Fourcroy, and I
composed upon the nomenclature of chemistry,
I have endeavoured, as much as possible, to de-
nominate simple bodies by simple terms, and I
was naturally led to name these first. It will be
recollected that we were obliged to retain that
name of any substance by which it had been
long known in the world, and that in two cases
only we took the liberty of making alterations ;
first, in the case of those which were but newly
discovered and had not yet obtained names, or
at least which had been known but for a short
time and the names of which had not yet re-
ceived the sanction of the public; and, second-
ly, when the names which had been adopted,
whether by the ancients or the moderns, ap-
peared to us to express evidently false ideas,
when they confounded the substances to which
they were applied with others possessed of dif-
ferent or perhaps opposite qualities. We made
no scruple, in this case, of substituting other
names in their room, and the greatest number
of these were borrowed from the Greek lan-
guage. We endeavoured to frame them in such
a manner as to express the most general and
the most characteristic quality of the sub-
stances; and this was attended with the addi-
tional advantage both of assisting the memory
of beginners, who find it difficult to remember
a new word which has no meaning, and of
accustoming them early to admit no word
without connecting with it some determinate
idea.

To those bodies which are formed by the un-
ion of several simple substances we gave new
names, compounded in such a manner as the
nature of the substances directed; but, as the
number of double combinations is already very
considerable, the only method by which we

could avoid confusion was to divide them into
classes. In the natural order of ideas, the name
of the class or genus is that which expresses a
quality common to a great number of individ-
uals : the name of the species, on the contrary,
expresses a quality peculiar to certain individ-
uals only.

These distinctions are not, as some may imag-
ine, merely metaphysical, but are established
by nature. "A child," says the Abbe* de Con-
dillac, " is taught to give the name tree to the
first one which is pointed out to him. The next
one he sees presents the same idea, and he gives
it the same name. This he does likewise to a
third and a fourth, till at last the word tree,
which he first applied to an individual, comes
to be employed by him as the name of a class
or a genus, an abstract idea, which comprehends
all trees in general. But, when he learns that all
trees serve not the same purpose, that they do
not all produce the same kind of fruit, he will
soon learn to distinguish them by specific and
particular names." This is the logic of all the
sciences and is naturally applied to chemistry.

The acids, for example, are compounded of
two substances, of the order of those which we
consider as simple; the one constitutes acidity,
and is common to all acids, and, from this sub-
stance, the name of the class or the genus ought
to be taken; the other is peculiar to each acid,
and distinguishes it from the rest, and from this
substance is to be taken the name of the spe-
cies. But, in the greatest number of acids, the
two constituent elements, the acidifying prin-
ciple and that which it acidifies, may exist in
different proportions, constituting all the pos-
sible points of equilibrium or of saturation. This
is the case in the sulphuric and the sulphurous
acids; and these two states of the same acid we
have marked by varying the termination of the
specific name.

Metallic substances which have been exposed
to the joint action of the air and of fire lose
their metallic lustre, increase in weight, and as-
sume an earthy appearance. In this state, like
the acids, they are compounded of a principle
which is common to all and one which is pecu-
liar to each. In the same way, therefore, we
have thought proper to class them under a ge-
neric name, derived from the common princi-
ple; for which purpose, we adopted the term ox-

PREFACE

ide; and we distinguish them from each other
by the particular name of the metal to which
each belongs.

Combustible substances, which in acids and
metallic oxides are a specific and particular
principle, are capable of becoming, in their turn
common principles of a great number of sub-
stances. The sulphurous combinations have
been long the only known ones in this kind.
Now, however, we know, from the experiments
of Messrs. Vandermonde, Monge, and Berthol-
let, that charcoal may be combined with iron,
and perhaps with several other metals, and that,
from this combination, according to the pro-
portions, may be produced steel, plumbago, &c.
We know likewise, from the experiments of M.
Pelletier, that phosphorus may be combined
with a great number of metallic substances.
These different combinations we have classed
under generic names taken from the common
substance, with a termination which marks
this analogy, specifying them by another name
taken from that substance which is proper
to each.

The nomenclature of bodies compounded of
three simple substances was attended with still
greater difficulty, not only on account of their
number, but, particularly, because we cannot
express the nature of their constituent princi-
ples without employing more compound names.
In the bodies which form this class, such as the
neutral salts for instance, we had to consider,
1st, the acidifying principle, which is common
to them all; 2nd, the acidifiable principle which
constitutes their peculiar acid; 3rd, the saline,
earthy, or metallic basis, which determines the
particular species of salt. Here we derived the
name of each class of salts from the name of the
acidifiable principle common to all the individ-
uals of that class and distinguished each spe-
cies by the name of the saline, earthy, or metal-
lic basis, which is peculiar to it.

A salt, though compounded of the same three
principles, may, nevertheless, by the mere dif-
ference of their proportion, be in three different
states. The nomenclature we have adopted
would have been defective had it not expressed
these different states ; and this we attained chief-
ly by changes of termination uniformly applied
to the same state of the different salts.

In short, we have advanced so far that from

the name alone may be instantly found what
the combustible substance is which enters into
any combination; whether that combustible
substance be combined with the acidifying prin-
ciple, and in what proportion; what is the state
of the acid ; with what basis it is united; wheth-
er the saturation be exact, or whether the acid
or the basis be in excess.

It may be easily supposed that it was not
possible to attain all these different obj ects with-
out departing, in some instances, from estab-
lished custom and adopting terms which at first
sight will appear uncouth and barbarous. But
we considered that the ear is soon habituated
to new words, especially when they are con-
nected with a general and rational S3 r stem. The
names, besides, which were formerly employed,
such as powder ofalgarothj salt ofalembroth, pom-
pholix, phagadenic water, turbith mineral, colco-
thar, and many others, were neither less bar-
barous nor less uncommon. It required a great
deal of practice, and no small degree of mem-
ory, to recollect the substances to which they
were applied, much more to recollect the genus
of combination to which they belonged. The
names of oil of tartar per deliquium, oil of vitriol,
butter of arsenic and of antimony, flowers of zinc>
&c. were still more improper, because they sug-
gested false ideas: for, in the whole mineral
kingdom, and particularly in the metallic class,
there exist no such things as gutters, oils, or
flowers; and, in short, the substances to which
they give these fallacious names are nothing
less than rank poisons.

When we published our essay on the nomen-
clature of chemistry, we were reproached for
having changed the language which was spok-
en by our masters, which they distinguished by
their authority and handed down to us. But
those who reproach us on this account have for-
gotten that it was Bergman and Macquer them-
selves who urged us to make this reformation.
In a letter which the learned Professor of Upp-
sala, M. Bergman, wrote, a short time before
he died, to M. de Morveau, he bids him spare
no improper names; those who are learned will al-
ways be learned, and those who are ignorant will
thus karn sooner.

There is an objection to the work which I am
going to present to the public, which is perhaps
better founded, that I have given no account of

LAVOISIER

the opinion of those who have gone before me;
that I have stated only my own opinion, with-
out examining that of others. By this I have
been prevented from doing that justice to my
associates, and more especially to foreign chem-
ists, which I wished to render them. But I be-
seech the reader to consider that, if I had filled
an elementary work with a multitude of quota-
tions, if I had allowed myself to enter into long
dissertations on the history of the science and
the works of those who have studied it, I must
have lost sight of the true object I had in view
and produced a work the reading of which must
have been extremely tiresome to beginners. It
is not to the history of the science, or of the hu-
man mind, that we are to attend in an elemen-
tary treatise : our only aim ought to be ease and
perspicuity and with the utmost care to keep
everything out of view which might draw aside
the attention of the student; it is a road which
we should be continually rendering more
smooth, and from which we should endeavour
to remove every obstacle which can occasion
delay. The sciences, from their own nature, pre-
sent a sufficient number of difficulties, though
we add not those which are foreign to them.
But, besides this, chemists will easily perceive
that, in the first part of my work, I make very
little use of any experiments but those which
were made by myself: if at any time I have
adopted, without acknowledgment, the experi-
ments or the opinions of M. Berthollet, M.
Fourcroy, M. de la Place, M. Monge, or, in
general, of any of those whose principles are the
same as my own, it is owing to this circum-
stance, that frequent intercourse, and the hab-
it of communicating our ideas, our observa-
tions, and our way of thinking to each other,
has established between us a sort of community
of opinions in which it is often difficult for every
one to know his own.

The remarks I have made on the order which
I thought myself obliged to follow in the ar-
rangement of proofs and ideas are to be applied
only to the first part of this work. It is the only
one which contains the general sum of the doc-
trine I have adopted and to which I wished to
give a form completely elementary.

The second part is composed chiefly of tables
of the nomenclature of the neutral salts. To
these I have only added general explanations,

the object of which was to point out the most
simple processes for obtaining the different
kinds of known acids. This part contains noth-
ing which I can call my own and presents only
a very short abridgment of the results of these
processes, extracted from the works of different
authors.

In the third part, I have given a description,
in detail, of all the operations connected with
modern chemistry. I have long thought that a
work of this kind was much wanted, and I am
convinced it will not be without use. The meth-
od of performing experiments, and particularly
those of modern chemistry, is not so generally
known as it ought to be; and had I, in the dif-
ferent Mtmoires which I have presented to the
Academy, been more particular in the detail of
the manipulations of my experiments, it is prob-
able I should have made myself better under-
stood, and the science might have made a more
rapid progress. The order of the different mat-
ters contained in this third part appeared to me
to be almost arbitrary; and the only one I have
observed was to class together, in each of the
chapters of which it is composed, those opera-
tions which are most connected with one an-
other. I need hardly mention that this part
could not be borrowed from any other work,
and that, in the principal articles it contains, I
could not derive assistance from anything but
the experiments which I have made myself.

I shall conclude this preface by transcribing,
literally, some observations of the Abb6 de
Condillac, which I think describe, with a good
deal of truth, the state of chemistry at a
period not far distant from our own. These
observations were made on a different sub-
ject; but they will not, on this account, have
less force, if the application of them be thought
just.

"Instead of applying observation to the
things we wished to know, we have chosen
rather to imagine them. Advancing from one ill-
founded supposition to another, we have at last
bewildered ourselves amidst a multitude of er-
rors. These errors becoming prejudices, are, of
course, adopted as principles, and we thus be-
wilder ourselves more and more. The method,
too, by which we conduct our reasonings is as
absurd; we abuse words which we do not un-
derstand, and call this the art of reasoning.

PREFACE

When matters have been brought this length,
when errors have been thus accumulated, there
is but one remedy by which order can be re-
stored to the faculty of thinking; this is to for-
get all that we have learned, to trace back our
ideas to their source, to follow the train in
which they rise, and, as Bacon says, to frame
the human understanding anew.

"This remedy becomes the more difficult in
proportion as we think ourselves more learned.
Might it not be thought that works which treat-
ed of the sciences with the utmost perspicuity,
with great precision and order, must be under-

stood by everybody? The fact is, those who
have never studied anything will understand
them better than those who have studied a
great deal, and especially than those who have
written a great deal."

At the end of the fifth chapter, the Abb6 de
Condillac adds: "But, after all, the sciences
have made progress, because philosophers have
applied themselves with more attention to ob-
serve and have communicated to their lan-
guage that precision and accuracy which they
have employed in their observations. In cor-
recting their language they reason better."

FIRST PART

OF THE FORMATION AND DECOMPOSITION OF AERIFORM

FLUIDS OF THE COMBUSTION OF SIMPLE BODIES,

AND THE FORMATION OF ACIDS

CHAPTER I

Of the Combinations of Caloric, and the Forma-
tion of Elastic Aeriform Fluids or gases

THAT every body, whether solid or fluid, is aug-
mented in all its dimensions by any increase of
its sensible heat was long ago fully established
as a physical axiom, or universal proposition,
by the celebrated Boerhaave. Such facts as
have been adduced for controverting the gen-
erality of this principle offer only fallacious re-
sults, or, at least, such as are so complicated
with foreign circumstances as to mislead the
j udgment : but, when we separately consider the
effects, so as to deduce each from the cause to
which they separately belong, it is easy to per-
ceive that the separation of particles by heat is
a constant and general law of nature.

When we have heated a solid body to a cer-
tain degree and have thereby caused its parti-
cles to separate from each other, if we allow
the body to cool, its particles again approach
each other in the same proportion in which
they were separated by the increased tempera-
ture; the body returns through the same de-
grees of expansion which it before extended
through; and, if it be brought back to the same
temperature from which we set out at the com-
mencement of the experiment, it recovers ex-
actly the same dimensions which it formerly oc-
cupied. But, as we are still very far from being
able to arrive at the degree of absolute cold, or
deprivation of all heat, being unacquainted with
any degree of coldness which we cannot sup-
pose capable of still further augmentation, it
follows that we are still incapable of causing
the ultimate particles of bodies to approach each
other as near as is possible and, consequently,
that the particles of all bodies do not touch
each other in any state hitherto known, which,
tho' a very singular conclusion, is yet impossi-
ble to be denied.

It is supposed that, since the particles of bo-
dies are thus continually impelled by heat to

separate from each other, they would have no
connection between themselves and, of conse-
quence, that there could be no solidity in na-
ture, unless they were held together by some
other power which tends to unite them, and,
so to speak, to chain them together ; which pow-
er, whatever be its cause or manner of opera-
tion, we name attraction.

Thus the particles of all bodies may be con-
sidered as subjected to the action of two oppo-
site powers, the one repulsive, the other attrac-
tive, between which they remain in equilibrio.
So long as the attractive force remains strong-
er, the body must continue in a state of solid-
ity; but if, on the contrary, heat has so far
removed these particles from each other as to
place them beyond the sphere of attraction,
they lose the adhesion they before had with each
other, and the body ceases to be solid.

Water gives us a regular and constant ex-
ample of these facts; whilst below zero 1 of the
French thermometer, or 32 of Fahrenheit, it
remains solid, and is called ice. Above that de-
gree of temperature, its particles being no long-
er held together by reciprocal attraction, it
becomes liquid ; and, when we raise its tempera-
ture above 80 (212), its particles, giving way
to the repulsion caused by the heat, assume the
state of vapour or gas, and the water is changed
into an aeriform fluid.

The same may be affirmed of all bodies in
nature: they are either solid or liquid, or in the
state of elastic aeriform vapour, according to
the proportion which takes place between the
attractive force inherent in their particles, and
the repulsive power of the heat acting upon
these; or, which amounts to the same thing, in
proportion to the degree of heat to which they
are exposed.

It is difficult to comprehend these phenom-

1 Whenever the degree of heat occurs in this work,
it is stated by the author according to Reaumur's
scale. The degrees within parentheses are the corre-
spondent degrees of Fahrenheit's scale, added by the
translator. TRANSLATOB.

LAVOISIER

ena, without admitting them as the effects of a
real and material substance, or very subtile
fluid, which, insinuating itself between the par-
ticles of bodies, separates them from each
other; and, even allowing the existence of this
fluid to be hypothetical, we shall see in the se-
quel that it explains the phenomena of nature
in a very satisfactory manner.

This substance, whatever it is, being the
cause of heat, or, in other words, the sensation
which we call warmth being caused by the ac-
cumulation of this substance, we cannot, in
strict language, distinguish it by the term heat;
because the same name would then very im-
properly express both cause and effect. For
this reason, in the Memoir which I published
in 1777 1 , I gave it the names of igneous fluid
and matter of heat: And, since that time, in the
work 2 published by M. de Morveau, M. Ber-
thollet, M. de Fourcroy, and myself, upon the
reformation of chemical nomenclature, we
thought it necessary to banish all periphrastic
expressions, which both lengthen physical lan-
guage and render it more tedious and less dis-
tinct, and which even frequently does not con-
vey sufficiently just ideas of the subject in-
tended. Wherefore, we have distinguished the
cause of heat, or that exquisitely elastic fluid
which produces it, by the term of caloric. Be-
sides that this expression fulfils our object in
the system which we have adopted, it possesses
this further advantage, that it accords with
every species of opinion, since, strictly speak-
ing, we are not obliged to suppose this to be a
real substance; it being sufficient, as will more
clearly appear in the sequel of this work, that
it be considered as the repulsive cause, what-
ever that may be, which separates the particles
of matter from each other, so that we are still
at liberty to investigate its effects in an ab-
stract and mathematical manner.

In the present state of our knowledge, we
are unable to determine whether light be a
modification of caloric, or if caloric be, on the
contrary, a modification of light. This, how-
ever, is indisputable, that, in a system where
only decided facts are admissible, and where
we avoid, as far as possible, to suppose any
thing to be that is not really known to exist,
we ought provisionally to distinguish, by dis-
tinct terms, such things as are known to
produce different effects. We therefore distin-
guish light from caloric ; though we do not there-

1 Collections of the French Academy of Sciences
for that year, p. 420.
8 Chemical Nomenclature.

fore deny that these have certain qualities in
common, and that, in certain circumstances,
they combine with other bodies almost in the
same manner, and produce, in part, the same
effects.

What I have already said may suffice to de-
termine the idea affixed to the word caloric;
but there remains a more difficult attempt,
which is to give a just conception of the man-
ner in which caloric acts upon other bodies.
Since this subtile matter penetrates through
the pores of all known substances ; since there
are no vessels through which it cannot escape,
and, consequently, as there are none which are
capable of retaining it, we can only come at
the knowledge of its properties by effects
which are fleeting and with difficulty ascer-
tainable. It is in these things which we neither
see nor feel that it is especially necessary to
guard against the extravagance of our imagi-
nation, which forever inclines to step beyond the
bounds of truth and is with great difficulty re-
strained within the narrow line of facts.

We have already seen that the same body be-
comes solid, or fluid, or aeriform, according to
the quantity of caloric by which it is penetrat-
ed; or, to speak more strictly, according as the
repulsive force exerted by the caloric is equal
to, stronger, or weaker, than the attraction of
the particles of the body it acts upon.

But, if these two powers only existed, bodies
would become liquid at an indivisible degree of
the thermometer and would almost instan-
taneously pass from the solid state of aggrega-
tion to that of aeriform elasticity. Thus water,
for instance, at the very moment when it
ceases to be ice, would begin to boil, and would
be transformed into an aeriform fluid, having
its particles scattered indefinitely through the
surrounding space. That this does not happen
must depend upon the action of some third
power. The pressure of the atmosphere pre-
vents this separation, and causes the water to
remain in the liquid state till it be raised to 80
of temperature (212) above zero of the French
thermometer, the quantity of caloric which it
receives in the lowest temperature being insuf-
ficient to overcome the pressure of the atmos-
phere.

Whence it appears that, without this atmos-
pheric pressure, we should not have any per-
manent liquid and should only be able to see
bodies in that state of existence in the very in-
stant of melting, as the smallest additional
caloric would instantly separate their particles
and dissipate them through the surrounding

CHEMISTRY

medium. Besides, without this atmospheric
pressure we should not even have any aeriform
fluids, strictly speaking, because the moment
the force of attraction is overcome by the re-
pulsive power of the caloric the particles would
separate themselves indefinitely, having noth-
ing to give limits to their expansion, unless
their own gravity might collect them together,
so as to form an atmosphere.

Simple reflection upon the most common ex-
periments is sufficient to evince the truth of
these positions. They are more particularly
proved by the following experiment, which I
published in the Recueil de V Acadtmie for
1777, p. 426.

Having filled with sulphuric ether 1 a small
narrow glass vessel A (Plate vu, Fig. 77),
standing upon its stalk P, the vessel, which is
from twelve to fifteen lines 2 diameter, is to be
covered by a wet bladder, tied round its neck
with several turns of strong thread; for greater
security, fix a second bladder over the first. The
vessel should be filled in such a manner with
the ether as not to leave the smallest portion of
air between the liquor and the bladder. It is
now to be placed under the recipient BCD of
an air-pump, of which the upper part B ought
to be fitted with a leathern lid, through which
passes a wire EF, having its point F very sharp;
and in the same receiver there ought to be
placed the barometer GH. The whole being
thus disposed, let the recipient be exhausted,
and then, by pushing down the wire EF, we
make a hole in the bladder. Immediately the
ether begins to boil with great violence and is
changed into an elastic aeriform fluid which
fills the receiver. If the quantity of ether be
sufficient to leave a few drops in the phial after
the evaporation is finished, the elastic fluid pro-
duced will sustain the mercury in the barom-
eter attached to the airpump, at eight or ten
inches in winter, and from twenty to twenty-
five in summer. To render this experiment more
complete, we may introduce a small thermom-
eter into the phial A, containing the ether, which
will descend considerably during the evapora-
tion.

The only effect produced in this experiment
is the taking away the weight of the atmos-
phere, which, in its ordinary state, presses on

1 As I shall afterwards give a definition, and ex-
plain the properties of the liquor called ether, I shall
only premise here, that it is a very volatile in-
flammable liquor, having a considerably smaller
specific gravity than water, or even spirit of wine.
AUTHOB.

> Line (from the French ligne) equals one-twelfth
of an inch. EDITOB.

the surface of the ether; and the effects result-
ing from this removal evidently prove that, in
the ordinary temperature of the earth, ether
would always exist ifr an aeriform state, but
for the pressure of the atmosphere, and that
the passing of the ether from the liquid to the
aeriform state is accompanied by a consider-
able lessening of heat; because, during the
evaporation, a part of the caloric, which was
before in a free state, or at least in equili-
brio in the surrounding bodies, combines with
the ether and causes it to assume the aeriform
state.

The same experiment succeeds with ail evap-
orable fluids, such as alcohol, water, and even
mercury with this difference, that the atmos-
phere formed in the receiver by alcohol only
supports the attached barometer about one
inch in winter, and about four or five inches in
summer; that formed by water, in the same
situation, raises the mercury only a few lines,
and that by quicksilver but a few fractions of
a line. There is therefore less fluid evaporated
from alcohol than from ether, less from water
than from alcohol, and still less from mercury
than from either; consequently there is less
caloric employed, and less cold produced, which
quadrates exactly with the results of these
experiments.

Another species of experiment proves very
evidently that the aeriform state is a modifica-
tion of bodies dependent on the degree of tem-
perature and on the pressure which these bod-
ies undergo. In a Memoire read by M. de La*
place and me to the Academy in 1777, which
has not been printed, we have shown that,
when ether is subjected to a pressure equal
to twenty-eight inches of the barometer or
about the medium pressure of the atmosphere,
it boils at the temperature of about 32 P (104),
or 33 (106.25), of the thermometer. M. de
Luc, who has made similar experiments with
spirit of wine, finds it boils at 67 (182.75).
And all the world knows that water boils at 80
(212) . Now, boiling being only the evaporation
of a liquid, or the moment of its passing frbm
the fluid to the aeriform state, it is evident
that, if we keep ether continually at the tem-
perature of 33 (106.25), and under the com-
mon pressure of the atmosphere, we shall have
it always in an elastic aeriform state; and that
the same thing will happen with alcohol when
above 67 (182.75), and with water when
above 80 (212); all which are perfectly con-
formable to the following experiment. 8

a Vid* Recueil de V Academic, 1780, p. 335.

LAVOISIER

I filled a large vessel ABCD (Plate vn, Fig.
16) with water at 35 (110.75), or 36 (113);
I suppose the vessel transparent, that we may
see what takes place in the experiment; and we
can easily hold the hands in water at that tem-
perature without inconvenience. Into it I
plunged some narrow necked bottles F, G,
which were filled with the water, after which
they were turned up, so as to rest on their
mouths on the bottom of the vessel. Having
next put some ether into a very small matrass,
with its neck a b c, twice bent as in the Plate, I
plunged this matrass into the water so as to
have its neck inserted into the mouth of one of
the bottles F. Immediately upon feeling the ef-
fects of the heat communicated to it by the
water in the vessel ABCD it began to boil ; and
the caloric, entering into combination with it,
changed it into elastic aeriform fluid, with
which I filled several bottles successively, F,
G, &c.

This is not the place to enter upon the ex-
amination of the nature and properties of this
aeriform fluid, which is extremely inflammable ;
but, confining myself to the object at present
in view, without anticipating circumstances
which I am not to suppose the reader to know,
I shall only observe that the ether, from this
experiment, is almost only capable of existing
in the aeriform state in our world; for, if the
weight of our atmosphere was only equal to
between 20 and 24 inches of the barometer, in-
stead of 28 inches, we should never be able to
obtain ether in the liquid state, at least in sum-
mer; and the formation of ether would conse-
quently be impossible upon mountains of a
moderate degree of elevation, as it would be
converted into gas immediately upon being
produced, unless we employed recipients of ex-
traordinary strength, together with refrigera-
tion and compression. And, lastly, the temper-
ature of the blood being nearly that at which
ether passes from the liquid to the aeriform
state, it must evaporate in the primae viae,
and consequently it is very probable the medi-
cal properties of this fluid depend chiefly upon
its mechanical effect.

These experiments succeed better with ni-
trous ether, because it evaporates in a lower
temperature than sulphuric ether. It is more
difficult to obtain alcohol in the aeriform state
because, as it requires 67 (182.75) to reduce
it to vapour, the water of the bath must be
almost boiling, and consequently it is impos-
sible to plunge the hands into it at that temper-
ature.

It is evident that, if water were used in the
foregoing experiment, it would be changed into
gas when exposed to a temperature superior to
that at which it boils. Although thoroughly
convinced of this, M. de Laplace and myself
judged it necessary to confirm it by the follow-
ing direct experiment. We filled a glass jar A
(Plate vn, Fig. 5.} with mercury, and placed
it with its mouth downwards in a dish B, like-
wise filled with mercury, and having intro-
duced about two gross of water into the jar,
which rose to the top of the mercury at CD,
we then plunged the whole apparatus into an
iron boiler, EFGH, full of boiling sea-water of
the temperature of 85 (123.25), placed upon
the furnace GHIK. Immediately upon the wa-
ter over the mercury attaining the tempera-
ture of 80 (212), it began to boil ; and, instead
of only filling the small space ACD, it was con-
verted into an aeriform fluid which filled the
whole jar; the mercury even descended below
the surface of that in the dish B; and the jar
must have been overturned if it had not been
very thick and heavy and fixed to the dish by
means of iron wire. Immediately after with-
drawing the apparatus from the boiler, the va-
pour in the jar began to condense, and the mer-
cury rose to its former station; but it returned
again to the aeriform state a few seconds after
replacing the apparatus in the boiler.

We have thus a certain number of sub-
stances, which are convertible into elastic aeri-
form fluids by degrees of temperature not much
superior to that of our atmosphere. We shall
afterwards find that there are several others
which undergo the same change in similar cir-
cumstances, such as muriatic or marine acid,
ammonia or volatile alkali, carbonic acid or
fixed air, sulphurous acid, <fec. All of these are
permanently elastic in or about the mean tem-
perature of the atmosphere and under its com-
mon pressure.

All these facts, which could be easily multi-
plied if necessary, give me full right to assume,
as a general principle, that almost every body
in nature is susceptible of three several states
of existence, solid, liquid, and aeriform, and
that these three states of existence depend
upon the quantity of caloric combhnd with
the body. Henceforwards I shall express these
elastic aeriform fluids by the generic term gas;
and in each species of gas I shall distinguish
between the caloric, which in some measure
serves the purpose of a solvent, and the sub-
stance, which in combination with the caloric,
forms the base of the gas.

CHEMISTRY

To these bases of the different gases, which
are but little known, we have been obliged to
assign names; these I shall point out in Chap-
ter IV of this work, when I have previously
given an account of the phenomena attendant
upon the heating and cooling of bodies, and
when I have established precise ideas concern-
ing the composition of our atmosphere.

We have already shown, that the particles
of every substance in nature exist in a certain
state of equilibrium, between that attraction
which tends to unite and keep the particles to-
gether and the effects of the caloric which
tends to separate them. Hence the caloric not
only surrounds the particles of all bodies on
every side but fills up every interval which the
particles of bodies leave between each other.
We may form an idea of this by supposing a
vessel filled with small spherical leaden bullets,
into which a quantity of fine sand is poured,
which, insinuating into the intervals between
the bullets, will fill up every void. The balls, in
this comparison, are to the sand which sur-
rounds them exactly in the same situation as
the particles of bodies are with respect to the
caloric; with this difference only, that the balls
are supposed to touch each other, whereas the
particles of bodies are not in contact, being re-
tained at a small distance from each other by
the caloric.

If, instead of spherical balls, we substitute
solid bodies of a hexahedral, octahedral, or any
other regular figure, the capacity of the inter-
vals between them will be lessened and conse-
quently will no longer contain the same quan-
tity of sand. The same thing takes place, with
respect to natural bodies; the intervals left be-
tween their particles are not of equal capacity
but vary in consequence of the different figures
and magnitude of their particles, and of the
distance at which these particles are main-
tained, according to the existing proportion
between their inherent attraction and the re-
pulsive force exerted upon them by the caloric.

In this manner we must understand the fol-
lowing expression, introduced by the English
philosophers, who have given us the first pre-
cise ideas upon this subject: the capacity of
bodies for containing the matter of heat. As com-
parisons with sensible objects are of great use
in assisting us to form distinct notions of ab-
stract ideas, we shall endeavour to illustrate
this by instancing the phenomena which take
place between water and bodies which are
wetted and penetrated by it, with a few reflec-
tions.

If we immerge equal pieces of different kinds
of wood, suppose cubes of one foot each, into
water, the fluid gradually insinuates itself into
their pores and the pieces of wood are aug-
mented both in weight and magnitude: but
each species of wood will imbibe a different
quantity of water ; the lighter and more porous
woods will admit a larger, the compact and
closer grained will admit of a lesser quantity;
for the proportional quantities of water im-
bibed by the pieces will depend upon the na-
ture of the constituent particles of the wood
and upon the greater or lesser affinity sub-
sisting between them and water. Very resinous
wood, for instance, though it may be at the
same time very porous, will admit but little
water. We may therefore say that the different
kinds of wood possess different capacities for
receiving water; we may even determine, by
means of the augmentation of their weights,
what quantity of water they have actually ab-
sorbed; but, as we are ignorant how much wa-
ter they contained previous to immersion, we
cannot determine the absolute quantity they
contain after being taken out of the water.

The same circumstances undoubtedly take
place with bodies that are immersed in caloric;
taking into consideration, however, that water
is an incompressible fluid, whereas caloric is,
on the contrary, endowed with very great elas-
ticity; or, in other words, the particles of ca-
loric have a great tendency to separate from
each other, when forced by any other power to
approach; this difference must of necessity oc-
casion very considerable diversities in the re-
sults of experiments made upon these two sub-
stances.

Having established these clear and simple
propositions, it will be very easy to explain the
ideas which ought to be affixed to the follow-
ing expressions, which are by no means syn-
onimous, but possess each a strict and deter-
minate meaning, as in the following definitions :

Free caloric is that which is not combined in
any manner with any other body. But, as we
live in a system to which caloric has a very strong
adhesion, it follows that we are never able to
obtain it in the state of absolute freedom.

Combined caloric is that which. is fixed in
bodies by affinity or elective attraction, so as
to form part of the substance of the body, even
part of its solidity.

By the expression specific caloric of bodies
we understand the respective quantities of ca-
loric requisite for raising a number of bodies of
the same weight to an equal degree of tempera-

LAVOISIER

ture. This proportional quantity of caloric de-
pends upon the distance between the constitu-
ent particles of bodies and their greater or less-
er degrees of cohesion ; and this distance, or rath-
er the space or void resulting from it, is, as I
have already observed, called the capacity of
bodies for containing caloric.

Heat, considered as a sensation, or, in other
words, sensible heat, is only the effect pro-
duced upon our sentient organs by the motion
or passage of caloric, disengaged from the sur-
rounding bodies. In general, we receive im-
pressions only in consequence of motion, and
we might establish it as an axiom that, WITH-
OUT MOTION, THERE IS NO SENSATION. This

general principle applies very accurately to the
sensations of heat and cold: when we touch a
cold body, the caloric which always tends to
become in equilibrio in all bodies, passes from
our hand into the body we touch, which gives
us the feeling or sensation of cold. The direct
contrary happens, when we touch a warm
body, the caloric then passing from the body
into our hand produces the sensation of heat.
If the hand and the body touched be of the
same temperature, or very nearly so, we re-
ceive no impression, either of heat or cold, be-
cause there is no motion or passage of caloric;
and thus no sensation can take place without
some correspondent motion to occasion it.

When the thermometer rises, it shows that
free caloric is entering into the surrounding
bodies : the thermometer, which is one of these,
receives its share in proportion to its mass and
to the capacity which it possesses for contain-
ing caloric. The change therefore which takes
place upon the thermometer only announces a
change of place of the caloric in those bodies
of which the thermometer forms one part; it
only indicates the portion of caloric received,
without being a measure of the whole quantity
disengaged, displaced, or absorbed.

The most simple and most exact method for
determining this latter point is that described
by M. de Laplace, in the Recueil de VAcaM-
mie 1780, p. 364, a summary explanation of
which will be found towards the conclusion of
this work. This method consists in placing a
body, or a combination of bodies, from which
caloric is disengaging, in the midst of a hollow
sphere of ice; and the quantity of ice melted
becomes an exact measure of the quantity of
caloric disengaged. It is possible, by means of
the apparatus which we have caused to be con-
structed upon this plan, to determine not, as
has been pretended, the capacity of bodies for

containing heat, but the ratio of the increase
or diminution of capacity produced by deter-
minate degrees of temperature. It is easy with
the same apparatus, by means of divers com-
binations of experiments, to determine the
quantity of caloric requisite for converting sol-
id substances into liquids, and liquids into elas-
tic aeriform fluids; and, vice versa, what quan-
tity of caloric escapes from elastic vapours in
changing to liquids, and what quantity escapes
from liquids during their conversion into sol-
ids. Perhaps, when experiments have been made
with sufficient accuracy, we may one day be
able to determine the proportional quantity of
caloric necessary for producing the several spe-
cies of gases. I shall hereafter, in a separate
chapter, give an account of the principal results
of such experiments as have been made upon
this head.

It remains, before finishing this article, to
say a few words relative to the cause of the
elasticity of gases and of fluids in the state of
vapour. It is by no means difficult to perceive
that this elasticity depends upon that of ca-
loric, which seems to be the most eminently
elastic body in nature. Nothing is more readily
conceived than that one body should become
elastic by entering into combination with an-
other body possessed of that quality. We must
allow that this is only an explanation of elastic-
ity, by an assumption of elasticity, and that
we thus only remove the difficulty one step
further, and that the nature of elasticity, and
the reason for caloric being elastic, remains
still unexplained. Elasticity in the abstract is
nothing more than that quality of the particles
of bodies by which they recede from each other
when forced together. This tendency in the
particles of caloric to separate, takes place
even at considerable distances. We shall be
satisfied of this, when we consider that air is
susceptible of undergoing great compression,
which supposes that its particles were pre-
viously very distant from each other; for the
power of approaching together certainly sup-
poses a previous distance, at least equal to the
degree of approach. Consequently, those par-
ticles of the air, which are already considerably
distant from each other, tend to separate still
farther. In fact, if we produce Boyle's vacuum
in a large receiver, the very last portion of air
which remains spreads itself uniformly through
the whole capacity of the vessel, however
large, fills it completely throughout, and presses
everywhere against its sides. We cannot, how-
ever, explain this effect without supposing that

CHEMISTRY

the particles make an effort to separate them-
selves on every side, and we are quite ignorant
at what distance, or what degree of rarefaction,
this effort ceases to act.

Here, therefore, exists a true repulsion be-
tween the particles of elastic fluids; at least,
circumstances take place exactly as if such a
repulsion actually existed; and we have very
good right to conclude that the particles of
caloric mutually repel ^ach other. When we are
once permitted to suppose this repelling force,
the rationale of the formation of gases, or
aeriform fluids becomes perfectly simple; tho'
we must, at the same time, allow that it is ex-
tremely difficult to form an accurate concep-
tion of this repulsive force acting upon very
minute particles placed at great distances from
each other.

It is, perhaps, more natural to suppose that
the particles of caloric have a stronger mutual
attraction than those of any other substance
and that these latter particles are forced
asunder in consequence of this superior attrac-
tion between the particles of the caloric, which
forces them between the particles of other
bodies that they may be able to reunite with
each other. We have somewhat analogous to
this idea in the phenomena which occur when
a dry sponge is dipped into water: the sponge
swells; its particles separate from each other;
and all its intervals are filled up by the water.
It is evident that the sponge in the act of
swelling, has acquired a greater capacity for
containing water than it had when dry. But we
cannot certainly maintain that the introduc-
tion of water between the particles of the
sponge has endowed them with a repulsive
power, which tends to separate them from each
other; on the contrary, the whole phenomena
are produced by means of attractive powers;
and these are, 1st, the gravity of the water,
and the power which it exerts on every side, in
common with all other fluids; 2nd, the force
of attraction which takes place between the
particles of the water, causing them to unite
together; 3rd, the mutual attraction of the
particles of the sponge with each other; and,
lastly, the reciprocal attraction which exists
between the particles of the sponge and those
of the water. It is easy to understand that the
explanation of this fact depends upon properly
appreciating the intensity of, and connection
between, these several powers. It is probable
that the separation of the particles of bodies,
occasioned by caloric, depends in a similar
manner upon a certain combination of differ-

ent attractive powers, which, in conformity
with the imperfection of our knowledge, we
endeavour to express by saying that caloric
communicates a power of repulsion to the par-
ticles of bodies.

CHAPTER II

General Views Relative to 'the Formation and
Composition of our Atmosphere

THESE views which I have taken of the forma-
tion of elastic aeriform fluids or gases throw
great light upon the original formation of the
atmospheres of the planets and particularly
that of our earth. We readily conceive that it
must necessarily consist of a mixture of the
following substances: 1st, of all bodies that are
susceptible of evaporation, or, more strictly
speaking, which are capable of retaining the
state of aeriform elasticity in the temperature
of our atmosphere, and under a pressure equal
to that of a column of twenty-eight inches of
quicksilver in the barometer; and, 2nd, of all
substances, whether liquid or solid, which are
capable of being dissolved by this mixture of
different gases.

The better to determine our ideas relating to
this subject, which has not hitherto been suf-
ficiently considered, let us, for a moment, con-
ceive what change would take place in the var-
ious substances which compose our earth, if its
temperature were suddenly altered. If, for
instance, we were suddenly transported into
the region of the planet Mercury, where prob-
ably the common temperature is much superior
to that of boiling water, the water of the earth
and all the other fluids which are susceptible of
the gaseous state at a temperature near to
that of boiling water, even quicksilver itself,
would become rarified;and all these substances
would be changed into permanent aeriform
fluids or gases, which would become part of
the new atmosphere. These new species of airs
or gases would mix with those already exist-
ing, and certain reciprocal decompositions and
new combinations would take place, until such
time as all the elective attractions or affinities
subsisting amongst all these new and old gase-
ous substances had operated fully; after which,
the elementary principles composing these
gases, being saturated, would remain at rest.
We must attend to this, however, that, even
in the above hypothetical situation, certain
bounds would occur to the evaporation of these
substances, produced by that very evapora-
tion itself; for as, in proportion to the increase

LAVOISIER

of elastic fluids, the pressure of the atmosphere
would be augmented, as every degree of pres-
sure tends, in some measure, to prevent evap-
oration, and as even the most evaporable
fluids can resist the operation of a very high
temperature without evaporating, if prevented
by a proportionally stronger compression, wa-
ter and all other liquids being able to sustain a
red heat in Papin's digester; we must admit
that the new atmosphere would at last arrive
at such a degree of weight that the water which
had not hitherto evaporated would cease to
boil and, of consequence, would remain liquid;
so that, even upon this supposition as in ail
others of the same nature, the increasing grav-
ity of the atmosphere would find certain limits
which it could not exceed. We might even ex-
tend these reflections greatly further, and ex-
amine what change might be produced in such
situations upon stones, salts, and the greater
part of the fusible substances which compose
the mass of our earth. These would be softened,
fused, and changed into fluids, &c. : but these
speculations carry me from my object, to
which I hasten to return.

By a contrary supposition to the one we
have been forming, if the earth were suddenly
transported into a very cold region, the water
which at present composes our seas, rivers, and
springs, and probably the greater number of
the fluids we are acquainted with, would be
converted into solid mountains and hard rocks,
at first diaphanous and homogeneous, like rock
crystal, but which, in time, becoming mixed
with foreign and heterogeneous substances,
would become opaque stones of various colours.
In this case, the air, or at least some part of the
aeriform fluids which now compose the mass of
our atmosphere, would doubtless lose its elas-
ticity for want of a sufficient temperature to
retain it in that state: it would return to the
liquid state of existence, and new liquids would
be formed, of whose properties we cannot, at
present, form the most distant idea.

These two opposite suppositions give a dis-
tinct proof of the following corollaries: 1st that
solidity, liquidity, and aeriform elasticity, are
only three different states of existence of the
same matter, or three particular modifications
which almost all substances are susceptible of
assuming successively, and which solely depend
upon the degree of temperature to which they
are exposed ; or, in other words, upon the quanti-
ty of caloric with which they are penetrated.
2nd, that it is extremely probable that air is a
Quid naturally existing in a state of vapour;

or, as we may better express it, that our atmos-
phere is a compound of all the fluids which are
susceptible of the vaporous or permanently
elastic state, in the usual temperature and un-
der the common pressure. 3rd, that it is not
impossible we may discover, in our atmos-
phere, certain substances naturally very com-
pact, even metals themselves; as a metallic
substance, for instance, only a little more vol-
atile than mercury, might exist in that sit-
uation,

Amongst the fluids with which we are ac-
quainted, some, as water and alcohol, are
susceptible of mixing with each other in all pro-
portions; whereas others, on the contrary, as
quicksilver, water, and oil, can only form a
momentary union; and, after being mixed to-
gether, separate and arrange themselves ac-
cording to their specific gravities. The same
thing ought to, or at least may, take place in
the atmosphere. It is possible, and even ex-
tremely probable, that, both at the first crea-
tion and every day, gases are formed, which
are with difficulty miscible with atmospheric
air and are continually separating from it. If
these gases bo specifically lighter than the gen-
eral atmospheric mass, they must, of course,
gather in the higher regions and form strata that
float upon the common air. The phenomena
which accompany igneous meteors induce me
to believe that there exists in the upper parts of
our atmosphere a stratum of inflammable fluid
in contact with those strata of air which pro-
duce the phenomena of the aurora borealis and
other fiery meteors. I mean hereafter to pur-
sue this subject in a separate treatise.

CHAPTER III

Analysis of Atmospheric Air, and its Division
into Two Elastic Fluids; the One Fit for Res-
piration, the Other Incapable of Being Respired.

FROM what has been premised, it follows that
our atmosphere is composed of a mixture of
every substance capable of retaining the gas-
eous or aeriform state in the common temper-
ature, and under the usual pressure which it
experiences. These fluids constitute a mass, in
some measure homogeneous, extending from
the surface of the earth to the greatest height
hitherto attained, of which the density contin-
ually decreases in the inverse ratio of the super-
incumbent weight. But, as I have before ob-
served, it is possible that this first stratum is
surmounted by several others consisting of
very different fluids.

CHEMISTRY

Our business, in this place, is to endeavour
to determine, by experiments, the nature of
the elastic fluids which compose the inferior
stratum of air which we inhabit. Modern chem-
istry has made great advances in this research;
and it will appear by the following details that
the analysis of atmospherical air has been more
rigorously determined than that of any other
substance of the class, phemistry affords two
general methods of determining the constitu-
ent principles of bodies, the method of analysis,
and that of synthesis. When, for instance, by
combining water with alcohol we form the
species of liquor called, in commercial lan-
guage, brandy or spirit of wine, we certainly
have a right to conclude that brandy, or spirit
of wine, is composed of alcohol combined with
water. We can produce the same result by the
analytical method; and in general it ought to
be considered as a principle in chemical science
never to rest satisfied without both these spe-
cies of proofs.

We have this advantage in the analysis of
atmospherical air, being able both to decom-
pound it, and to form it anew in the most sat-
isfactory manner. I shall, however, at present
confine myself to recount such experiments as
are most conclusive upon this head ; and I may
consider most of these as my own, having
either first invented them or having repeated
those of others, with the intention of analysing
atmospherical air t in perfectly new points of
view.

I took a matrass A (Plate n, Fig. 14) of
about 36 cubic inches capacity, having a long
neck BCDE of six or seven lines internal diam-
eter, and having bent the neck as in Plate IV,
Fig. 2, so as to allow of its being placed in the
furnace MMNN, in such a manner that the
extremity of its neck E might be inserted under
a bell-glass FG, placed in a trough of quick-
silver RRSS; I introduced four ounces of pure
mercury into the matrass and, by means of a
siphon, exhausted the air in the receiver FG,
so as to raise the quicksilver to LL, and I care-
fully marked the height at which it stood by
pasting on a slip of paper. Having accurately
noted the height of the thermometer and ba-
rometer, I lighted a fire in the furnace MMNN,
which I kept up almost continually during
twelve days, so as to keep the quicksilver al-
ways almost at its boiling point. Nothing re-
markable took place during the first day: the
mercury, though not boiling, was continually
evaporating and covered the interior surface of
the vessels with small drops, at first very mi-

nute, which, gradually augmenting to a suffi-
cient size, fell back into the mass at the bottom
of the vessel. On the second day, small red
particles began to appear on the surface of the
mercury, which, during the four or five follow-
ing days, gradually increased in size and num-
ber, after which they ceased to increase in
either respect. At the end of twelve days, see-
ing that the calcination of the mercury did not
at all increase, I extinguished the fire, and al-
lowed the vessels to cool. The bulk of air in the
body and neck of the matrass, and in the bell-
glass, reduced to a medium of 28 inches of the
barometer and 10 (54.5) of the thermometer,
at the commencement of the experiment was
about 50 cubic inches. At the end of the ex-
periment the remaining air, reduced to the
same medium pressure and temperature, was
only between 42 and 43 cubic inches; conse-
quently it had lost about % of its bulk. After-
wards, having collected all the red particles
formed during the experiment from the run-
ning mercury in which they floated, I found
these to amount to 45 grains.

I was obliged to repeat this experiment seve-
ral times, as it is difficult in one experiment
both to preserve the whole air upon which we
operate and to collect the whole of the red
particles, or calx of mercury, which is formed
during the calcination. It will often happen in
the sequel that I shall, in this manner, give in
one detail the results of two or three experi-
ments of the same nature.

The air which remained after the calcination
of the mercury in this experiment, and which
was reduced to % of its former bulk, was no
longer fit either for respiration or for combus-
tion; animals being introduced into it were
suffocated in a few seconds, and when a taper
was plunged into it, it was extinguished as if it
had been immersed into water.

In the next place, I took the 45 grains of red
matter formed during this experiment, which I
put into a small glass retort, having a proper
apparatus for receiving such liquid, or gaseous
product, as might be extracted : having applied
a fire to the retort in a furnace, I observed that,
in proportion as the red matter became heated,
the intensity of its colour augmented. When the
retort was almost red hot, the red matter began
gradually to decrease in bulk, and a few min-
utes afterwards, it disappeared altogether; at
the same time 41 J^ grains of running mercury
were collected in the recipient, and 7 or 8 cubic
inches of elastic fluid, greatly more capable of
supporting both respiration and combustion

LAVOISIER

than atmospherical air, were collected in the
bell-glass.

A part of this air being put into a glass tube
of about an inch diameter showed the follow-
ing properties: a taper burned in it with a daz-
zling splendour and charcoal, instead of con-
suming quietly as it does in common air, burnt
with a flame, attended with a decrepitating
noise, like phosphorus, and threw out such a
brilliant light that the eyes could hardly en-
dure it. This species of air was discovered al-
most at the same time by M. Priestley, M.
Scheele, and myself. M. Priestley gave it the
name of dephlogisticated air, M. Scheele called
it empyreal air. At first I named it highly res-
pirable air, to which has since been substituted
the term of vital air. We shall presently see
what we ought to think of these denomina-
tions.

In reflecting upon the circumstances of this
experiment, we readily perceive that the mer-
cury, during its calcination, absorbs the salu-
brious and respirable part of the air, or, to
speak more strictly, the base of this respirable
part; that the remaining air is a species of me-
phitis, incapable of supporting combustion or
respiration ; and consequently that atmospheric
air is composed of two elastic fluids of different
and opposite qualities. As a proof of this im-
portant truth, if we recombine these two elastic
fluids, which we have separately obtained in
the above experiment, viz., the 42 cubic inches
of mephitis, with the 8 cubic inches of respir-
able air, we reproduce an air precisely similar
to that of the atmosphere and possessing nearly
the same power of supporting combustion and
respiration, and of contributing to the calcina-
tion of metals.

Although this experiment furnishes us with
a very simple means of obtaining the two prin-
cipal elastic fluids which compose our atmos-
phere separate from each other, yet it does not
give us an exact idea of the proportion in which
these two enter into its composition: for the
attraction of mercury to the respirable part of
the air, or rather to its base, is not sufficiently
strong to overcome all the circumstances which
oppose this union. These obstacles are the mu-
tual adhesion of the two constiutent parts of
the atmosphere for each other and the elective
attraction which unites the base of vital air
with caloric ; in consequence of these, when the
calcination ends, or is at least carried as far as
is possible in a determinate quantity of atmos-
pheric air, there still remains a portion of
respirable air united to the mephitis, which

the mercury cannot separate. I shall after-
wards show that, at least in our climate,
the atmospheric air is composed of respir-
able, and mephitic airs, in the proportion
of 27 and 73; and I shall then discuss the
causes of the uncertainty which still exists
with respect to the exactness of that propor-
tion.

Since, during the calcination of mercury, air
is decomposed, and the base of its respirable
part is fixed and combined with the mercury,
it follows, from the principles already estab-
lished, that caloric and light must be disen-
gaged during the process: but the two follow-
ing causes prevent us from being sensible of
this taking place: as the calcination lasts dur-
ing several days, the disengagement of caloric
and light, spread out in a considerable space of
time, becomes extremely small for each par-
ticular moment of that time, so as not to be
perceptible; and, in the next place, the opera-
tion being carried on by means of fire in a fur-
nace, the heat produced by the calcination it-
self becomes confounded with that proceeding
from the furnace. I might add the respirable
part of the air, or rather its base, in entering
into combination with the mercury, does not
part with all the caloric which it contained but
still retains a part of it after forming the new
compound; but the discussion of this point,
and its proofs from experiment, do not belong
to this part of our subject.

It is, however, easy to render this disengage-
ment of caloric and light evident to the senses,
by causing the decomposition of air to take
place in a more rapid manner. And for this
purpose, iron is excellently adapted, as it pos-
sesses a much stronger affinity for the base of
respirable air than mercury. The elegant ex-
periment of M. Ingenhouz, upon the combus-
tion of iron, is well known. Take a piece of
fine iron wire twisted into a spiral BC (Plate
iv, Fig. 17), fix one of its extremities B into
the cork A, adapted to the neck of the bottle
DEFG, and fix to the other extremity of the
wire C a small morsel of tinder. Matters being
thus prepared, fill the bottle DEFG with air
deprived of its mephitic part; then light the
tinder and introduce it quickly, with the wire
upon which it is fixed, into the bottle which
you stop up with the cork A, as is shown in the
figure (17, Plate iv). The instant the tinder
comes into contact with the vital air it begins
to burn with great intensity; and, communi-
cating the inflammation to the iron-wire, it too
takes fire and burns rapidly, throwing out

CHEMISTRY

brilliant sparks, which fall to the bottom of the
vessel in rounded globules, which become black
in cooling but retain a degree of metallic splen-
dour. The iron thus burnt is more brittle even
than glass and is easily reduced into powder,
and is still attractable by the magnet, though
not so powerfully as it was before combustion.
As M. Ingenhouz has neither examined the
change produced on iron nor upon the air by
this operation, I have repeated the experiment
under different circumstances, in an apparatus
adapted to answer my particular views, as
follows.

Having filled a bell-glass A (Plate iv, Fig. 3)
of about six pints measure with pure air, or the
highly respirable part of air, I transported this
jar by means of a very flat vessel, into a quick-
silver bath in the basin BC, and I took care to
render the surface of the mercury perfectly dry
both within and without the jar with blotting
paper. I then provided a small capsule of china-
ware D, very flat and open, in which I placed
some small pieces of iron, turned spirally and
arranged in such a way as seemed most favour-
able for the combustion being communicated
to every part. To the end of one of these pieces
of iron was fixed a small morsel of tinder, to
which was added about the sixteenth part of a
grain of phosphorus, and, by raising the bell-
glass a little, the china capsule, with its con-
tents, were introduced into the pure air. I know
that, by this means, some common air must
mix with the pure air in the glass; but this,
when it is done dexterously, is so very trifling
as not to injure the success of the experiment.
This being done, a part of the air is sucked out
from the bell-glass, by means of a siphon GHI,
so as to raise the mercury within the glass to
EF; and, to prevent the mercury from getting
into the siphon, a small piece of paper is twist-
ed round its extremity. In sucking out the air,
if the motion of the lungs only be used,
we cannot make the mercury rise above an
inch or an inch and a half; but, by properly
using the muscles of the mouth, we can, with-
out difficulty, cause it to rise six or seven
inches.

I next took an iron wire, (MN, Plate iv, Fig.
16) properly bent for the purpose, and making
it red hot in the fire passed it through the mer-
cury into the receiver and brought it in contact
with the small piece of phosphorus attached to
the tinder. The phosphorus instantly takes
fire, which communicates to the tinder, and
from that to the iron. When the pieces have
been properly arranged, the whole iron burns,

even to the last particle, throwing out a white
brilliant light similar to that of Chinese fire-
works. The great heat produced by this com-
bustion melts the iron into round globules of
different sizes, most of which fall into the china
cup; but some are thrown out of it and swim
upon the surface of the mercury. At the begin-
ning of the combustion, there is a slight aug-
mentation in the volume of the air in the bell-
glass, from the dilatation caused by the heat;
but, presently afterwards, a rapid diminution
of the air takes place and the mercury rises in
the glass; insomuch that, when the quantity of
iron is sufficient, and the air operated upon is
very pure, almost the whole air employed is
absorbed.

It is proper to remark in this place that, un-
less in making experiments for the purpose of
discovery, it is better to be contented with
burning a moderate quantity of iron; for, when
this experiment is pushed too far, so as to ab-
sorb much of the air, the cup D, which floats
upon the quicksilver, approaches too near the
bottom of the bell-glass; and the great heat
produced, which is followed by a very sudden
cooling, occasioned by the contact of the cold
mercury, is apt to break the glass. In which
case, the sudden fall of the column of mercury,
which happens the moment the least flaw is
produced in the glass, causes such a wave as
throws a great part of the quicksilver from
the basin. To avoid this inconvenience, and
to ensure success to the experiment, one
gross and a half of iron is sufficient to burn
in a bell-glass, which holds about eight pints
of air. The glass ought likewise to be strong,
that it may be able to bear the weight of
the column of mercury which it has to sup-
port.

By this experiment, it is not possible to de-
termine, at one time, both the additional weight
acquired by the iron, and the changes which
have taken place in the air. If it is wished to
ascertain what additional weight has been
gained by the iron, and the proportion be-
tween that and the air absorbed, we must
carefully mark upon the bell-glass, with a dia-
mond, the height of the mercury, beth before
and after the experiment. After this, the si-
phon GH (Plate iv, Fig. 8) guarded, as before,
with a bit of paper, to prevent its filling with
mercury, is to be introduced under the bell-
glass, having the thumb placed upon the ex-
tremity, G, of the siphon, to regulate the pas-
sage of the air; and by this means the air is
gradually admitted, so as to let the mercury

LAVOISIER

fall to its level. This being done, the bell-glasa
is to be carefully removed, the globules of
melted iron contained in the cup, and those
which have been scattered about, and swim
upon the mercury are to be accurately col-
lected, and the whole is to be weighed. The iron
will be found in that state called martial ethiops
by the old chemists, possessing a degree of me-
tallic brilliancy,, very friable, and readily re-
ducible into powder under the hammer or with
a pestle and mortar. If the experiment has suc-
ceeded well, from 100 grains of iron will be ob-
tained 135 or 136 grains of ethiops, which is an
augmentation of 35 per cent.

If all the attention has been paid to this ex-
periment which it deserves, the air will be
found diminished in weight exactly equal to
what the iron has gained. Having therefore
burnt 100 grains of iron, which has acquired an
additional weight of 35 grains, the diminution
of air will be found exactly 70 cubic inches;
and it will be found, in the sequel, that the
weight of vital air is pretty nearly half a grain
for each cubic inch; so that, in effect, the aug-
mentation of weight in the one exactly coin-
cides with the loss of it in the other.

I shall observe here, once for all, that, in
every experiment of this kind, the pressure and
temperature of the air, both before and after
the experiment, must be reduced, by calcula-
tion, to a common standard of 10 (54.5) of
the thermometer and 28 inches of the barom-
eter. Towards the end of this work, the manner
of performing this very necessary reduction
will be found accurately detailed.

If it be required to examine the nature of the
air which remains after this experiment, we
must operate in a somewhat different manner.
After the combustion is finished, and the ves-
sels have cooled, we first take out the cup, and
the burnt iron, by introducing the hand through
the quicksilver under the bell-glass; we next
introduce some solution of potash, or caustic
alkali, or of the sulphuret of potash, or such
other substance as is judged proper for exam-
ining their action upon the residuum of air. I
shall, in the sequel, give an account of these
methods of analysing air, when I have ex-
plained the nature of these different substances,
which are only here in a manner accidentally
mentioned. After this examination, so much
water must be let into the glass as will displace
the quicksilver, and then, by means of a shal-
low dish placed below the bell-glass, it is to be
removed into the common watej pneumato-
chemical apparatus, where the air remaining

may be examined at large and with great fa-
cility.

When very soft and very pure iron has been
employed in this experiment, and, if the com-
bustion has been performed in the purest respir-
able or vital air, free from all admixture of the
noxious or mephitic part, the air which remains
after the combustion will be found as pure as it
was before; but it is difficult to find iron en-
tirely free from a small portion of charry mat-
ter, which is chiefly abundant in steel. It is
likewise exceedingly difficult to procure the
pure air perfectly free from some admixture of
mephitis, with which it is almost always con-
taminated ; but this species of noxious air does
not in the smallest degree disturb the result of
the experiment, as it is always found at the
end exactly in the same proportion as at the
beginning.

I mentioned before that we have two ways
of determining the constituent parts of atmos-
pheric air, the method of analysis, and that by
synthesis. The calcination of mercury has fur-
nished us with an example of each of these
methods, since, after having robbed the respir-
able part of its base, by means of the mercury,
we have restored it, so as to recompose an air
precisely similar to that of the atmosphere.
But we can equally accomplish this synthetic
composition of atmospheric air by borrowing
the materials of which it is composed from dif-
ferent kingdoms of nature. We shall see here-
after that when animal substances are dis-
solved in the nitric acid a great quantity of gas
is disengaged, which extinguishes light and
is unfit for animal respiration, being exactly
similar to the noxious or mephitic part of at-
mospheric air. And, if we take 73 parts, by
weight, of this elastic fluid, and mix it with 27
parts of highly respirable air, procured from
calcined mercury, we will form an elastic fluid
precisely similar to atmospheric air in all its
properties.

There are many other methods of separating
the respirable from the noxious part of the at-
mospheric air, which cannot be taken notice of
in this part without anticipating information
which properly belongs to the subsequent
chapters. The experiments already adduced
may suffice for an elementary treatise; and, in
matters of this nature, the choice of our evi-
dences is of far greater consequence than their
number.

I shall close this article by pointijig out the
property which atmospheric air, and all the
known gases, possess of dissolving water, which

CHEMISTRY

is of great consequence to be attended to in all
experiments of this nature. M. Saussure found,
by experiment, that a cubic foot of atmos-
pheric air is capable of holding 12 grains of
water in solution: other gases, as carbonic acid,
appear capable of dissolving a greater quan-
tity; but experiments are still wanting by
which to determine their several proportions.
This water, held in solution by gases, gives rise
to particular phenomena in many experiments
which require great attention and which has
frequently proved the source of great errors to
chemists in determining the results of their
experiments.

CHAPTER IV

Nomenclature of the Several Constituent Parts of
Atmospheric Air

HITHERTO I have been obliged to make use of
circumlocution to express the nature of the
several substances which constitute our at-
mosphere, having provisionally used the terms
of respirable and noxious, or non-respirable
parts of the air. But the investigations I mean
to undertake require a more direct mode of
expression; and, having now endeavoured to
give simple and distinct ideas of the different
substances which enter into the composition of
the atmosphere, I shall henceforth express
these ideas by words equally simple.

The temperature of our earth being very
near to that at which water becomes solid and
reciprocally changes from solid to fluid, and as
this phenomenon takes place frequently under
our observation, it has very naturally fol-
lowed that, in the languages of at least every
climate subjected to any degree of winter, a
term has been used for signifying water in the
state of solidity when deprived of its caloric.
The same, however, has not been found neces-
sary with respect to water reduced to the state
of vapour by an additional dose of caloric;
since those persons who do not make a partic-
ular study of objects of this kind are still ig-
norant that water, when in a temperature only
a little above the boiling heat, is changed into
an elastic aeriform fluid, susceptible, like all
other gases, of being received and contained in
vessels and preserving its gaseous form so long
as it remains at the temperature of 80 (212)
and under a pressure not exceeding 28 inches
of the mercurial barometer. As this phenom-
enon has not been generally observed, no lan-
guage has used a particular term for express-
ing water in this state; and the same thing

occurs with all fluids and all substances which
do not evaporate in the common temperature
and under the usual pressure of our atmos-
phere.

For similar reasons, names have not been
given to the liquid or concrete states of most of
the aeriform fluids: these were not known to
arise from the combination of caloric with cer-
tain bases; and, as they had not been seen
either in the liquid or solid states, their exist-
ence, under these forms, was even unknown to
natural philosophers.

We have not pretended to make any altera-
tion upon such terms as are sanctified by an-
cient custom and, therefore, continue to use
the words water and ice in their common accep-
tation. We likewise retain the word air to ex-
press that collection of elastic fluids which com-
poses our atmosphere ; but we have not thought
it necessary to preserve the same respect for
modern terms, adopted by latter philosophers,
having considered ourselves as at liberty to
reject such as appeared liable to occasion er-
roneous ideas of the substances they are meant
to express, and either to substitute new terms,
or to employ the old ones after modifying them
in such a manner as to convey more determi-
nate ideas. New words have been drawn, chiefly
from the Greek language, in such a manner as
to make their etymology convey some idea of
what was meant to be represented; and these
we have always endeavoured to make short
and of such a nature as to be changeable into
adjectives and verbs.

Following these principles, we have, after
M. Macquer's example, retained the term gas
employed by van Helmont, having arranged
the numerous classes of elastic aeriform fluids
under that name, excepting only atmospheric
air. Gas, therefore, in our nomenclature be-
comes a generic term, expressing the fullest
degree of saturation in any body with caloric ;
being, in fact, a term expressive of a mode of
existence. To distinguish each species of gas,
we employ a second term from the name of the
base, which, saturated with caloric, forms each
particular gas. Thus, we name water combined
to saturation with caloric, so as to form an
elastic fluid, aqueous gas; ether, combined in
the same manner, etherial gas; the combination
of alcohol with caloric becomes alcoholic gas;
and, following the same principles, we have
muriatic acid gas, ammoniacal gas, and so on of
every substance susceptible of being combined
with caloric, in such a manner as to assume the
gaseous or elastic aeriform state.

LAVOISIER

We have already seen that the atmospheric
air is composed of two gases, or aeriform fluids,
one of which is capable, by respiration, of con-
tributing to animal life, and in which metals
are calcinable and combustible bodies may
burn; the other, on the contrary, is endowed
with directly opposite qualities; it cannot be
breathed by animals, neither will it admit of
the combustion of inflammable bodies, nor of
the calcination of metals. We have given to
the base of the former, or respirable portion of
the air, the name of oxygen, from ovs, acidum,
and ydvopai, gignor; because, in reality, one
of the most general properties of this base is to
form acids by combining with many different
substances. The union of this base with caloric
we term oxygen gas, which is the same with
what was formerly called pure or vital air. The
weight of this gas, at the temperature of 10
(54.50), and under a pressure equal to 28
inches of the barometer, is half a grain for each
cubic inch, or an ounce and a half to each
cubic foot.

The chemical properties of the noxious por-
tion of atmospheric air being hitherto but little
known, we have been satisfied to derive the
name of its base from its known quality of kill-
ing such animals as are forced to breathe it,
giving it the name of azote, from the Greek
privative particle a and fan), vita; hence the
name of the noxious part of atmospheric air is
azotic gas; the weight of which, in the same
temperature and under the same pressure, is
1 oz. 2 gros 1 and 48 grs. to the cubic foot, or
0.4444 of a grain to the cubic inch. We cannot
deny that this name appears somewhat ex-
traordinary; but this must be the case with all
new terms, which cannot be expected to be-
come familiar until they have been some time
in use. We long endeavoured to find a more
proper designation without success; it was at
first proposed to call it alkaligen gas, as, from
the experiments of M. Berthollet, it appears
to enter into the composition of ammonia, or
volatile alkali; but then, we have as yet no
proof of its making one of the constituent ele-
ments of the other alkalies; beside, it is proved
to compose a part of the nitric acid, which
gives as good reason to have called it nitrogen.
For these reasons, finding it necessary to reject
any name upon systematic principles, we have
considered that we run no risk of mistake in
adopting the terms of azote and azotic gas,
which only express a matter of fact, or that
property which it possesses, of depriving such

1 Gros equals one-eighth of an ounce. EDITOR.

animals as breathe it of their lives.

I should anticipate subjects more properly
reserved for the subsequent chapters were I in
this place to enter upon the nomenclature of
the several species of gases: it is sufficient, in
this part of the work, to establish the prin-
ciples upon which their denominations are
founded. The principal merit of the nomen-
clature we have adopted is that, when once
the simple elementary substance is distin-
guished by an appropriate term, the names of
all its compounds derive readily, and neces-
sarily, from this first denomination.

CHAPTER V

Of the Decomposition of Oxygen Gas by Sulphur,
Phosphorus, and Charcoal, and of the Forma-
tion of Acids in General

IN performing experiments, it is a necessary
principle, which ought never to be deviated
from, that they be simplified as much as pos-
sible, and that every circumstance capable of
rendering their results complicated be carefully
removed. Wherefore, in the experiments which
form the object of this chapter, we have never
employed atmospheric air, which is not a sim-
ple substance. It is true that the azotic gas,
which forms a part of its mixture, appears to
be merely passive during combustion and cal-
cination; but, besides that it retards these
operations very considerably, we are not cer-
tain but it may even alter their results in some
circumstances; for which reason I have thought
it necessary to remove even this possible cause
of doubt, by only making use of pure oxygen
gas in the following experiments which show
the effects produced by combustion in that
gas; and I shall advert to such differences as
take place in the results of these, when the
oxygen gas, or pure vital air, is mixed, in dif-
ferent proportions, with azotic gas.

Having filled a bell-glass A (Plate iv, Fig. 8),
of between five and six pints measure, with
oxygen gas, I removed it from the water
trough, where it was filled, into the quicksilver
bath by means of a shallow glass dish slipped
underneath, and having dried the mercury I
introduced 61 J^ grains of Kunkel's phosphorus
in two little china cups, like that represented
at D (Fig. 8), under the glass A; and that I
might set fire to each of the portions of phos-
phorus separately, and to prevent the one from
catching fire from the other, one of the dishes
was covered with a piece of flat glass. I next

CHEMISTRY

raised the quicksilver in the bell-glass up to
EF, by sucking out a sufficient portion of the
gas by means of the siphon GHI. After this,
by means of the crooked iron wire (Fig. 16),
made red hot, I set fire to the two portions of
phosphorus successively, first burning that
portion which was not covered with the piece
of glass. The combustion was extremely rapid,
attended with a very brilliant flame and con-
siderable disengagement of light and heat. In
consequence of the great heat induced, the gas
was at first much dilated, but soon after the
mercury returned to its level and a consider-
able absorption of gas took place; at the same
time, the whole inside of the glass became
covered with white light flakes of concrete
phosphoric acid.

At the beginning of the experiment, the
quantity of oxygen gas, reduced, as above di-
rected, to a common standard, amounted to
162 cubic inches; and, after the combustion
was finished, only 23J4 cubic inches, likewise
reduced to the standard, remained ; so that the
quantity of oxygen gas absorbed during the
combustion was 138% cubic inches, equal to
69.375 grains.

A part of the phosphorus remained uncon-
sumed in the bottom of the cups, which being
washed on purpose to separate the acid weighed
about 16J4 grains; so that about 45 grains of
phosphorus had been burned: but, as it is
hardly possible to avoid an error of one or two
grains, I leave the quantity so far qualified.
Hence, as nearly 45 grains of phosphorus had,
in this experiment, united with 69.375 grains
of oxygen, and as no gravitating matter could
have escaped through the glass, we have a
right to conclude that the weight of the sub-
stance resulting from the combustion in form
of white flakes must equal that of the phos-
phorus and oxygen employed, which amounts
to 114.375 grains. And we shall presently find
that these flakes consisted entirely of a solid or
concrete acid. When we reduce these weights
to hundredth parts, it will be found that 100
parts of phosphorus require 154 parts of oxy-
gen for saturation and that this combination
will produce 254 parts of concrete phosphoric
acid, in form of white fleecy flakes.

This experiment proves, in the most con-
vincing manner, that, at a certain degree of
temperature, oxygen possesses a stronger elec-
tive attraction, or affinity, for phosphorus than
for caloric; that, in consequence of this, the
phosphorus attracts the base of oxygen gas
from the caloric, which, being set free, spreads

itself over the surrounding bodies. But, though
this experiment be so far perfectly conclusive,
it is not sufficiently rigorous, as, in the appa-
ratus described, it is impossible to ascertain
the weight of the flakes of concrete acid which
are formed; we can therefore only determine
this by calculating the weights of oxygen and
phosphorus employed; but as, in physics
and in chemistry, it is not allowable to sup-
pose what is capable of being ascertained by
direct experiment, I thought it necessary to
repeat this experiment as follows, upon a
larger scale and by means of a different appa-
ratus.

I took a large glass balloon A (Plate iv, Fig.
4) with an opening three inches diameter, to
which was fitted a crystal stopper ground with
emery, and pierced with two holes for the
tubes yyy, xxx. Before shutting the balloon
with its stopper, I introduced the support BC,
surmounted by the china cup D, containing
150 grs. of phosphorus; the stopper was then
fitted to the opening of the balloon, luted with
fat lute, and covered with slips of linen spread
with quicklime and white of eggs: when the
lute was perfectly dry, the weight of the whole
apparatus was determined to within a grain or
a grain and a half. I next exhausted the balloon,
by means of an air pump applied to the tube
xxx, and then introduced oxygen gas by means
of the tube yyy, having a stop-cock adapted to
it. This kind of experiment is most readily and
most exactly performed by means of the hydro-
pneumatic machine described by M. Meus-
nier and me in the Recueil de I AcaMmie for
1782, page 466, and explained in the latter
part of this work, with several important addi-
tions and corrections since made to it by M.
Meusnier. With this instrument we can readily
ascertain, in the most exact manner, both the
quantity of oxygen gas introduced into the
balloon and the quantity consumed during the
course of the experiment.

When all things were properly disposed, I
set fire to the phosphorus with a burning glass.
The combustion was extremely rapid, accom-
panied with a bright flame and much heat; as
the operation went on, large quantities of white
flakes attached themselves to the inner surface
of the balloon, so that at last it was rendered
quite opaque. The quantity of these flakes at
last became so abundant that although fresh
oxygen gas was continually supplied, which
ought to have supported the combustion, yet
the phosphorus was soon extinguished. Having
allowed the apparatus to cool completely, I

LAVOISIER

first ascertained the quantity of oxygen gas
employed, and weighed the balloon accurately,
before it was opened. I next washed, dried, and
weighed the small quantity of phosphorus re-
maining in the cup, on purpose to determine
the whole quantity of phosphorus consumed in
the experiment; this residuum of the phos-
phorus was of a yellow ochre colour. It is evi-
dent that by these several precautions I could
easily determine, 1st, the weight of the phos-
phorus consumed; 2nd, the weight of the flakes
produced by the combustion; and, 3rd, the
weight of the oxygen which had combined with
the phosphorus. This experiment gave very
nearly the same results with the former, as it
proved that the phosphorus, during its com-
bustion, had absorbed a little more than one
and a half its weight of oxygen; and I learned
with more certainty that the weight of the new
substance produced in the experiment exactly
equalled the sum of the weights of the phos-
phorus consumed and oxygen absorbed, which
indeed was easily determinable a priori. If the
oxygen gas employed be pure, the residuum
after combustion is as pure as the gas em-
ployed; this proves that nothing escapes from
the phosphorus capable of altering the purity
of the oxygen gas, and that the only action
of the phosphorous is to separate the oxygen
from the caloric with which it was before
united.

I mentioned above, that when any combus-
tible body is burnt in a hollow sphere of ice, or
in an apparatus properly constructed upon
that principle, the quantity of ice melted dur-
ing the combustion is an exact measure of the
quantity of caloric disengaged. Upon this head,
the Mtmoire given by M. de Laplace and me,
1780, p. 355, may be consulted. Having sub-
mitted the combustion of phosphorus to this
trial, we found that one pound of phosphorus
melted a little more than 100 pounds of ice
during its combustion.

The combustion of phosphorus succeeds
equally well in atmospheric air as in oxygen
gas, with this difference, that the combustion
is vastly slower, being retarded by the large
proportion of azotic gas mixed with the oxy-
gen gas, and that only about one-fifth part of
the air employed is absorbed, because as the
oxygen gas only is absorbed the proportion of
the azotic gas becomes so great toward the
close of the experiment as to put an end to the
combustion.

I have already shown that phosphorus is
changed by combustion into an extremely light,

white, flaky matter; and its properties are
entirely altered by this transformation: from
being insoluble in water, it becomes not only
soluble, but so greedy of moisture as to attract
the humidity of the air with astonishing rapid-
ity; by this means it is converted into a liquid
considerably more dense and of more specific
gravity than water. In the state of phos-
phorus before combustion, it had scarcely any
sensible taste; by its union with oxygen it
acquires an extremely sharp and sour taste:
in a word, from one of the class of combustible
bodies it is changed into an incombustible
substance and becomes one of those bodies
called acids.

This property of a combustible substance to
be converted into an acid, by the addition of
oxygen, we shall presently find belongs to a
great number of bodies: wherefore, strict logic
requires that we should adopt a common term
for indicating all these operations which pro-
duce analogous results; this is the true way to
simplify the study of science, as it would be
quite impossible to bear all its specific details
in the memory if they were not classically ar-
ranged. For this reason, we shall distinguish
this conversion of phosphorus into an acid by
its union with oxygen, and in general every
combination of oxygen with a combustible
substance, by the term of oxygenation: from
which I shall adopt the verb to oxygenate, and
of consequence shall say, that in oxygenating
phosphorus we convert it into an acid.

Sulphur is likewise a combustible body or, in
other words, it is a body which possesses the
power of decomposing oxygen gas by attract-
ing the oxygen from the caloric with which it
was combined. This can very easily be proved
by means of experiments quite similar to those
we have given with phosphorus ; but it is neces-
sary to premise that in these operations with
sulphur the same accuracy of result is not to be
expected as with phosphorus; because the acid
which is formed by the combustion of sulphur
is difficultly condensible, and because sulphur
burns with more difficulty, and is soluble in
the different gases. But I can safely assert,
from my own experiments, that sulphur in
burning absorbs oxygen gas; that the resulting
acid is considerably heavier than the sulphur
burnt; that its weight is equal to the sum of
the weights of the sulphur which has been
burnt and of the oxygen absorbed; and, lastly,
that this acid is weighty, incombustible, and
miscible with water in all proportions: the only
uncertainty remaining upon this head is with

CHEMISTRY

regard to the proportions of sulphur and of
oxygen which enter into the composition of the
acid.

Charcoal, which, from all our present knowl-
edge regarding it, must be considered as a sim-
ple combustible body, has likewise the prop-
erty of decomposing oxygen gas by absorbing
its base from the caloric : but the acid resulting
from this combustion does not condense in the
common temperature; under the pressure of
our atmosphere, it remains in the state of
gas, and requires a large proportion of water
to combine with or be dissolved in. This
acid has, however, all the known properties
of other acids, though in a weaker degree,
and combines, like them, with all the bases
which are susceptible of forming neutral
salts.

The combustion of charcoal in oxygen gas
may be effected like that of phosphorus in the
bell-glass A (Plate iv, Fig. 3) placed over mer-
cury: but, as the heat of red hot iron is not suf-
ficient to set fire to the charcoal, we must add
a small morsel of tinder with a minute particle
of phosphorus, in the same manner as directed
in the experiment for the combustion of iron.
A detailed account of this experiment will be
found in the Recueil de I' Academic for 1781, p.
448. By that experiment it appears that 28
parts by weight of charcoal require 72 parts of
oxygen for saturation and that the aeriform
acid produced is precisely equal in weight to
the sum of the weights of the charcoal and
oxygen gas employed. This aeriform acid was
called fixed or fixable air by the chemists who
first discovered it; they did not then know
whether it was air resembling that of the at-
mosphere or some other elastic fluid, vitiated
and corrupted by combustion; but since it is
now ascertained to be an acid, formed like all
others by the oxygenation of its peculiar base,
it is obvious that the name of fixed air is quite
ineligible.

By burning charcoal in the apparatus men-
tioned, p. 24, M. de Laplace and I found that
one Ib. of charcoal melted 96 Ibs. 6 oz. of ice;
that, during the combustion, 2 Ibs. 9 oz. 1 gros
10 grs. of oxygen were absorbed, and that 3 Ibs.
9 oz. 1 gros 10 grs. of acid gas were formed. This
gas weighs 0.695 parts of a grain for each cubic
inch, in the common standard temperature and
pressure mentioned above, so that 34,242 cubic
inches of acid gas are produced by the com-
bustion of one pound of charcoal.

I might multiply these experiments and show
by a numerous succession of facts that all acids

are formed by the combustion of certain sub-
stances; but I am prevented from doing so in
this place by the plan which I have laid down,
of proceeding only from facts already ascer-
tained to such as are unknown and of drawing
my examples only from circumstances already
explained. In the mean time, however, the
three examples above cited may suffice for
giving a clear and accurate conception of the
manner in which acids are formed. By these it
may be clearly seen that oxygen is an element
common to them all which constitutes their
acidity, and that they differ from each other
according to the nature of the oxygenated or
acidified substance. We must therefore, in
every acid, carefully distinguish between the
acidifiable base, which M. de Morveau calls
the radical, and the acidifying principle or
oxygen.

CHAPTER VI

Of the Nomenclature of Acids in General , and
Particularly of Those Drawn from Nitre and
Sea-Salt

IT becomes extremely easy, from the principles
laid down in the preceding chapter, to establish
a systematic nomenclature for the acids: the
word acid being used as a generic term, each
acid falls to be distinguished in language, as
in nature, by the name of its base or radical.
Thus, we give the generic name of acids to the
products of the combustion or oxygenation of
phosphorus, of sulphur, and of charcoal; and
these products are respectively named the
phosphoric acid, the sulphuric add, and the
carbonic acid.

There is, however, a remarkable circum-
stance in the oxygenation of combustible
bodies, and of a part of such bodies as are con-
vertible into acids, that they are susceptible of
different degrees of saturation with oxygen,
and that the resulting acids, though formed by
the union of the same elements, are possessed
of different properties, depending upon that
difference of proportion. Of this, the phos-
phoric acid, and more especially the sulphuric,
furnishes us with examples. When sulphur is
combined with a small proportion of oxygen,
it forms, in this first or lower degree of oxy-
genation, a volatile acid, having a penetrating
odour and possessed of very particular qual-
ities. By a larger proportion of oxygen, it is
changed into a fixed, heavy acid, without any
odour, and which, by combination with other
bodies, gives products quite different from

LAVOISIER

those furnished by the former. In this instance,
the principles of our nomenclature seem to
fail; and it seems difficult to derive such terms
from the name of the acidifiable base as shall
distinctly express these two degrees of satura-
tion, or oxygenation, without circumlocution.
By reflection, however, upon the subject, or
perhaps rather from the necessity of the case,
we have thought it allowable to express these
varieties in the oxygenation of the acids by
simply varying the termination of their spe-
cific names. The volatile acid produced from
sulphur was anciently known to Stahl under
the name of sulphurous acid. We have pre-
served that term for this acid from sulphur
under-saturated with oxygen; and distinguish
the other, or completely saturated or oxygen-
ated acid, by the name of sulphuric acid. We
shall therefore say, in this new chemical lan-
guage, that sulphur, in combining with oxygen,
is susceptible of two degrees of saturation ; that
the first or lesser degree constitutes sulphurous
acid, which is volatile and penetrating; whilst
the second or higher degree of saturation pro-
duces sulphuric acid, which is fixed and inodor-
ous. We shall adopt this difference of termina-
tion for all the acids which assume several
degrees of saturation. Hence we have a phos-
phorous and a phosphoric acid, an acetous and
an acetic acid; and so on, for others in similar
circumstances.

This part of chemical science would have
been extremely simple, and the nomenclature
of the acids would not have been at all per-
plexed as it is now in the old nomenclature, if
the base or radical of each acid had been known
when the acid itself was discovered. Thus, for
instance, phosphorus being a known substance
before the discovery of its acid, this latter was
rightly distinguished by a term drawn from
the name of its acidifiable base. But when, on
the contrary, an acid happened to be discov-
ered before its base, or rather when the acidi-
fiable base from which it was formed remained
unknown, names were adopted for the two,
which have not the smallest connection; and
thus, not only the memory, became burdened
with useless appellations, but even the minds
of students, nay even of experienced chemists,
became filled with false ideas, which time and
reflection alone are capable of eradicating. We
may give an instance of this confusion with
respect to the acid sulphur: the former chem-
ists having procured this acid from the vitriol
of iron gave it the name of the vitriolic acid

from the name of the substance which pro-
duced it; and they were then ignorant that the
acid procured from sulphur by combustion was
exactly the same.

The same thing happened with the aeriform
acid formerly called fixed air; it not being
known that this acid was the result of combin-
ing charcoal with oxygen, a variety of denom-
inations have been given to it, not one of which
conveys just ideas of its nature or origin. We
have found it extremely easy to correct and
modify the ancient language with respect to
these acids proceeding from known bases, hav-
ing converted the name of vitriolic add into
that of sulphuric, and the name of fixed air
into that of carbonic acid; but it is impossible
to follow this plan with the acids whose bases
are still unknown; with these we have been
obliged to use a contrary plan and, instead of
forming the name of the acid from that of its
base, have been forced to denominate the un-
known base from the name of the known acid,
as happens in the case of the acid which is pro-
cured from sea-salt.

To disengage this acid from the alkaline
base with which it is combined, we have only
to pour sulphuric acid upon sea-salt; imme-
diately a brisk effervescence takes place, white
vapours arise, of a very penetrating odour,
and, by only gently heating the mixture, all
the acid is driven off. As in the common tem-
perature and pressure of our atmosphere this
acid is naturally in the state of gas, we must
use particular precautions for retaining it in
proper vessels. For small experiments, the
most simple and most commodious apparatus
consists of a small retort G (Plate v, Fig. 5\
into which the sea-salt is introduced, well
dried; we then pour on some concentrated sul-
phuric acid, and immediately introduce the
beak of the retort under little jars or bell-
glasses A (same Plate and Fig.), previously
filled with quicksilver. In proportion as the
acid gas is disengaged, it passes into the jar
and gets to the top of the quicksilver, which it
displaces. When the disengagement of the gas
slackens, a gentle heat is applied to the retort
and gradually increased till nothing more
passes over. This acid gas has a very strong
affinity with water, which absorbs an enor-
mous quantity of it, as is proved by introduc-
ing a very thin layer of water into the glass
which contains the gas; for, in an instant, the
whole acid gas disappears and combines with
the water.

CHEMISTRY

This latter circumstance is taken advantage
of in laboratories and manufactures on purpose
to obtain the acid of sea-salt in a liquid form;
and for this purpose the apparatus (Plate iv,
Fig. 1) is employed. It consists, 1st, of a tabu-
lated retort A, into which the sea-salt, and after
it the sulphuric acid, are introduced through the
opening II ; 2nd, of the balloon or recipient c, b,
intended for containing the small quantity of
liquid which passes over during the process;
and, 3rd, of a set of bottles, with two mouths,
L,L,L,L, half filled with water, intended for
absorbing the gas disengaged by the distilla-
tion. This apparatus will be more amply de-
scribed in the latter part of this work.

Although we have not yet been able, either
to compose or to decompound this acid of sea-
salt, we cannot have the smallest doubt that it,
like all other acids, is composed by the union
of oxygen with an acidifiable base. We have
therefore called this unknown substance the
muriatic base, or muriatic radical, deriving this
name, after the example of M. Bergman and
M. de Morveau, from the Latin word muria,
which was anciently used to signify sea-salt.
Thus, without being able exactly to determine
the component parts of muriatic acid, we de-
sign by that term a volatile acid, which retains
the form of gas in the common temperature
and pressure of our atmosphere, which com-
bines with great facility, and in great quantity,
with water, and whose acidifiable base adheres
so very intimately with oxygen that no method
has hitherto been devised for separating them.
If ever this acidifiable base of the muriatic
acid is discovered to be a known substance,
though now unknown in that capacity, it
will be requisite to change its present denom-
ination for one analogous with that of its
base.

In common with sulphuric acid, and several
other acids, the muriatic is capable of different
degrees of oxygenation; but the excess of oxy-
gen produces quite contrary effects upon it
from what the same circumstance produces
upon the acid of sulphur. The lower degree of
oxygenation converts sulphur into a volatile
gaseous acid, which only mixes in small pro-
portions with water, whilst a higher oxygena-
tion forms an acid possessing much stronger
acid properties, which is very fixed and cannot
remain in the state of gas but in a very high
temperature, which has no smell, and which
mixes in large proportion with water. With
muriatic acid, the direct reverse takes place;

an additional saturation with oxygen renders
it more volatile, of a more penetrating odour,
less miscible with water, and diminishes its
acid properties. We were at first inclined to
have denominated these two degrees of satura-
tion in the same manner as we had done with
the acid of sulphur, calling the less oxygen-
ated muriatous acid, and that which is more
saturated with oxygen muriatic acid: but, as
this latter gives very particular results in
its combinations, and as nothing analo-
gous to it is yet known in chemistry, we have
left the name of muriatic acid to the less
saturated and given the latter the more com-
pounded appellation of oxygenated muriatic
acid.

Although the base or radical of the acid
which is extracted from nitre or saltpetre be
better known, we have judged proper only to
modify its name in the same manner with that
of the muriatic acid. It is drawn from nitre by
the intervention of sulphuric acid, by a process
similar to that described for extracting the
muriatic acid, and by means of the same ap-
paratus (Plate iv, Fig. l).ln proportion as the
acid passes over, it is in part condensed in
the balloon or recipient and the rest is ab-
sorbed by the water contained in the bottles
L, L, L, L; the water becomes first green, then
blue, and at last yellow, in proportion to the
concentration of the acid. During this opera-
tion, a large quantity of oxygen gas, mixed
with a small proportion of azotic gas, is dis-
engaged.

This acid, like all others, is composed of oxy-
gen, united to an acidifiable base, and is even
the first acid in which the existence of oxygen
was well ascertained. Its two constituent ele-
ments are but weakly united and are easily
separated by presenting any substance with
which oxygen has a stronger affinity than with
the acidifiable base peculiar to this acid. By
some experiments of this kind, it was first dis-
covered that azote, or the base of mephitis or
azotic gas, constituted its acidifiable base or
radical, and consequently that the acid of nitre
was really an azotic acid, having azote for its
base, combined with oxygen. For these rea-
sons, that we might be consistent with our
principles, it appeared necessary either to call
the acid by the name of azotic or to name the
base nitric radical; but from either of these 1 we !
were dissuaded by the following considerations.
In the first place, it seemed difficult to change
the name of nitre or saltpetre, which has been

LAVOISIER

universally adopted in society, in manufac-
tures, and in chemistry; and, on the other
hand, azote having been discovered by M.
Berthollet to be the base of volatile alkali, or
ammonia, as well as of this acid, we thought it
improper to call it nitric radical. We have
therefore continued the term of azote to the
base of that part of atmospheric air which is
likewise the nitric and ammoniacal radical;
and we have named the acid of nitre, in its
lower and higher degrees of oxygenation, ni-
trous add in the former and nitric acid in the
latter state; thus preserving its former appella-
tion properly modified.

Several very respectable chemists have dis-
approved of this deference for the old terms
and wished us to have persevered in perfecting
a new chemical language, without paying any
respect for ancient usage; so that, by thus
steering a kind of middle course, we have ex-
posed ourselves to the censures of one sect of
chemists, and to the expostulations of the op-
posite party.

The acid of nitre is susceptible of assuming a
great number of separate states, depending up-
on its degree of oxygenation or upon the pro-
portions in which azote and oxygen enter into
its composition. By a first or lowest degree of
oxygenation it forms a particular species of
gas, which we shall continue to name nitrous
gas; this is composed nearly of two parts, by
weight, of oxygen combined with one part of
azote; and in this state it is not miscible with
water. In this gas, the azote is by no means
saturated with oxygen, but, on the contrary,
has still a very great affinity for that element
and even attracts it from atmospheric air, im-
mediately upon getting into contact with it.
This combination of nitrous gas with atmos-
pheric air has even become one of the methods
for determining the quantity of oxygen con-
tained in air and consequently for ascertaining
its degree of salubrity.

This addition of oxygen converts the nitrous
gas into a powerful acid, which has a strong
affinity with water and which is itself suscep-
tible of various additional degrees of oxygena-
tion. When the proportions of oxygen and
azote is below three parts, by weight, of the
former to one of the latter, the acid is red col-
oured and emits copious fumes. In this state,
by the application of a gentle heat, it gives out
nitrous gas, and we term it, in this degree of
oxygenation, nitrous acid. When four parts, by
weight, of oxygen are combined with one part

of azote, the acid is clear and colourless, more
fixed in the fire than the nitrous acid, has less
odour, and its constituent elements are more
firmly united. This species of aeid, in conform-
ity with our principles of nomenclature, is
called nitric acid.

Thus, nitric acid is the acid of nitre, sur-
charged with oxygen; nitrous &cid is the acid
of nitre surcharged with azote or, what is the
same thing, with nitrous gas; and this latter is
azote not sufficiently saturated with oxygen to
possess the properties of an acid. To this de-
gree of oxygenation, we have afterwards, in
the course of this work, given the generical
name of oxide.

CHAPTER VII

Of the Decomposition of Oxygen Gas by Means of
Metals and the Formation of Metallic Oxides

OXYGEN has a stronger affinity with metals
heated to a certain degree than with caloric;
in consequence of which, ail metallic bodies,
excepting gold, silver, and platinum, have the
property of decomposing oxygen gas, by at-
tracting its base from the caloric with which it
was combined. We have already shown in what
manner this decomposition takes place, by
means of mercury and iron; having observed,
that, in the case of the first, it must be consid-
ered as a kind of gradual combustion, whilst,
in the latter, the combustion is extremely
rapid and attended with a brilliant flame. The
use of the heat employed in these operations
is to separate the particles of the metal from
each other and to diminish their attraction
of cohesion or aggregation or, which is the
same thing, their mutual attraction for each
other.

The absolute weight of metallic substances
is augmented in proportion to the quantity of
oxygen they absorb; they, at the same time,
lose their metallic splendour, and are reduced
into an earthy pulverulent matter. In this state
metals must not be considered as entirely sat-
urated with oxygen, because their action upon
this element is counterbalanced by >the power
of affinity between it and caloric. During the
calcination of metals the oxygen is, therefore,
acted upon by two separate and opposite pow-
ers, that of its attraction for caloric and that
exerted by the metal, and only tends to unite
with the latter in consequence of the excess of
the latter over the former, which is, in general,

CHEMISTRY

very inconsiderable. Wherefore, when metallic
substances are oxygenated in atmospheric air
or in oxygen gas, they are not converted into
acids like sulphur, phosphorus, and charcoal,
but are only changed into intermediate sub-
stances, which, though approaching to the
nature of salts, have not acquired all the saline
properties. The old chemists have affixed the
name of calx not only to metals in this state
but to every body which has been long exposed
to the action of fire without being melted.
They have converted this word calx into a
generical term, under which they confound
calcareous earth, which, from a neutral salt,
which it really was before calcination, has been
changed by fire into an earthy alkali, by losing
half of its weight, with metals which, by the
same means, have joined themselves to a new
substance, whose quantity often exceeds half
their weight, and by which they have been
changed almost into the nature of acids. This
mode of classifying substances of so very op-
posite natures under the same generic name
would have been quite contrary to our prin-
ciples of nomenclature, especially as, by re-
taining the above term for this state of metal-
lic substances, we must have conveyed very
false ideas of its nature. We have, therefore,
laid aside the expression metallic calx alto-
gether and have substituted in its place the
term oxide, from the Greek word ous.

By this may be seen that the language we
have adopted is both copious and expressive.
The first, or lowest, degree of oxygenation in
bodies converts them into oxides; a second de-
gree of additional oxygenation constitutes the
class of acids, of which the specific names,
drawn from their particular bases, terminate
in ous, as the nitrous and sulphurous acids; the
third degree of oxygenation changes these into
the species of acids distinguished by the term-
ination in ic, as the nitric and sulphuric acids;
and, lastly, we can express a fourth, or highest
degree of oxygenation, by adding the word
oxygenated to the name of the acid, as has been
already done with the oxygenated muriatic
acid.

We have not confined the term oxide to ex-
pressing the combinations of metals with oxy-
gen, but have extended it to signify that first
degree of oxygenation in all bodies, which,
without converting them into acids, causes
them to approach to the nature of salts. Thus,
we give the name of oxide of sulphur to that
soft substance into which sulphur is converted

by incipient combustion; and we call the yel-
low matter left by phosphorus, after combus-
tion, by the name of oxide of phosphorus. In
the same manner, nitrous gas, which is azote
in its first degree of oxygenation, is the oxide of
azote. We have likewise oxides in great num-
bers from the vegetable and animal kingdoms;
and I shall show, in the sequel, that this new
language throws great light upon all the oper-
ations of art and nature.

We have already observed that almost all
the metallic oxides have peculiar and perma-
nent colours. These vary not only in the differ-
ent species of metals, but even according to
the various degrees of oxygenation in the same
metal. Hence we are under the necessity of
adding two epithets to each oxide, one of which
indicates the metal oxidated, while the other
indicates the peculiar colour of the oxide. Thus,
we have the black oxide of iron, the red oxide
of iron, and the yellow oxide of iron; which
expressions respectively answer to the old
unmeaning terms of martial ethiops, colco-
thar, and rust of iron, or ochre. We have like-
wise the gray, yellow, and red oxides of lead,
which answer to the equally false or insig-
nificant terms, ashes of lead, massicot, and
minium.

These denominations sometimes become ra-
ther long, especially when we mean to indicate
whether the metal has been oxidated in the
air, by detonation with nitre, or by means of
acids; but then they always convey just and
accurate ideas of the corresponding object
which we wish to express by their use. All this
will be rendered perfectly clear and distinct by
means of the tables which are added to this
work.

CHAPTER VIII

Of the Radical Principle of Water and of its De-
composition by Charcoal and Iron

UNTIL very lately, water has always been
thought a simple substance, insomuch that the
older chemists considered it as an element.
Such it undoubtedly was to them, as they were
unable to decompose it; or, at least, since the
decomposition which took place daily before
their eyes was entirely unnoticed. But we
mean to prove that water is by no means a
simple or elementary substance. I shall not
here pretend to give the history of this recant
and hitherto contested discovery, which is de-
tailed in the Recueil de V Academic for 1781, but

LAVOISIER

shall only bring forwards the principal proofs
of the decomposition and composition of wa-
ter; and I may venture to say that these will be
convincing to such as consider them impartially.

First Experiment

Having fixed the glass tube EF (Plate vn,
Fig. 11) of from 8 to 12 lines diameter across a
furnace, with a small inclination from E to F,
lute the superior extremity E to the glass re-
tort A, containing a determinate quantity of
distilled water, and to the inferior extremity F
the worm SS fixed into the neck of the doubly
tubulated bottle H, which has the bent tube
KK adapted to one of its openings, in such a
manner as to convey such aeriform fluids or
gases as may be disengaged, during the exper-
iment, into a proper apparatus for determining
their quantity and nature.

To render the success of this experiment cer-
tain, it is necessary that the tube EF be made
of well annealed and difficultly fusible glass,
and that it be coated with a lute composed of
clay mixed with powdered stone- ware; besides
which, it must be supported about its middle
by means of an iron bar passed through the
furnace, lest it should soften and bend during
the experiment. A tube of chinaware, or por-
celain, would answer better than one of glass
for this experiment, were it not difficult to pro-
cure one so entirely free from pores as to pre-
vent the passage of air or of vapours.

When things are thus arranged, a fire is
lighted in the furnace EFCD, which is sup-
ported of such a strength as to keep the tube
EF red hot but not to make it melt; and, at
the same time, such a fire is kept up in the fur-
nace WXX as to keep the water in the retort
A continually 'boiling.

In proportion as the water in the retort A is
evaporated it fills the tube EF, and drives out
the air it contained by the tube KK; the aque-
ous gas formed by evaporation is condensed by
cooling in the worm SS and falls, drop by drop,
into the tubulated bottle H. Having continued
this operation until all the water be evaporated
from the retort, and having carefully emptied
ail the vessels employed, we find that a quan-
tity of water has passed over into the bottle H
exactly equal to what was before contained in
the retort A, without any disengagement of
gas whatsoever: so that this experiment turns
out to be a simple distillation, and the result
would have been exactly the same, if the water
had been run from one vessel into the other,

through the tube EF, without having under-
gone the intermediate incandescence.

Second Experiment

The apparatus being disposed, as in the for-
mer experiment, 28 grs. of charcoal, broken into
moderately small parts and which have pre-
viously been exposed for a long time to a red
heat in close vessels, are introduced into the
tube EF. Everything else is managed as in the
preceding experiment.

The water contained in the retort A is dis-
tilled, as in the former experiment, and, being
condensed in the worm, falls into the bottle H;
but, at the same time, a considerable quantity
of gas is disengaged, which, escaping by the
tube KK, is received in a convenient apparatus
for that purpose. After the operation is fin-
ished, we find nothing but a few atoms of ashes
remaining in the tube EF, the 28 grs. of char-
coal having entirely disappeared.

When the disengaged gases are carefully ex-
amined, they are found to weigh 113.7 grs.; 1
these are of two kinds, viz., 144 cubic inches of
carbonic acid gas weighing 100 grs. and 380
cubic inches of a very light gas weighing only
13.7 grs. y which takes fire when in contact with
air, by the approach of a lighted body; and,
when the water which has passed over into the
bottle H is carefully examined, it is found to
have lost 85.7 grs. of its weight. Thus, in this
experiment, 85.7 grs. of water, joined to 28 grs.
of charcoal, have combined in such a way as to
form 100 grs. of carbonic acid, and 13.7 grs. of
a particular gas capable of being burnt.

I have already shown, that 100 grs. of car-
bonic acid gas consists of 72 grs. of oxygen
combined with 28 grs. of charcoal; hence the 28
grs. of charcoal placed hi the glass tube have
acquired 72 grs. of oxygen from the water; and
it follows that 85.7 grs. of water are composed
of 72 grs. of oxygen combined with 13.7 grs. of a
gas susceptible of combustion. We shall see pres-
ently that this gas cannot possibly have been
disengaged from the charcoal and must, con-
sequently, have been produced from the water.

I have suppressed some circumstances in the
above account of this experiment, which would
only have complicated and obscured its results
hi the minds of the reader. For instance, the
inflammable gas dissolves a very small part of

1 In the latter part of this work will be found a
particular account of the processes necessary for
separating the different kinds of gases, and for deter-
mining their quantities. AUTHOR.

CHEMISTRY

the charcoal, by which means its weight is
somewhat augmented and that of the carbonic
gas proportionally diminished. Altho' the al-
teration produced by this circumstance is very
inconsiderable, yet I have thought it necessary
to determine its effects by rigid calculation,
and to report, as above, the results of the ex-
periment in its simplified state, as if this cir-
cumstance had not happened. At any rate,
should any doubts remain respecting the con-
sequences I have drawn from this experiment,
they will be fully dissipated by the following
experiments, which I am going to adduce in
support of my opinion.

Third Experiment

The apparatus being disposed exactly as in
the former experiment, with this difference,
that instead of the 28 grs. of charcoal the tube
EF is filled with 274 grs. of soft iron in thin
plates, rolled up spirally. The tube is made red
hot by means of its furnace, and the water in
the retort A is kept constantly boiling till it be
all evaporated, and has passed through the
tube EF so as to be condensed in the bottle H.

No carbonic acid gas is disengaged in this
experiment, instead of which we obtain 416
cubic inches, or 15 grs. of inflammable gas,
thirteen times lighter than atmospheric air. By
examining the water which has been distilled,
it is found to have lost 100 grs. and the 274 grs.
of iron confined in the tube are found to have
acquired 85 grs. additional weight and its mag-
nitude is considerably augmented. The iron is
now hardly at all attractable by the magnet;
it dissolves in acids without effervescence; and,
in short, it is converted into a black oxide, pre-
cisely similar to that which has been burnt in
oxygen gas.

In this experiment we have a true oxidation
of iron, by means of water, exactly similar to
that produced in air by the assistance of heat.
One hundred grains of water having been de-
composed, 85 grs. of oxygen have combined
with the iron, so as to convert it into the state
of black oxide, and 15 grs. of a peculiar inflam-
mable gas are disengaged: from all this it clear-
ly follows that water is composed of oxygen
combined with the base of an inflammable gas,
in the respective proportions of 85 parts, by
weight of the former, to 15 parts of the latter,

Thus water, besides the oxygen which is one
of its elements in common with many other
substances, contains another element as its
constituent base or radical and for which we

must find an appropriate term. None that we
could think of seemed better adapted than the
word hydrogen, which signifies the generative
principle of water, from vBop aqua, and 7ewo-
/*eu gignor. 1 We call the combination of this
element with caloric hydrogen gas; and the
term hydrogen expresses the base of that gas,
or the radical of water.

This experiment furnishes us with a new
combustible body, or, in other words, a body
which has so much affinity with oxygen as to
draw it from its connection with caloric and to
decompose air or oxygen gas. This combustible
body has itself so great affinity with caloric
that, unless when engaged in a combination
with some other body, it always subsists in the
aeriform or gaseous state, in the usual temper-
ature and pressure of our atmosphere. In this
state of gas it is about YIS of the weight of an
equal bulk of atmospheric air; it is not ab-
sorbed by water, though it is capable of hold-
ing a small quantity of that fluid in solution,
and it is incapable of being used for respiration.

As the property this gas possesses, in com-
mon with all other combustible bodies, is no-
thing more than the power of decomposing air
and carrying off its oxygen from the caloric
with which it was combined, it is easily under-
stood that it cannot burn unless in contact
with air or oxygen gas. Hence, when we set fire
to a bottle full of this gas, it burns gently, first
at the neck of the bottle, and then in the inside
of it, in proportion as the external air gets in.
This combustion is slow and successive and only
takes place at the surface of contact between
the two gases. It is quite different when the
two gases are mixed before they are set on fire:
if, for instance, after having introduced one
part of oxygen gas into a narrow mouthed bot-
tle, we fill it up with two parts of hydrogen gas
and bring a lighted taper or other burning
body to the mouth of the bottle, the combus-
tion of the two gases takes place instantaneously
with a violent explosion. This experiment
ought only to be made in a bottle of very strong
green glass, holding not more than a pint, and
wrapped round with twine, otherwise the oper-
ator will be exposed to great danger from the

1 This expression hydrogen has been very severely
criticised by some, who pretend that it signifies en-
gendered by water and not that which engenders
water. The experiments related in this chapter prove
that when water is decomposed hydrogen is pro-
duced, and that when hydrogen is combined with
oxygen water is produced : so that we may say, with
equal truth, that water is produced from hydrogen,
or hydrogen is produced from water. AUTHOK.

LAVOISIER

rupture of the bottle, of which the fragments
will be thrown about with great force.

If all that has been related above, concern-
ing the decomposition of water, be exactly con-
formable to truth; if, as I have endeavoured
to prove, that substance be really composed of
hydrogen, as its proper constituent element,
combined with oxygen, it ought to follow that,
by reuniting these two elements together, we
should recompose water; and that this actually
happens may be judged of by the following
experiment.

Fourth Experiment

I took a large crystal balloon A (Plate iv, Fig.
6) holding about 30 pints, having a large open-
ing, to which was cemented the plate of copper
BC pierced with four holes in which four tubes
terminate. The first tube, H^, is intended to
be adapted to an air pump, by which the balloon
is to be exhausted of its air. The second ture
gg, communicates, by its extremity MM, with
a reservoir of oxygen gas, with which the bal-
loon is to be filled. The third tube dDd' com-
municates, by its extremity dNN, with a res-
ervoir of hydrogen gas. The extremity d' of
this tube terminates in a capillary opening,
through which the hydrogen gas contained in
the reservoir is forced, with a moderate degree
of quickness, by the pressure of one or two
inches of water. The fourth tube contains a
metallic wire GL, having a knob at its extrem-
ity L, intended for giving an electrical spark
from L to d', on purpose to set fire to the hy-
drogen gas: this wire is moveable in the tube,
that we may be able to separate the knob L
from the extremity d' of the tube Dd f . The
three tubes dDd', gg, and H/i, are all provided
with stop-cocks.

That the hydrogen gas and oxygen gas may
be as much as possible deprived of water, they
are made to pass, in their way to the baloon A,
through the tubes MM, NN, of about an inch
diameter, and filled with salts, which, from
their deliquescent nature, greedily attract the
moisture of the air: such are the acetite of
potash, and the muriate or nitrate of lime. 1
These salts must only be reduced to a coarse
powder, lest they run into lumps, and prevent
the gases from getting through their inter-
stices.

We must be provided beforehand with a
sufficient quantity of oxygen gas, carefully
purified from all admixture of carbonic acid by

1 See the nature of these salts in the second part of
this book. AUTHOR.

long contact with a solution of potash. 2

We must likewise have a double quantity of
hydrogen gas, carefully purified in the same
manner by long contact with a solution of pot-
ash in water. The best way of obtaining this
gas free from mixture is by decomposing water
with very pure soft iron, as directed in Exp. 3
of this chapter.

Having adjusted everything properly, as
above directed, the tube HA is adapted to an
air-pump, and the balloon A is exhausted of its
air. We next admit the oxygen gas so as to fill
the balloon and then, by means of pressure as
is before mentioned, force a small stream of
hydrogen gas through its tube Dd 1 , which we
immediately set on fire by an electric spark.
By means of the above described apparatus,
we can continue the mutual combustion of
these two gases for a long time, as we have the
power of supplying them to the balloon from
their reservoirs, in proportion as they are con-
sumed. I have in another place 3 given a de-
scription of the apparatus used in this experi-
ment and have explained the manner of ascer-
taining the quantities of the gases consumed
with the most scrupulous exactitude.

In proportion to the advancement of the
combustion, there is a deposition of water upon
the inner surface of the balloon or matrass A :
the water gradually increases in quantity and,
gathering into large drops, runs down to the
bottom of the vessel. It is easy to ascertain the
quantity of water collected, by weighing the
balloon both before and after the experiment.
Thus we have a twofold verification of our ex-
periment, by ascertaining both the quantities
of the gases employed and of the water formed
by their combustion : these two quantities must
be equal to each other. By an operation of this
kind, M. Meusnier and I ascertained that it
required 85 parts, by weight, of oxygen, united
to 15 parts of hydrogen, to compose 100 parts
of water. This experiment, which has not
hitherto been published, was made in pres-
ence of a numerous committee from the Royal
Academy. We exerted the most scrupulous
attention to its accuracy and have reason to
believe that the above propositions cannot vary
a two-hundredth part from absolute truth.

From these experiments, both analytical and
synthetic, we may now affirm that we have
ascertained, with as much certainty as is pos-

1 The method of obtaining this pure alkali of pot-
ash will be given in the sequel. AUTHOR.
8 See the third part of this work. AUTHOR.

CHEMISTRY

sible in physical or chemical subjects, that
water is not a simple elementary substance
but is composed of two elements, oxygen and
hydrogen; which elements, when existing
separately, have so strong affinity for caloric
as only to subsist under the form of gas in the
common temperature and pressure of our
atmosphere.

This decomposition and recomposition of
water is perpetually operating before our eyes,
in the temperature of the atmosphere, by
means of compound elective attraction. We
shall presently see that the phenomena attend-
ant upon vinous fermentation, putrefaction,
and even vegetation, are produced, at least in
a certain degree, by decomposition of water.
It is very extraordinary that this fact should
have hitherto been overlooked by natural phi-
losophers and chemists: indeed, it strongly
proves that, in chemistry as in moral philos-
ophy, it is extremely difficult to overcome prej-
udices imbibed in early education and to search
for truth in any other road than the one we
have been accustomed to follow.

I shall finish this chapter by an experiment
much less demonstrative than those already
related, but which has appeared to make more
impression than any other upon the minds of
many people. When 16 ounces of alcohol are
burnt in an apparatus 1 properly adapted for
collecting all the water disengaged during the
combustion, we obtain from 17 to 18 ounces of
water. As no substance can furnish a product
larger than its original bulk, it follows that
something else has united with the alcohol dur-
ing its combustion; and I have already shown
that this must be oxygen, or the base of air.
Thus alcohol contains hydrogen, which is one
of the elements of water; and the atmospheric
air contains oxygen, which is the other element
necessary to the composition of water. This
experiment is a new proof that water is a com-
pound substance.

CHAPTER IX

Of the Quantities of Caloric Disengaged from
Different Species of Combustion

WE have already mentioned that, when any
body is burnt in the center of a hollow sphere
of ice and supplied with air at the temperature
of zero (32), the quantity of ice melted from
the inside of the sphere becomes a measure of

* See an aocount of this apparatus in the third part
of this work. AUTHOR.

the relative quantities of caloric disengaged.
M. de Laplace and I gave a description of the
apparatus employed for this kind of experiment
in the Recueil de I'Academie for 1780, p. 355;
and a description and plate of the same appa-
ratus will be found in the third part of this work.
With this apparatus, phosphorus, charcoal, and
hydrogen gas, gave the following results:

one pound of phosphorus melted 1 00 Ibs . of ice ;

one pound of charcoal melted 96 Ibs. 8 oz;

one pound of hydrogen gas melted 295 Ibs.
9 oz. %y<i gros.

As a concrete acid is formed by the combus-
tion of phosphorus, it is probable that very
little caloric remains in the acid and, conse-
quently, that the above experiment gives us
very nearly the whole quantity of caloric con-
tained in the oxygen gas. Even if we suppose
the phosphoric acid to contain a good deal of
caloric, yet, as the phosphorus must have con-
tained nearly an equal quantity before com-
bustion, the error must be very small, as it will
only consist of the difference between what
was contained in the phosphorus before, and
in the phosphoric acid after combustion.

I have already shown in Chapter V that one
pound of phosphorus absorbs one pound eight
ounces of oxygen during combustion; and
since, by the same operation, 100 Ibs. of ice are
melted, it follows that the quantity of caloric
contained in one pound of oxygen gas is ca-
pable of melting 66 Ibs. 10 oz.5gros 24 grs. of ice.

One pound of charcoal during combustion
melts only 96 Ibs. 8 oz. of ice, whilst it absorbs
2 Ibs. 9 oz. 1 gros 10 grs. of oxygen. By the ex-
periment with phosphorus, this quantity of
oxygen gas ought to disengage a quantity of
caloric sufficient to melt 171 Ibs. 6 oz. 5 gros of
ice; consequently, during this experiment, a
quantity of caloric sufficient to melt 74 Ibs. 14
oz. 5 gros of ice disappears. Carbonic acid is
not, like phosphoric acid, in a concrete state
after combustion but in the state of gas and re-
quires to be united with caloric to enable it to
subsist in that state; the quantity of caloric
missing in the last experiment is evidently em-
ployed for that purpose. When we divide that
quantity by the weight of carbonic acid formed
by the combustion of one pound of charcoal,
we find that the quantity of caloric necessary
for changing one pound of carbonic acid from
the concrete to the gaseous state would be ca-
pable of melting 20 Ibs. 15 oz. 5 gros of ice.

We may make a similar calculation with the
combustion of hydrogen gas and the conse-

LAVOISIER

quent formation of water. During the combus-
tion of one pound of hydrogen gas, 5 Ibs. 10 oz.
5 gros 24 grs. of oxygen gas are absorbed, and
295 Ibs. 9 oz. 3J/ gros of ice are melted. But 5
Ibs. 10 oz. 5 gros 24 grs. of oxygen gas, in chang-
ing from the aeriform to the solid state, loses,
according to the experiment with phosphorus,
enough of caloric to have melted 377 /6s. 12 oz.
3 gros of ice. There is only disengaged from the
same quantity of oxygen, during its combus-
tion with hydrogen gas, as much caloric as
melts 295 Ibs. 2 oz. 3% gros; wherefore there
remains in the water at zero (32), formed,
during this experiment, as much caloric as
would melt 82 Ibs. 9 oz. 7 % gros of ice.

Hence, as 6 Ibs. 10 oz. 5 gros 24 grs. of water
are formed from the combustion of one pound
of hydrogen gas with 5 Ibs. 10 oz. 5 gros 24 grs.
of oxygen, it follows that in each pound of
water, at the temperature of zero (32), there
exists as much caloric as would melt 12 Ibs.
5 oz. 2 gros 48 grs. of ice, without taking into
account the quantity originally contained in the
hydrogen gas, which we have been obliged to
omit for want of data to calculate its quantity.
From this it appears that water, even in the
state of ice, contains a considerable quantity
of caloric, and that oxygen, in entering into that
combination, retains likewise a good proportion.

From these experiments, we may assume the
following results as sufficiently established.

Combustion of phosphorus

From the combustion of phosphorus, as re-
lated in the foregoing experiments, it appears
that one pound of phosphorus requires 1 Ib. 8 oz.
of oxygen gas for its combustion and that 2 /6s.
8 oz. of concrete phosphoric acid are produced.

The quantity of caloric disengaged by
the combustion of one pound of phos-
phorus, expressed by the number of
pounds of ice melted during that op-
eration, is 100.00000
The quantity disengaged from each
pound of oxygen during the combus-
tion of phosphorus, expressed in the
same manner, is 66.66667
The quantity disengaged during the
formation of one pound of phosphoric
acid 40.00000
The quantity remaining in each pound
of phosphoric acid O.OOOOO 1

1 We here suppose the phosphoric acid not to con-
tain any caloric, which is not strictly true; but, as
I have before observed, the quantity it really con-
tains is probably very small, and we have not given
it a value, for want of sufficient data to go upon.
AUTHOR.

Combustion of charcoal

In the combustion of one pound of charcoal,
2 Ibs. 9 oz. 1 gros 10 grs. of oxygen gas are ab-
sorbed, and 3 Ibs. 9 oz. 1 gros 10 grs. of carbonic
acid gas are formed.

Caloric disengaged during the combus-
tion of one pound of charcoal 96.50000
Caloric disengaged during the combus-
tion of charcoal, from each pound of
oxygen gas absorbed 37.52823
Caloric disengaged during the formation
of one pound of carbonic acid gas 27.02024
Caloric retained by each pound of oxy-
gen after the combustion 29.13844
Caloric necessary for supporting one
pound of carbonic acid in the state of
gas 20.97960

Combustion of hydrogen gas

In the combustion of one pound of hydrogen
gas, 5 Ibs. 10 oz. 5 gros 24 grs. of oxygen gas are
absorbed and 6 Ibs. 10 oz. 5 gros 24 grs. of water
are formed.

Caloric from each Ib. of hydrogen gas 295.58950
Caloric from each Ib. of oxygen gas 52.16280
Caloric disengaged during the forma-
tion of each pound of water 44.33840
Caloric retained by each Ib. of oxygen
after combustion with hydrogen 14.50386
Caloric retained by each Ib. of water at
the temperature of zero (32) 12.32823

Formation of nitric add

When we combine nitrous gas with oxygen
gas so as to form nitric or nitrous acid a degree
of heat is produced which is much less consid-
erable than what is evolved during the other
combinations of oxygen; whence it follows
that oxygen, when it becomes fixed in nitric
acid, retains a great part of the heat which it
possessed in the state of gas. It is certainly pos-
sible to determine the quantity of caloric which
is disengaged during the combination of these
two gases and consequently to determine what
quantity remains after the combination takes
place. The first of these quantities might be
ascertained by making the combination of the
two gases in an apparatus surrounded by ice;
but, as the quantity of caloric disengaged is
very inconsiderable, it would be necessary to
operate upon a large quantity of the two gases
in a very troublesome and complicated appa-
ratus. By this consideration, M. de Laplace
and I have hitherto been prevented from mak-

CHEMISTRY

ing the attempt. In the meantime, the place of
such an experiment may be supplied by cal-
culations, the results of which cannot be very
far from truth.

M. de Laplace and I deflagrated a conven-
ient quantity of nitre and charcoal in an ice
apparatus and found that twelve pounds of ice
were melted by the deflagration of one pound
of nitre. We shall see, in the sequel, that one
pound of nitre is composed, as below, of

potash 7 oz. 6 gros 51.84 grs. = 4515.84 grs.
dry acid 8 1 21.16 = 4700.16

The above quantity of dry acid is com-
posed of

oxygen 6 oz. 3 gros 66.34 grs. = 3738.34 grs'
azote 1 5 25.82 = 961.82

By this we find that during the above de-
flagration 2 gros l}s gr. of charcoal have suf-
fered combustion, alongst with 3738.34 grs.
or 6 oz. 3 gros 66.34 grs. of oxygen. Hence,
since 12 Ibs. of ice were melted during the com-
bustion, it follows that one pound of oxygen
burnt in the same manner would have melted
29.58320 Ibs. of ice. To which the quantity of
caloric, retained by a pound of oxygen after
combining with charcoal to form carbonic acid
gas, being added which was already ascer-
tained to be capable of melting 29.13844 Ibs.
of ice, we have for the total quantity of caloric
remaining in a pound of oxygen, when com-
bined with nitrous gas in the nitric acid
58.72164; which is the number of pounds of ice
the caloric remaining in the oxygen in that
state is capable of melting.

We have before seen that, in the state of
oxygen gas, it contained at least 66.66667;
wherefore it follows that, in combining with
azote to form nitric acid, it only loses 7.94502.
Further experiments upon this subject are
necessary to ascertain how far the results of
this calculation may agree with direct fact.
This enormous quantity of caloric retained by
oxygen in its combination into nitric acid ex-
plains the cause of the great disengagement of
caloric during the deflagrations of nitre; or,
more strictly speaking, upon all occasions of
the decomposition of nitric acid.

Combustion of wax

Having examined several cases of simple
combustion, I mean now to give a few examples
of a more complex nature. One pound of wax-
taper being allowed to burn slowly in an ice ap-
paratus melted 133 Ibs. 2 oz. 5% gros of ice.

According to my experiments in the Recueil de
V Academic for 1784, p. 606, one pound of wax-
taper consists of 13 oz. 1 gros 23 grs. of char-
coal and 2 oz. 6 gros 49 grs. of hydrogen.

By the foregoing experi-
ments, the above quantity
of charcoal ought to melt 79.39390 Ibs. of ice
The hydrogen should melt 52.37605

Total 131. 76995 Ibs.

Thus, we see the quantity of caloric disen-
gaged from a burning taper is pretty exactly
conformable to what was obtained by burning
separately a quantity of charcoal and hydrogen
equal to what enters into its composition. These
experiments with the taper were several times
repeated, so that I have reason to believe them
accurate.

Combustion of Olive Oil

We included a burning lamp, containing a
determinate quantity of olive oil, in the ordi-
nary apparatus and, when the experiment was
finished, we ascertained exactly the quantities
of oil consumed and of ice melted; the result
was that during the combustion of one pound
of olive oil, 148 Ibs. 14 oz. 1 gros of ice were
melted. By my experiments in the Recueil de
I'Acadtmie for 1784, and of which the follow-
ing chapter contains an abstract, it appears
that one pound of olive oil consists of 12 oz. 5
gros 5 grs. of charcoal and 3 oz. 2 gros 67 grs. of
hydrogen. By the foregoing experiments, that
quantity of charcoal should rneit 76.18723 Ibs.
of ice, and the quantity of hydrogen in a pound
of the oil should melt 62.15053 Ibs. The sum of
these two gives 138.33776 Ibs. of ice, which the
two constituent elements of the oil would have
melted had they separately suffered combus-
tion, whereas the oil really melted 148.88330
Ibs. which gives an excess of 10.54554 in the
result of the experiment above the calculated
result, from data furnished by former experi-
ments.

This difference, which is by no means very
considerable, may arise from errors which are
unavoidable in experiments of this nature, or
it may be owing to the composition of oil not
being as yet exactly ascertained. It proves,
however, that there is a great agreement be-
tween the results of our experiments, respect-
ing the combination of caloric and those which
regard its disengagement.

The following desiderata still remain to be
determined, viz : what quantity of caloric is re-

LAVOISIER

tained by oxygen, after combining with metals,
so as to convert them into oxides; what quan-
tity is contained by hydrogen, in its different
states of existence; and to ascertain, with more
precision than is as yet attained, how much
caloric is disengaged during the formation of
water, as there still remain considerable doubts
with respect to our present determination of
this point, which can only be removed by fur-
ther experiments. We are at present occupied
with this inquiry and when once these several
points are well ascertained, which we hope they
will soon be, we shall probably be under the
necessity of making considerable corrections
upon most of the results of the experiments
and calculations in this chapter. I did not,
however, consider this as a sufficient reason
for withholding so much as is already known
from such as may be inclined to labour upon
the same subject. It is difficult in our endeav-
ours to discover the principles of a new science,
to avoid beginning by guess-work; and it is
rarely possible to arrive at perfection from the
first setting out.

CHAPTER X

Of the Combination of Combustible Substances

with Each Other

As combustible substances in general have a
great affinity for oxygen, they ought likewise
to attract or tend to combine with each other ;
quae sunt eadem uni tertio, sunt eadem inter se;
and the axiom is found to be true. Almost all
the metals, for instance, are capable of uniting
with each other and forming what are called
alloys, 1 in common language. Most of these,
like all combinations, are susceptible of sev-
eral degrees of saturation; the greater number
of these alloys are more brittle than the pure
metals of which they are composed, especially
when the metals alloyed together are consid-
erably different in their degrees of fusibility.
To this difference in fusibility part of the phe-
nomena attendant upon alloyage are owing,
particularly the property of iron called by
workmen hotshort. This kind of iron must be
considered as an alloy, or mixture of pure iron,
which is almost infusible, with a small portion
of some other metal which fuses in a much low-
er degree of heat. So long as this alloy remains
cold, and both metals are in the solid state, the

1 This term alloy, which we have from the lan-
guage of the arts, serves exceedingly well for dis-
tinguishing all the combinations or intimate unions
of metals with each other, and is adopted in our new
nomenclature for that purpose. AUTHOB.

mixture is malleable; but, if heated to a suf-
ficient degree to liquefy the more fusible metal,
the particles of the liquid metal, which are
interposed between the particles of the metal
remaining solid, must destroy their continuity
and occasion the alloy to become brittle. The
alloys of mercury, with the other metals, have
usually been called amalgams, and we see no
inconvenience from continuing the use of that
term.

Sulphur, phosphorus, and charcoal readily
unite with metals. Combinations of sulphur
with metals are usually named pyrites. Their
combinations with phosphorus and charcoal
are either not yet named or have received new
names only of late; so that we have not scru-
pled to change them according to our prin-
ciples. The combinations of metal and sulphur
we call sulphurets, those with phosphorus phos-
phurets, and those formed with charcoal carbu-
rets. These denominations are extended to all
the combinations into which the above three
substances enter, without being previously oxy-
genated. Thus, the combination of sulphur
with potash, or fixed vegetable alkali, is called
sulphuret of potash; that which it forms with
ammonia, or volatile alkali, is termed sulphuret
of ammonia.

Hydrogen is likewise capable of combining
with many combustible substances. In the
state of gas it dissolves charcoal, sulphur, phos-
phorus, and several metals; we distinguish
these combinations by the terms, carbonated
hydrogen gas, sulphurated hydrogen gas, and
phosphorated hydrogen gas. The sulphurated
hydrogen gas was called hepatic air by former
chemists, or foetid air from sulphur, by M.
Scheele. The virtues of several mineral waters,
and the foetid smell of animal excrements,
chiefly arise from the presence of this gas. The
phosphorated hydrogen gas is remarkable for
the property, discovered by M. Gengembre,
of taking fire spontaneously upon getting into
contact with atmospheric air, or, what is bet-
ter, with oxygen gas. This gas has a strong fla-
vour, resembling that of putrid fish, and it is
very probable that the phosphorescent quality
of fish in the state of putrefaction arises from
the escape of this species of gas. When hydro-
gen and charcoal are combined together, with-
out the intervention of caloric to bring the hy-
drogen into the state of gas, they form oil,
which is either fixed or volatile according to
the proportions of hydrogen and charcoal in its
composition. The chief difference between fixed
or fat oils drawn from vegetables by expres-

CHEMISTRY

sion, and volatile or essential oils, is that the
former contains an excess of charcoal, which is
separated when the oils are heated above the
degree of boiling water; whereas the volatile
oils, containing a just proportion of these two
constituent ingredients, are not liable to be de-
composed by that heat, but, uniting with ca-
loric into the gaseous state, pass over in dis-
tillation unchanged.

In the Recueil de V Academic for 1784, p. 593,
I gave an account of my experiments upon the
composition of oil and alcohol, by the union of
hydrogen with charcoal, and of their combina-
tion with oxygen. By these experiments, it ap-
pears that fixed oils combine with oxygen dur-
ing combustion and are thereby converted
into water and carbonic acid. By means of cal-
culation applied to the products of these ex-
periments, we find that fixed oil is composed of
21 parts, by weight, of hydrogen combined
with 79 parts of charcoal. Perhaps the solid
substances of an oily nature, such as wax, con-
tain a proportion of oxygen to which they owe
their state of solidity. I am at present engaged
in a series of experiments, which I hope will
throw great light upon this subject.

It is worthy of being examined whether hy-
drogen in its concrete state, uncombined with
caloric, be susceptible of combination with sul-
phur, phosphorus, and the metals. There is
nothing that we know of which, a priori, should
render these combinations impossible ; for com-
bustible bodies being in general susceptible of
combination with each other, there is no evi-
dent reason for hydrogen being an exception
to the rule: however, no direct experiment as
yet establishes either the possibility or impos-
sibility of this union. Iron and zinc are the
most likely, of all the metals, for entering into
combination with hydrogen; but, as these have
the property of decomposing water, and as it is
very difficult to get entirely free from moisture
in chemical experiments, it is hardly possible
to determine whether the small portions of
hydrogen gas obtained in certain experiments
with these metals were previously combined
with the metal in the state of solid hydrogen,
or if they were produced by the decomposition
of a minute quantity of water. The more care
we take to prevent the presence of water in
these experiments, the less is the quantity of
hydrogen gas procured; and, when very accu-
rate precautions are employed, even that quan-
tity becomes hardly sensible.

However this inquiry may turn out respect-
ing the power of combustible bodies, as sul-

phur, phosphorus, and metals, to absorb hy-
drogen, we are certain that they only absorb a
very small portion ; and that this combination,
instead of being essential to their constitution,
can only be considered as a foreign substance
which contaminates their purity. It is the
province of the advocates for this system to
prove, by decisive experiments, the real exis-
tence of this combined hydrogen, which they
have hitherto only done by conjectures founded
upon suppositions.

CHAPTER XI

Observations upon Oxides and Acids with Sev-
eral Bases, and upon the Composition of Ani-
mal and Vegetable Substances

WE have in Chapters V and VIII examined the
products resulting from the combustion of the
four simple combustible substances, sulphur,
phosphorus, charcoal, and hydrogen: we have
shown in Chapter X that the simple combus-
tible substances are capable of combining with
each other into compound combustible sub-
stances and have observed that oils in general,
and particularly the fixed vegetable oils, belong
to this class, being composed of hydrogen and
charcoal. It remains, in this chapter, to treat
of the oxygenation of these compound com-
bustible substances and to show that there
exist acids and oxides having double and triple
bases. Nature furnishes us with numerous
examples of this kind of combination, by
means of which, chiefly, she is enabled to pro-
duce a vast variety of compounds from a very
limited number of elements or simple sub-
stances.

It was long ago well known that when mu-
riatic and nitric acids were mixed together a
compound acid was formed, having properties
quite distinct from those of either of the acids
taken separately. This acid was called aqua
regia, from its most celebrated property of dis-
solving gold, called king of metals by the alche-
mists. M. Berthollet has distinctly proved that
the peculiar properties of this acid arise from the
combined action of its two acidifiable bases;
and for this reason we have judged it necessary
to distinguish it by an appropriate name: that
of nitro-muriatic acid appears extremely ap-
plicable, from its expressing the nature of the
two substances which enter into its composition,
plicable, from its expressing the nature of
the two substances which enter into its com-
position.

This phenomenon of a double base in one

LAVOISIER

acid, which had formerly been observed only
in the nitro-muriatic acid, occurs continually
in the vegetable kingdom, in which a simple
acid, or one possessed of a single acidifiable
base, is very rarely found. Almost all the acids
procurable from this kingdom have bases com-
posed of charcoal and hydrogen, or of charcoal,
hydrogen, and phosphorus, combined with
more or less oxygen. All these bases, whether
double or triple, are likewise formed into ox-
ides, having less oxygen than is necessary to
give them the properties of acids. The acids
and oxides from the animal kingdom are still
more compound, as their bases generally con-
sist of a combination of charcoal, phosphorus,
hydrogen, and azote.

As it is but of late that I have acquired any
clear and distinct notions of these substances,
I shall not, in this place, enlarge much upon
the subject, which I mean to treat of very fully
in some Mtmoires I am preparing to lay before
the Academy. Most of my experiments are al-
ready performed ; but, to be able to give exact
reports of the resulting quantities, it is neces-
sary that they be carefully repeated and in-
creased in number: wherefore, I shall only give
a short enumeration of the vegetable and ani-
mal acids and oxides and terminate this article
by a few reflections upon the composition of
vegetable and animal bodies.

Sugar, mucus, under which term we include
the different kinds of gums, and starch, are
vegetable oxides, having hydrogen and char-
coal combined, in different proportions, as their
radicals or bases, and united with oxygen so as
to bring them to the state of oxides. From the
state of oxides they are capable of being changed
into acids by the addition of a fresh quantity
of oxygen; and, according to the degrees of
oxygenation, and the proportion of hydrogen
and charcoal, in their bases, they form the sev-
eral kinds of vegetable acids.

It would be easy to apply the principles of
our nomenclature to give names to these vege-
table acids and oxides by using the names of
the two substances which compose their bases:
they would thus become hydro-carbonous acids
and oxides. In this method we might indicate
which of their elements existed in excess, with-
out circumlocution, after the manner used by
M. Rouelle for naming vegetable extracts: he
calls these extracto-resinous when the extractive
matter prevails in their composition, and resir
no-extractive when they contain a larger pro-
portion of resinous matter. Upon that plan,
and by varying the terminations according to

the formerly established rules of our nomen-
clature, we have the following denominations:
hydro-carbonou8, hydro-carbonic; carbono-hyd-
rous, and carbono-hydric oxides. And for the
acids: hydro-carbonous, hydro carbonic, oxygen-
ated hydro-carbonic; carbono-hydrous, carbono-
hydric, and oxygenated carbono-hydric. It is
probable that the above terms would suffice
for indicating all the varieties in nature, and
that, in proportion as the vegetable acids be-
come well understood, they will naturally ar-
range themselves under these denominations.
But, though we know the elements of which
these are composed, we are as yet ignorant of
the proportions of these ingredients and are
still far from being able to class them in the
above methodical manner; wherefore, we have
determined to retain the ancient names pro-
visionally. I am somewhat further advanced in
this inquiry than at the time of publishing our
conjunct essay upon chemical nomenclature,
yet it would be improper to draw decided con-
sequences from experiments not yet sufficiently
precise. Though I acknowledge that this part
of chemistry still remains in some degree ob-
scure, I must express my expectations of its
being very soon elucidated.

I am still more forcibly necessitated to fol-
low the same plan in naming the acids which
have three or four elements combined in their
bases; of these we have a considerable number
from the animal kingdom, and some even from
vegetable substances. Azote, for instance, joined
to hydrogen and charcoal forms the base or
radical of prussic acid; we have reason to be-
lieve that the same happens with the base of
gallic acid; and almost all the animal acids
have their bases composed of azote, phosphor-
us, hydrogen, and charcoal. Were we to en-
deavour to express at once all these four com-
ponent parts of the bases, our nomenclature
would undoubtedly be methodical; it would
have the property of being clear and determin-
ate; but this assemblage of Greek and Latin
substantives and adjectives, which are not yet
universally admitted by chemists, would have
the appearance of a barbarous language, diffi-
cult both to pronounce and to be remembered.
Besides, this part of chemistry being still far
from that accuracy it must arrive to, the per-
fection of the science ought certainly to pre-
cede that of its language; and we must still,
for some time, retain the old names for the
animal oxides and acids. We have only ven-
tured to make a few slight modifications of
these names, by changing the termination into

CHEMISTRY

oua when we have reason to suppose the base
to be in excess, and into ic when we suspect the
oxygen predominates.

The following are all the vegetable acids
hitherto known:

CHAPTER XII

8. Pyro-mucous acid

9. Pyro-lignous acid

10. Gallic acid

11. Benzoic acid

12. Camphoric acid

13. Succinic acid

1. Acetous acid

2. Acetic acid

3. Oxalic acid

4. Tartarous acid

5. Pyro-tartarous acid

6. Citric acid

7. Malic acid

Though all these acids, as has been already
said, are chiefly, and almost entirely, composed
of hydrogen, charcoal, and oxygen, yet, prop-
erly speaking, they contain neither water, car-
bonic acid, nor oil but only the elements neces-
sary for forming these substances. The power
of affinity reciprocally exerted by the hydro-
gen, charcoal, and oxygen, in these acids is in a
state of equilibrium only capable of existing in
the ordinary temperature of the atmosphere;
for, when they are heated but a very little
above the temperature of boiling water, this
equilibrium is destroyed, part of the oxygen
and hydrogen unite and form water; part of
the charcoal and hydrogen combine into oil;
part of the charcoal and oxygen unite to form
carbonic acid; and, lastly, there generally re-
mains a small portion of charcoal, which, being
in excess with respect to the other ingredients,
is left free. I mean to explain this subject some-
what farther in the succeeding chapter.

The oxides of the animal kingdom are less
known than those from the vegetable kingdom,
and their number is as yet not at ail deter-
mined. The red part of the blood, lymph, and
most of the secretions, are true oxides, under
which point of view it is very important to con-
sider them. We are only acquainted with six
animal acids, several of which, it is probable,
approach very near each other in their nature,
or, at least, differ only in a scarcely sensible
degree. I do not include the phosphoric acid
amongst these, because it is found in all the
kingdoms of nature. They are:

1. Lactic acid 4. Formic acid

2. Saccho-lactic acid 5. Sebacic acid

3. Bombic acid 6. Prussic acid
The connection between the constituent ele-
ments of the animal oxides and acids is not
more permanent than in those from the vege-
table kingdom, as a small increase of tempera-
ture is sufficient to overturn it. I hope to ren-
der this subject more distinct in the following
chapter than has been done hitherto.

Of the Decomposition of Vegetable and Animal
Substances by the Action of Fire

BEFORE we can thoroughly comprehend what
takes place during the decomposition of vege-
table substances by fire, we must take into
consideration the nature of the elements which
enter into their composition, the different af-
finities which the particles of these elements
exert upon each other, and the affinity which
caloric possesses with them. The true constit-
uent elements of vegetables are hydrogen, oxy-
gen, and charcoal: these are common to all
vegetables, and no vegetable can exist without
them. Such other substances as exist in partic-
ular vegetables are only essential to the com-
position of those in which they are found and
do not belong to vegetables in general.

Of these elements, hydrogen and oxygen
have a strong tendency to unite with caloric
and be converted into gas, whilst charcoal is a
fixed element having but little affinity with
caloric. On the other hand, oxygen, which, in
the usual temperature, tends nearly equally to
unite with hydrogen and with charcoal, has a
much stronger affinity with charcoal when at
red heat 1 and then unites with it to form car-
bonic acid.

Although we are far from being able to ap-
preciate all these powers of affinity, or to ex-
press their proportional energy by numbers,
we are certain that, however variable they may
be when considered in relation to the quantity
of caloric with which they are combined, they
are all nearly in equilibrium in the usual tem-
perature of the atmosphere; hence vegetables
neither contain oil, 2 water, nor carbonic acid,
tho' they contain all the elements of these sub-
stances. The hydrogen is neither combined
with the oxygen nor with the charcoal, and re-
ciprocally; the particles of these three sub-
stances form a triple combination which remains
in equilibrium whilst undisturbed by caloric,
but a very slight increase of temperature is suf-

i Though this term, red heat, does not indicate any
absolutely determinate degree of temperature, I
shall use it sometimes to express a temperature con-
siderably above that of boiling water. AUTHOR.

> I must be understood here to speak of vegetables
reduced to a perfectly dry state; and, with respect to
oil, I do not mean that which is procured by expres-
sion either in the cold, or in a temperature not ex-
ceeding that of boiling water; I only allude to the
empyreumatic oil procured by distillation with a
naked fire, in a heat superior to the temperature of
boiling water; which is the only oil declared to be
produced by the operation of fire. What I have pub-
lished upon this subject in the Recueil de VAcadtmie
for 1786 may be consulted. AUTHOR.

LAVOISIER

ficient to overturn this structure of combination.

If the increased temperature to which the
vegetable is exposed does not exceed the heat
of boiling water, one part of the hydrogen com-
bines with the oxygen and forms water, the
rest of the hydrogen combines with a part of
the charcoal and forms volatile oil, whilst the
remainder of the charcoal, being set free from its
combination with the other elements, remains
fixed in the bottom of the distilling vessel.

When, on the contrary, we employ red heat,
no water is formed, or, at least, any that may
have been produced by the first application of
the heat is decomposed, the oxygen having a
greater affinity with the charcoal at this de-
gree of heat combines with it to form carbonic
acid, and the hydrogen being left free from
combination with the other elements unites
with caloric and escapes in the state of hydro-
gen gas. In this high temperature, either no oil
is formed, or, if any was produced during the
lower temperature at the beginning of the ex-
periment, it is decomposed by the action of
the red heat. Thus the decomposition of vege-
table matter, under a high temperature, is pro-
duced by the action of double and triple affin-
ities; while the charcoal attracts the oxygen on
purpose to form carbonic acid, the caloric at-
tracts the hydrogen and converts it into hy-
drogen gas.

The distillation of every species of vegetable
substance confirms the truth of this theory, if
we can give that name to a simple relation of
facts. When sugar is submitted to distillation,
so long as we only employ a heat but a little
below that of boiling water, it only loses its
water of crystallization, it still remains sugar
and retains all its properties; but, immediately
upon raising the heat only a little above that
degree, it becomes blackened, a part of the
charcoal separates from the combination, water
slightly acidulated passes over accompanied
by a little oil, and the charcoal which remains
in the retort is nearly a third part of the orig-
inal weight of the sugar.

The operation of affinities which take place
during the decomposition, by fire, of vegetables
which contain azote, such as the cruciferous
plants, and of those containing phosphorus, is
more complicated; but, as these substances
only enter into the composition of vegetables
in very small quantities, they only, apparent-
ly, produce slight changes upon the products
of distillation; the phosphorus seems to com-
bine with the charcoal and, acquiring fixity
from that union, remains behind in the retort,

while the azote, combining with a part of the
hydrogen, forms ammonia or volatile alkali.

Animal substances, being composed nearly
of the same elements with cruciferous plants,
give the same products in distillation, with
this difference that, as they contain a greater
quantity of hydrogen and azote, they produce
more oil and more ammonia. I shall only pro-
duce one fact as a proof of the exactness with
which this theory explains all the phenomena
which occur during the distillation of animal
substances, which is the rectification and total
decomposition of volatile animal oil, commonly
known by the name of Dippel's oil. When
these oils are procured by a first distillation in
a naked fire they are brown, from containing a
little charcoal almost in a free state; but they
become quite colourless by rectification. Even
in this state the charcoal in their composition
has so slight a connection with the other ele-
ments as to separate by mere exposure to the
air. If we put a quantity of this animal oil, well
rectified, and consequently clear, limpid, and
transparent, into a bell-glass filled with oxygen
gas over mercury, in a short time the gas is
much diminished, being absorbed by the oil,
the oxygen combining with the hydrogen of
the oil forms water which sinks to the bottom,
at the same time the charcoal which was com-
bined with the hydrogen, being set free, man-
ifests itself by rendering the oil black. Hence
the only way of preserving these oils colourless
and transparent, is by keeping them in bottles
perfectly full and accurately corked, to hinder
the contact of air, which always discolours them.

Successive rectifications of this oil furnish
another phenomenon confirming our theory.
In each distillation a small quantity of charcoal
remains in the retort, and a little water is
formed by the union of the oxygen contained
in the air of the distilling vessels with the hy-
drogen of the oil. As this takes place in each
successive distillation, if we make use of large
vessels and a considerable degree of heat, we
at last decompose the whole of the oil and
change it entirely into water and charcoal.
When we use small vessels, and especially when
we employ a slow fire or degree of heat little
above that of boiling water, the total decom-
position of these oils, by repeated distillation,
is greatly more tedious, and more difficult to
accomplish. I shall give a particular detail to
the Academy, in a separate Mtmoire, of all my
experiments upon the decomposition of oil;
but what I have related above may suffice to
give just ideas of the composition of animal

CHEMISTRY

and vegetable substances and of their decom-
position by the action of fire.

CHAPTER XIII

Of the Decomposition of Vegetable Oxides by the
Vinous Fermentation

THE manner in which wine, cider, mead, and
all the liquors formed by the spiritous fermen-
tation, are produced is well known to everyone.
The juice of grapes or of apples being expressed,
and the latter being diluted with water, they
are put into large vats which are kept in a
temperature of at least 10 (54.5) of the ther-
mometer. A rapid intestine motion, or fer-
mentation, very soon takes place; numerous
globules of gas form in the liquid and burst at
the surface; when the fermentation is at its
height, the quantity of gas disengaged is so
great as to make the liquor appear as if boiling
violently over a fire. When this gas is carefully
gathered, it is found to be carbonic acid per-
fectly pure and free from admixture with any
other species of air or gas whatever.

When the fermentation is completed, the
juice of grapes is changed from being sweet and
full of sugar into a vinous liquor which no
longer contains any sugar, and from which we
procure, by distillation, an inflammable liquor,
known in commerce under the name of spirit of
wine. As this liquor is produced by the fer-
mentation of any saccharine matter whatever
diluted with water, it must have been contrary
to the principles of our nomenclature to call it
spirit of wine rather than spirit of cider or of
fermented sugar; wherefore, we have adopted
a more general term, and the Arabic word
alcohol seems extremely proper for the purpose.

This operation is one of the most extraordi-
nary in chemistry. We must examine whence
proceed the disengaged carbonic acid and the
inflammable liquor produced and in what man-
ner a sweet vegetable oxide becomes thus con-
verted into two such opposite substances,
whereof one is combustible and the other em-
inently the contrary. To solve these two ques-
tions, it is necessary to be previously acquaint-
ed with the analysis of the fermentable sub-
stance and of the products of the fermentation.
We may lay it down as an incontestible axiom
that, in all the operations of art and nature,
nothing is created; an equal quantity of matter
exists both before and after the experiment;
the quality and quantity of the elements remain
precisely the same and nothing takes place be-
yond changes and modifications in the combina-

tion of these elements. Upon this principle the
whole art of performing chemical experiments
depends. We must always suppose an exact
equality between the elements of the body ex-
amined and those of the products of its analysis.

Hence, since from must of grapes we procure
alcohol and carbonic acid, I have an undoubted
right to suppose that must consists of carbonic
acid and alcohol. From these premises, we
have two methods of ascertaining what passes
during vinous fermentation, by determining
the nature of, and the elements which compose,
the fermentable substances, or by accurately
examining the products resulting from fermen-
tation; and it is evident that the knowledge of
either of these must lead to accurate conclu-
sions concerning the nature and composition of
the other. From these considerations, it be-
came necessary accurately to determine the
constituent elements of the fermentable sub-
stances; and, for this purpose, I did not make
use of the compound juices of fruits, the rigor-
ous analysis of which is perhaps impossible,
but made choice of sugar, which is easily ana-
lyzed and the nature of which I have already
explained. This substance is a true vegetable
oxide with two bases, composed of hydrogen
and charcoal brought to the state of an oxide
by a certain proportion of oxygen; and these
three elements are combined in such a way
that a very slight force is sufficient to destroy
the equilibrium of their connection. By a long
train of experiments, made in various ways,
and often repeated, I ascertained that the pro-
portion in which these ingredients exist in
sugar are nearly eight parts of hydrogen, 64
parts of oxygen, and 28 parts of charcoal, all
by weight, forming 100 parts of sugar.

Sugar must be mixed with about four times
its weight of water to render it susceptible of
fermentation; and even then the equilibrium
of its elements would remain undisturbed,
without the assistance of some substance to
give a commencement to the fermentation.
This is accomplished by means of a little yeast
from beer; and, when the fermentation is once
excited, it continues of itself until completed.
I shall, in another place, give an account of the
effects of yeast, and other ferments, upon fer-
mentable substances. I have usually employed
10 Ibs. of yeast, in the state of paste, for each
100 Ibs. of sugar, with as much water as is four
times the weight of the sugar. I shall give the
results of my experiments exactly as they were
obtained, preserving even the fractions pro-
duced by calculation.

LAVOISIER

TABLE I. Materials of Fermentation

Water
Sugar

Yeast in paste, 10 Ibs. composed of

Water
Dry yeast

Total

Ibs. oz. gros grs.

400

100

7 3 6 44

2 12 1 28

510

TABLE II. Constituent Elements of the Materials
of Fermentation

407 Ibs. 3 oz. 6 gros 44 grs. of water,
composed of

100 Ibs. sugar, composed of

2 Ibs. 12 oz. 1 gros 28 grs. of dry
yeast, composed of

Ibs.

oz.

gros

grs.

Hydrogen

71.40

Oxygen

346

44.60

Hydrogen

Oxygen

Charcoal

Hydrogen

9.30

Oxygen

28.76

Charcoal

Azote

2.94

Total 510

TABLE III. Recapitulation of these Elements

Ibs. oz. gros grs. Ibs. oz. gros grs.

of water

340

of water in yeast
of sugar

6
64

44.60

411

1.36

of dry yeast

28.76

of water

of water in yeast
of sugar

71.40

8.70

of dry yeast

9.30

of sugar
of yeast

59.00

Azote of yeast

2.94

Total

510

Having thus accurately determined the na-
ture and quantity of the constituent elements
of the materials submitted to fermentation, we
have next to examine the products resulting
from that process. For this purpose, I placed
the above 510 Ibs. of fermentable liquor in a
proper 1 apparatus, by means of which I could
accurately determine the quantity and quality
of gas disengaged during the fermentation, and
could even weigh every one of the products
separately, at any period of the process I j udged
proper. An hour or two after the substances
are mixed together, especially if they are kept
in a temperature of from 15 (65.75) to 18

The above apparatus is described in the Third
Part. AUTHOR.

(72.5) of the thermometer, the first marks of
fermentation commence; the liquor turns thick
and frothy, little globules of air are disengaged
which rise and burst at the surface; the quan-
tity of these globules quickly increases, and
there is a rapid and abundant production of
very pure carbonic acid, accompanied with a
scum which is the yeast separating from the
mixture. After some days, less or more accord-
ing to the degree of heat, the intestine motion
and disengagement of gas diminish; but these
do not cease entirely, nor is the fermentation
completed for a considerable time. During the
process, 35 Ibs. 5 oz. 4 gros 19 grs. of dry car-
bonic acid are disengaged, which carry alongst
with them 13 Ibs. 14 oz. 5 gros of water. There

CHEMISTRY

remains in the vessel 460 Ibs. 11 oz. 6 gros 53
grs. of vinous liquor, slightly acidulous. This
is at first muddy, but clears of itself, and de-
posits a portion of yeast. When we separately
analyse all these substances, which is effected

by very troublesome processes, we have the re-
sults as given in the following tables. This proc-
ess, with all the subordinate calculations and
analyses, will be detailed at large in the Recueil
de I' Academic.

TABLE IV. Products of Fermentation

Ibs. oz. gros grs.

35 Ibs. 5 oz. 4 gros 19 grs. of
carbonic acid, composed
of

Oxygen 25
Charcoal 9

7
14

1
2

34
57

408 Ibs. 15 oz. 5 gros 14 grs.

Oxygen 347

'59

of water, composed of

Hydrogen 61

Oxygen, combined

with hydrogen 31

Hydrogen, combined

57 Ibs. 1 1 oz. 1 gros 58 grs. of

with oxygen 5

dry alcohol, composed

Hydrogen, combined

with charcoal 4

Charcoal, combined

with hydrogen 16

2 Ibs. 8 oz. of dry acetous
acid, composed of

Hydrogen
Oxygen 1
Charcoal

11
10

4
4

4 Ibs. 1 oz. 4 gros 3 grs. of

Hydrogen

residuum of sugar,

Oxygen 2

composed of

Charcoal 1

Hydrogen

1 Ib. 6 oz. gros 5 grs. of

Oxygen

dry yeast, composed of

Charcoal

Azote

510 Ibs. Total 510

TABLE V. Recapitulation of the Products

Ibs.

oz.

gros

grs.

Water 347

Carbonic acid 25

409 Ibs. 10 oz. gros 54 grs.

Alcohol 31

of oxygen contained in

Acetous acid 1

the

Residuum of sugar 2

Yeast

Carbonic acid 9

28 Ibs. 12 oz. 5 gros 59 grs.
of charcoal contained in

thft

Alcohol 16
Acetous acid
Residuum of sugar 1

11
10
2

I/ 11"

Yeast

Water 61

Water of the alcohol 5

71 Ibs. 8 oz. 6 gros 66 grs. of
hydrogen, contained in

Combined with the
charcoal of the al-
cohol 4

the

Acetous acid

Residuum of sugar

Yeast

2 gros 37 grs. of azote in the yeast

510 Ibs. Total 510

LAVOISIER

In these results I have been exact, even to
grains; not that it is possible, in experiments
of this nature, to carry our accuracy so far, but
as the experiments were made only with a few
pounds of sugar, and as, for the sake of com-
parison, I reduced the results of the actual ex-
periments to the quintal or imaginary hundred
pounds, I thought it necessary to leave the
fractional parts precisely as produced by cal-
culation.

When we consider the results presented by
these tables with attention, it is easy to dis-
cover exactly what occurs during fermentation.
In the first place, out of the 100 Ibs. of sugar
employed, 4 /6s. 1 oz. 4 gros 3 grs. remain, with-
out having suffered decomposition; so that, in
reality, we have only operated upon 95 Ibs. 14
oz. 3 gros 69 grs. of sugar; that is to say, upon
61 Ibs. 6 oz. 45 grs. of oxygen, 7 Ibs. 10 oz. 6 gros
6 grs. of hydrogen, and 26 Ibs. 13 oz. 5 gros 19
grs. of charcoal. By comparing these quanti-
ties, we find that they are fully sufficient for
forming the whole of the alcohol, carbonic
acid and acetous acid produced by the fer-
mentation. It is not, therefore, necessary to
suppose that any water has been decomposed
during the experiment, unless it be pretended
that the oxygen and hydrogen exist in the
sugar in that state. On the contrary, I have al-
ready made it evident that hydrogen, oxygen
and charcoal, the three constituent elements of
vegetables, remain in a state of equilibrium or
mutual union with each other which subsists
so long as this union remains undisturbed by
increased temperature, or by some new com-
pound attraction; and that then only these ele-
ments combine, two and two together, to form
water and carbonic acid.

The effects of the vinous fermentation upon
sugar is thus reduced to the mere separation of
its elements into two portions; one part is oxy-
genated at the expense of the other so as to
form carbonic acid, whilst the other part, be-
ing disoxygenated in favour of the former, is
converted into the combustible substance alco-
hol; therefore, if it were possible to reunite al-
cohol and carbonic acid together, we ought to
form sugar. It is evident that the charcoal and
hydrogen in the alcohol do not exist in the
state of oil. They are combined with a portion
of oxygen, which renders them miscible with
water; wherefore these three substances, oxy-
gen, hydrogen, and charcoal, exist here like-
wise in a species of equilibrium or reciprocal
combination; and in fact, when they are made
to pass through a red hot tube of glass or por-

celain, this union or equilibrium is destroyed,
the elements become combined, two and two,
and water and carbonic acid are formed.

I had formally advanced, in my first Mem-
oires upon the formation of water, that it was
decomposed in a great number of chemical ex-
periments and particularly during the vinous
fermentation. I then supposed that water ex-
isted ready formed in sugar, though I am now
convinced that sugar only contains the ele-
ments proper for composing it. It may be read-
ily conceived that it must have cost me a good
deal to abandon my first notions, but by sev-
eral years reflection, and after a great number
of experiments- and observations upon vege-
table substances, I have fixed my ideas as
above.

I shall finish what I have to say upon vinous
fermentation by observing that it furnishes us
with the means of analysing sugar and every
vegetable fermentable matter. We may con-
sider the substances submitted to fermenta-
tion, and the products resulting from that op-
eration, as forming an algebraic equation; and,
by successively supposing each of the elements
in this equation unknown, we can calculate
their values in succession, and thus verify our
experiments by calculation, and our calculation
by experiment reciprocally. I have often suc-
cessfully employed this method for correcting
the first results of my experiments and to direct
me in the proper road for repeating them to
advantage. I have explained myself at large
upon this subject, in a Memoir e upon vinous
fermentation already presented to the Acad-
emy which will speedily be published.

CHAPTER XIV

Of the Putrefactive Fermentation

THE phenomena of putrefaction are caused,
like those of vinous fermentation, by the oper-
ation of very complicated affinities. The con-
stituent elements of the bodies submitted to
this process cease to continue in equilibrium in
the threefold combination and form themselves
anew into binary combinations, or compounds,
consisting of two elements only; but these are
entirely different from the results produced by
the vinous fermentation. Instead of one part of
the hydrogen remaining united with part of
the water and charcoal to form alcohol, as in
the vinous fermentation, the whole of the hy-
drogen is dissipated, during putrefaction, in
the form of hydrogen gas, whilst, at the same

CHEMISTRY

time, the oxygen and charcoal, uniting with
caloric, escape in the form of carbonic acid gas ;
so that, when the whole process is finished, es-
pecially if the materials have been mixed with
a sufficient quantity of water, nothing remains
but the earth of the vegetable mixed with a
small portion of charcoal and iron. Thus pu-
trefaction is nothing more than a complete
analysis of vegetable substance, during which
the whole of the constituent elements is disen-
gaged in form of gas, except the earth which
remains in the state of mould. 1

Such is the result of putrefaction when the
substances submitted to it contain only oxy-
gen, hydrogen, charcoal and a little earth. But
this case is rare, and these substances putrify
imperfectly and with difficulty, and require a
considerable time to complete their putrefac-
tion. It is otherwise with substances contain-
ing azote, which indeed exists in all animal
matters and even in a considerable number of
vegetable substances. This additional element
is remarkably favourable to putrefaction; and
for this reason animal matter is mixed with
vegetable when the putrefaction of these is
wished to be hastened. The whole art of form-
ing composts and dunghills, for the purposes of
agriculture, consists in the proper application
of this admixture.

The addition of azote to the materials of
putrefaction not only accelerates the process;
that element likewise combines with part of
the hydrogen and forms a new substance called
volatile alkali or ammonia. The results obtained
by analysing animal matters, by different proc-
esses, leave no room for doubt with regard to
the constituent elements of ammonia; when-
ever the azote has been previously separated
from these substances, no ammonia is pro-
duced; and in all cases they furnish ammonia
only in proportion to the azote they contain.
This composition of ammonia is likewise fully
proved by M. Berthollet, in the Recueil de
VAcademie for 1785, p. 316, where he gives a
variety of analytical processes by which am-
monia is decomposed and its two elements,
azote and hydrogen, procured separately.

I mentioned in Chapter X that almost all
combustible bodies were capable of combining
with each other. Hydrogen gas possesses this
quality in an eminent degree; it dissolves char-
coal, sulphur, and phosphorus, producing the
compounds named carbonated hydrogen gas,

In the Third Part will be given the description of
an apparatus proper for being used in experiments of
this kind. AUTHOR.

sulphurated hydrogen gas, and phosphorated hy-
drogen gas. The two latter of these gases have a
peculiarly disagreeable flavour; the sulphur-
ated hydrogen gas has a strong resemblance
to the smell of rotten eggs, and the phosphor-
ated smells exactly like putrid fish. Ammonia
has likewise a peculiar odour, not less pene-
trating or less disagreeable than these other
gases. From the mixture of these different fla-
vours proceeds the fetor which accompanies
the putrefaction of animal substances. Some-
times ammonia predominates, which is easily
perceived by its sharpness upon the eyes;
sometimes, as in feculent matters, the sulphur-
ated gas is most prevalent; and sometimes, as
in putrid herrings, the phosphorated hydrogen
gas is most abundant.

I long supposed that nothing could derange
or interrupt the course of putrefaction; but M.
Fourcroy and M. Thouret have observed
some peculiar phenomena in dead bodies,
buried at a certain depth and preserved to a
certain degree from contact with air, having
found the muscular flesh frequently converted
into true animal fat. This must have arisen
from the disengagement of the azote, naturally
contained in the animal substance, by some
unknown cause, leaving only the hydrogen
and charcoal remaining, which are the ele-
ments proper for producing fat or oil. This ob-
servation upon the possibility of converting
animal substances into fat may some time or
other Lead to discoveries of great importance
to society. The faeces of animals, and other ex-
crementitious matters, are chiefly composed of
charcoal and hydrogen and approach consider-
ably to the nature of oil, of which they furnish
a considerable quantity by distillation with a
naked fire; but the intolerable fetor which ac-
companies all the products of these substances
prevents our expecting that, at least for a long
time, they can be rendered useful in any other
way than as manures.

I have only given conjectural approxima-
tions in this chapter upon the composition of
animal substances, which is hitherto but im-
perfectly understood. We know that they are
composed of hydrogen, charcoal, azote, phos-
phorus, and sulphur, all of which, in a state of
quintuple combination, are brought to the state
of oxides by a larger or smaller quantity of oxy-
gen. We are, however, still unacquainted with
the proportions in which these substances are
combined, and must leave it to time to com-
plete this part of chemical analysis, as it has
already done with several others.

LAVOISIER

CHAPTER XV
Of the Acetous Fermentation

THE acetous fermentation is nothing more
than the acidification or oxygenation of wine,
produced in the open air by means of the ab-
sorption of oxygen. The resulting acid is the
acetous acid, commonly called vinegar, which
is composed of hydrogen and charcoal united
together in proportions not yet ascertained
and changed into the acid state by oxygen. As
vinegar is an acid, we might conclude from
analogy that it contains oxygen, but this is put
beyond doubt by direct experiments: in the
first place, we cannot change wine into vinegar
without the contact of air containing oxygen;
secondly, this process is accompanied by a di-
minution of the volume of the air in which it is
carried on from the absorption of its oxygen;
and, thirdly, wine may be changed into vinegar
by any other means of oxygenation.

Independent of the proofs which these facts
furnish of the acetous acid being produced by
the oxygenation of wine, an experiment made
by M. Chaptai, Professor of Chemistry at
Montpellier, gives us a distinct view of what
takes place in this process. He impregnated
water with about its own bulk of carbonic aeid
from fermenting beer and placed this water in
a cellar in vessels communicating with the air,
and in a short time the whole was converted
into acetous acid. The carbonic acid gas pro-
cured from beer vats in fermentation is not
perfectly pure but contains a small quantity of
alcohol in solution, wherefore water impreg-
nated with it contains all the materials neces-
sary for forming the acetous acid. The alcohol
furnishes hydrogen and one portion of char-
coal, the carbonic acid furnishes oxygen and
the rest of the charcoal, and the air of the at-
mosphere furnishes the rest of the oxygen nec-
essary for changing the mixture into acetous
acid. From this observation it follows that
nothing but hydrogen is wanting to convert
carbonic acid into acetous acid; or more gen-
erally that, by means of hydrogen and accord-
ing to the degree of oxygenation, carbonic acid
may be changed into all the vegetable acids;
and, on the contrary, that, by depriving any
of the vegetable acids of their hydrogen, they
may be converted into carbonic acid.

Although the principal facts relating to the
acetous acid are well known, yet numerical ex-
actitude is still wanting, till furnished by more
exact experiments than any hitherto performed ;
wherefore I shall not enlarge any farther upon

the subject. It is sufficiently shown by what
has been said that the constitution of all the
vegetable acids and oxides is exactly conform-
able to the formation of vinegar; but further
experiments are necessary to teach us the pro-
portion of the constituent elements in all these
acids and oxides. We may easily perceive, how-
ever, that this part of chemistry, like all the
rest of its divisions, makes rapid progress to-
wards perfection, and that it is already rendered
greatly more simple than was formerly believed.

CHAPTER XVI

Of the Formation of Neutral Salts and of their
Different Bases

WE have just seen that all the oxides and acids
from the animal and vegetable kingdoms are
formed by means of a small number of simple
elements, or at least of such as have not hither-
to been susceptible of decomposition, by means
of combination with oxygen; these are azote,
sulphur, phosphorus, charcoal, hydrogen, and
the muriatic radical. We may justly admire
the simplicity of the means employed by na-
ture to multiply qualities and forms, whether
by combining three or four acidifiable bases in
different proportions or by altering the dose of
oxygen employed for oxidating or acidifying
them. We shall find the means no less simple
and diversified, and as abundantly productive
of forms and qualities, in the order of bodies
we are now about to treat of.

Acidifiable substances, by combining with
oxygen and their consequent conversion into
acids, acquire great susceptibility of further
combination; they become capable of uniting
with earthy and metallic bodies, by which
means neutral salts are formed. Acids may
therefore be considered as true salifying prin-
ciples, and the substances with which they
unite to form neutral salts may be called sali-
fiable bases. The nature of the union which
these two principles form with each other is
meant as the subject of the present chapter.

This view of the acids prevents me from con-
sidering them as salts, though they are pos-
sessed of many of the principal properties of
saline bodies, as solubility in water, &c. I have
already observed that they are the result of a
first order of combination, being composed of
two simple elements, or at least of elements
which act as if they were simple, and we may
therefore rank them, to use the language of
Stahl, in the order of mixts. The neutral salts,

CHEMISTRY

on the contrary, are of a secondary order of
combination, being formed by the union of two
mixts with each other, and may therefore be
termed compounds. Hence I shall not arrange
the alkalies 1 or earths in the class of salts, to
which I allot only such as are composed of an
oxygenated substance united to a base.

I have already enlarged sufficiently upon the
formation of acids in the preceding chapter
and shall not add anything further upon that
subject; but having as yet given no account of
the salifiable bases which are capable of uniting
with them to form neutral salts, I mean in this
chapter to give an account of the nature and
origin of each of these bases. These are potash,
soda, ammonia, lime, magnesia, barytes, ar-
gill, and all the metallic bodies.

Of Potash

We have already shown that, when a vege-
table substance is submitted to the action of
fire in distilling vessels, its component elements,
oxygen, hydrogen, and charcoal, which formed
a threefold combination in a state of equilib-
rium, unite, two and two, in obedience to affin-
ities which act conformably to the degree of
heat employed. Thus, at the first application
of the fire, whenever the heat produced ex-
ceeds the temperature of boiling water, part of
the oxygen and hydrogen unite to form water;
soon after, the rest of the hydrogen, and part
of the charcoal, combine into oil; and, lastly,
when the fire is pushed to red heat, the oil and
water, which had been formed in the early part
of the process, become again decomposed, the
oxygen and charcoal unite to form carbonic
acid, a large quantity of hydrogen gas is set free,
and nothing but charcoal remains in the retort.

A great part of these phenomena occur dur-
ing the combustion of vegetables in the open
air; but, in this case, the presence of the air in-
troduces three new substances, the oxygen and
azote of the air, and caloric, of which two at
least produce considerable changes in the re-
sults of the operation. In proportion as the hy-
drogen of the vegetable, or that which results
from the decomposition of the water, is forced
out in the form of hydrogen gas by the progress
of the fire, it is set on fire immediately upon
getting in contact with the air, water is again

1 Perhaps my thus rejecting the alkalies, from the
class of salts may be considered as a capital defect in
the method I have adopted, and I am ready to admit
the charge; but this inconvenience is compensated
by so many advantages, that I could not think it of
sufficient consequence to make me alter my plan.
AUTHOB.

formed, and the greater part of the caloric of
the two gases becoming free produces flame.
When all the hydrogen gas is driven out, burnt,
and again reduced to water, the remaining
charcoal continues to burn, but without flame;
it is formed into carbonic acid, which carries off
a portion of caloric sufficient to give it the gas-
eous form; the rest of the caloric, from the oxy-
gen of the air, being set free, produces the heat
and light observed during the combustion of
charcoal. The whole vegetable is thus reduced
into water and carbonic acid, and nothing re-
mains but a small portion of gray earthy mat-
ter called ashes, being the only really fixed
principles which enter into the constitution of
vegetables.

The earth, or rather ashes, which seldom ex-
ceeds a twentieth part of the weight of the veg-
etable, contains a substance of a particular na-
ture, known under the name of fixed vegetable
alkali or potash. To obtain it, water is poured
upon the ashes, which dissolves the potash and
leaves the ashes which are insoluble; by after-
wards evaporating the water, we obtain the
potash in a white concrete form : it is very fixed
even in a very high degree of heat. I do not
mean here to describe the art of preparing pot-
ash, or the method of procuring it in a state of
purity, but have entered upon the above detail
that I might not use any word not previously
explained.

The potash obtained by this process is al-
ways less or more saturated with carbonic acid,
which is easily accounted for. As the potash
does not form, or at least is not set free, but in
proportion as the charcoal of the vegetable is
converted into carbonic acid by the addition of
oxygen, either from the air or the water, it fol-
lows that each particle of potash, at the instant
of its formation, or at least of its liberation, is
in contact with a particle of carbonic acid, and,
as there is a considerable affinity between these
two substances, they naturally combine to-
gether. Although the carbonic acid has lees af-
finity with potash than any other acid, yet it
is difficult to separate the last portions from it.
The most usual method of accomplishing this
is to dissolve the potash in water; to this solu-
tion add two or three times its weight of quick-
lime, then filtrate the liquor and evaporate it
in close vessels; the saline substance left by the
evaporation is potash almost entirely deprived
of carbonic acid. In this state it is soluble in an
equal weight of water, and even attracts the
moisture of the air with great avidity; by this
property it furnishes us with an excellent means

LAVOISIER

of rendering air or gas dry by exposing them to
its action. In this state it is soluble in alcohol,
though not when combined with carbonic acid;
and M. Berthollet employs this property as a
method of procuring potash in the state of per-
fect purity.

All vegetables yield less or more of potash in
consequence of combustion, but it is furnished
in various degrees of purity by different vege-
tables; usually, indeed, from all of them it is
mixed with different salts from which it is easi-
ly separable. We can hardly entertain a doubt
that the ashes or earth which is left by vege-
tables in combustion pre-existed in them be-
fore they were burnt, forming what may be
called the skeleton or osseous part of the veg-
etable. But it is quite otherwise with potash;
this substance has never yet been procured
from vegetables but by means of processes or
intermedia capable of furnishing oxygen and
azote, such as combustion, or by means of ni-
tric acid; so that it is not yet demonstrated
that potash may not be a produce from these
operations. I have begun a series of experi-
ments upon this object and hope soon to be
able to give an account of their results.

Of Soda

Soda, like potash, is an alkali procured by
lixiviation from the ashes of burnt plants, but
only from those which grow upon the seaside,
and especially from the herb kali, whence is de-
rived the name alkali given to this substance
by the Arabians. It has some properties in com-
mon with potash and others which are entirely
different. In general, these two substances have
peculiar characters in their saline combinations
which are proper to each and consequently dis-
tinguish them from each other ; thus soda, which,
as obtained from marine plants, is usually en-
tirely saturated with carbonic acid, does not at-
tract the humidity of the atmosphere like pot-
ash, but, on the contrary, desiccates, its crystals
effloresce and are converted into a white pow-
der having all the properties of soda, which it
really is, having only lost its water of crystal-
lization.

We are not better acquainted with the con-
stituent elements of soda than with those of
potash, being equally uncertain whether it
previously existed ready formed in the vege-
table or is a combination of elements effected
by combustion. Analogy leads us to suspect
that azote is a constituent element of all the
alkalies, as is the case with ammonia; but we
have only slight presumptions, unconfirmed

by any decisive experiments, respecting the
composition of potash and soda.

Of Ammonia

We have, however, very accurate knowledge
of the composition of ammonia, or volatile al-
kali as it is called by the old chemists. M. Ber-
thollet, in the Recueil de I'Acadtmie for 1784,
p. 316, has proved by analysis, that 1000 parts
of this substance consist of about 807 parts of
azote combined with 193 parts of hydrogen.

Ammonia is chiefly procurable from animal
substances by distillation, during which proc-
ess the azote and hydrogen necessary to its for-
mation unite in proper proportions; it is not,
however, procured pure by this process, being
mixed with oil and water and mostly saturated
with carbonic acid. To separate these sub-
stances it is first combined with an acid, the
muriatic for instance, and then disengaged
from that combination by the addition of lime
or potash. When ammonia is thus produced in
its greatest degree of purity, it can only exist
under the gaseous form, at least in the usual
temperature of the atmosphere; it has an ex-
cessively penetrating smell, is absorbed in
large quantities by water, especially if cold and
assisted by compression. Water thus saturated
with ammonia has usually been termed volatile
alkaline fluor; we shall call it either simply am-
monia, or liquid ammonia, and ammoniacal gas
when it exists in the aeriform state.

Of Lime, Magnesia, Barytes, and Argill

The composition of these four earths is total-
ly unknown, and, until by new discoveries their
constituent elements are ascertained, we are
certainly authorised to consider them as simple
bodies. Art has no share in the production of
these earths, as they are all procured ready
formed from nature; but, as they have all, es-
pecially the three first, great tendency to com-
bination, they are never found pure. Lime is
usually saturated with carbonic acid in the
state of chalk, calcareous spars, most of the
marbles, &c.; sometimes with sulphuric acid,
as in gypsum and plaster stones; at other times
with fluoric acid forming vitreous or fluor spars ;
and, lastly, it is found in the waters of the sea,
and of saline springs, combined with muriatic
acid. Of all the salifiable bases it is the most
universally spread through nature.

Magnesia is found in mineral waters, for the
most part combined with sulphuric acid; it is
likewise abundant in sea-water, united with
muriatic acid; and it exists in a great number

CHEMISTRY

of stones of different kinds.

Barytes is much less common than the three
preceding earths; it is found in the mineral
kingdom, combined with sulphuric acid, form-
ing heavy spars, and sometimes, though rarely,
united to carbonic acid.

Argill, or the base of alum, having less tend-
ency to combination than the other earths, is
often found in the state of argill, uncombined
with any acid. It is chiefly procurable from
clays, of which, properly speaking, it is the
base or chief ingredient.

Of Metallic Bodies

The metals, except gold and sometimes sil-
ver, are rarely found in the mineral kingdom in
their metallic state, being usually less or more
saturated with oxygen, or combined with sul-
phur, arsenic, sulphuric acid, muriatic acid,
carbonic acid, or phosphoric acid. Metallurgy,
or the docimastic art, teaches the means of
separating them from these foreign matters;
and for this purpose we refer to such chemical
books as treat upon these operations.

We are probably only acquainted as yet
with a part of the metallic substances existing
in nature, as all those which have a stronger
affinity to oxygen than charcoal possesses are
incapable of being reduced to the metallic
state and, consequently, being only presented
to our observation under the form of oxides,
are confounded with earths. It is extremely
probable that barytes, which we have just
now arranged with earths, is in this situation;
for in many experiments it exhibits proper-
ties nearly approaching to those of metallic
bodies. It is even possible that ail the sub-
stances we call earths may be only metallic
oxides, irreducible by any hitherto known
process.

Those metallic bodies we are at present ac-
quainted with, and which we can reduce to the
metallic or reguline state, are the following
seventeen:

1. Arsenic 7. Bismuth 13. Copper

2. Molybdenum 8. Antimony 14. Mercury

3. Tungsten 9. Zinc 15. Silver

4. Manganese 10. Iron 16. Platinum

5. Nickel 11. Tin 17. Gold

6. Cobalt 12. Lead

I only mean to consider these as salifiable
bases, without entering at all upon the consid-
eration of their properties in the arts and for
the uses of society. In these points of view each
metal would require a complete treatise, which

would lead me far beyond the bounds I have
prescribed for this work.

CHAPTER XVII

Continuation of the Observations upon Salifiabk
Bases and the Formation of Neutral Salts

IT is necessary to remark that earths and al-
kalies unite with acids to form neutral salts
without the intervention of any medium, where-
as metallic substances are incapable of forming
this combination without being previously less
or more oxygenated; strictly speaking, there-
fore, metals are not soluble in acids but only
metallic oxides. Hence, when we put a metal
into an acid for solution, it is necessary, in the
first place, that it become oxygenated, either
by attracting oxygen from the acid or from the
water; or, in other words, that a metal cannot
be dissolved in an acid unless the oxygen, either
of the acid or of the water mixed with it, has
a stronger affinity to the metal than to the hy-
drogen or the acidifiable base ; or, which amounts
to the same thing, that no metallic solution
can take place without a previous decomposi-
tion of the water or the acid in which it is made.
The explanation of the principal phenomena of
metallic solution depends entirely upon this
simple observation, which was overlooked even
by the illustrious Bergman.

The first and most striking of these is the ef-
fervescence, or, to speak less equivocally, the
disengagement of gas which takes place during
the solution; in the solutions made in nitric
acid this effervescence is produced by the dis-
engagement of nitrous gas; in solutions with
sulphuric acid it is either sulphurous acid gas
or hydrogen gas, according as the oxidation of
the metal happens to be made at the expense
of the sulphuric acid or of the water. As both
nitric acid and water are composed of elements
which, when separate, can only exist in the
gaseous form, at least in the common tempera-
ture of the atmosphere, it is evident that, when-
ever either of these is deprived of its oxygen,
the remaining element must instantly expand
and assume the state of gas; the effervescence
is occasioned by this sudden conversion from
the liquid to the gaseous state. The same de-
composition, and consequent formation of gas,
takes place when solutions of metals are made
in sulphuric acid. In general, especially by the
humid way, metals do not attract all the oxy-
gen it contains; they therefore reduce it, not
into sulphur, but into sulphurous acid, and as
this acid can only exist as gas in the usual tern-

LAVOISIER

perature it is disengaged and occasions effer-
vescence.

The second phenomenon is that when the
metals have been previously oxidated they all
dissolve in acids without effervescence. This is
easily explained; because, not having now any
occasion for combining with oxygen, they nei-
ther decompose the acid nor the water by
which, in the former case, the effervescence is
occasioned.

A third phenomenon, which requires partic-
ular consideration, is that none of the metals
produce effervescence by solution in oxygen-
ated muriatic acid. During this process the
metal, in the first place, carries off the excess of
oxygen from the oxygenated muriatic acid, by
which it becomes oxidated, and reduces the
acid to the state of ordinary muriatic acid. In
this case there is no production of gas, not that
the muriatic acid does not tend to exist in the
gaseous state in the common temperature,
which it does equally with the acids formerly
mentioned, but because this acid, which other-
wise would expand into gas, finds more water
combined with the oxygenated muriatic acid
than is necessary to retain it in the liquid form ;
hence it does not disengage like the sulphurous
acid, but remains and quietly dissolves and
combines with the metallic oxide previously
formed from its superabundant oxygen.

The fourth phenomenon is that metals are
absolutely insoluble in such acids as have their
bases joined to oxygen by a stronger affinity
than these metals are capable of exerting upon
that acidifying principle. Hence silver, mer-
cury, and lead, in their metallic states, are in-
soluble in muriatic acid, but, when previously
oxidated, they become readily soluble without
effervescence.

From these phenomena it appears that oxy-
gen is the bond of union between metals and
acids; and from this we are led to suppose that
oxygen is contained in all substances which
have a strong affinity with acids. Hence it is
very probable the four eminently salifiable
earths contain oxygen, and their capability of
uniting with acids is produced by the interme-
diation of that element. What I have formerly
noticed relative to these earths is considerably
strengthened by the above considerations, viz.
that they may very possibly be metallic oxides,
with which oxygen has a stronger affinity than
with charcoal, and consequently not reducible
by any known means.

All the acids hitherto known are enumerated
in the following table, the first column of which

contains the names of the acids according to
the new nomenclature, and in the second col-
umn are placed the bases or radicals of these
acids, with observations.

Names of
the Acids

1. Sulphurous

2. Sulphuric

3. Phosphorous

4. Phosphoric

5. Muriatic

6. Oxygenated

muriatic

7. Nitrous

8. Nitric

9. Oxygenated
nitric

10. Carbonic

11. Acetous

12. Acetic

13. Oxalic

14. Tartarous

15. Pyro-tartarous

16. Citric

17. Malic

18. Pyro-lignous

19. Pyro-mucous

20. Gallic

21. Prussic

22. Benzoic

23. Succinic

24. Camphoric

25. Lactic

26. Saccho-lactic

27. Bombic

28. Formic

29. Sebacic

30. Boracic

31. Fluoric

32. Antimonic

33. Argentic

34. Arseniac

35. Bismuthic

36. Cotmltic

37. Cupric

38. Stannic

39. Ferric

40. Munganic

41. Mercuric

42. Molybdic

43. Nickolic

44. Auric

45. Platinic

46. Plumbic

47. Tungstic

48. Zincic

Names of the Bases, with
Observations

Sulphur
Phosphorus

Muriatic radical or base,
hitherto unknown

Azote

Charcoal

The bases or radicals of all
these acids seem to be formed
by a combination of charcoal
and hydrogen; and the only
difference seems to be owing
to the different proportions in
which these elements combine
to form their bases, and to the
different doses of oxygen in
their acidification. A connect-
ed series of accurate experi-
ments is still wanted upon
this subject

Our knowledge of the bases
of these acids is hitherto im-
perfect; we only know that
they contain hydrogen and
charcoal as principal elements,
and that the prussic acid con-
tains azote

The base of these and all the
acids procured from animal
substances seems to consist of
charcoal, hydrogen, phosphor-
us, and azote

The bases of these two are
hitherto entirely unknown

Antimony

Silver

Arsenic

Bismuth

Cobalt

Copper

Tin

Iron

Manganese

Mercury

Molybdenum

Nickel

Gold

Platinum

Lead

Tungsten

Zinc

CHEMISTRY

In this list, which contains 48 acids, I have
enumerated 17 metallic acids hitherto very im-
perfectly known, but upon which M. Ber-
thollet is about to publish a very important
work. It cannot be pretended that all the acids
which exist in nature, or rather all the acidifi-
able bases, are yet discovered; but, on the
other hand, there are considerable grounds for
supposing that a more accurate investigation
than has hitherto been attempted will diminish
the number of the vegetable acids by showing
that several of these, at present considered
as distinct acids, are only modifications of
others. All that can be done in the present
state of our knowledge is to give a view of
chemistry as it really is and to establish fun-
damental principles by which such bodies
as may be discovered in future may re-
ceive names in conformity with one uniform
system.

The known salifiable bases, or substances
capable of being converted into neutral salts by
union with acids, amount to 24; viz., 3 alkalies,
4 earths, and 17 metallic substances; so that,
in the present state of chemical knowledge, the
whole possible number of neutral salts amounts
to 1152. This number is upon the supposition
that the metallic acids are capable of dissolving
other metals, which is a new branch of chem-
istry not hitherto investigated, upon which de-
pends all the metallic combinations named
vitreous. There is reason to believe that many
of these supposable saline combinations are
not capable of being formed, which must greatly
reduce the real number of neutral salts produc-
ible by nature and art. Even if we suppose the
real number to amount only to five or six hun-
dred species of possible neutral salts, it is evi-
dent that, were we to distinguish them after
the manner of the ancients, either by the names
of their first discoverers or by terms derived
from the substances from which they are pro-
cured, we should at last have such a confusion
of arbitrary designations as no memory could
possibly retain. This method might be toler-
able in the early ages of chemistry, or even till
within these twenty years, when only about
thirty species of salts were known; but, in the
present times, when the number is augmenting
daily, when every new acid gives us 24 or 48
new salts according as it is capable of one or
two degrees of oxygenation, a new method is
certainly necessary. The method we have adopt-
ed, drawn from the nomenclature of the acids,
is perfectly analogical and, following nature in
the simplicity of her operations, gives a na-

tural and easy nomenclature applicable to every
possible neutral salt.

In giving names to the different acids, we ex-
press the common property by the genericai
term add and distinguish each species by the
name of its peculiar acidiftable base. Hence the
acids formed by the oxygenation of sulphur,
phosphorus, charcoal, &c. are called sulphuric
add, phosphoric add, carbonic acid, &c. We
thought it likewise proper to indicate the dif-
ferent degrees of saturation with oxygen by
different terminations of the same specific
names. Hence we distinguish between sulphur-
ous and sulphuric, and between phosphorous
and phosphoric acids, &c.

By applying these principles to the nomen-
clature of neutral salts, we give a common term
to all the neutral salts arising from the combi-
nation of one acid and distinguish the species
by adding the name of the salifiable base. Thus,
all the neutral salts having sulphuric acid in
their composition are named sulphates; those
formed by the phosphoric acid, phosphates, &c.
The species being distinguished by the names
of the salifiable bases gives us sulphate of pot-
ash, sulphate of soda, sulphate of ammoniac, sul-
phate of lime, sulphate of iron, &c. As we are ac-
quainted with 24 salifiable bases, alkaline,
earthy, and metallic, we have consequently 24
sulphates, as many phosphates, and so on
through all the acids. Sulphur is, however, sus-
ceptible of two degrees of oxygenation, the first
of which produces sulphurous and the second,
sulphuric acid; and, as the neutral salts pro-
duced by these two acids have different prop-
erties and are in fact different salts, it becomes
necessary to distinguish these by peculiar term-
inations; we have therefore distinguished the
neutral salts formed by the acids in the first or
lesser degree of oxygenation by changing the
termination ate into ite, as sulphites, phosphites,
&c. Thus, oxygenated or acidified sulphur, in
its two degrees of oxygenation is capable of
forming 48 neutral salts, 24 of which are sul-
phites, and as many sulphates; which is like-
wise the case with all the acids capable of two
degrees of oxygenation.

It were both tiresome and unnecessary to
follow these denominations through all the va-
rieties of their possible application; it is enough
to have given the method of naming the vari-
ous salts which, when once well understood, is
easily applied to every possible combination.
The name of the combustible and acidifiable
body being once known, the names of the acid
it is capable of forming, and of all the neutral

LAVOISIfiR

combinations the acid is susceptible of entering
into, are most readily remembered. Such as re-
quire a more complete illustration of the meth-
ods in which the new nomenclature is applied
will, in the second part of this book, find tables
which contain a full enumeration of all the neu-
tral salts and, in general, all tire possible chem-
ical combinations, so far as is consistent with
the present state of our knowledge. To these I
shall subjoin short explanations, containing
the best and most simple means of procuring
the different species of acids, and some account
of the general properties of the neutral salts
they produce.

I shall not deny that, to render this work
more complete, it would have been necessary
to add particular observations upon each spe-
cies of salt, its solubility in water and alcohol,
the proportions of acid and of salifiable base in
its composition, the quantity of its water of
crystallization, the different degrees of satura-
tion it is susceptible of, and, finally, the degree
of force or affinity with which the acid adheres
to the base. This immense work has been al-

ready begun by MM. Bergman, Morveau,
Kirwan, and other celebrated chemists, but is
hitherto only in a moderate state of advance-
ment; even the principles upon which it is
founded are not perhaps sufficiently accurate.
These numerous details would have swelled
this elementary treatise to much too great a
size; besides that, to have gathered the neces-
sary materials, and to have completed all the
series of experiments requisite, must have re-
tarded the publication of this book for many
years. This is a vast field for employing the
zeal and abilities of young chemists, whom I
would advise to endeavour rather to do well
than to do much, and to ascertain, in the first
place, the composition of the acids, before en-
tering upon that of the neutral salts. Every
edifice which is intended to resist the ravages
of time should be built upon a sure foundation;
and, in the present state of chemistry, to at-
tempt discoveries by experiments, either not
perfectly exact or not sufficiently rigorous, will
serve only to interrupt its progress, instead of
contributing to its advancement.

SECOND PART

OF THE COMBINATION OF ACIDS WITH SALIFIABLE BASES,
AND OF THE FORMATION OF NEUTRAL SALTS

INTRODUCTION

IF I had strictly followed the plan I at first laid
down for the conduct of this work, I would
have confined myself, in the tables and accom-
panying observations which compose this sec-
ond part, to short definitions of the several
known acids and abridged accounts of the proc-
esses by which they are obtainable, with a mere
nomenclature or enumeration of the neutral
salts which result from the combination of
these acids with the various salifiable bases.
But I afterwards found that the addition of
similar tables of all the simple substances which
enter into the composition of the acids and
oxides, together with the various possible com-
binations of these elements, would add greatly
to the utility of this work without being any

great increase to its size. These additions, which
are all contained in the twelve first sections of
this part and the tables annexed to these, form
a kind of recapitulation of the first fifteen chap-
ters of the first part. The rest of the tables and
sections contain all the saline combinations.

It must be very apparent that, in this part
of the work, I have borrowed greatly from
what has been already published by M. de
Morveau in the first volume of the Encyclo-
pedic par ordre des Matieres. I could hardly
have discovered a better source of information,
especially when the difficulty of consulting
books in foreign languages is considered. I make
this general acknowledgment on purpose to
save the trouble of references to M. de Mor-
veau's work in the course of the following part
of mine.

TABLE of Simple Substances Belonging to All the

Kingdoms of Nature, Which May Be Considered as the

Elements of Bodies

Old Names
Light

Heat

Principle or element of heat
Fire. Igneous fluid
Matter of fire and of heat
Dephlogisticated air
Empyreal air

Vital air, or base of vital air
Phlogisticated air or gas
Mephitis, or its base
Inflammable air or gas, or the base of
inflammable air

New Names
Light

Caloric

Oxygen

Azote

Hydrogen

Oxidable and Acidifiable Simple Substances Not Metallic

New Names Old Names

Sulphur

Phosphorus The same names

Charcoal
Muriatic radical

Fluoric radical Still unknown

Boracic radical

LAVOISIER

TABLE of Simple Substances, Continued
Oxiddble and Acidifiable Simple Metallic Bodies

SECTION I

New Names
Antimony
Arsenic
Bismuth
Cobalt
Copper
Gold
Iron
Lead

Manganese
Mercury
Molybdenum
Nickel
Platinum
Silver
Tin

Tungsten
Zinc

Old Names
Antimony
Arsenic
Bismuth
Cobalt
Copper
Gold
Iron
Lead

Manganese
Mercury
Molybdenum
Nickel
Platinum
Silver
Tin

Tungsten
Zinc

Salifiable Simple Earthy Substances

New Names
Lime

Magnesia

Barytes

Argill

Silex

Old Names

Chalk, calcareous earth
Quicklime

Magnesia, base of Epsom salt
Calcined or caustic magnesia
Barytcs, or heavy earth
Clay, earth of alum
Siliceous or verifiable earth

Observations upon the Tabk of Simple Sub-
stances

The principal object of chemical experiments
is to decompose natural bodies, so as separate-
ly to examine the different substances which
enter into their composition. By consulting
chemical systems, it will be found that this sci-
ence of chemical analysis has made rapid prog-
ress in our own times. Formerly oil and salt
were considered as elements of bodies, whereas
later observation and experiment have shown
that all salts, instead of being simple, are com-
posed of an acid united to a base. The bounds
of analysis have been greatly enlarged by mod-
ern discoveries; 1 the acids are shown to be
composed of oxygen, as an acidifying principle
common to all, united in each to a particular
base. I have proved what M. Hassenfratz had
before advanced, that these radicals of the
acids are not all simple elements, many of
them being, like the oily principle, composed
of hydrogen and charcoal. Even the bases of
neutral salts have been proved by M. Ber-
th ollet to be compounds, as he has shown that
ammonia is composed of azote and hydrogen.

1 See Recueil de I'Acadtmie for 1776, p. 671; and
for 1778, p. 535. AUTHOR.

TABLE of Compound Oxidable and Acidifiable Bases

Names of the Radicals

Oxidable or acidifiable base, from
the mineral kingdom

Oxidable or acidifiable hydro-car-
bonous or carbono-hydrous radi-
cals from the vegetable kingdom. 2

Oxidable or acidifiable radicals
from the animal kingdom, which
mostly contain azote, and frequent-
ly phosphorus

Nitro-muriatic radical or

base of the acid formerly

called aqua regia

Tartarous radical or base

Malic

Citric

Pyro-lignous

Pyro-mucous

Pyro-tartarous

Oxalic

Acetous

Succinic

Benzoic

Camphoric

Gallic

Lactic

Saccholactic

Formic

Bombic

Sebacic

Lithic

Prussic

1 Note. The radicals from the vegetable kingdom are converted by a
first degree of oxygenation into vegetable oxides, suoh as sugar, starch,
and gum or mucus: those of the animal kingdom by the same means
form animal oxides, as lymph, <fcc. AUTHOR.

CHEMISTRY

Thus, as chemistry advances towards per-
fection, by dividing and subdividing, it is im-
possible to say where it is to end; and these
things we at present suppose simple may
soon be found quite otherwise. All we dare
venture to affirm of any substance is that it
must be considered as simple in the present
state of our knowledge and so far as chemical
analysis has been able to show. We may even
presume that the earths must soon cease to be
considered as simple bodies; they are the only
bodies of the salifiable class which have no
tendency to unite with oxygen; and I am
much inclined to believe that this proceeds
from their being already saturated with that
element. If so, they will fall to be considered
as compounds consisting of simple substances,
perhaps metallic, oxidated to a certain de-
gree. This is only hazarded as a conjecture;
and I trust the reader will take care not
to confound what I have related as truths,
fixed on the firm basis of observation and
experiment, with mere hypothetical conjec-
tures.

The fixed alkalies, potash, and soda, are
omitted in the foregoing table, because they
are evidently compound substances, though
we are ignorant as yet what are the elements
they are composed of.

SECTION II

Observations upon the Table of Compound
Radicals

The older chemists being unacquainted with
the composition of acids and not suspecting
them to be formed by a peculiar radical or
base for each, united to an acidifying principle
or element common to all, could not conse-
quently give any name to substances of which
they had not the most distant idea. We had
therefore to invent a new nomenclature for
this subject, though we were at the same time
sensible that this nomenclature must be sus-
ceptible of great modification when the nature
of the compound radicals shall be better
understood. 1

The compound oxidable and acidifiable rad-
icals from the vegetable and animal king-
doms, enumerated in the foregoing table, are
not reducible to systematic nomenclature,
because their exact analysis is as yet un-
known. We only know hi general, by some
experiments of my own and some made by

*See Part 1, Chapter XI, upon this subject.
AUTHOB.

M. Hassenfratz, that most of the vegetable
acids, such as the tartarous, oxalic, citric,
malic, acetous, pyrotartarous, and pyromucous,
have radicals composed of hydrogen and char-
coal, combined in such a way as to form
single bases, and that these acids only differ
from each other by the proportions in which
these two substances enter into the composi-
tion of their bases, and by the degree of oxy-
genation which these bases have received. We
know further, chiefly from the experiments of
M. Berthollet, that the radicals from the
animal kingdom, and even some of those
from vegetables, are of a more compound na-
ture, and, besides hydrogen and charcoal,
that they often contain azote, and sometimes
phosphorus; but we were not possessed of
sufficiently accurate experiments for calculat-
ing the proportions of these several substances.
We are therefore forced, in the manner of
the older chemists, still to name these acids
after the substances from which they are pro-
cured. There can be little doubt that these
names will be laid aside when our knowledge
of these substances becomes more accurate and
extensive; the terms hydro-carbonous, hydro-
carbonic, carbono-hydrous, and carbono-hydric,*
will then become substituted for those we now
employ, which will then only remain as testi-
monies of the imperfect state in which this
part of chemistry was transmitted to us by our
predecessors.

It is evident that the oils, being composed of
hydrogen and charcoal combined, are true car-
bono-hydrous or hydro-carbonous radicals ; and,
indeed, by adding oxygen, they are convertible
into vegetable oxides and acids according to
their degrees of oxygenation. We cannot, how-
ever, affirm that oils enter in their entire state
into the composition of vegetable oxides and
acids; it is possible that they previously lose a
part either of their hydrogen or charcoal, and
that the remaining ingredients no longer exist
in the proportions necessary to constitute oils.
We still require further experiments to eluci-
date these points.

Properly speaking, we are only acquainted
with one compound radical from the mineral
kingdom, the nitro-muriatic, which is formed
by the combination of azote with the muriatic
radical. The other compound mineral acids
have been much less attended to, from their
producing less striking phenomena.

1 See Part I, Chapter XI, upon the application of
these names according to the proportions of the two
ingredients. AUTHOB.

PQ
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0? 3

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uddxo

CHEMISTRY

SECTION III

Observations upon the Combinations of Light
and Caloric with Different Substances

I have not constructed any table of the com-
binations of light and caloric with the various
simple and compound substances, because our
conceptions of the nature of these combina-
tions are not hitherto sufficiently accurate. We
know, in general, that all bodies in nature are
imbued, surrounded, and penetrated in every
way with caloric, which fills up every interval
left between their particles; that, in certain
cases, caloric becomes fixed in bodies, so as to
constitute a part even of their solid substance,
though it more frequently acts upon them with
a repulsive force, from which, or from its ac-
cumulation in bodies to a greater or lesser de-
gree, the transformation of solids into fluids,
and of fluids to aeriform elasticity, is entirely
owing. We have employed the generic name
gas to indicate this aeriform state of bodies pro-
duced by a sufficient accumulation of caloric,
so that, when we wish to express the aeriform
state of muriatic acid, carbonic acid, hydrogen,
water, alcohol, &c. we do it by adding the word
gas to their names; thus muriatic acid gas,
carbonic acid gas, hydrogen gas, aqueous gas,
alcoholic gas, &c.

The combinations of light, and its mode of
acting upon different bodies, is still less known.
By the experiments of M. Bertholiet, it ap-
pears to have great affinity with oxygen, is sus-
ceptible of combining with it, and contributes
alongst with caloric to change it into the state
of gas. Experiments upon vegetation give rea-
son to believe that light combines with certain
parts of vegetables, and that the green of their
leaves, and the various colours of their flowers,
is chiefly owing to this combination. This much
is certain, that plants which grow in darkness
are perfectly white, languid, and unhealthy,
and that to make them recover vigour, and to
acquire their natural colours, the direct influ-
ence of light is absolutely necessary. Some-
thing similar takes place even upon animals:
mankind degenerate to a certain degree when
employed in sedentary manufactures, from liv-
ing in crowded houses or in the narrow lanes of
large cities; whereas they improve in their na-
ture and constitution in most of the country
labours which are carried on in the open air.
Organization, sensation, spontaneous motion,
and all the operations of life, only exist at the
surface of the earth, and in places exposed to
the influence of light. Without it nature itself

would be lifeless and inanimate. By means of
light, the benevolence of the Deity hath filled
the surface of the earth with organization, sen-
sation, and intelligence. The fable of Prome-
theus might perhaps be considered as giving a
hint of this philosophical truth, which had
even presented itself to the knowledge of the
ancients. I have intentionally avoided any dis-
quisitions relative to organized bodies in this
work, for which reason the phenomena of res-
piration, sanguification, and animal heat, are
not considered; but I hope, at some future time,
tp be able to elucidate these curious subjects.

SECTION IV

Observations upon the Combinations of Oxygen
with the Simple Substances

Oxygen forms almost a third of the mass of
our atmosphere and is consequently one of the
most plentiful substances in nature. All the
animals and vegetables live and grow in this
immense magazine of oxygen gas, and from it
we procure the greatest part of what we em-
ploy in experiments. So great is the reciprocal
affinity between this element and other sub-
stances that we cannot procure it disengaged
from all combination. In the atmosphere it is
united with caloric, in the state of oxygen gas,
and this again is mixed with about two thirds
of its weight of azotic gas.

Several conditions are requisite to enable a
body to become oxygenated or to permit oxy-
gen to enter into combination with it. In the
first place, it is necessary that the particles of
the body to be oxygenated shall have less re-
ciprocal attraction with each other than they
have for the oxygen, which otherwise cannot
possibly combine with them. Nature, in this
case, may be assisted by art, as we have it in
our power to diminish the attraction of the
particles of bodies almost at will by heating
them, or, in other words, by introducing caloric
into the interstices between their particles;
and, as the attraction of these particles for
each other is diminished in the inverse ratio of
their distance, it is evident that there must be
a certain point of distance of particles when
the affinity they possess with each other be-
comes less than that they have for oxygen, and
at which oxygenation must necessarily take
place if oxygen be present.

We can readily conceive that the degree of
heat at which this phenomenon begins must be
different in different bodies. Hence, on purpose
to oxygenate most bodies, especially the great-

LAVOISIER

er part of the simple substances, it is only nec-
essary to expose them to the influence of the
air of the atmosphere in a convenient degree of
temperature. With respect to lead, mercury,
and tin, this needs be but little higher than the
medium temperature of the earth; but it re-
quires a more considerable degree of heat to
oxygenate iron, copper, &c., by the dry way, or
when this operation is not assisted by moisture.
Sometimes oxygenation takes place with great
rapidity and is accompanied by great sensible
heat, light, and flame; such is the combustion
of phosphorus in atmospheric air and of iron
in oxygen gas. That of sulphur is less rapid;
and the oxygenation of lead, tin, and most of
the metals, takes place vastly slower, and con-
sequently the disengagement of caloric, and
more especially of light, is hardly perceptible.
Some substances have so strong an affinity
with oxygen, and combine with it in such low
degrees of temperature, that we cannot pro-
cure them in their unoxygenated state; such is
the muriatic acid, which has not hitherto been

decomposed by art, perhaps even not by na-
ture, and which consequently has only been
found in the state of acid. It is probable that
many other substances of the mineral kingdom
are necessarily oxygenated in the common tem-
perature of the atmosphere, and that being al-
ready saturated with oxygen prevents their
further action upon that element.

There are other means of oxygenating simple
substances besides exposure to air in a certain
degree of temperature, such as by placing them
in contact with metals combined with oxygen
and which have little affinity with that ele-
ment. The red oxide of mercury is one of the
best substances for this purpose, especially
with bodies which do not combine with that
metal. In this oxide the oxygen is united with
very little force to the metal, and can be driven
out by a degree of heat only sufficient to make
glass red hot; wherefore such bodies as are cap-
able of uniting with oxygen are readily oxy-
genated by means of being mixed with red
oxide of mercury and moderately heated. The

TABLE of the Combinations of Oxygen with the
Compound Radicals

Names of the Radicals Names of the Resulting Acids
New Names Old Names
Nitro-muriatic XT:A . .. . , A .

Unknown till lately

Ditto

Acid of lemons

Empyreumatic acid of

wood

pjmpyr. acid of sugar
i Empyr. acid of tartar
Acid of sorel

Vinegar, or acid of vinegar
Radical vinegar
Volatile salt of amber
Flowers of benzoin
Unknown till lately

I The astringent principle
of vegetables

Acid of sour whey
Unknown till lately
Acid of ants
Unknown till lately
Ditto

Urinary calculus
Colouring matter of Prus-
sian blue

Note 1 : These radicals by a first degree of oxygenation form vegetable
oxides, as sugar, starch, mucus, <fec. AUTHOR.

Note 2: These radicals by a first degree of oxygenation form the animal
oxides, as lymph, red part of the blood, animal secretions, &c. AUTHOR.

radical

iMwu-iiiunatiu aci

Tartaric
Malic
Citric

Tartarous acid
Malic acid
Citric acid

Pyro-lignous

Pyro-lignous acid

T 1

Pyro-mucous
Pyro-tartarous
Oxalic

Pyro-mucous acid
Pyro-tartarous aci
Oxalic acid

Acetic

Acetous acid
Acetic acid

Succinic
Benzoic
Camphoric

Saccinic acid
Benzotic acid
Camphoric acid

Gallic

Gallic acid

See Note 2

Lactic
Saccholactic
Formic
Bombic
Sebacic
Lithic

Lactic acid
Saccholactic acid
Formic acid
Bombic acid
Sebacic acid
Lithic acid

Prussic

Prussic acid

CHEMISTRY

same effect may be, to a certain degree, pro-
duced by means of the black oxide of mangan-
ese, the red oxide of lead, the oxides of silver,
and by most of the metallic oxides, if we only
take care to choose such as have less affinity
with oxygen than the bodies they are meant to
oxygenate. All the metallic reductions and re-
vivifications belong to this class of operations,
being nothing more than oxygenations of char-
coal by means of the several metallic oxides.
The charcoal combines with the oxygen and
with caloric and escapes in form of carbonic
acid gas, while the metal remains pure and re-
vivified, or deprived of the oxygen which be-
fore combined with it in the form of oxide.

All combustible substances may likewise be
oxygenated by means of mixing them with ni-
trate of potash or of soda, or with oxygenated
muriate of potash, and subjecting the mixture
to a certain degree of heat; the oxygen, in this
case, quits the nitrate or the muriate, and com-
bines with the combustible body. This species
of oxygenation requires to be performed with
extreme caution and only with very small quan-
tities; because, as the oxygen enters into the
composition of nitrates, and more especially of
oxygenated muriates, combined with almost as
much caloric as is necessary for converting it
into oxygen gas, this immense quantity of ca-
loric becomes suddenly free the instant of the
combination of the oxygen with the combust-
ible body and produces such violent explosions
as are perfectly irresistible.

By the humid way we can oxygenate most
combustible bodies, and convert most of the
oxides of the three kingdoms of nature into
acids. For this purpose we chiefly employ the
nitric acid, which has a very slight hold of oxy-
gen, and quits it readily to a great number of
bodies by the assistance of a gentle heat. The
oxygenated muriatic acid may be used for sev-
eral operations of this kind, but not in them all.

I give the name of binary to the combinations
of oxygen with the simple substances, because
in these only two elements are combined. When
three substances are united in one combina-
tion I call it ternary, and quaternary when the
combination consists of four substances united.

SECTION V

Observations upon the Combinations of Oxygen
with the Compound Radicals

I published a new theory of the nature and
formation of acids in the Recueil de I' Academic
for 1776, p. 671 and 1778, p. 535 in which I

concluded that the number of acids must be
greatly larger than was till then supposed.
Since that time, a new field of inquiry has been
opened to chemists; and, instead of five or six
acids which were then known, near thirty new
acids have been discovered, by which means
the number of known neutral salts have been
increased in the same proportion. The nature
of the acidifiable bases or radicals of the acids,
and the degrees of oxygenation they are sus-
ceptible of, still remain to be inquired into. I
have already shown that almost all the oxid-
able and acidifiable radicals from the mineral
kingdom are simple, and that, on the contrary,
there hardly exists any radical in the vegetable,
and more especially in the animal kingdom,
but is composed of at least two substances, hy-
drogen and charcoal, and that azote and phos-
phorus are frequently united to these, by which
we have compound radicals of two, three, and
four bases or simple elements united.

From these observations, it appears that the
vegetable and animal oxides and acids may differ
from each other in three several ways: 1st, ac-
cording to the number of simple acidifiable
elements of which their radicals are composed:
2nd, according to the proportions in which
these are combined together: and, 3rd, accord-
ing to their different degrees of oxygenation:
which circumstances are more than sufficient
to explain the great variety which nature pro-
duces in these substances. It is not at all sur-
prising, after this, that most of the vegetable
acids are convertible into each other, nothing
more being requisite than to change the pro-
portions of the hydrogen and charcoal in their
composition, and to oxygenate them in a greater
or lesser degree. This has been done by M.
Crell in some very ingenious experiments,
which have been verified and extended by M.
Hassenfratz. From these it appears that char-
coal and hydrogen by a first oxygenation pro-
duce tartarous acid, oxalic acid by a second
degree, and acetous or acetic acid by a third,
or higher oxygenation; only, that charcoal
seems to exist in a rather smaller proportion in
the acetous and acetic acids. The citric and
malic acids differ little from the preceding acids.

Ought we then to conclude that the oils are
the radicals of the vegetable and animal acids?
I have already expressed my doubts upon this
subject: 1st, although the oils appear to be
formed of nothing but hydrogen and charcoal,
we do not know if these are in the precise pro-
portion necessary for constituting the radicals
of the acids: 2nd, since oxygen enters into the

LAVOISIER

composition of these acids equally with hydro-
gen and charcoal, there is no more reason for
supposing them to be composed of oil rather
than of water or of carbonic acid. It is true
that they contain the materials necessary for
all these combinations, but then these do not
take place in the common temperature of the
atmosphere; all the three elements remain

either to a solid or liquid form. This is likewise
one of the essential constituent elements of
animal bodies, in which it is combined with
charcoal and hydrogen, and sometimes with
phosphorus; these are united together by a
certain portion of oxygen, by which they are
formed into oxides or acids according to the
degree of oxygenation. Hence the animal sub-

Simple
Substances

Caloric
Hydrogen

Oxygen

Charcoal

Phosphorus

Sulphur

Compound
radicals

Metallic

substances

Lime

Magnesia

Barytes

Argill

Potash

Soda

TABLE of the Binary Combinations of Azote with the
Simple Substances

Results of the Combinations

New Names
Azotic gas
Ammonia
Nitrous oxide
Nitrous acid
Nitric acid

Old Names

Phlogisticated air, or Mephitis
Volatile alkali

Base of Nitrous gas
Smoking nitrous acid
Pale nitrous acid
Oxygenated nitric acid Unknown

This combination is unknown ; should it ever be discovered*
it will be called, according to the principles of our nomen-
clature, Azuret of Charcoal. Charcoal dissolves in azotic
gas and forms carbonated azotic gas

Azuret of phosphorus. Still unknown
Azuret of sulphur. Still unknown. We know that
sulphur dissolves in azotic gas, forming sulphurated
azotic gas

Azote combines with charcoal and hydrogen, and some-
times with phosphorus, in the compound oxydable and
acidifiable bases, and is generally contained in the radi-
cals of the animal acids

Such combinations are unknown; if ever discovered, they
will form metallic azurets, as azuret of gold, of silver, <fec.

Entirely unknown. If over discovered, they will form
azuret of lime, azuret of magnesia, &c.

combined in a state of equilibrium which is
readily destroyed by a temperature only a
little above that of boiling water. 1

SECTION VI

Observations upon the Combinations of Azote
with the Simple Substances

Azote is one of the most abundant elements;
combined with caloric it forms azotic gas, or
mephitis, which composes nearly two thirds of
the atmosphere. This element is always in the
state of gas in the ordinary pressure and tem-
perature, and no degree of compression or of
cold has been hitherto capable of reducing it

See Part I, Chapter XII, upon this subject.

AXTTBOB*

stances may be varied, in the same way with
vegetables, in three different manners: 1st,
according to the number of elements which
enter into the composition of the base or radi-
cal; 2nd, according to the proportions of these
elements; 3rd, according to the degree of oxy-
genation.

When combined with oxygen, azote forms
the nitrous and nitric oxides and acids; when
with hydrogen, ammonia is produced. Its com-
binations with the other simple elements are
very little known; to these we give the name of
azurets , preserving the, termination in uret for
all non-oxygenated compounds. It is extremely
probable that all the alkaline substances may
hereafter be found to belong to this genus of
azurets.

CHEMISTRY

The azotic gas may be procured from atmos-
pheric air, by absorbing the oxygen gas which
is mixed with it by means of a solution of sul-
phuret of potash, or sulphuret of lime. It re-
quires twelve or fifteen days to complete this
process, during which time the surface in con-
tact must be frequently renewed by agitation
and by breaking the pellicle which forms on
the top of the solution. It may likewise be pro-
cured by dissolving animal substances in dilute
nitric acid very little heated. In this operation
the azote is disengaged in form of gas, which
we receive under bell glasses filled with water
in the pneumato-chemicai apparatus. We may
procure this gas by deflagrating nitre with
charcoal, or any other combustible substance;
when with charcoal, the azotic gas is mixed
with carbonic acid gas, which may be absorbed
by a solution of caustic alkali or by lime water,
after which the azotic gas remains pure. We
can procure it in a fourth manner from com-
binations of ammonia with metallic oxides, as
pointed out by M. cle Fourcroy: the hydrogen
of the ammonia combines with the oxygen of
the oxide, and forms water; whilst the azote
being left free escapes in form of gas.

The combinations of azote were but lately
discovered: M. Cavendish first observed it in
nitrous gas and acid, and M. Rerthollet in am-
monia and the prussic acid. As no evidence of
its decomposition has hitherto appeared, we
are fully entitled to consider azote as a simple
elementary substance.

SECTION VII

Observations upon Hydrogen and Its Combina-
tions with Simple Substances

Hydrogen, as its name expresses, is one of
the constituent elements of water, of which it
forms fifteen hundredth parts by weight, com-
bined with eighty-five hundredth parts of oxy-
gen. This substance, the properties and even
existence of which was unknown till lately, is
very plentifully distributed in nature and acts
a very considerable part in the processes of the
animal and vegetable kingdoms. As it possesses
so great affinity with caloric as only to exist in
the state of gas, it is consequently impossible
to procure it in the concrete or liquid state, in-
dependent of combination.

To procure hydrogen, or rather hydrogen
gas, we have only to subject water to the ac-
tion of a substance with which oxygen has
greater affinity than it has to hydrogen; by this
means the hydrogen is set free and, by uniting
with caloric, assumes the form of hydrogen gas.
Red hot iron is usually employed for this pur-
pose: the iron, during the process, becomes
oxidated, and is changed into a sukstance re-
sembling the iron ore from the island of Elba.
In this state of oxide it is much less attractible
by the magnet, and dissolves in acids without
effervescence.

Charcoal, in a red heat, has the same power
of decomposing water, by attracting the oxy-
gen from its combination with hydrogen. In

TABLE of the Binary Combinations of Hydrogen with
Simple Substances

Simple
Substances
Caloric
Azote
Oxygen

Sulphur
Phosphorus

Charcoal

Metallic substances,!
as iron, &c |

Resulting Compounds

New Names
Hydrogen gas
Ammonia
Water

I Hydruret of sulphur, or
sulphuret of hydrogen
Hydruret of phosphorus,
or phosphuret of hydrogen
Hydro-carbonous, or car-
bono hydrous radicals 2
Metallic hydrurets 8 , as
hydruret of iron, &c

Old Names
Inflammable air
Volatile Alkali
Water

Hitherto unknown 1

Not known till lately
Hitherto unknown

1 These combinations take place in the state of gas, and form, respective-
ly, sulphurated and phosphorated oxygen gas. AUTHOR.

This combination of hydrogen with charcoal includes the fixed and
volatile oils, and forms the radicals of a considerable part of the vegetable
and animal oxides and acids. When it takes place in the state of gas it
forms carbonated hydrogen gas. AUTHOR.

8 None of these combinations are known, and it is probable that they
cannot exist, at least in the usual temperature of the atmosphere, owing
to the great affinity of hydrogen for caloric. AUTHOR.

LAVOISIER

this process carbonic acid gas is formed and
mixes with the hydrogen gas but is easily sep-
arated by means of water or alkalies, which
absorb the carbonic acid and leave the hydro-
gen gas pure. We may likewise obtain hydro-
gen gas by dissolving iron or zinc in dilute sul-
phuric acid. These two metals decompose wa-
ter very slowly, and with great difficulty, when
alone, but do it with great ease and rapidity
when assisted by sulphuric acid; the hydrogen
unites with caloric during the process and is
disengaged in form of hydrogen gas, while the
oxygen of the water unites with the metal in
the form of oxide, which is immediately dis-
solved in the acid, forming a sulphate of iron
or of zinc.

Some very distinguished chemists consider
hydrogen as the phlogiston of Stahl; and as

that celebrated chemist admitted the existence
of phlogiston in sulphur, charcoal, metals, &c.,
they are, of course, obliged to suppose that hy-
drogen exists in all these substances, though
they cannot prove their supposition; even if
they could, it would not avail much, since this
disengagement of hydrogen is quite insufficient
to explain the phenomena of calcination and
combustion. We must always recur to the ex-
amination of this question, "Are the heat and
light which are disengaged during the different
species of combustion furnished by the burning
body or by the oxygen which combines in all
these operations? " And certainly the supposi-
tion of hydrogen being disengaged throws no
light whatever upon this question. Besides, it
belongs to those who make suppositions to
prove them; and, doubtless, a doctrine which

TABLE of the Binary Combinations of Sulphur with
Simple Substances

Simple
Substances
Caloric

Oxygen

Hydrogen

Azote

Phosphorus

Charcoal

Antimony

Silver

Arsenic

Bismuth

Cobalt

Copper

Tin

Iron

Manganese

Mercury

Molybdenum

Nickel

Gold

Platinum

Lead

Tungsten

Zinc

Potash
Soda

Ammonia

Lime
Magnesia
Barytes
Argill

Resulting Compounds
New Names Old Names

Sulphuric gas

Oxide of sulphur

Sulphurous acid

Sulphuric acid

Sulphuret of hydrogen
azote

phosphorus
charcoal
antimony
silver
arsenic
bismuth
cobalt
copper
tin
iron

manganese
mercury
molybdenum
nickel
gold

platinum
lead

tungsten
zinc

potash
soda

ammonia

lime

magnesia
barytes
argill

Soft sulphur
Sulphureous acid
Vitriolic acid

Unknown combinations

Crude antimony
Orpiment, realgar

Copper pyrites

Iron pyrites

Ethiops mineral, cinnabar

Galena

Blende

Alkaline liver of sulphur
with fixed vegetable alkali
Alkaline liver of sulphur
with fixed mineral alkali
Volatile liver of sulphur,
smoking liquor of Boyle
Calcareous li ver of sulphur
Magnesian liver of sulphur
Barytic liver of sulphur
Yet unknown

CHEMISTRY

without any supposition explains the phenom-
ena as well and as naturally as theirs does by
supposition has at least the advantage of great-
er simplicity. 1

SECTION VIII
Observations on Sulphur and its Combinations

Sulphur is a combustible substance, having
a very great tendency to combination; it is
naturally in a solid state in the ordinary tem-
perature, and requires a heat somewhat higher
than boiling water to make it liquify. Sulphur
is formed by nature in a considerable degree of
purity in the neighbourhood of volcanos; we
find it likewise, chiefly in the state of sulphuric
acid, combined with argil! in aluminous schist,
with lime in gypsum, &c. From these combi-
nations it may be procured in the state of sul-
phur, by carrying off its oxygen by means of
charcoal in a red heat; carbonic acid is formed
and escapes in the state of gas; the sulphur re-
mains combined with the clay, lime, &c. in the
state of sulphuret, which is decomposed by
acids; the acid unites with the earth into a neu-
tral salt, and the sulphur is precipitated.

TABLE of the Binary Combinations of
Phosphorus with the Simple Substances

SECTION IX

Resulting Compounds
Phosphoric gas
Oxide of phosphorus
Phosphorous acid
Phosphoric acid
Phosphuret of hydrogen
Phosphuret of azote
Phosphuret of sulphur
Phosphuret of charcoal
Phosphuret of metals 2

Phosphuret of Potash,
Soda, &c. 8

Argill

1 Those who wish to see what has been said upon
this great chemical question by MM. de Morvoau,
Berthollet, de Fourcroy, and myself may consult
our translation of M. Kir wan 's Essay upon Phlo-
giston. AUTHOR.

Of all these combinations of phosphorus with
metals, that with iron only is hitherto known, form-
ing the substance formerly called siderite; neither is
it yet ascertained whether, in this combination, the
phosphorus be oxygenated or not. AUTHOR.

1 These combinations of phosphorus with the alka-
lies and earths are not yet known; and, from the ex-
periments of M. Gengembre, they appear to be im-
possible. AUTHOB.

Simple Substances
Caloric

Oxygen

Hydrogen

Azote

Sulphur

Charcoal

Metallic substances

Potash

Soda

Ammonia

Lime

Barytes

Observations upon Phosphorus and its Combi-
nations

Phosphorus is a simple combustible sub-
stance, which was unknown to chemists till
1667, when it was discovered by Brandt, who
kept the process secret; soon after, Kunkel
found out Brandt's method of preparation and
made it public. It has been ever since known
by the name of Kunkel's phosphorus. It was
for a long time procured only from urine; and,
though Homberg gave an account of the proc-
ess in the Recueil de I'Acadtmie for 1692, all
the philosophers of Europe were supplied with
it from England. It was first made in France in
1737, before a committee of the Academy at
the Royal Garden. At present it is procured in
a more commodious and more economical man-
ner from animal bones, which are real calcar-
eous phosphates, according to the process of
MM. Gahn, Scheele, Roueile, &c. The bones
of adult animals, being calcined to whiteness,
are pounded and passed through a fine silk
sieve; pour upon the fine powder a quantity of
dilute sulphuric acid, less than is sufficient for
dissolving the whole. This acid unites with the
calcareous earth of the bones into a sulphate of
lime, and the phosphoric acid remains free in
the liquor. The liquid is decanted off, and the
residuum washed with boiling water; this wa-
ter which has been used to wash out the adher-
ing acid is joined with what was before decant-
ed off, and the whole is gradually evaporated;
the dissolved sulphate of lime crystallizes in
form of silky threads, which are removed, and
by continuing the evaporation we procure the
phosphoric acid under the appearance of a
white pellucid glass. When this is powdered
and mixed with one third its weight of char-
coal, we procure very pure phosphorus by sub-
limation. The phosphoric acid, as procured by
the above process, is never so pure as that ol>
tained by oxygenating pure phosphorus either
by combustion or by means of nitric acid;
wherefore this latter should always be em-
ployed in experiments of research.

Phosphorus is found in almost all animal
substances, and in some plants which give a
kind of animal analysis. In all these it is usu-
ally combined with charcoal, hydrogen, and
azote, forming very compound radicals, which
are, for the most part, in the state of oxides by
a first degree of union with oxygen. The dis-
covery of M. Hassenfratz, of phosphorus be-
ing contained in charcoal, gives reason to BUS-

LAVOISIER

pect that it is more common in the vegetable
kingdom than has generally been supposed. It
is certain that by proper processes it may be
procured from every individual of some of the
families of plants. As no experiment has hith-
erto given reason to suspect that phosphorus
is a compound body, I have arranged it with
the simple or elementary substances. It takes
fire at the temperature of 32 (104) of the
thermometer.

In the business of charring wood, this is done
by a less expensive process. The wood is dis-
posed in heaps and covered with earth, so as to
prevent the access of any more air than is ab-
solutely necessary for supporting the fire, which
is kept up till all the water and oil is driven off,
after which the fire is extinguished by shutting
up all the air-holes.

We may analyse charcoal either by combus-
tion in air, or rather in oxygen gas, or by means

Simple
Substances

Oxygen

Sulphur

Phosphorus

Azote

Hydrogen

Metallic sub-
stances

TABLE of Binary Combinations of Charcoal
Resulting Compounds

New Names

I Oxide of charcoal
Carbonic acid
Carburet of sulphur
Carburet of phosphorus
Carburet of azote

ICarbono-hydrous radical
Fixed and volatile oils

Carburets of metals

Old Names
Unknown
Fixed air, chalky acid

Unknown

Alkalies and earths Carburet of potash, &c.

Of these only the car-
burets of iron and zinc
are known, and were
formerly called Plum-
bago
Unknown

SECTION X

Observations upon Charcoal and its Combina-
tions with Simple Substances

As charcoal has not been hitherto decom-
posed, it must, in the present state of our
knowledge, be considered as a simple substance.
By modern experiments it appears to exist
ready formed in vegetables; and I have already
remarked that in these it is combined with hy-
drogen, sometimes with azote and phosphorus,
forming compound radicals which may be
changed into oxides or acids according to their
degree of oxygenation.

To obtain the charcoal contained in vege-
table or animal substances, we subject them
to the action of fire, at first moderate and
afterwards very strong, on purpose to drive off
the last portions of water, which adhere very
obstinately to the charcoal. For chemical pur-
poses, this is usually done in retorts of stone-
ware or porcelain, into which the wood, or
other matter, is introduced, and then placed
in a reverberatory furnace, raised gradually to
its greatest heat. The heat volatilizes, or changes
into gas, all the parts of the body susceptible of
combining with caloric into that form, and the
charcoal, being more fixed in its nature, re-
mains in the retort combined with a little earth
and some fixed salts.

of nitric acid. In either case we convert it into
carbonic acid, and sometimes a little potash
and some neutral salts remain. This analysis
has hitherto been but little attended to by
chemists ; and we are not even certain if potash
exists in charcoal before combustion or wheth-
er it be formed by means of some unknown
combination during that process.

SECTION XI

Observations upon the Muriatic, Fluoric, and Bo-
racic Radicals and their Combinations

As the combinations of these substances,
either with each other or with the other com-
bustible bodies, are entirely unknown, we have
not attempted to form any table for their no-
menclature. We only know that these radicals
are susceptible of oxygenation, and of forming
the muriatic, fluoric, and boracic acids, and
that in the acid state they enter into a number
of combinations, to be afterwards detailed.
Chemistry has hitherto been unable to disoxy-
genate any of them, so as to produce them in a
simple state. For this purpose, some substance
must be employed to which oxygen has a
stronger affinity than to their radicals, either
by means of single affinity or by double elec-
tive attraction. All that is known relative to
the origin of the radicals of these acids will be

CHEMISTRY

mentioned in the sections set apart for consider-
ing their combinations with the salifiable bases.

SECTION XII

Observations upon the Combinations of Metals
with Each Other

Before closing our account of the simple or
elementary substances, it might be supposed
necessary to give a table of alloys or combina-
tions of metals with each other; but, as such a
table would be both exceedingly voluminous
and very unsatisfactory, without going into a

series of experiments not yet attempted, I have
thought it adviseable to omit it altogether. All
that is necessary to be mentioned is that these
alloys should be named according to the metal
in largest proportion in the mixture or combi-
nation; thus the term alloy of gold and silver, or
gold alloyed with silver, indicates that gold is
the predominating metal.

Metallic alloys, like all other combinations,
have a point of saturation. It would even ap-
pear, from the experiments of M. de la Briche,
that they have two perfectly distinct degrees
of saturation.

Nitrate of barytes
potash

TABLE of the Combinations of Azote, Completely Saturated

with Oxygen, in the State of Nitric Acid, with the Salifiable

Bases, in the Order of the Affinity with the Acid

Bases Names of the Resulting Neutral Salts

New Names Old Names

Nitre, with a base of
heavy earth

Nitre, Saltpetre; Nitre
with base of potash
Quadrangular nitre;
Nitre with base of
mineral alkali
Calcareous nitre; Nitre
with calcareous base;
Mother water of nitre, or
saltpetre

Magnesian nitre; Nitre
with base of magnesia

Ammoniacal nitre

Nitrous alum; Argillace-
ous nitre; Nitre with base
of earth of alum

Nitre of zinc

Nitre of iron; Martial

nitre; Nitrated iron

Nitre of manganese
Nitre of cobalt
Nitre of nickel

Barytes
Potash

Soda

Lime

Magnesia
Ammonia

Argill

Oxide of zinc
iron

soda

lime

magnesia

ammonia

argill

iron

manganese

cobalt

nickel

manganese

cobalt

nickel

lead

tin

copper

bismuth
antimony
arsenic
mercury

silver

gold
platinum

lead

tin

copper

bismuth
antimony
arsenic
mercury

silver

gold
platinum

I Saturnine nitre; Nitre of
lead

Nitre of tin

I Nitre of copper or of
Venus

Nitre of bismuth
Nitre of antimony
Arsenical nitre
Mercurial nitre

I Nitre of silver or luna;
Lunar caustic

Nitre of gold
Nitre of platinum

LAVOISIER

TABLE of the Combinations of Azote in the State of Nitrous

Acid with the Salifiable Bases, Arranged According to

the Affinities of These Bases with the Acid

Names of the

Bases

Neutral Salts

New Names Notes

Barytes

Nitrite of barytes

Potash

potash

Soda

soda

These salts are only

Lime
Magnesia

lime f
magnesia

known of late and have re-
ceived no particular name
in the old nomenclature.

Ammonia

ammonia

Argill

argill

Oxide of zinc

zinc

As metals dissolve both

iron

in nitrous and nitric acids,

manganese manganese

metallic salts must of con-

cobalt*

cobalt

sequence be formed having

nickel

different degrees of oxygen-
ation. Those wherein the

lead

metal is least oxygenated

tin

must be called Nitrites,

when more so, Nitrates; but

copper
bismuth

the limits of this distinc-
tion are difficultly ascertain-

antimony

able. The older chemists

arsenic

were not acquainted with
any of these salts.

mercury

silver

It is extremely probable that gold, silver, and

gold

platinum only form nitrates, and cannot subsist in

platinum

the state of nitrites.

SECTION XIII

Observations upon Nitrous and Nitric Acids and
their Combinations with Salifiable Bases

The nitrous and nitric acids are procured
from a neutral salt long known in the arts un-
der the name of saltpetre. This salt is extracted
by lixiviation from the rubbish of old buildings,
from the earth of cellars, stables, or barns, and
in general of all inhabited places. In these
earths the nitric acid is usually combined with
lime and magnesia, sometimes with potash,
and rarely with argill. As all these salts, ex-
cepting the nitrate of potash, attract the
moisture of the air, and consequently would
be difficultly preserved, advantage is taken,
in the manufactures of saltpetre and the
royal refining-house, of the greater affinity
of the nitric acid to potash than these other
bases, by which means the lime, magnesia,
and argill, are precipitated, and all these
nitrates are reduced to the nitrate of potash or
saltpetre.

The nitric acid is procured from this salt by
distillation, from three parts of pure saltpetre
decomposed by one part of concentrated sul-
phuric acid, in a retort with Woulfe's appara-
tus, (Plate iv, Fig. 1) having its bottles half

rilled with water, and all its joints carefully
luted. The nitrous acid passes over in form of
red vapours surcharged with nitrous gas, or, in
other words, not saturated with oxygen. Part
of the acid condenses in the recipient in form
of a dark orange red liquid, while the rest com-
bines with the water in the bottles. During the
distillation, a large quantity of oxygen gas es-
capes, owing to the greater affinity of oxygen
to caloric in a high temperature than to nitrous
ncid, though in the usual temperature of the
atmosphere this affinity is reversed. It is from
the disengagement of oxygen that the nitric
acid of the neutral salt is in this operation con-
verted into nitrous acid. It is brought back to
the state of nitric acid by heating over a gentle
fire, which drives off the superabundant nitrous
gas, and leaves the nitric acid much diluted
with water.

Nitric acid is procurable in a more concen-
trated state, and with much less loss, by mix-
ing very dry clay with saltpetre. This mixture
is put into an earthen retort and distilled with
a strong fire. The clay combines with the pot-
ash, for which it has great affinity, and the ni-
tric acid passes over, slightly impregnated with
nitrous gas. This is easily disengaged by heat-
ing the acid gently in a retort; a small quantity

CHEMISTRY

of nitrous gas passes over into the recipient,
and very pure concentrated nitric acid remains
in the retort.

We have already seen that azote is the nitric
radical. If to 20}^ parts, by weight, of azote
43J^ parts of oxygen be added, 64 parts of ni-
trous gas are formed; and, if to this we join 36
additional parts of oxygen, 100 parts of nitric
acid result from the combination. Intermedi-
ate quantities of oxygen between these two
extremes of oxygenation produce different spe-
cies of nitrous acid, or, in other words, nitric
acid less or more impregnated with nitrous gas.
I ascertained the above proportions by means
of decomposition; and, though I cannot answer
for their absolute accuracy, they cannot be far

removed from truth. M. Cavendish, who first
showed by synthetic experiments that azote is
the base of nitric acid, gives the proportions of
azote a little larger than I have done; but, as
it is not improbable that he produced the ni-
trous acid and not the nitric, that circumstance
explains in some degree the difference in the
results of our experiments.

As in all experiments of a philosophical na-
ture the utmost possible degree of accuracy is
required, we must procure the nitric acid for
experimental purposes from nitre which has
been previously purified from ail foreign matter.
If, after distillation, any sulphuric acid is sus-
pected in the nitric acid, it is easily separated
by dropping in a little nitrate of barytes, so

TABLE of the Combinations of Sulphuric Acid with the
Salifiable Bases, in the Order of Affinity

Names of the

Resulting Compounds
New Names Old Names

Barytes

Potash

Soda
Lime

Magnesia

Ammonia
Argill

Oxide of zinc

Sulphate of barytes

potash

soda
lime

magnesia

ammonia
argill

zinc

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

mercury

silver

gold

platinum

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

mercury

silver

gold

platinum

Heavy spar; vitriol of
heavy earth

Vitriolated tartar; sal
de duobus; arcanum dup-
licatam

Glauber's salt

Selenitc, gypsum, cal-
careous vitriol

Epsom salt, sedlitz salt,
magnesian vitriol

Glauber's secret sal am-
moniac

Alum

White vitriol, goslar
vitriol, white coperas,
vitriol of zinc

Green coperas, green
vitriol, martial vitriol,
vitriol of iron

Vitriol of manganese
Vitriol of cobalt
Vitriol of nickel
Vitriol of lead
Vitriol of tin

Blue coperas,, blue vi-
triol, Roman vitriol, vi-
triol of copper

Vitriol of bismuth
Vitriol of antimony
Vitriol of arsenic
Vitriol of mercury
Vitriol of silver
Vitriol of gold
Vitriol of platinum

LAVOISIER

long as any precipitation takes place; the sul-
phuric acid, from its greater affinity, attracts
the barytes and forms with it an insoluble neu-
tral salt, which falls to the bottom. It may be
purified in the same manner from muriatic
acid, by dropping in a little nitrate of silver so
long as any precipitation of muriate of silver is
produced. When these two precipitations are
finished, distill off about seven-eighths of the
acid by a gentle heat, and what comes over is
in the most perfect degree of purity.

The nitric acid is one of the most prone to
combination and is at the same time very eas-
ily decomposed. Almost all the simple sub-
stances, with the exception of gold, silver, and
-platinum, rob it less or more of its oxygen;
some of them even decompose it altogether. It
was very anciently known, and its combina-
tions have been more studied by chemists than
those of any other acid. These combinations
were named nitres by MM. Macquer and
Beaum6; but we have changed their names to
nitrates and nitrites, according as they are
formed by nitric or by nitrous acid, and have
added the specific name of each particular base,
to distinguish the several combinations from
each other.

SECTION XIV

Observations upon Sulphuric Acid and its Com-
binations

For a long time this acid was procured by
distillation from sulphate of iron, in which sul-
phuric acid and oxide of iron are combined ac-
cording to the process described by Basil Val-
entine in the fifteenth century; but, in modern
times, it is procured more economically by the
combustion of sulphur in proper vessels. Both
to facilitate the combustion, and to assist the
oxygenation of the sulphur, a little powdered
saltpetre, nitrate of potash, is mixed with it;
the nitre is decomposed and gives out its oxy-
gen to the sulphur, which contributes to its
conversion into acid. Notwithstanding this ad-
dition, the sulphur will only continue to burn
in close vessels for a limited time; the combi-
nation ceases, because the oxygen is exhausted
and the air of the vessels reduced almost to
pure azotic gas, and because the acid itself re-
mains long in the state of vapour and hinders
the progress of combustion.

In the factories for making sulphuric acid in
the large way, the mixture of nitre and sulphur
is burnt in large close-built chambers lined
with lead, having a little water at the bottom

for facilitating the condensation of the vapours.
Afterwards, by distillation m large retorts with
a gentle heat, the water passes over, slightly
impregnated with acid, and the sulphuric acid
remains behind in a concentrated state. It is
then pellucid, without any flavour, and nearly
double the weight of an equal bulk of water.
This process would be greatly facilitated, and
the combustion much prolonged, by introduc-
ing fresh air into the chambers by means of
several pairs of bellows directed towards the
flame of the sulphur, and by allowing the ni-
trous gas to escape through long serpentine ca-
nals, in contact with water, to absorb any sul-
phuric or sulphurous acid gas it might contain.
By one experiment, M. Berthollet found
that 69 parts of sulphur in combustion united
with 31 parts of oxygen to form 100 parts of
sulphuric acid; and, by another experiment,
made in a different manner, he calculates that
100 parts of sulphuric acid consists of 72 parts
sulphur, combined with 28 parts of oxygen, all
by weight.

TABLE of the Combinations of the Sulphurous

Acid with the Salifiable Bases, in the

Order of Affinity

Names of the Bases

Names of the Neutral Salts

Barytes

Sulphite of barytes

Potash

potash

Soda

soda

Lime

lime

Magnesia

magnesia

Ammonia

ammonia

Argill

argill

Oxide of zinc

zinc

iron

manganese manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

mercury mercury

silver silver

gold gold

platinum platinum

Note. The only one of these salts known to the old
chemists was the sulphite of potash, under the name
of Stahl's sulphureous salt. So that, before our new
nomenclature, these compounds must have been
named Stahl's sulphureous salt, having base of fixed
vegetable alkali, and so of the rest.

In this table we have followed Bergman's order of
affinity of the sulphuric acid, which is the same in
regard to the earths and alkalies, but it is not certain
if the order be the same for the metallic oxides.

AUTHOB.

CHEMISTRY 9

This acid, in common with every other, can SECTION XV
only dissolve metals when they have been pre- ... . . , , . . , , ..
viously oxidated; but most of the metals are Observations upon Sulphurous Acid and its
capable of decomposing a part of the acid, so Cantonaton, mth Salifiabk Bases
as to carry off a sufficient quantity of oxygen The sulphurous acid is formed by the union
to render themselves soluble in the part of the of oxygen with sulphur by a lesser degree of
acid which remains undecomposed. This hap- oxygenation than the sulphuric acid. It is pro-
pens with silver, mercury, iron, and zinc, in curable either by burning sulphur slowly, or by
boiling concentrated sulphuric acid; they be- distilling sulphuric acid from silver, antimony,
come first oxidated by decomposing part of lead, mercury, or charcoal; by which operation
the acid, and then dissolve in the other part; a part of the oxygen quits the acid and unites
but they do not sufficiently disoxygenate the to these oxidabie bases, and the acid passes
decomposed part of the acid to reconvert it over in the sulphurous state of oxygenation.
into sulphur; it is only reduced to the state of This acid, in the common pressure and tem-
sulphurous acid, which, being volatilised by perature of the air, can only exist in form of
the heat, flies off in form of sulphurous acid gas. gas; but it appears, from the experiments of

Silver, mercury, and all the other metals ex- M. Clouet, that, in a very low temperature, it

cept iron and zinc, are insoluble in diluted sul- condenses and becomes fluid. Water absorbs a

phuric acid, because they have not sufficient great deal more of this gas than of carbonic

affinity with oxygen to draw it off from its com- acid gas, but much less than it does of muriatic

bination either with the sulphur, the sulphur- acid gas.

ous acid, or the hydrogen; but iron and zinc, That the metals cannot be dissolved in acids
being assisted by the action of the acid, de- without being previously oxidated, or by pro-
compose the water and become oxidated at its curing oxygen for that purpose from the acids
expense, without the help of heat. during solution, is a general and well estab-

TABLE of the Combinations of Phosphorous and Phosphoric
Acids, with the Salifiable Bases, in Order of Affinity

Names of the Names of the Neutral Salts formed by

Bases Phosphorous Add Phosphoric Acid

Lime Phosphites of lime 2 Phosphates of lime 3

Barytes barytes barytes

Magnesia magnesia magnesia

Potash potash potash

Soda soda soda

Ammonia ammonia ammonia

Argill argill argill

Oxides of zinc 1 zinc zinc

iron iron iron

manganese manganese manganese

cobalt cobalt cobalt

nickel nickel nickel

lead lead lead

tin tin tin

copper copper copper

bismuth bismuth bismuth

antimony antimony antimony

arsenic arsenic arsenic

mercury mercury mercury

silver silver silver

gold gold gold

platinum platinum platinum

1 The existence of metallic phosphites supposes that metals are suscep-
tible of solution in phosphoric acid at different degrees of oxygenation,
which is not yet ascertained. AUTHOR.

a All the phosphites were unknown till lately, and consequently have
not yet received names. AUTHOR.

The greater part of the phosphates were only discovered of late, and
have not yet been named. AUTHOR.

LAVOISIER

lished fact which I have perhaps repeated too
often. Hence, as sulphurous acid is already de-
prived of great part of the oxygen necessary
for forming the sulphuric acid, it is more dis-
posed to recover oxygen than to furnish it to
the greatest part of the metals; and, for this
reason, it cannot dissolve them unless previous-
ly oxidated by other means. From the same
principle it is that the metallic oxides dissolve
without effervescence, and with great facility,
in sulphurous acid. This acid, like the muri-
atic, has even the property of dissolving me-
tallic oxides surcharged with oxygen, and con-
sequently insoluble in sulphuric acid, and in
this way forms true sulphates. Hence we might
be led to conclude that there are no metallic
sulphites, were it not that the phenomena
which accompany the solution of iron, mer-

cury, and some other metals, convince us that
these metallic substances are susceptible of
two degrees of oxidation, during their solution
in acids. Hence the neutral salt in which the
metal is least oxidated must be named sulphite,
and that in which it is fully oxidated must be
called sulphate. It is yet unknown whether this
distinction is applicable to any of the metallic
sulphates, except those of iron and mercury.

SECTION XVI

Observations upon Phosphorous and Phosphoric
Acids and their Combinations with Salifiable
Bases

Under the article Phosphorus, Part II, Sec-
tion IX, we have already given a history of the
discovery of that singular substance, with some

TABLE of the Combinations of Carbonic Acid, with the
Salifiable Bases, in the Order of Affinity

Resulting Neutral Salts

Old Names

Aerated or effervescent heavy earth
Chalk, calcareous spar, aerated cal-
careous earth

Effervescing or aerated fixed vege-
table alkali, mephitis of potash
Aerated or effervescing fixed mineral
alkali, mephitic soda
Aerated, effervescing, mild, or me-
phitic magnesia

Aerated, effervescing, mild, or me-
phitic volatile alkali
Aerated or effervescing argillaceous
earth, or earth of alum
Zinc spar, mephitic or aerated zinc
Sparry iron-ore, mephitic or aerated
iron

Aerated manganese
Aerated cobalt
Aerated nickel

Sparry lead-ore, or aerated lead

Aerated tin

Aerated copper

Aerated bismuth

Aerated antimony

Aerated arsenic

Aerated mercury

Aerated silver

Aerated gold

Aerated platinum

i As these salts have only been understood of late, they have not, properly
speaking, any old names. M. Morveau, in the first volume of the Encyclopedia,
calls them Mephites; M. Bergman gives them the name of aerated; and M. de
Fourcroy, wljo calls.the carbonic acid chalky add, gives them the name of chalks.
AUTHOR.

Names of Resul
Bases 1 New Names

Barytes Carbonates

of barytes

Lime

lime

Potash

potash

Soda

soda

Magnesia

magnesia

Ammonia

ammonia

Argill

argill

Oxide of zinc

zinc

iron

manganese
cobalt

nickel

lead

tin

copper
bismuth

antimony

arsenic

mercury
silver

gold
platinum

CHEMISTRY

observations upon the mode of its existence in
vegetable and animal bodies. The best method
of obtaining this acid in a state of purity is by
burning well purified phosphorus under bell-
glasses, moistened on the inside with distilled
water; during combustion it absorbs twice and
a half its weight of oxygen; so that 100 parts of
phosphoric acid is composed of 28^ parts of
phosphorus united to 71J^ parts of oxygen.
This acid may be obtained concrete, in form of
white flakes which greedily attract the moist-
ure of the air, by burning phosphorus in a dry
glass over mercury.

To obtain phosphorous acid, which is phos-
phorus less oxygenated than in the state of
phosphoric acid, the phosphorus must be burnt
by a very slow spontaneous combustion over
a glass-funnel leading into a crystal phial; after
a few days, the phosphorus is found oxygen-
ated, and the phosphorous acid, in proportion
as it forms, has attracted moisture from the
air and dropped into the phial. The phospho-
rous acid is readily changed into phosphoric
acid by exposure for a long time to the free air;
it absorbs oxygen from the air and becomes
fully oxygenated.

As phosphorus has a sufficient affinity for
oxygen to attract it from the nitric and muri-
atic acids, we may form phosphoric acid by
means of these acids in a very simple and cheap
manner. Fill a tubulated receiver half full of
concentrated nitric acid and heat it gently,
then throw in small pieces of phosphorus
through the tube; these are dissolved with ef-
fervescence and red fumes of nitrous gas fly
off; add phosphorus so long as it will dissolve,
and then increase the fire under the retort to
drive off the last particles of nitric acid ; phos-
phoric acid, partly fluid and partly concrete,
remains in the retort.

SECTION XVII

Observations upon Carbonic Acid and its Com-
binations with Salifiable Bases

Of all the known acids, the carbonic is the
most abundant in nature ; it exists ready formed
in chalk, marble, and all the calcareous stones,
in which it is neutralized by a particular earth
called lime. To disengage it from this combi-
nation, nothing more is requisite than to add
some sulphuric acid, or any other which has a
stronger affinity for lime; a brisk effervescence
ensues, which is produced by the disengagement
of the carbonic acid which assumes the state of
gas immediately upon being set free. This gas,

incapable of being condensed into the solid or
liquid form by any degree of cold or of pressure
hitherto known, unites to about its own bulk
of water and thereby forms a very weak acid.
It may likewise be obtained in great abund-
ance from saccharine matter in fermentation
but is then contaminated by a small portion of
alcohol which it holds in solution.

As charcoal is the radical of this acid, we
may form it artificially by burning charcoal
in oxygen gas, or by combining charcoal,
and metallic oxides in proper proportions; the
oxygen of the oxide combines with the char-
coal, forming carbonic acid gas, and the metal
being left free recovers its metallic or reguline
form.

We are indebted for our first knowledge of
this acid to Dr. Black, before whose time its
property of remaining always in the state of
gas had made it to elude the researches of
chemistry.

It would be a most valuable discovery to so-
ciety if we could decompose this gas by any
cheap process, as by that means we might ob-
tain, for economical purposes, the immense
store of charcoal contained in calcareous earths,
marbles, limestones, &c. This cannot be ef-
fected by single affinity, because to decompose
the carbonic acid it requires a substance as

TABLE of the Combinations of Oxygenated

Muriatic Acid with the Salifiable Bases,

in the Order of Affinity

Names of the Bases Neutral Salts, New Names
Barytes Oxygenated muriate of barytes

Potash potash

Soda soda

Lime lime

Magnesia magnesia

Argill argill

Oxide of zinc zinc

iron iron

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

mercury

silver

gold

platinum

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

mercury

silver

gold

platinum

This order of salts, entirely unknown to the an-
cient chemists, was discovered in 1786 by M. Ber-
thollet. AUTHOR.

Names of the

Bases New Names

Barytes Muriate of barytes

Potash

Soda
Lime

Magnesia
Ammonia
Argill

Oxide of zinc
iron

manganese
cobalt
nickel

lead

potash

soda
lime

magnesia
ammonia
argill

zinc

iron

manganese

cobalt

nickel

lead

TABLE of the Combinations of Muriatic Acid with the
Salifiable Bases in the Order of Affinity

Resulting Neutral Salts

Old Names

Sea-salt, having base of
heavy earth

Febrifuge salt of Sylvius;
Muriated vegetable fixed
alkali
Sea-salt
Muriated lime
Oil of lime
Marine Epsom salt
Muriated magnesia
Sal ammoniac

Muriated alum, sea-salt with
base of earth of alum
Sea-salt of, or muriatic zinc
Salt of iron, Martial sea-salt
Sea-salt of manganese
Sea-salt of cobalt
Sea-salt of nickel
Horny-lead; plumbum
corneum

Smoking liquor of Libavius
Solid butter of tin
Sea-salt of copper
Sea-salt of bismuth
Sea-salt of antimony
Sea-salt of arsenic
Sweet sublimate of mercury,
calomel, aquila alba
Corrosive sublimate of
mercury

Horny silver, argentum

tin

1 smoking of tin
solid of tin

copper
bismuth

antimony

arsenic

mercury

silver

gold
platinum

sweet of mercury

corrosive of
mercury

silver

gold
platinum

corneum, luna cornea
Sea-salt of gold
Sea-salt of platinum

combustible as charcoal itself, so that we should
only make an exchange of one combustible
body for another not more valuable ; but it may
possibly be accomplished by double affinity,
since this process is so readily performed by
nature during vegetation from the most com-
mon materials.

SECTION XVIII

Observations upon Muriatic andOxygenatedMu-
riatic Acid and their Combinations with Sali-
fiable Bases

Muriatic acid is very abundant in the min-
eral kingdom naturally combined with differ-
ent salifiable bases, especially with soda, lime,
and magnesia. In sea-water, and the water of

several lakes, it is combined with these three
bases, and in mines of rock-salt it is chiefly
united to soda. This acid does not appear to
have been hitherto decomposed in any chem-
ical experiment; so that we have no idea what-
ever of the nature of its radical and only con-
clude from analogy with the other acids that it
contains oxygen as its acidifying principle. M.
Bertholiet suspects the radical to be of a me-
tallic nature; but, as nature appears to form
this acid daily in inhabited places by combin-
ing miasmata with aeriform fluids, this must
necessarily suppose a metallic gas to exist in
the atmosphere, which is certainly not impos-
sible but cannot be admitted without proof.

The muriatic acid has only a moderate ad-
herence to the salifiable bases and can readily

CHEMISTRY

be driven from its combination with these by
sulphuric acid. Other acids, as the nitric for
instance, may answer the same purpose; but
nitric acid being volatile would mix, during
distillation, with the muriatic. About one part
of sulphuric acid is sufficient to decompose two
parts of decrepitated sea-salt. This operation
is performed in a tubulated retort, having
WouhVs apparatus, (Plate iv, Fig. 1), adapted
to it. When ail the junctures are properly luted,
the sea-salt is put into the retort through the
tube, the sulphuric acid is poured on, and the
opening immediately closed with its ground
crystal stopper. As the muriatic acid can only
subsist in the gaseous form in the ordinary
temperature, we could not condense it without
the presence of water. Hence the use of the
water with which the bottles in Woulfe's ap-
paratus are half filled; the muriatic acid gas,
driven off from the sea-salt in the retort, com-
bines with the water and forms what the old
chemists called smoking spirit of salt, or Glau-
ber's spirit of sea-salt, which we now name
muriatic acid.

TABLE of the Combinations of Nitro- Muriatic

Acid with the Salifiable Bases in the Order

of Affinity so Far as is Known

Names of the Bases Names of the Neutral Salts
Argill Nitro-muriate of argill

Ammonia ammonia

Oxide of antimony antimony

silver silver

arsenic
Barytes

Oxide of bismuth
Lime
Oxide of cobalt

copper

tin

iron

Magnesia
Oxide of manganese

mercury

molybdenum

nickel

gold

platinum

lead
Potash ,
Soda
Oxide of tungsten

zinc

arsenic

barytes

bismuth

lime

cobalt

copper

tin

iron

magnesia

manganese

mercury

molybdenum

nickel

gold

platinum

lead

potash

soda

tungsten

zinc

Note. Most of these combinations, especially
those with the earths and alkalies, have been little
examined, and we are yet to learn whether they
form a mixed salt in which the compound radical
remains combined, or if the two acids separate to
form two distinct neutral salts. AUTHOR.

The acid obtained by the above process is
still capable of combining with a further dose
of oxygen, by being distilled from the oxides of
manganese, lead, or mercury, and the resulting
acid, which we name oxygenated muriatic acid,
can only, like the former, exist in the gaseous
form and is absorbed in a much smaller quan-
tity by water. When the impregnation of water
with this gas is pushed beyond a certain point,
the superabundant acid precipitates to the
bottom of the vessels in a concrete form. M.
Berthollet has shown that this acid is capable
of combining with a great number of the sal-
ifiable bases; the neutral salts which result
from this union are susceptible of deflagrating
with charcoal and many of the metallic sub-
stances; these deflagrations are very violent
and dangerous, owing to the great quantity of
caloric which the oxygen carries alongst with
it into the composition of oxygenated muriatic
acid.

SECTION XIX

Observations upon Nitro-Muriatic Acid and its
Combinations with Salifiable Bases

The nitro-muriatic acid, formerly called aqua
regia, is formed by a mixture of nitric and mu-
riatic acids; the radicals of these two acids
combine together and form a compound base,
from which an acid is produced, having prop-
erties peculiar to itself and distinct from those
of all other acids, especially the .property of
dissolving gold and platinum.

In dissolutions of metals in this acid, as in
all other acids, the metals are first oxidated by
attracting a part of the oxygen from the com-
pound radical. This occasions a disengagement
of a particular species of gas not hitherto de-
scribed, which may be called nitro-muriqtic gas;
it has a very disagreeable smell and is fatal to
animal life when respired; it attacks iron and
causes it to rust; it is absorbed in considerable
quantity by water, wh ich thereby acquires some
slight characters of acidity. Ihad occasion tb
make these remarks during a course of experi-
ments upon platinum, in which I dissolved a
considerable quantity of that metal iri nitro-
muriatic acid.

I at first suspected that in the mixture of ni-
tric and muriatic acids the' latter attracted a
part of the oxygen from the former and became
converted into oxygenated muriatic acid, whifch
gave it the property of dissolving gold; but
several facts remain inexplicable upon this sup*-
position. Were it sb, we must be able to diseri-

LAVOISIER '

gage nitrous gas by heating this acid, which
however does not 'sensibly happen. From these
considerations, I am led to adopt the opinion
of M. Berthollet and to consider nitro-muri-
atic acid as a single acid, with a compound
base or radical.

TABLE of the Combinations of Fluoric Acid
with the Salifiable Bases, in the Order
. of Affinity

Names of the Bases

Names of the Neutral Salts

Lime

Flu at of lime

Barytes

barytes

Magnesia

magnesia

Potash , ,

potash

Soda

soda

Ammonia

ammonia

Oxide of zinc

zinc

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic

bismuth

mercury

silver

gold

platinum

And by -the dry way,

Argill

Fluat of argill

Note. These combinations were entirely unknown
to the old chemists, and consequently have no names
in the old nomenclature. AUTHOR.

SECTION XX

Observations upon the Fluoric Acid and its
Combinations with Salifiable Bases

Fluoric exists ready formed b}' nature in the
fluoric spars, combined with calcareous earth
so a,s to form an insoluble neutral salt. To ob-
tain it disengaged froin that combination, fluor
spar, or fluat of lime,: is put into a leaden re-
tort, with a proper quantity of sulphuric acid;
a recipient likewise of lead, half full of water, is
adapted, and fire is applied to the retort. The
sulphuric acid, from its greater affinity, expels
the fluoric acid which passes over and is ab-
sorlpedvby the water in, the receiver. As fluoric
acid is naturally, in the gaseous form in the or-
dinary temperature, w,e caja receive it in a pneu-
rnato-chemical apparatus over mercury. We
are obliged, to, employ metallic vessels in this
process, beqause fluoric acid dissolves glass and

silicious earth and even renders these bodies
volatile, carrying them over with itself in dis-
tillation in the gaseous form.

We are indebted to M. Margraff for our
first acquaintance with this acid, though, as he
could never procure it free from combination
with a considerable quantity of silicious earth,
he was ignorant of its being an acid sui generis.
The Duke de Liancourt, under the name of M.
Boulanger, considerably increased our knowl-
edge of its properties; and M. Scheele seems
to have exhausted the subject. The only thing
remaining is to endeavour to discover the na-
ture of the fluoric radical, of which we cannot
form any ideas as the acid does not appear to
have been decomposed in any experiment. It is
only by means of compound affinity that ex-
periments can be made with this view with any
probability of success.

TABLE of the Combinations of Boracic Acid

with the Salifiable Bases, in the Order

of Affinity

Bases

Lime

Barytes

Magnesia

Potash

Soda

Ammonia

Oxide of zinc
iron
lead
tin

cobalt
copper
nickel
mercury

Argill

Neutral Salts
Borate of lime

barytes

magnesia

potash

soda

ammonia

zinc

iron

lead

tin

cobalt

copper

nickel

mercury

argill

Note. Most of these combinations were neither
known nor named by the old chemists. The boracic
acid was formerly called sedative salt and its com-
pounds borax, with base of fixed vegetable alkali,
<fcc. AUTHOR.

SECTION XXI

Observations upon Boracic Acid and its Com-
binations with Salifiable Bases

This is a concrete acid extracted from a salt
procured from India called borax or tincall. Al-
though borax has been very long employed in
the arts, we have as yet very imperfect knowl-
edge of its origin and of the methods by which
it is extracted and purified; there is reason to
believe it to be a native salt, found in the earth
in certain parts of the east and in the water of
some lakes. The whole trade of borax is in the

CHEMISTRY

hands of the Dutch, who have been exclusive-
ly possessed of the art of purifying it till very
lately when MM. L/Eguillier of Paris have
rivalled them in the manufacture ; but the proc-
ess still remains a secret to the world.

By chemical analysis we learn that borax is
a neutral salt with excess of base, consisting of
soda, partly saturated with a peculiar acid
long called Homberg's sedative salt, now the bo-
ratio acid. This acid is found in an uncombined
state in the waters of certain lakes. That of
Cherchiaio in Italy contains 94}^ grains in
each pint of water.

To obtain boracic acid, dissolve some borax
in boiling water, filtrate the solution, and add
sulphuric acid, or any other having greater af-
finity to soda than the boracic acid ; this latter
acid is separated and is procured in a crystal-
line form by cooling. This acid was long con-
sidered as being formed during the process by
which it is obtained and was consequently sup-
posed to differ according to the nature of the
acid employed in separating it from the soda;
but it is now universally acknowledged that it
is identically the same acid, in whatever way
procured, provided it be properly purified from
mixture of other acids by washing and by re-

TABLE of the Combinations of Arseniac Acid

with the Salifiable Bases, in the Order

of Affinity

Bases

Neutral Salts

Lime

Arseniate of lime

Barytes

barytes

Magnesia

magnesia

Potash

potash

Soda

soda

Ammonia

ammonia

Oxide of zinc

zinc

manganese

iron

lead

tin

cobalt

copper

nickel

bismuth

mercury

antimony

silver

gold

platinum

Argill

argill

Note. This order of salts was entirely unknown
to the ancient chemists. M. Macquer, in 1746, dis-
covered the combinations of arseniac acid with
potash and soda, to which he gave the name of
arsenical neutral salts. AUTHOR.

peated solution and crystallization. It is solu-
ble both in water and alcohol anfl has the prop-
erty of communicating a greefl colour to ttye
flame of that spirit. This circumstance, led to a
suspicion of its containing copper, which is not
confirmed by any decisive experiment. On the
contrary, if it contain any of that metal, it
must only be considered as an accidental mix-
ture. It combines with the saiifiable bases in
the humid way; and, though, in this manner, it
is incapable of dissolving any of the metals di-
rectly, this combination is readily effected by
compound affinity.

The table presents its combinations in the
order of affinity in the humid way; but there is
a considerable change in the order when we
operate via sicca; for, in that case, argill, though
the last in our list, must be placed immediately
after soda. r

The boracic radical is hitherto unknown; no
experiments having as yet been able to decom-
pose the acid ; we conclude, from analogy with
the other acids, that oxygen exists in its com-
position as the acidifying principle.

SECTION XXII

Observations upon Arseniac Acid and its Com-
binations with Salifiable Bases

In the Recueil de I'Acadtmie for 1746, M.
Macquer shows that when a mixture of white
oxide of arsenic and nitre are subjected to the
action of a strong fire a neutral salt is obtained,
which he calls neutral salt of arsenic. At that
time, the cause of this singular phenomenon,
in which a metal acts the part of an acid, was
quite unknown; but more modern experiments
teach that during this process the arsenic be-
comes oxygenated, by carrying off the oxygen
of the nitric acid; it is thus converted into a
real acid and combines with the potash. There
are other methods now known for oxygenating
arsenic and obtaining its acid free from com-
bination, The most simple and most effectual
of these is as follows: dissolve white oxide of
arsenic in three parts, by weight, of muriatic
acid; to this solution, in a boiling state, add
two parts of nitric acid and evaporate to dry-
ness. In this process the nitric acid is decom-
posed, its, oxygen unites with the oxide of ar-
senic and converts it into an acid, and the ni-
trous radical flies off in the state of nitrous gas;
whilst the muriatic acid is converted by the
heat into muriatic acid gas and may be col-
lected in proper vessels. The arseniac acid is

LAVOISIER

entirely fre$$ from the other acids employed
during the process by heating it in a crucible
till it begins to grow red; what remains is pure
concrete arseniac acid.

M. Scheele's process, which was repeated
with great success by M. Morveau in the lab-
oratory at Dijon, is as follows: distil muriatic
acid from the black oxide of manganese; this
converts it into oxygenated muriatic acid; by
carrying off the oxygen from the manganese;
receive this in a recipient containing white
oxide of arsenic, covered by a little distilled
water; the arsenic decomposes the oxygenated
muriatic acid by carrying off its supersatura-
tion of oxygen ; the arsenic is converted into ar-
seniac acid, and the oxygenated muriatic acid
is brought back to the state of common muri-
atic acid. The two acids are separated by dis-
tillation, with a gentle heat increased towards
the end of the operation; the muriatic acid
passes over and the arseniac acid remains be-
hind in a white concrete form.

The arseniac acid is considerably less vola-
tile than white oxide of arsenic; it often con-
tains white oxide of arsenic in solution, owing
to its not being sufficiently oxygenated; this is
prevented by continuing to add nitrous acid,
as in the former process, till no more nitrous
gas is produced. From ail these observations I
would give the following definition of arseniac
acid . It is a white concrete metallic acid, formed
by the combination of arsenic with oxygen,
fixed in a red heat, soluble in water, and ca-
pable of combining with many of the salifiable

SECTION XXIII

Observations upon Molybdic Acid and its Com*
binations with Salifiable Bases

Molybdenum is a particular metallic body,
capable of being oxygenated so far as to be-
come a true concrete acid. 1 For this purpose,
one part ore of molybdenum, which is a natural
sulphuret of that metal, is put into a retort
with five or six parts nitric acid, diluted with a
quarter of its weight of wafer, and heat is ap-
plied to the retort; the oxygen of the nitric acid
acts both upon the molybdenum and the sul-
phur, converting the one into molybdic and
the other into sulphuric acid; pour on fresh
Quantities of nitric acid so long as any red
fumes of nitrous gas escape; the molybdenum

This acid was discovered by M. J Scheele, to
whom chemistry is indebted for the discovery of
several other acids.

is then oxygenated as far as is possible and is
found at the bottom of the retort in a pulveru-
lent form, resembling chalk. It must be washed
in warm water, to separate any adhering parti-
cles of sulphuric acid; and, as it is hardly sol-
uble, we lose very little of it in this operation.
All its combinations with salifiable bases were
unknown to the ancient chemists.

TABLE of the Combinations of Tungstic Acid
with the Salifiable Bases

Bases
Lime
Barytes
Magnesia
Potash
Soda
Ammonia
Argill
Oxide of antimony,

Neutral Salts
Tungstate of lime
barytes
magnesia
potash
soda
ammonia
argill
&c. antimony, &c. 2

SECTION XXIV

Observations upon Tungstic Acid and its Com-
binations with Salifiable Bases

Tungsten is a particular metal, the ore of
which has frequently been confounded with
that of tin. The specific gravity of this ore is to
water as 6 to 1 ; in its form of crystallization it
resembles the garnet and varies in colour from
a pearl-white to yellow and reddish ; it is found
in several parts of Saxony and Bohemia. The
mineral called wolfram, which is frequent in
the mines of Cornwall, is likewise an ore of
this metal. In all these ores the metal is oxi-
dated; and, in some of them, it appears even
to be oxygenated to the state of acid, being
combined with lime into a true tungstate of
lime.

To obtain the acid free, mix one part of ore
of tungsten with four parts of carbonate of pot-
ash and melt the mixture in a crucible; then
powder and pour on twelve parts of boiling wa-
ter, add nitric acid, and the tungstic acid pre-
cipitates in a concrete form. Afterwards, to in-
sure the complete oxygenation of the metal,
add more nitric acid and evaporate to dryness,
repeating this operation so long as red fumes of
nitrous gas are produced. To procure tungstic
acid perfectly pure, the fusion of the ore with
carbonate of potash must be made in a crucible
of platinum, otherwise the earth of the com-

'All these salts were unknown to the ancient
chemists. AUTHOR.

CHEMISTRY

mon crucibles will mix with the products and
adulterate the acid.

TABLE of the Combinations of Tartarous Acid

with the Salifiable Bases, in the Order

of Affinity

Bases

Neutral Salts

Lime

Tartarite of lime

Barytes

barytes

Magnesia

magnesia

Potash

potash

Soda

soda

Ammonia

ammonia

Argill

argill

Oxide of zinc

zinc

iron

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

silver

mercury

gold

platinum

SECTION XXV

Observations upon Tartarous Add and its Com-
binations with Salifiable Bases

Tartar, or the concretion which fixes to the
inside of vessels in which the fermentation of
wine is completed, is a well known salt, com-
posed of a peculiar acid united in considerable
excess to potash. M. Scheele first pointed out
the method of obtaining this acid pure. Having
observed that it has a greater affinity to lime
than to potash, he directs us to proceed in the
following manner. Dissolve purified tartar in
boiling water and add a sufficient quantity of
lime till the acid be completely saturated. The
tartarite of lime which is formed, being almost
insoluble in cold water, falls to the bottom and
is separated from the solution of potash by de-
cantation; it is afterwards washed in cold wa-
ter and dried ; then pour on some sulphuric acid,
diluted with eight or nine parts of water, digest
for twelve hours in a gentle heat, frequently
stirring the mixture; the sulphuric acid com-
bines with the lime, and the tartarous acid is
left free. A small quantity of gas, not yet ex-
amined, is disengaged during this process. At

the end of twelve hours, having decanted off
the clear liquor, wash the sulphate of lime in
cold water, which add to the decanted liquor,
then evaporate the whole, and the tartarous
acid is obtained in a concrete form. Two pounds
of purified tartar, by means of from eight to
ten ounces of sulphuric acid, yield about elev-
en ounces of tartarous acid.

As the combustible radical exists in excess,
or as the acid from tartar is not fully saturated
with oxygen, we call it tartarous acid, and the
neutral salts formed by its combinations with
Salifiable bases tartarites. The base of the tar-
tarous acid is a carbono-hydrous or hydro-car-
bonous radical, less oxygenated than in the ox-
alic acid; and it would appear, from the exper-
iments of M. Hassenfratz, that azote enters
into the composition of the tartarous radical
even in considerable quantity. By oxygenating
the tartarous acid, it is convertible into oxalic,
malic, and acetous acids ; but it is probable the
proportions of hydrogen and charcoal in the
radical are changed during these conversions,
and that the difference between these acids
does not alone consist in the different degrees
of oxygenation.

The tartarous acid is susceptible of two de-
grees of saturation in its combinations with the
fixed alkalies; by one of these a salt is formed
with excess of acid, improperly called cream of
tartar, which in our new nomenclature is named
acidulous tartarite of potash; by a second or
equal degree of saturation a perfectly neutral
salt is formed, formerly called vegetable salt,
which we name tartarite of potash. With soda
this acid forms tartarite of soda, formerly called
sal de Seignette, or sal polychrest of RochelL

SECTION XXVI

Observations upon Malic Acid and its Combinor
tions with Salifiable Bases

The malic acid exists ready formed in the
sour juice of ripe and unripe apples, and many
other fruits, and is obtained as follows: satu-
rate the juice of apples with potash or soda and
add a proper proportion of acetite of lead dis-
solved in water; a double decomposition takes
place; the malic acid combines with the oxide
of lead and precipitates, being almost insolu-
ble, and the acetite of potash or soda remains
in the liquor. The malate of lead being separat-
ed by decantation is washed with cold water,
and some dilute sulphuric acid is added; this

LAVOISIER

unites with the lead into an insoluble sul-
phate and the malic acid remains free in the
liquor.

This acid, which is found mixed with citric
and tartarous acid in a great number of fruits,
is a kind of medium between oxalic and
acetous acids, being more oxygenated than the
former and less so than the latter. From this
circumstance, M. Hermbstadt calls it imper-
fect vinegar; but it differs likewise from ace-
tous acid, by having rather more charcoal
and less hydrogen in the composition of its
radical.

When an acid much diluted has been used in
the foregoing process, the liquor contains oxalic
as well as malic acid and probably a little tar-
tarous; these are separated by mixing lime-
water with the acids, oxalate, tartarite, and
malate of lime are produced; the two former,

TABLE of the Combinations of Citric Acid

with the Salifiable Bases, in the Order

of Affinity 1

Bases
Barytes
Lime
Magnesia
Potash
Soda
Ammonia
Oxide of zinc

manganese

iron

lead

cobalt

copper

arsenic

mercury

antimony

silver

gold

platinum

Neutral Salts
Citrate of barytes
lime

magnesia
potash
soda

ammonia
zinc

manganese
iron
lead
cobalt
copper
arsenic
mercury
antimony
silver
gold

platinum
argill

Argill

being insoluble, are precipitated, and the
malate of lime remains dissolved; from this the
pure malic acid is separated by the acetite of
lead and afterwards by sulphuric acid, as direct-
ed above.

SECTION XXVII

Observations upon Citric Acid and its Combina-
tions with Salifiable Bases

The citric acid is procured by expression
from lemons and is found in the juices of many

1 These combinations were unknown to the ancient
chemists. The order of affinity of the salifiable bases
with this acid was determined by M. Bergman and
by M. de Breney of the Dijon Academy. AUTHOR.

other fruits mixed with malic acid. To obtain
it pure and concentrated, it is first allowed to
depurate from the mucous part of the fruit by
long rest in a cool cellar, and is afterwards
concentrated by exposing it to the temperature
of 4 or 5 degrees below zero, from 21 to 23
of Fahrenheit; the water is frozen, and the

TABLE of the Combinations of Pyro-lignous

Acid with the Salifiable Bases, in the Order

of Affinity*

Bases Neutral Salts

Lime Pyro-mucite
Barytes
Potash
Soda

of lime
barytes
potash
soda

Magnesia
Ammonia

magnesia
ammonia

Oxide of zinc

zinc

manganese

iron

lead

tin

cobalt

copper
nickel

arsenic

bismuth

mercury

antimony
silver

gold
platinum

Argill

argill

acid remains liquid, reduced to about an eighth
part of its original bulk. A lower degree of
cold would occasion the acid to be engaged
amongst the ice, and render it difficultly separ-
able. This process was pointed out by M.
Georgius.

It is more easily obtained by saturating the
lemon-juice with lime, so as to form a citrate
of lime which is insoluble in water; wash this
salt and pour on a proper quantity of sulphuric
acid; this forms a sulphate of lime, which pre-
cipitates and leaves the citric acid free in the
liquor.

SECTION XXVIII

Observations upon Pyro-lignous Acid and its
Combinations with Salifiable Bases

The ancient chemists observed that most of
the woods, especially the more heavy and com-
pact ones, gave out a particular acid spirit, by
distillation, in a naked fire; but, before M.

* The above affinities were determined by MM.
de Mprveau and Elos Bourfier de Clervaux. These
combinations were entirely unknown till lately.
AUTHOR.

CHEMISTRY

Goetling, who gives an account of his experi-
ments upon this subject in Creli's Chemical
Journal for 1779, no one had ever made any
inquiry into its nature and properties. This
acid appears to be the same, whatever be the
wood it is procured from. When first distilled,
it is of a brown colour and considerably im-
pregnated with charcoal and oil; it is purified
from these by a second distillation. The pyro-
lignous radical is chiefly composed of hydrogen
and charcoal.

SECTION XXIX

Observations upon Pyro-tartarous Add and its
Combinations with Salifiable Bases

The name of Pyro-tartarous acid is given to a
dilute empyreumatic acid obtained from puri-
fied acidulous tartarite of potash by distilla-
tion in a naked fire. To obtain it, let a retort be
half filled with powdered tartar, adapt a tubu-
lated recipient, having a bent tube communi-
cating with a bell-glass in a pneumato-chemical
apparatus; by gradually raising the fire under
the retort, we obtain the pyro-tartarous acid
mixed with oil, which is separated by means of
a funnel. A vast quantity of carbonic acid gas
is disengaged during the distillation. The acid
obtained by the above process is much contam-
inated with oil, which ought to be separated
from it. Some authors advise to do this by a
second distillation; but the Dijon academicians
inform us that this is attended with great dan-

TABLE of the Combinations of Pyro-mucous

Add, with the Salifiable Bases, in the Order

of Affinity 1

Bases
Potash
Soda
Barytes
Lime
Magnesia
Ammonia
Argill
Oxide of zinc

Neutral Salts
Pyro-mucite of potash
soda
barytes
lime

magnesia
ammonia
argill
zinc

manganese

iron

lead

tin

cobalt

copper

nickel

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic arsenic

bismuth bismuth

antimony antimony

iAll these combinations were unknown to the
ancient chemists. AUTHOR.

ger from explosions which take place during
the process.

SECTION XXX

Observations upon Pyro-mucous Add and its
Combinations with Salifiable Bases

This acid is obtained by distillation in a na-
ked fire from sugar and all the saccharine bod-
ies; and, as these substances swell greatly in
the fire, it is necessary to leave seven-eighths
of the retort empty. It is of a yellow colour,
verging to red, and leaves a mark upon the
skin which will not remove but alongst with
the epidermis. It may be procured less coloured,
by means of a second distillation, and is con-
centrated by freezing, as is directed for the
citric acid. It is chiefly composed of water and
oil slightly oxygenated and is convertible into
oxalic and malic acids by farther oxygenation
with the nitric acid.

It has been pretended that a large quantity
of gas is disengaged during the distillation of
this acid, which is not the case if it be conduct-
ed slowly by means of moderate heat.

SECTION XXXI

Observations upon Oxalic Add and its Combi-
nations with Salifiable Bases

The oxalic acid is mostly prepared in Swit-
zerland and Germany from the expressed juice

TABLE of the Combinations of the Oxalic Acid,

with the Salifiable Bases, in the Order

of Affinity 2

Bases Neutral Salts

Lime Oxalate of lime

Barytes barytes

Magnesia magnesia

Potash potash

Soda soda

Ammonia ammonia

Argill argill

Oxide of zinc zinc

iron iron

manganese manganese

cobalt cobalt

nickel nickel

lead lead

copper copper

bismuth bismuth

antimony antimony

arsenic arsenic

mercury mercury

silver silver

gold gold

platinum platinum
* All unknown to the ancient chemists. AUTHOR.

LAVOISIER

of sorrel, from which it crystallizes by being
left long at rest; in this state it is partly sat-
urated with potash, forming a true acidulous
oxalate of potash, or salt with excess of acid. To
obtain it pure, it must be formed artificially by
oxygenating sugar, which seems to be the true
oxalic radical. Upon one part of sugar pour six
or eight parts of nitric acid and apply a gentle
heat; a considerable effervescence takes place,
and a great quantity of nitrous gas is disen-
gaged; the nitric acid is decomposed, and its
oxygen unites to the sugar. By allowing the
liquor to stand at rest, crystals of pure oxalic
acid are formed, which must be dried upon

blotting paper to separate any remaining por-
tions of nitric acid; and, to ensure the purity of
the acid, dissolve the crystals in distilled water
and crystallize them afresh.

From the liquor remaining after the first
crystallization of the oxalic acid we may obtain
malic acid by refrigeration. This acid is more
oxygenated than the oxalic; and, by a further
oxygenation, the sugar is convertible into ace-
tous acid, or vinegar.

The oxalic acid, combined with a small quan-
tity of soda or potash, has the property, like
the tartarous acid, of entering into a number
of combinations without suffering decomposi-

TABLE of the Combinations of Acetous Acid with the Salifiable Bases
in the Order of Affinity

Barytes

Potash

Soda

Lime

Magnesia
Ammonia

Oxide of zinc

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic

Neutral Salts
Acetite of barytes

potash

soda

lime

magnesia
ammonia

zinc

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic

bismuth Acetite of bismuth

mercury

antimony
silver

gold
platinum

Argill

mercury

antimony
silver

gold

platinum

argill

Names of the Resulting Neutral Salts
According to the Old Names

Unknown to the ancients. Discovered by
M. de Morveau, who calls it barotic acte.

Secret terra foliata tartari of Muller. Arcanum
tartari of Basil Valentin and Paracelsus.
Purgative magistery of tartar of Schroeder.
Essential salt of wine of Zwelfer. Regenerated
tartar of Tachonius. Diuretic salt of Sylvius
and Wilson.

Foliated earth with base of mineral alkali'
Mineral or crystallizable foliated earth. Min-
eral acetous salt.

Salt of chalk, coral, or crabs eyes; mentioned
by Hartman.

First mentioned by M. Wonzel.
Spiritus Minder eri. Ammoniacal acetous salt-
Known to Glauber, Schwedemberg, Respour,
Pott, de Lassone, and Wenzel, but not named.
Unknown to the ancients.
Martial vinegar. Described by Monnet, Wen-
zel, and the Duke d'Ayen.
Sugar, vinegar, and salt of lead or Saturn.
Known to Lemery, Margraff, Monnet, Wes-
lendorf, and Wenzel, but not named.
Sympathetic ink of M. Cadet.
Verdigris, crystals of verditer, verditer, dis-
tilled verdigris, crystals of Venus or of copper.
Unknown to the ancients.
Arsenico-acetous fuming liquor, liquid phos-
phorus of M. Cadet.

Sugar of bismuth of M. Geoffroy. Known to
Gellert, Pott, Weslendorf, Bergman, and de
Morveau.

Mercurial foliated earth, Keyser's famous
antivenereal remedy. Mentioned by Gebaver
in 1748; known to Helot, Margraff, Baume,
Bergman, and de Morveau.

Unknown.

Described by Margraff, Monnet, and Wenzel;

unknown to the ancients.

Little known, mentioned by SchroSder and

Juncker.

Unknown.

According to M. Wenzel, vinegar dissolves

only a very small proportion of argill.

CHEMISTRY

tion. These combinations form triple salts, or
neutral salts with double bases, which ought to
have proper names. The salt of sorrel, which is
potash having oxalic acid combined in excess,
is named acidulous oxalate of potash in our
new nomenclature.

The acid procured from sorrel has been known
to chemists for more than a century, being
mentioned by M. Duclos in the Recueil de
I' Academic for 1688, and was pretty accurately
described by Boerhaave; but M. Scheele first
showed that it contained potash and demon-
strated its identity with the acid formed by the
oxygenation of sugar.

SECTION XXXII

Observations upon Acetous Acid and its Com-
binations with Salifidble Bases

This acid is composed of charcoal and hydro-
gen united together and brought to the state of
an acid by the addition of oxygen; it is conse-
quently formed by the same elements with the
tartarous oxalic, citric, malic acids, and others,
but the elements exist in different proportions
in each of these; and it would appear that the
acetous acid is in a higher state of oxygenation
than these other acids. I have some reason to
believe that the acetous radical contains a
small portion of azote; and, as this element is
not contained in the radicals of any vegetable
acid except the tartarous, this circumstance is
one of the causes of difference. The acetous acid,
or vinegar, is produced by exposing wine to a
gentle heat, with the addition of some ferment:
this is usually the dregs, or mother, which have
separated from other vinegar during fermenta-
tion, or some similar matter. The spiritous part
of the wine, which consists of charcoal and
hydrogen, is oxygenated and converted into
vinegar. This operation can only take place
with free access of air and is always attended
by a diminution of the air employed in conse-
quence of the absorption of oxygen; wherefore,
it ought always to be carried on in vessels only
half filled with the vinous liquor submitted to
the acetous fermentation. The acid formed dur-
ing this process is very volatile, is mixed with a
large proportion of water and with many foreign
substances; and, to obtain it pure, it is distilled
in stone or glass vessels by a gentle fire. The acid
which passes over in distillation is somewhat
changed by the process, and is not exactly of the
same nature with what remains in the alembic,
but seems less oxygenated. This circumstance
has not been formerly observed by chemists.

Distillation is not sufficient for depriving
this acid of all its unnecessary water; an<dj for
this purpose, the best way is by exposing it to a
degree of cold from 4 to 6 below the freezing
point, from 19 to 23 of Fahrenheit; by this
means the aqueous part becomes frozen and
leaves the acid in a liquid state and consider-
ably concentrated. In the usual temperature of
the air, this acid can only exist in the gaseous
form and can only be retained by combination
with a large proportion of water. There are
other chemical processes for obtaining the ace-
tous acid, which consist in oxygenating the
tartarous, oxalic, or malic acids, by means of
nitric acid; but there is reason to believe the
proportions of the elements of the radical are
changed during this process. M. Hassenfratz
is at present engaged in repeating the experi-
ments by which these conversions are said to
be produced.

The combinations of acetous acid with the
various salifiable bases are very readily formed ;
but most of the resulting neutral salts are not
crystallizable, whereas those produced by the
tartarous and oxalic acids are, in general, hard-
ly soluble. Tartarite and oxalate of lime are
not soluble in any sensible degree. The malates
are a medium between the oxalates and ace-

TABLE of the Combinations of Acetic Acid with
the Salifiable Bases, in the Order of Affinity

Bases Neutral Salts
Barytes Acetate of barytes

Potash potash

Soda soda

Lime lime

Magnesia magnesia

Ammonia ammonia

Oxide of zinc zinc

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic

bismuth

manganese

iron

lead

tin

cobalt

copper

nickel

arsenic

bismuth

mercury mercury

antimony antimony

silver silver

gold gold

platinum platinum

Argill argill

Note. All these salts were unknown to the an-
cients; and even those chemists who are most vers-
ant in modern discoveries, are yet at a loss whether
the greater part of the salts produced by the oxygen-
ated aoetio radical belong properly to the class of
acetites, or to that of acetates. AUTHOR.

LAVOISIER

tites, with respect to solubility, and the malic
acid is in the middle degree of saturation be-
tween the oxalic and acetous acids. With this,
as with all the acids, the metals require to be
oxidated previous to solution.

The ancient chemists knew hardly any of
the salts formed by the combinations of ace-
tous acid with the salifiable bases, except the
acetites of potash, soda, ammonia, copper, and
lead. M. Cadet discovered the acetite of ar-
senic; 1 M. Wenzel, the Dijon academicians,
M. de Lassone, and M. Proust, made us ac-
quainted with the properties of the other ace-
tites. From the property which acetite of pot-
ash possesses, of giving out ammonia in distil-
lation, there is some reason to suppose that,
besides charcoal and hydrogen, the acetous
radical contains a small proportion of azote,
though it is not impossible but the above pro-
duction of ammonia may be occasioned by the
decomposition of the potash.

SECTION XXXIII

Observations upon Acetic Acid and its Combina-
tions with Salifiable Bases

We have given to radical vinegar the name
of acetic acid, from supposing that it consists

TABLE of the Combinations of Succinic Acid

with the Salifiable Bases, in the Order

of Affinity

Bases

Neutral Salts

Barytes Succinate
Lime

of barytes
lime

Potash
Soda

potash
soda

Ammonia

ammonia

Magnesia
Argill
Oxide of zinc

magnesia
argill
zinc

iron

manganese
cobalt

nickel

lead

tin

copper
bismuth

antimony

arsenic

mercury
silver

gold
platinum

Note. All the succinates were unknown to the
ancient chemists. AUTHOR.
i Savans Etrangers, Vol. III.

of the same radical with that of the acetous
acid but more highly saturated with oxygen.
According to this idea, acetic acid is the highest
degree of oxygenation of which the hydro-car-
bonous radical is susceptible; but, although
this circumstance be extremely probable, it re-
quires to be confirmed by further and more de-
cisive experiments, before it be adopted as an
absolute chemical truth. We procure this acid
as follows: upon three parts acetite of potash
or of copper pour one part of concentrated sul-
phuric acid, and, by distillation, a very highly
concentrated vinegar is obtained, which we call
acetic acidj formerly named radical vinegar. It
is not rigorously proved that this acid is more
highly oxygenated than the acetous acid, nor
that the difference between them may not con-
sist in a different proportion between the ele-
ments of the radical or base.

SECTION XXXIV

Observations upon Succinic Acid and its Com-
binations with Salifiable Bases

The succinic acid is drawn from amber by
sublimation in a gentle heat and rises in a con-
crete form into the neck of the subliming ves-
sel. The operation must not be pushed too far,
or by too strong a fire, otherwise the oil of the
amber rises alongst with the acid. The salt is
dried upon blotting paper and purified by re-
peated solution and crystallization.

This acid is soluble in twenty-four times its
weight of cold water and in a much smaller
quantity of hot water. It possesses the qual-
ities of an acid in a very small degree and only
affects the blue vegetable colours very slightly.
The affinities of this acid, with the salifiable
bases, are taken from M. de Morveau, who is
the first chemist that has endeavoured to as-
certain them.

SECTION XXXV

Observations upon Benzoic Acid and its Com-
binations with Salifiable Bases

This acid was known to the ancient chemists
under the name of Flowers of Benjamin, or of
Benzoin, and was procured, by sublimation,
from the gum or resin called Benzoin. The
means of procuring it, via humida, was discov-
ered by M. Geoffrey and perfected by M.
Scheele. Upon benzoin, reduced to powder,
pour strong lime-water, having rather an excess
of lime; keep the mixture continually stirring

CHEMISTRY

and, after half an hour's digestion, pour off the
liquor and use fresh portions of lime-water in
the same manner, so long as there is any ap-
pearance of neutralization. Join all the de-
canted liquors and evaporate, as far as possi-
ble, without occasioning crystallization, and,
when the liquor is cold, drop in muriatic acid till
no more precipitate is formed. By the former
part of the process a benzoate of lime is form-
ed, and by the latter the muriatic acid com-
bines with the lime, forming muriate of lime,
which remains dissolved, while the benzoic acid,
being insoluble, precipitates in a concrete state.

SECTION XXXVI

Observations upon Camphoric Acid and its Com-
binations with Salifiable Bases

Camphor is a concrete essential oil, obtained,
by sublimation from a species of laurus which
grows in China and Japan. By distilling nitric
acid eight times from camphor, M. Kosegar-
ten converted it into an acid analogous to the
oxalic; but, as it differs from that acid in some
circumstances, we have thought necessary to
give it a particular name till its nature be more
completely ascertained by farther experiment.

As camphor is a carbono-hydrous or hydro-
carbonous radical, it is easily conceived that,
by oxygenation, it should form oxalic, malic,
and several other vegetable acids. This conjec-
ture is rendered not improbable by the experi-
ments of M. Kosegarten; and the principal
phenomena exhibited in the combinations of
camphoric acid with the salifiable bases, being
very similar to those of the oxalic and malic
acids, lead me to believe that it consists of a
mixture of these two acids.

SECTION XXXVII

Observations upon Gallic Acid, and its Com-
binations with Salifiable Bases 1

The gallic acid, formerly called principle of
astringency, is obtained from gall nuts, either
by infusion or decoction with water, or by dis-
tillation with a very gentle heat. This acid has
only been attended to within these few years.
The Committee of the Dijon Academy have
followed it through all its combinations and
give the best account of it hitherto produced.

* Those combinations, which are called gallates,
were all unknown to the ancients; and the order of
their affinity is not established. AUTHOR.

Its acid properties are very weak; it reddens
the tincture of turnsole, decomposes sulphur-
ets, and unites to all the metals when they have
been previously dissolved in some other acid.
Iron, by this combination, is precipitated of a
very deep blue or violet colour. The radical of
this acid, if it deserves the name of one, is hith-
erto entirely unknown; it is contained in oak
willow, marsh iris, the strawberry, nymphea,
Peruvian bark, the flowers and bark of pome-
granate, and in many other woods and barks.

SECTION XXXVIII

Observations upon Lactic Acid and its Combina-
tions with Salifiable Bases 2

The only accurate knowledge we have of
this acid is from the works of M. Scheele. It is
contained in whey, united to a small quantity
of earth, and is obtained as follows: reduce
whey to one eighth part of its bulk by evapo-
ration and filtrate, to separate all its cheesy
matter; then add as much lime as is necessary
to combine with the acid; the lime is afterwards
disengaged by the addition of oxalic acid, which
combines with it into an insoluble neutral salt.
When the oxalate of lime has been separated by

TABLE of the Combinations of Saccho-lactic

Acid with the Salifiable Bases, in the Order

of Affinity

Neutral Salts

Lime Saccholate

of lime

Barytes
Magnesia
Potash
Soda

barytes
magnesia
potash
soda

Ammonia

ammonia

Argill
Oxide of zinc

argill
zinc

manganese

iron

lead

tin

cobalt

copper
nickel

arsenic

bismuth

mercury
antimony
silver

Note. All these were unknown to the ancient
chemists. AUTHOR.

* These combinations are called lactates; they were
all unknown to the ancient chemists and their affini-
ties have not yet been ascertained. AUTHOR.

LAVOISIER

decantation, evaporate the remaining liquor to
the consistence of honey; the lactic acid is dis-
solved by alcohol, which does not unite with
the sugar of milk and other foreign matters;
these are separated by filtration from the alco-
hol and acid ; and the alcohol being evaporated,
or distilled off, leaves the lactic acid behind.

This acid unites with all the salifiable bases,
forming salts which do not crystallize; and it
seems considerably to resemble the acetous
acid.

SECTION XXXIX

Observations upon Saccho-lactic Add and its
Combinations with Salifiable Bases

A species of sugar may be extracted, by evap-
oration, from whey, which has long been known
in pharmacy, and which has a considerable re-
semblance to that procured from sugar canes.
This saccharine matter, like ordinary sugar,
may be oxygenated by means of nitric acid.
For this purpose, several portions of nitric acid
are distilled from it; the remaining liquid is
evaporated and set to crystallize, by which
means crystals of oxalic acid are procured; at
the same time a very fine white powder precip-
itates, which is the saccho lactic acid discov-
ered by Scheele. It is susceptible of combining
with the alkalies, ammonia, the earths, and
even with the metals. Its action upon the latter
is hitherto but little known, except that, with
them, it forms difficultly soluble salts. The
order of affinity in the table is taken from
Bergman.

TABLE of Combinations of Formic Acid with
the Salifiable Bases, in the Order of Affinity

SECTION XL

Bases

Neutral Salts

Barytes

Formiate of barytes

Potash

potash

Soda

soda

Lime

lime

Magnesia

magnesia

Ammonia

ammonia

Oxide of zinc

zinc

manganese manganese

iron

lead

tin

cobalt

copper

nickel

bismuth

silver

Argill

argill

Observations upon Formic Acid and its Combi-
nations with Salifiable Bases

This acid was first obtained by distillation
from ants in the last century, by Samuel Fisher.
The subject was treated of by Margraff in 1749,
and by MM. Ardwisson and Ochrn of Leipzig
in 1777. The formic acid is drawn from a large
species of red ants, formica rufa, Lin., which
form large ant hills in woody places. It is pro-
cured either by distilling the ants with a gentle
heat in a glass retort or an alembic; or, after
having washed the ants in cold water and dried
them upon a cloth, by pouring on boiling water,
which dissolves the acid ; or the acid may be pro-
cured by gentle expression from the insects, in
which case it is stronger than in any of the form-
er ways. To obtain it pure, we must rectify, by
means of distillation, which separates it from
the uncombined oily and charry matter; and it
may be concentrated by freezing, in the man-
ner recommended for treating the acetous acid.

SECTION XLI

Observations upon Bombic Acid and its Com-
binations with Salifiable Bases 1

The juices of the silk worm seem to assume
an acid quality when that insect changes from

TABLE of the Combinations of the Sebacic Acid
with the Salifiable Bases, in the Order of Affinity

Bases

Neutral Salts

Barytes
Potash
Soda

Sebate of barytes
potash
soda

Lime

lime

Magnesia
Ammonia

magnesia
ammonia

Argill
Oxide of zinc

argill
zinc

manganese

iron

lead

tin

cobalt

copper
nickel

arsenic

bismuth

Note. All unknown to the ancient c hernia ts.-
AUTHOR.

mercury mercury

antimony antimony

silver silver

Note. All these were unknown to the ancient
chemists. AUTHOR.

1 These combinations named bombates were un-
known to the ancient chemists; and the affinities of
the salifiable bases with the bombic acid are unde-
termined . AUTHOR.

CHEMISTRY

a larva to a chrysalis. At the moment of its es-
cape from the latter to the butterfly form, it
emits a reddish liquor which reddens blue pa-
per, and which was first attentively observed
by M. Chaussier of the Dijon Academy, who
obtains the acid by infusing silk worm chrysa-
lids in alcohol, which dissolves their acid with-
out being charged with any of the gummy parts
of the insect; and, by evaporating the alcohol,
the acid remains tolerably pure. The proper-
ties and affinities of this acid are not hitherto
ascertained with any precision; and we have
reason to believe that analogous acids may be
procured from other insects. The radical of
this acid is probably, like that of the other
acids from the animal kingdom, composed of
charcoal, hydrogen, and azote, with the addi-
tion, perhaps, of phosphorus.

SECTION XLII

Observations upon Sebacic Acid and its Combi-
nations with Salijiable Bases

To obtain the sebacic acid, let some suet be
melted in a skillet over the fire, alongst with
some quicklime in fine powder, and constantly
stirred, raising the fire towards the end of the
operation, and taking care to avoid the vap-
ours, which are very offensive. By this process
the sebacic acid unites with the lime into a
sebate of lime, which is with difficulty soluble in
water; it is, however, separated from the fatty
matters with which it is mixed by solution in a
large quantity of boiling water. From this the
neutral salt is separated by evaporation; and,
to render it pure, is calcined, redissolved, and
again crystallized. After this we pour on a
proper quantity of sulphuric acid, and the se-
bacic acid passes over by distillation.

SECTION XLIII

Observations upon Lithic Acid and its Combina-
tions with Salifiable Bases 1

From the later experiments of Bergman and
Scheele, the urinary calculus appears to be a
species of salt with an earthy basis; it is slight-
ly acidulous, and requires a large quantity of
water for solution, three grains being scarcely
soluble in a thousand grains of boiling water,
and the greater part again crystallizes when
cold. To this concrete acid, which M. de Mor-
veau calls lithiasic acid, we give the name of

i All the combinations of this acid, should it final-
ly turn out to be one, were unknown to the ancient
chemists, and its affinities with the salifiable bases
have not been determined. AUTHOR.

lithic acid, the nature and properties of which
are as yet very little known. There is some ap-
pearance that it is an acidulous neutral salt, or
acid combined in excess with a salifiable base;
and I have reason to believe that it really is an
acidulous phosphate of lime; if so, it must be
excluded from the class of peculiar acids.

TABLE of the Combinations of the Prussic Acid

with the Salifiable Bases, in the Order

of Affinity

Bases
Potash
Soda

Ammonia
Lime
Barytes
Magnesia
Oxide of zinc

Neutral Salts
Prussiate of potash
soda

ammonia
lime
barytes
magnesia
zinc

iron

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

silver

mercury

gold

platinum

iron

manganese

cobalt

nickel

lead

tin

copper

bismuth

antimony

arsenic

silver

mercury

gold

platinum

Note. All these were unknown to former chem-
ists. AUTHOR.

SECTION XLIV

Observations upon the Prussic Acid and its Com-
binations with Salifiable Bases

As the experiments which have been made
hitherto upon this acid seem still to leave a con-
siderable degree of uncertainty with regard to
its nature, I shall not enlarge upon its proper-
ties, and the means of procuring it pure and
disengaged from combination. It combines with
iron, to which it communicates a blue colour,
and is equally susceptible of entering into com-
bination with most of the other metals, which
are precipitated from it by the alkalies, am-
monia, and lime, in consequence of greater af-
finity. The prussic radical, from the experi-
ments of Scheele, and especially from those of
M. Berthollet, seems composed of charcoal
and azote; hence it is an acid with a double
base. The phosphorus which has been found
combined with it appears, from the experiments
of M. Hassenfratz, to be only accidental.

86 LAVOISIER

Although this acid combines with alkalies, in the class of acids; but, as I have already ob-
earths, and metals, in the same way with other served, it is difficult to form a decided opinion
acids, it possesses only some of the properties upon the nature of this substance until the
we have been used to attribute to acids, and it subject has been farther elucidated by a great-
may consequently be improperly ranked here er number of experiments.

THIRD PART

DESCRIPTION OF THE INSTRUMENTS AND OPERATIONS
OF CHEMISTRY

INTRODUCTION

IN the two former parts of this work I designed-
ly avoided being particular in describing the
manual operations of chemistry, because I had
found from experience that, in a work appro-
priated to reasoning, minute descriptions of
processes and of plates interrupt the chain of
ideas and render the attention necessary both
difficult and tedious to the reader. On the
other hand, if I had confined myself to the sum-
mary descriptions hitherto given, beginners
could have only acquired very vague concep-
tions of practical chemistry from my work and
must have wanted both confidence and interest
in operations they could neither repeat nor
thoroughly comprehend. This want could not
have been supplied from books; for, besides that
there are not any which describe the modern
instruments and experiments sufficiently at
large, any work that could have been consulted
would have presented these things under a very
different order of arrangement and in a different
chemical language, which must greatly tend to
injure the main object of my performance.

Influenced by these motives, I determined
to reserve, for a third part of my work, a sum-
mary description of all the instruments and
manipulations relative to elementary chemis-
try. I considered it as better placed at the end,
rather than at the beginning of the book, be-
cause I must have been obliged to suppose the
reader acquainted with circumstances which a
beginner cannot know and must therefore have
read the elementary part to become acquainted
with. The whole of this third part may there-
fore be considered as resembling the explana-
tions of plates which are usually placed at the
end of academic memoirs that they may not
interrupt the connection of the text by length-
ened description. Though I have taken great
pains to render this part clear and methodical
and have not omitted any essential instrument
or apparatus, I am far from pretending by it to
set aside the necessity of attendance upon lec-

tures and laboratories for such as wish to ac-
quire accurate knowledge of the science of
chemistry. These should familiarise themselves
to the employment of apparatus, and to the
performance of experiments by actual experi-
ence. Nihil est in intellectu quod non priusfuerit
in sensu, the motto which the celebrated Rou-
elle caused to be painted in large characters in
a conspicuous part of his laboratory, is an im-
portant truth never to be lost sight of either by
teachers or students of chemistry.

Chemical operations may be naturally di-
vided into several classes, according to the pur-
poses they are intended for performing. Some
may be considered as purely mechanical, such
as the determination of the weight and bulk of
bodies, trituration, ievigation, searching, wash-
ing, filtration, <fec. Others may be considered
as real chemical operations, because they are
performed by means of chemical powers and
agents; such are solution, fusion, &c. Some of
these are intended for separating the elements
of bodies from each other, some for reuniting
these elements together; and some, as combus-
tion, produce both these effects during the
same process.

Without rigorously endeavouring to follow
the above method, I mean to give a detail of
the chemical operations in such order of ar-
rangement as seemed best calculated for con-
veying instruction. I shall be more particular
in describing the apparatus connected with
modern chemistry, because these are little
known by men who have devoted much of their
time to chemistry and even by many professors
of the science.

CHAPTER I

Of the Instruments Necessary for Determining
the Absolute and Specific Gravities of Solid
and Liquid Bodies

THE best method known for determining the
quantities of substances submitted to chemical
experiment or resulting from them, is by means

LAVOISIER

of an accurately constructed beam and scales,
with properly regulated weights, which well
known operation is called weighing. The de-
nomination and quantity of the weights used
as an unit or standard for this purpose are ex-
tremely arbitrary, and vary not only in differ-
ent kingdoms, but even in different provinces
of the same kingdom, and in different cities of
the same province. This variation is of infinite
consequence to be well understood in commerce
and in the arts; but, in chemistry, it is of no
moment what parti cular denomination of weigh t
be employed, provided the results of experi-
ments be expressed in convenient fractions of
the same denomination. For this purpose, until
all the weights used in society be reduced to
the same standard, it will be sufficient for chem-
ists in different parts to use the common pound
of their own country as the unit or standard,
and to express all its fractional parts in deci-
mals instead of the arbitrary divisions now in
use. By this means the chemists of all countries
will be thoroughly understood by each other,
as, although the absolute weights of the ingred-
ients and products cannot be known, they will
readily, and without calculation, be able to de-
termine the relative proportions of these to
each other with the utmost accuracy; so that
in this way we shall be possessed of an univer-
sal language for this part of chemistry.

With this view I have long projected to have
the pound divided into decimal fractions, and
I have of late succeeded through the assistance
of M. Fourche, balance-maker at Paris, who
has executed it for me with great accuracy and
judgment. I recommend to all who carry on ex-
periments to procure similar divisions of the
pound, which they will find both easy and sim-
ple in its application, with a very small knowl-
edge of decimal fractions. 1

As the usefulness and accuracy of chemistry
depend entirely upon the determination of the
weights of the ingredients and products both
before and after experiments, too much preci-
sion cannot be employed in this part of the sub-
ject; and, for this purpose, we must be provid-
ed with good instruments. As we are often
obliged, in chemical processes, to ascertain,
within a grain or less, the tare or weight of
large and heavy instruments, we must have
beams made with peculiar niceness by accurate

1 M. Lavoisier's very accurate directions for re-
ducing the common subdivisions of the French pound
into decimal fractions, and vice versa, given in tables
subjoined to this 3d part are not printed in this edi-
tion , TRANSLATOR.

workmen, and these must always be kept apart
from the laboratory in some place where the
vapours of acids, or other corrosive liquors,
cannot have access; otherwise the steel will
rust, and the accuracy of the balance be de-
stroyed. I have three sets, of different sizes,
made by M. Fontin with the utmost nicety,
and, excepting those made by M. Ramsden of
London, I do not think any can compare with
them for precision and sensitivity. The largest
of these is about three feet long in the beam
for large weights, up to fifteen or twenty pounds ;
the second, for weights of eighteen or twenty
ounces, is exact to a tenth part of a grain; and
the smallest, calculated only for weighing about
one gros, is sensibly affected by the five hun-
dredth part of a grain.

Besides these nicer balances, which are only
used for experiments of research, we must have
others of less value for the ordinary purposes of
the laboratory. A large iron balance, capable
of weighing forty or fifty pounds within half a
dram, one of a middle size, which may ascer-
tain eight or ten pounds, within ten or twelve
grains, and a small one, by which about a
pound may be determined, within one grain.

We must likewise be provided with weights
divided into their several fractions, both vul-
gar and decimal, with the utmost nicety, and
verified by means of repeated and accurate
trials in the nicest scales; and it requires some
experience, and to be accurately acquainted
with the different weights, to be able to use
them properly. The best way of precisely as-
certaining the weight of any particular sub-
stance is to weigh it twice, once with the deci-
mal divisions of the pound and another time
with the common subdivisions or vulgar frac-
tions, and, by comparing these, we attain the
utmost accuracy.

By the specific gravity of any substance is
understood the quotient of its absolute weight
divided by its magnitude, or, what is the same,
the weight of a determinate bulk of any body.
The weight of a determinate magnitude of wa-
ter has been generally assumed as unity for
this purpose; and we express the specific grav-
ity of gold, sulphuric acid, &c. by saying that
gold is nineteen times, and sulphuric acid twice
the weight of water, and so of other bodies.

It is the more convenient to assume water as
unity in specific gravities, that those substances
whose specific gravity we wish to determine are
most commonly weighed in water for that pur-
pose. Thus, if we wish to determine the spe-

CHEMISTRY

cific gravity of gold flattened under the ham-
mer, and supposing the piece of gold to weigh
8 02. 4 gros 2% grs. in the air, 1 it is suspended
by means of a fine metallic wire under the scale
of a hydrostatic balance so as to be entirely
immersed in water and again weighed. The
piece of gold in Mr. Brisson's experiment lost
by this means 3 gros 37 grs.; and, as it is evi-
dent that the weight lost by a body weighed in
water is precisely equal to the weight of the
water displaced, or to that of an equal volume
of water, we may conclude that, in equal mag-
nitudes, gold weighs 4893H 9 r s> and water 253
grs. which, reduced to unity, gives 1.0000 as
the specific gravity of water and 19.3617 for
that of gold. We may operate in the same man-
ner with all solid substances. We have rarely
any occasion, in chemistry, to determine the
specific gravity of solid bodies, unless when
operating upon alloys or metallic glasses; but
we have very frequent necessity to ascertain
that of fluids, as it is often the only means of
judging of their purity or degree of concen-
tration.

This object may be very fully accomplished
with the hydrostatic balance, by weighing a
solid body; such, for example, as a little ball of
rock crystal suspended by a very fine gold wire,
first in the air, and afterwards in the fluid whose
specific gravity we wish to discover. The weight
lost by the crystal, when weighed in the liquor,
is equal to that of an equal bulk of the liquid.
By repeating this operation successively in wa-
ter and different fluids, we can very readily as-
certain, by a simple and easy calculation, the
relative specific gravities of these fluids, either
with respect to each other or to water. This
method is not, however, sufficiently exact, or,
at least, is rather troublesome, from its extreme
delicacy, when used for liquids differing but
little in specific gravity from water; such, for
instance, as mineral waters, or any other water
containing very small portions of salt in solu-
tion.

In some operations of this nature, which have
not hitherto been made public, I employed an
instrument of great sensitivity for this purpose
with great advantage. It consists of a hollow
cylinder A b cf (Plate vu, Fig. 6), of brass, or
rather of silver, loaded at its bottom, bcf,
with tin, as represented swimming in a jug of
water, Imno. To the upper part of the cylin-
der is attached a stalk of silver wire, not more

i Vide Mr. Brisson's Essay upon Specific Gravity,
p. 5. AUTHOR.

than three fourths of a line diameter, sur-
mounted by a little cup d, intended for contain-
ing weights; upon the stalk a mark is made at
0, the use of which we shall presently explain.
This cylinder may be made of any size; but, to
be accurate, ought at least to displace four
pounds of water. The weight of tin with which
this instrument is loaded ought to be such as
will make it remain almost in equilibrium in
distilled water and should not require more
than half a dram, or a dram at most, to make it
sink to g.

We must first determine, with great preci-
sion, the exact weight of the instrument and
the number of additional grains requisite for
making it sink, in distilled water of a deter-
minate temperature, to the mark. We then per-
form the same experiment upon all the fluids
of which we wish to ascertain the specific grav-
ity, and, by means of calculation, reduce the
observed differences to a common standard of
cubic feet, pints or pounds, or of decimal frac-
tions, comparing them with water. This method,
joined to experiments with certain reagents,
is one of the best for determining the quality of
waters and is even capable of pointing out dif-
ferences which escape the most accurate chem-
ical analysis. I shall, at some future period,
give an account of a very extensive set of
experiments which I have made upon this
subject.

These metallic hydrometers are only to be
used for determining the specific gravities of
such waters as contain only neutral salts or al-
kaline substances; and they may be construct-
ed with different degrees of ballast for alcohol
and other spiritous liquors. When the specific
gravities of acid liquors are to be ascertained,
we must use a glass hydrometer (Plate vu, Fig.
14). This consists of a hollow cylinder of glass,
abcf, hermetically sealed at its lower end, and
drawn out at the upper into a capillary tube a,
ending in the little cup or basin d. This instru-
ment is ballasted with more or less mercury, at
the bottom of the cylinder introduced through
the tube, in proportion to the weight of the
liquor intended to be examined. We may intro-
duce a small graduated slip of paper into the
tube ad; and, though these degrees do not ex-
actly correspond to the fractions of grains in
the different liquors, they may be rendered
very useful in calculation.

What is said in this chapter may suffice,
without further enlargement, for indicating the
means of ascertaining the absolute and specific

LAVOISIER

gravities of solids and fluids, as the necessary
instruments are generally known, and may easi-
ly be procured. But, as the instruments I have
used for measuring the gases are not anywhere
described, I shall give a more detailed account
of these in the following chapter.

CHAPTER II

Of Gazometry, or the Measurement of the Weight
and Volume of Aeriform Substances

SECTION I Of the Pneumato-chemical Apparatus

THE French chemists have of late applied the
name of pneumato-chemical apparatus to the
very simple and ingenious contrivance, invent-
ed by Dr. Priestley, which is now indispensably
necessary to every laboratory. This consists of
a wooden trough, of larger or smaller dimen-
sions as is thought convenient, lined with plate-
lead or tinned copper, as represented in per-
spective, Plate v. In Fig. 1 the same trough or
cistern is supposed to have two of its sides cut
away, to show its interior construction more
distinctly. In this apparatus, we distinguish be-
tween the shelf ABCD (Figs. 1 and 0) and the
bottom or body of the cistern FGHI (Fig. 2) . The
jars or bell-glasses are filled with water in this
deep part, and, being turned with their mouths
downwards, are afterwards set upon the shelf
ABCD, as shown (Plate x, Fig. 1, F) The
upper parts of the sides of the cistern above
the level of the shelf are called the rim or
borders.

The cistern ought to be filled with water, so
as to stand at least an inch and a half deep up-
on the shelf, and it should be of such dimen-
sions as to admit of at least one foot of water in
every direction in the well. This size is suffici-
ent for ordinary occasions; but it is often con-
venient, and even necessary, to have more
room. I would therefore advise such as intend
to employ themselves usefully in chemical ex-
periments, to have this apparatus made of con-
siderable magnitude, where their place of
operating will allow. The well of my princi-
pal cistern holds four cubic feet of water,
and its shelf has a surface of fourteen square
feet; yet, in spite of this size, which I at first
thought immoderate, I am often straitened
for room.

In laboratories, where a considerable num-
ber of experiments are performed, it is neces-
sary to have several lesser cisterns, besides the
large one, which may be called the general mag-

azine; and even some portable ones, which may
be moved, when necessary, near a furnace or
wherever they may be wanted. There are like-
wise some operations which dirty the water of
the apparatus and therefore require to be car-
ried on in cisterns by themselves.

It were doubtless considerably cheaper to
use cisterns, or iron-bound tubs, of wood sim-
ply dove-tailed, instead of being lined with lead
or copper; and in my first experiments I used
them made in that way; but I soon discovered
their inconvenience. If the water be not always
kept at the same level, such of the dovetails
as are left dry shrink, and when more water is
added it escapes through the joints, and runs
out.

We employ crystal jars or bell-glasses, (Plate
v, Fig. 9, A) for containing the gases in this
apparatus; and, for transporting these, when
full of gas, from one cistern to another, or for
keeping them in reserve when the cistern is too
full, we make use of a flat dish BC, surrounded
by a standing up rim or border, with two han-
dles DE for carrying it by.

After several trials of different materials, I
have found marble the best substance for con-
structing the mercurial pneumato-chemical ap-
paratus, as it is perfectly impenetrable by mer-
cury, and is not liable, like wood, to separate at
the junctures, or to allow the mercury to es-
cape through chinks; neither does it run the
risk of breaking, like glass, stone-ware, or por-
celain. Take a block of marble BCDE (Plate v,
Figs. 8 and 4), about two feet long, 15 or 18
inches broad, and ten inches thick, and cause
it to be hollowed out as at m n (Fig. 5) about
four inches deep, as a reservoir for the mer-
cury; and, to be able more conveniently to fill
the jars, cut the gutter TV (Figs. 3, 4, and 5) at
least four inches deeper; and, as this trench
may sometimes prove troublesome, it is made
capable of being covered at pleasure by thin
boards, which slip into the grooves x y, (Fig.
5). I have two marble cisterns upon this con-
struction, of different sizes, by which I can al-
ways employ one of them as a reservoir of mer-
cury, which it preserves with more safety than
any other vessel, being neither subject to over-
turn, nor to any other accident. We operate
with mercury in this apparatus exactly as with
water in the one before described; but the bell-
glasses must be of smaller diameter and much
stronger; or we may use glass tubes, having
their mouths widened, as in Fig. 7; these are
called eudiometers by the glass-men who sell
them. One of the bell-glasses is represented,

CHEMISTRY

Fig. 5, A, standing in its place, and what is
called a jar is engraved Fig. 6.

The mercurial pneumato-chemical apparatus
is necessary in all experiments wherein the dis-
engaged gases are capable of being absorbed by
water, as is frequently the case, especially in
all combinations, excepting those of metals, in
fermentation, &c.

SECTION II Of the Gazometer

I give the name of gazometer to an instru-
ment which I invented and caused constructed,
for the purpose of a kind of bellows which
might furnish an uniform and continued stream
of oxygen gas in experiments of fusion. M.
Meusnier and I have since made very consid-
erable corrections and additions, having con-
verted it into what may be called an universal
instrument, without which it is hardly pos-
sible to perform most of the very exact experi-
ments. The name we have given the instru-
ment indicates its intention for measuring the
volume or quantity of gas submitted to it for
examination.

It consists of a strong iron beam, DE (Plate
vin, Fig. 1), three feet long, having at each end,
D and E, a segment of a circle, likewise strong-
ly constructed of iron, and very firmly joined.
Instead of being poised as in ordinary balances,
this beam rests, by means of a cylindrical axis
of polished steel F (Fig. 9), upon two large
moveable brass friction-wheels, by which the
resistance to its motion from friction is consid-
erably diminished, being converted into fric-
tion of the second order. As an additional pre-
caution, the parts of these wheels which sup-
port the axis of the beam are covered with
plates of polished rock-crystal. The whole of
this machinery is fixed to the top of the solid
column of wood BC (Fig. l).To one extremity
D of the beam, a scale P for holding weights is
suspended by a flat chain, which applies to the
curvature of the arc riDo, in a groove made for
the purpose. To the other extremity E of the
beam is applied another flat chain, ikm, so
constructed as to be incapable of lengthening
or shortening, by being less or more charged
with weight; to this chain, an iron trivet, with
three branches, ai, ci, and hi, is strongly fixed
at i, and these branches support a large invert-
ed jar A, of hammered copper, of about 18
inches diameter and 20 inches deep. The whole
of this machine is represented in perspective,
Plate vm, Fig. 1; and Plate ix, Figs. 2 and 4
give perpendicular sections, which show its in-
terior structure.

/Round the bottom of the jar, on its outside,
is fixed (Plate ix, Fig. 2) a border divided into
compartments 1, 2, 3, 4, &c., intended to re-
ceive leaden weights separately represented 1,
2, 3, Fig. 3. These are intended for increasing
the weight of the jar when a considerable pres-
sure is requisite, as will be afterwards explained,
though such necessity seldom occurs. The cy-
lindrical jar A is entirely open below, de (Plate
ix, Fig. 4)', but is closed above with a copper
lid, abc, open at bf, and capable of being shut
by the cock g. This lid, as may be seen by in-
specting the figures, is placed a few inches within
the top of the jar to prevent the jar from being
ever entirely immersed in the water and cov-
ered over. Were I to have this instrument
made over again, I should cause the lid to be
considerably more flattened, so as to be almost
level. This jar or reservoir of air is contained in
the cylindrical copper vessel LMNO (Plate
vm, Fig. 1) filled with water.

In the middle of the cylindrical vessel LMNO
(Plate ix, Fig. 4) are placed two tubes st, xy,
which are made to approach each other at their
upper extremities ty\ these are made of such a
length as to rise a little above the upper edge
LM of the vessel LMNO, and when the jar
abcde touches the bottom NO, their upper ends
enter about half an inch into the conical hol-
low b leading to the stop-cock g.

The bottom of the vessel LMNO is repre-
sented, Plate ix, Fig. 3, in the middle of which
a small hollow semispherical cap is soldered,
which may be considered as the broad end of a
funnel reversed; the two tubes st, xy (Fig. 4)
are adapted to this cap at s and x, and by this
means communicate with the tubes mm, nn,
oo, pp (Fig. 3), which are fixed horizontally up-
on the bottom of the vessel, and all of which
terminate in, and are united by, the spherical
cap sx. Three of these tubes are continued out
of the vessel, as in Plate vm, Fig. 1. The first
marked in that figure 1, 2, 3, is inserted at its
extremity 3 by means of an intermediate stop-
cock 4 to the jar V which stands upon the shelf
of a small pneumato-chemical apparatus GHIK,
the inside of which is shown Plate ix, Fig. 1.
The second tube is applied against the outside
of the vessel LMNO from 6 to 7, is continued
at 8, 9, 10, and at 11 is engaged below the jar
V. The former of these tubes is intended for
conveying gas into the machine and the latter
for conducting small quantities for trials under
jars. The gas is made either to flow into or out
of the machine, according to the degree of pres-
sure it receives; and this pressure is varied at

LAVOISIER

pleasure, by loading the scale P less or more by
means of weights. When gas is to be introduced
into the machine, the pressure is taken off, or
even rendered negative; but, when gas is to be
expelled, a pressure is made with such degree
of force as is found necessary.

The third tube 12, 13, 14, 15, is intended for
conveying air or gas to any necessary place or
apparatus for combustions, combinations, or
any other experiment in which it is required.

To explain the use of the fourth tube, I must
enter into some discussions. Suppose the vessel
LMNO (Plate vm, Fig. 1) full of water, and
the jar A partly filled with gas, and partly with
water; it is evident that the weights in the ba-
sin P may be so adjusted as to occasion an ex-
act equilibrium between the weight of the ba-
sin and of the jar, so that the external air shall
not tend to enter into the jar nor the gas to es-
cape from it; and in this case the water will
stand exactly at the same level both within
and without the jar. On the contrary, if the
weight in the basin P be diminished, the jar
will then press downwards from its own grav-
ity, and the water will stand lower within the
jar than it does without; in this case, the in-
cluded air or gas will suffer a degree of com-
pression above that experienced by the extern-
al air, exactly proportioned to the weight of a
column of water, equal to the difference of the
external and internal surfaces of the water.
From these reflections, M. Meusnier contrived
a method of determining the exact degree of
pressure to which the gas contained in the jar
is at any time exposed. For this purpose, he
employs a double glass siphon 19, 20, 21, 22,
23, firmly cemented at 19 and 23. The extrem-
ity 19 of this siphon communicates freely with
the water in the external vessel of the machine,
and the extremity 23 communicates with the
fourth tube at the bottom of the cylindrical
vessel, and consequently, by means of the per-
pendicular tube st (Plate ix, Fig. 4) with the
air contained in the jar. He likewise cements,
at 16 (Plate vm, Fig. Jf), another glass tube 16,
17, 18, which communicates at 16 with the wa-
ter in the exterior vessel LMNO, and, at its
upper end 18, is open to the external air.

By these several contrivances, it is evident
that the water must stand in the tube 16, 17,
18, at the same level with that in the cistern
LMNO; and, on the contrary, that, in the
branch 19, 20, 21, it must stand higher or lower
according as the air in the jar is subjected to a
greater or lesser pressure than the external air.
To ascertain these differences, a brass scale di-

vided into inches and lines is fixed between
these two tubes. It is readily conceived that, as
air, and all other elastic fluids must increase in
weight by compression, it is necessary to know
their degree of condensation to be enabled to
calculate their quantities and to convert the
measure of their volumes into correspondent
weights; and this object is intended to be ful-
filled by the contrivance now described.

But, to determine the specific gravity of air
or of gases, and to ascertain their weight in a
known volume, it is necessary to know their
temperature as well as the degree of pressure
under which they subsist; and this is accom-
plished by means of a small thermometer,
strongly cemented into a brass collet which
screws into the lid of the jar A. This thermom-
eter is represented separately, Plate vm, Fig.
10, and in its place 24, 25, Fig. 1 and Plate ix,
Fig. 4> The bulb is in the inside of the jar A,
and its graduated stalk rises on the outside of
the lid.

The practice of gazometry would still have
laboured under great difficulties without fur-
ther precautions than those above described.
When the jar A sinks in the water of the cistern
LMNO, it must lose a weight equal to that of
the water which it displaces; and consequently
the compression which it makes upon the con-
tained air or gas must be proportionally dimin-
ished. Hence the gas furnished, during experi-
ments from the machine, will not have the same
density towards the end that it had at the be-
ginning, as its specific gravity is continually
diminishing. This difference may, it is true, be
determined by calculation; but this would have
occasioned such mathematical investigations
as must have rendered the use of this appara-
tus both troublesome and difficult. M. Meus-
nier has remedied this inconvenience by the
following contrivance. A square rod of iron, 26,
27 (Plate vm, Fig. 1), is raised perpendicular
to the middle of the beam DE. This rod passes
through a hollow box of brass 28, which opens,
and may be filled with lead; and this box is
made to slide alongst the rod by means of a
toothed pinion playing in a rack, so as to raise
or lower the box and to fix it at such places as
is judged proper.

When the lever or beam DE stands horizon-
tal, this box gravitates to neither side; but,
when the jar A sinks into the cistern LMNO,
so as to make the beam incline to that side, it
is evident the loaded box 28, which then passes
beyond the center of suspension, must gravi-
tate to the side of the jar and augment its

CHEMISTRY

pressure upon the included air. This is increased
in proportion as the box is raised towards 27,
because the same weight exerts a greater power
in proportion to the length of the lever by
which it acts. Hence, by moving the box 28
alongst the rod 26, 27, we can augment or di-
minish the correction it is intended to make
upon the pressure of the jar; and both expe-
rience and calculation show that this may be
made to compensate very exactly for the loss
of weight in the jar at all degrees of pressure.

I have not hitherto explained the most im-
portant part of the use of this machine, which
is the manner of employing it for ascertaining
the quantities of the air or gas furnished during
experiments. To determine this with the most
rigorous precision, and likewise the quantity
supplied to the machine from experiments, we
fixed to the arc which terminates the arm of
the beam E (Plate vm, Fig. 1), the brass sector
I w, divided into degrees and half degrees, which
consequently moves in common with the beam ;
and the lowering of this end of the beam is
measured by the fixed index 29, 30, which has
a nonius giving hundredth parts of a degree at
its extremity 30.

The whole particulars of the different parts
of the above described machine are represented
in Plate vui as follow:

Fig. % is the flat chain invented by M. Vau-
canson and employed for suspending the scale
or basin P, Fig. 1; but, as this lengthens or
shortens according as it is more or less loaded,
it would not have answered for suspending the
jar A, Fig. 1.

Fig. 5 is the chain ikm, which in Fig. 1 sus-
tains the jar A. This is entirely formed of plates
of polished iron interlaced into each other and
held together by iron pins. This chain does not
lengthen in any sensible degree, by any weight
it is capable of supporting.

Fig. 6. The trivet, or three branched stirrup,
by which the jar A is hung to the balance, with
the screw by which it is fixed in an accurately
vertical position.

Fig. 3. The iron rod 26, 27, which is fixed
perpendicular to the center of the beam, with
its box 28.

Figs. 7 & 8. The friction-wheels, with the
plates of rock-crystal Z as points of contact by
which the friction of the axis of the lever of the
balance is avoided.

Fig. 4- The piece of metal which supports
the axis of the friction-wheels.

Fig. 9. The middle of the lever or beam, with
the axis upon which it moves.

Fig. 10. The thermometer for determining
the temperature of the air or gas contained in
the jar.

When this gazometer is to be used, the cis-
tern or external vessel LMNO (Plate vui, Fig.
1) is to be filled with water to a determinate
height, which should be the same in all experi-
ments. The level of the water should be taken
when the beam of the balance stands horizon-
tal; this level, when the jar is at the bottom of
the cistern, is increased by all the water which
it displaces and is diminished in proportion as
the jar rises to its highest elevation. We next
endeavour, by repeated trials, to discover at
what elevation the box 28 must be fixed to ren-
der the pressure equal in all situations of the
beam. I should have said nearly, because this
correction is not absolutely rigorous; and dif-
ferences of a quarter, or even of half a line, are
not of any consequence. This height of the box
28 is not the same for every degree of pressure,
but varies according as this is of one, two, three,
or more inches. All these should be registered
with great order and precision.

We next take a bottle which holds eight or
ten pints, the capacity of which is very accu-
rately determined by weighing the water it is
capable of containing. This bottle is turned
bottom upwards, full of water, in the cistern of
the pneumato-chemical apparatus GHIK (Fig.
1), and is set on its mouth upon the shelf of the
apparatus, instead of the glass jar V, having
the extremity 11 of the tube 7, 8, 9, 10, 11, in-
serted into its mouth. The machine is fixed at
zero of pressure, and the degree marked by the
index 30 upon the sector ml is accurately ob-
served; then, by opening the stop-cock 8, and
pressing a little upon the jar A, as much air is
forced into the bottle as fills it entirely. The de-
gree marked by the index upon the sector is
now observed, and we calculate what number
of cubic inches correspond to each degree. We
then fill a second and third bottle, and so on,
in the same manner, with the same precautions,
and even repeat the operation several times
with bottles of different sizes, till at last, by
accurate attention, we ascertain the exact gage
or capacity of the jar A, in all its parts; but it
is better to have it formed at first accurately
cylindrical, by which we avoid these calcula-
tions and estimates.

The instrument I have been describing was
constructed with great accuracy and uncom-
mon skill by M. Meignie, Jr., engineer and
physical instrument-maker. It is a most valu-
able instrument, from the great number of pur-

LAVOISIER

poses to which it is applicable; and, indeed,
there are many experiments which are almost
impossible to perform without it. It becomes
expensive, because, in many experiments, such
as the formation of water and of nitric acid, it
is absolutely necessary to employ two of the
same machines. In the present advanced state
of chemistry, very expensive and complicated
instruments are become indispensably neces-
sary for ascertaining the analysis and synthesis
of bodies with the requisite precision as to quan-
tity and proportion; it is certainly proper to
endeavour to simplify these and to render them
less costly; but this ought by no means to be
attempted at the expense of their convenience
of application, and much less of their accuracy.

SECTION III Some Other Methods of Measuring
the Volume of Gases

The gazometer described in the foregoing
section is too costly and too complicated for
being generally used in laboratories for meas-
uring the gases and is not even applicable to
every circumstance of this kind. In numerous
series of experiments, more simple and more
readily applicable methods must be employed.
For this purpose I shall describe the means I
used before I was in possession of a gazometer
and which I still use in preference to it in the
ordinary course of my experiments.

Suppose that, after an experiment, there is a
residuum of gas, neither absorbable by alkali
nor water, contained in the upper part of the
jar AEF (Plate iv, Fig. 8) standing on the shelf
of a pneuma to-chemical' apparatus, of which
we wish to ascertain the quantity. We must
first mark the height to which the mercury or
water rises in the jar with great exactness, by
means of slips of paper pasted in several parts
round the jar. If we have been operating in
mercury, we begin by displacing the mercury
from the jar by introducing water in its stead.
This is readily done by filling a bottle quite full
of water; having stopped it with your finger,
turn it up, and introduce its mouth below the
edge of the jar; then, turning down its body
again, the mercury, by its gravity, falls into
the bottle, and the water rises in the jar, and
takes the place occupied by the mercury. When
this is accomplished, pour so much water into
the cistern ABCD as will stand about an inch
over the surface of the mercury; then pass the
dish BC (Plate v, Fig. 9) under the jar, and
carry it to the water cistern (Figs. 1 and #). We
here exchange the gas into another jar, which
has been previously graduated in the manner

to be afterwards described; and we thus judge
of the quantity or volume of the gas by means
of the degrees which it occupies in the gradu-
ated jar.

There is another method of determining the
volume of gas, which may either be substituted
in place of the one above described or may be
usefully employed as a correction or proof of
that method. After the air or gas is exchanged
from the first jar, marked with slips of paper,
into the graduated jar, turn up the mouth of
the marked jar and fill it with water exactly to
the marks EF (Plate iv, Fig. 3), and by weigh-
ing the water we determine the volume of the
air or gas it contained, allowing one cubic foot,
or 1 728 cubic inches, of water for each 70 pounds,
French weight.

The manner of graduating jars for this pur-
pose is very easy, and we ought to be provided
with several of different sizes, and even several
of each size in case of accidents. Take a tall,
narrow, and strong glass jar, and, having filled
it with water in the cistern (Plate v, Fig. 1),
place it upon the shelf ABCD ; we ought always
to use the same place for this operation, that
the level of the shelf may be always exactly
similar, by which almost the only error to which
this process is liable will be avoided. Then take
a narrow mouthed phial which holds exactly 6
02. 3 gros 61 grs. of water, which corresponds to
10 cubic inches. If you have not one exactly of
this dimension, choose one a little larger, and
diminish its capacity to the size requisite by
dropping in a little melted wax and rosin. This
bottle serves the purpose of a standard for
gauging the jars. Make the air contained in
this bottle pass into the jar and mark exactly
the place to which the water has descended;
add another measure of air and again mark the
place of the water, and so on, till ail the water
be displaced. It is of great consequence that,
during the course of this operation, the bottle
and jar be kept at the same temperature with
the water in the cistern; and, for this reason,
we must avoid keeping the hands upon either
as much as possible; or, if we suspect they have
been heated, we must cool them by means of
the water in the cistern. The height of the ba-
rometer and thermometer during this experi-
ment is of no consequence.

When the marks have been thus ascertained
upon the jar for every ten cubic inches, we en-
grave a scale upon one of its sides by means of
a diamond pencil. Glass tubes are graduated
in the same manner for use in the mercurial ap-
paratus, only they must be divided into cubic

CHEMISTRY

inches, 'and tenths of a cubic inch. The bottle
used for gauging these must hold 8 02. 6 gros 25
grs. of mercury, which exactly corresponds to
a cubic inch of that metal.

The method of determining the volume of
air or gas by means of a graduated jar has the
advantage of not requiring any correction for
the difference of height between the surface of
the water within the jar and in the cistern; but
it requires corrections with respect to the height
of the barometer and thermometer. But, when
we ascertain the volume of air by weighing the
water which the jar is capable of containing,
up to the marks EF, it is necessary to make a
further correction for the difference between
the surface of the water in the cistern and the
height to which it rises within the jar. This will
be explained in the fifth section of this chapter.

SECTION IV Of the Method of Separating the
Different Gases from Each Other

As experiments often produce two, three, or
more species of gas, it is necessary to be able to
separate these from each other that we may as-
certain the quantity and species of each. Sup-
pose that under the jar A (Plate iv, Fig. 3), is
contained a quantity of different gases mixed
together and standing over mercury; we begin
by marking with slips of paper, as before direct-
ed, the height at which the mercury stands
within the glass; then introduce about a cubic
inch of water into the jar, which will swim over
the surface of the mercury. If the mixture of
gas contains any muriatic or sulphurous acid
gas, a rapid and considerable absorption will
instantly take place, from the strong tendency
these two gases have, especially the former, to
combine with or be absorbed by water. If the
water only produces a slight absorption of gas
hardly equal to its own bulk, we conclude that
the mixture neither contains muriatic acid, sul-
phuric acid, or ainmoniacal gas, but that it
contains carbonic acid gas, of which water only
absorbs about its own bulk. To ascertain this
conjecture, introduce some solution of caustic
alkali, and the carbonic acid gas will be grad-
ually absorbed in the course of a few hours; it
combines with the caustic alkali or potash, and
the remaining gas is left almost perfectly free
from any sensible residuum of carbonic acid gas.

After each experiment of this kind, we must
carefully mark the height at which the mercury
stands within the jar by slips of paper pasted
on and varnished over when dry, that they
may not be washed off when placed in the wa-
ter apparatus. It is likewise necessary to regis-

ter the difference between the surface of the
mercury in the cistern and that in the jar, and
the height of the barometer and thermometer,
at the end of each experiment.

When all the gas or gases absorbable by wa-
ter and potash are absorbed, water is admitted
into the jar to displace the mercury; and, as is
described in the preceding section, the mercury
in the cistern is to be covered by one or two
inches of water. After this, the jar is to be trans-
ported by means of the flat dish BC (Plate v,
Fig. 9) into the water apparatus; and the quan-
tity of gas remaining is to be ascertained by
changing it into a graduated jar. After this,
small trials of it are to be made by experiments
in little jars, to ascertain nearly the nature of
the gas in question. For instance, into a small
jar full of the gas (Plate v, Fig. 8) a lighted ta-
per is introduced ; if the taper is not immediately
extinguished, we conclude the gas to contain
oxygen gas; and, in proportion to the bright-
ness of the flame, we may judge if it contain
less or more oxygen gas than atmospheric air
contains. If, on the contrary, the taper be in-
stantly extinguished, we have strong reason to
presume that the residuum is chiefly composed
of azotic gas. If, upon the approach of the ta-
per, the gas takes fire and burns quietly at the
surface with a white flame, we conclude it to be
pure hydrogen gas; if this flame is blue, we
judge it consists of carbonated hydrogen gas;
and, if it takes fire with a sudden deflagration,
that it is a mixture of oxygen and hydrogen
gas. If, again, upon mixing a portion of the re-
siduum with oxygen gas, red fumes are pro-
duced, we conclude that it contains nitrous gas.

These preliminary trials give some general
knowledge of the properties of the gas and na-
ture of the mixture, but arc not sufficient to de-
termine the proportions and quantities of the
several gases of which it is composed. For this
purpose all the methods of analysis must be
employed; and, to direct these properly, it is of
great use to have a previous approximation by
the above methods. Suppose, for instance, we
know that the residuum consists of oxygen and
azotic gas mixed together; put a determinate
quantity, 100 parts, into a graduated tube of
ten or twelve lines diameter, introduce a solu-
tion of sulphuret of potash in contact with the
gas, and leave them together for some days;
the suiphuret absorbs the whole oxygen gas
and leaves the azotic gas pure.

If it is known to contain hydrogen gas, a de-
terminate quantity is introduced into Volta's
eudiometer alongst with a known proportion of

LAVOISIER

hydrogen gas; these are deflagrated together
by means of the electrical spark; fresh portions
of oxygen gas are successively added till no fur-
ther deflagration takes place and till the great-
est possible diminution is produced. By this
process water is formed, which is immediately
absorbed by the water of the apparatus; but, if
the hydrogen gas contain charcoal, carbonic
acid is formed at the same time, which is not
absorbed so quickly; the quantity of this is
readily ascertained by assisting its absorption,
by means of agitation. If the residuum con-
tains nitrous gas, by adding oxygen gas, with
which it combines into nitric acid, we can very
nearly ascertain its quantity from the diminu-
tion produced by this mixture.

I confine myself to these general examples,
which are sufficient to give an idea of this kind
of operation; a whole volume would not serve
to explain every possible case. It is necessary
to become familiar with the analysis of gases
by long experience; we must even acknowledge
that they mostly possess such powerful affini-
ties to each other that we are not always cer-
tain of having separated them completely. In
these cases, we must vary our experiments in
every possible point of view, add new agents to
the combination, and keep out others, and con-
tinue our trials till we are certain of the truth
and exactitude of our conclusions.

SECTION V Of the Necessary Corrections of the
Volume of Gases, According to the Pressure of
the Atmosphere

All elastic fluids are compressible or conden-
sable in proportion to the weight with which
they are loaded. Perhaps this law, which is
ascertained by general experience, may suffer
some irregularity when these fluids are under
a degree of condensation almost sufficient to
reduce them to the liquid state, or when either
in a state of extreme rarefaction or condensa-
tion; but we seldom approach either of these
limits with most of the gases which we submit
to our experiments. I understand this proposi-
tion of gases being compressible, in proportion
to their superincumbent weights, as follows:

A barometer, which is an instrument gener-
ally known, is, properly speaking, a species of
siphon, ABCD (Plate xn, Fig. 16), whose leg
AB is filled with mercury, whilst the leg CD is
full of air. If we suppose the branch CD indef-
initely continued till it equals the height of our
atmosphere, we can readily conceive that the
barometer is, in reality, a sort of balance, in
which a column of mercury stands in equilibri-

um with a column of air of the same weight.
But it is unnecessary to prolongate the branch
CD to such a height, as it is evident that the
barometer, being immersed in air, the column
of mercury AB will be equally in equilibrium
with a column of air of the same diameter,
though the leg CD be cut off at C, and the part
CD be taken away altogether.

The medium height of mercury in equilibri-
um with the weight of a column of air, from
the highest part of the atmosphere to the sur-
face of the earth, is about twenty-eight French
inches in the lower parts of the city of Paris;
or, in other words, the air at the surface of the
earth at Paris is usually pressed upon by a
weight equal to that of a column of mercury
twenty-eight inches in height. I must be under-
stood in this way in the several parts of this
publication when talking of the different gases,
as, for instance, when the cubic foot of oxygen
gas is said to weigh 1 oz. 4 gros, under 28 inches
pressure. The height of this column of mercury,
supported by the pressure of the air, diminish-
es in proportion as we are elevated above the
surface of the earth, or rather above the level
of the sea, because the mercury can only form
an equilibrium with the column of air which is
above it and is not in the smallest degree af-
fected by the air which is below its level.

In what ratio does the mercury in the barom-
eter descend in proportion to its elevation; or,
which is the same thing, according to what law
or ratio do the several strata of the atmosphere
decrease in density? This question, which has
exercised the ingenuity of natural philosophers
during the last century, is considerably eluci-
dated by the following experiment.

If we take the glass siphon ABCDE (Plate
xn, Fig. 17), shut at E and open at A, and in-
troduce a few drops of mercury, so as to inter-
cept the communication of air between the leg
AB and the leg BE, it is evident that the air
contained in BCDE is pressed upon, in com-
mon with the whole surrounding air, by a
weight or column of air equal to 28 inches of
mercury. But, if we pour 28 inches of mercury
into the leg AB, it is plain the air in the branch
BCDE will now be pressed upon by a weight
equal to twice 28 inches of mercury, or twice
the weight of the atmosphere; and experience
shows that, in this case, the included air, in-
stead of filling the tube from B to E, only oc-
cupies from C to E, or exactly one half of the
space it filled before. If to this first column of
mercury we add two other portions of 28 inches
each, in the branch AB, the air in the branch

CHEMISTRY

BCDE will be pressed upon by four times the
weight of the atmosphere, or four times the
weight of 28 inches of mercury, and it will then
only fill the space from D to E, or exactly one
quarter of the space it occupied at the com-
mencement of the experiment. From these ex-
periments, which may be infinitely varied, has
been deduced as a general law of nature, which
seems applicable to all permanently elastic flu-
ids, that they diminish in volume in proportion
to the weights with which they are pressed up-
on; or, in other words: "the volume of all elastic
fluids is in the inverse ratio of the weight by which
they are compressed."

The experiments which have been made for
measuring the heights of mountains by means
of the barometer confirm the truth of these de-
ductions; and, even supposing them in some
degree inaccurate, these differences are so ex-
tremely small that they may be reckoned as
nullities in chemical experiments. When this
law of the compression of elastic fluids is once
well understood, it becomes easily applicable
to the corrections necessary in pneumato-
chemical experiments upon the volume of gas
in relation to its pressure. These corrections
are of two kinds, the one relative to the vari-
ations of the barometer and the other for the
column of water or mercury contained in the
jars. I shall endeavour to explain these by
examples, beginning with the most simple
case.

Suppose that 100 cubic inches of oxygen gas
are obtained at 10 (54.5) of the thermometer,
and at 28 inches 6 lines of the barometer, it is
required to know what volume the 100 cubic
inches of gas would occupy, under the pressure
of 28 inches, 1 and what is the exact weight of
the 1 00 inches of oxygen gas? Let the unknown
volume, or the number of inches this gas would
occupy at 28 inches of the barometer, be ex-
pressed by x; and, since the volumes are in the
inverse ratio of their superincumbent weights,
we have the following statement: 100 cubic
inches is to x inversely as 28.5 inches of pres-
sure is to 28.0 inches; or directly 28:28.5::100:
2=101.786 cubic inches, at 28 inches baro-
metrical pressure; that is to say, the same gas
or air which at 28.5 inches of the barometer oc-
cupies 100 cubic inches of volume, will occupy
101.786 cubic inches when the barometer is at
28 inches. It is equally easy to calculate the

* According to the proportion of 114 to 107, given
between the French and English foot, 28 inches of
the French barometer are equal to 29.83 inches of
the English. TRANSLATOR.

weight of this gas occupying 100 cubic inches,
under 28.5 inches of barometrical pressure; for,
as it corresponds to 101.786 cubic inches at the
pressure of 28, and as, at this pressure, and at
10 (54.5) of temperature, each cubic inch of
oxygen gas weighs half a grain, it follows that
100 cubic inches, under 28.5 barometrical pres-
sure, must weigh 50.893 grains. This conclu-
sion might have been formed more directly, as,
since the volume of elastic fluids is in the in-
verse ratio of their compression, their weights
must be in the direct ratio of the same com-
pression: hence, since 100 cubic inches weigh
50 grains under the pressure of 28 inches, we
have the following statement to determine the
weight of 100 cubic inches of the same gas at
28.5 barometrical pressure; 28:50::28.5:x, the
unknown quantity, = 50.893.

The following case is more complicated. Sup-
pose the jar A (Plate xn, Fig. 18) to contain a
quantity of gas in its upper part ACD, the rest
of the jar below CD being full of mercury, and
the whole standing in the mercurial basin or
reservoir GHIK, filled with mercury up to EF,
and that the difference between the surface CD
of the mercury in the jar, and EF, that in the
cistern, is six inches, while the barometer stands
at 27.5 inches. It is evident from these data
that the air contained in ACD is pressed upon
by the weight of the atmosphere, diminished
by the weight of the column of mercury CE, or
by 27.56 = 21.5 inches of barometrical pres-
sure. This air is therefore less compressed than
the atmosphere at the mean height of the ba-
rometer, and consequently occupies more space
than it would occupy at the mean pressure,
the difference being exactly proportional to the
difference between the compressing weights.
If, then, upon measuring the space ACD, it is
found to be 120 cubic inches, it must be re-
duced to the volume which it would occupy
under the mean pressure of 28 inches. This is
done by the following statement: 120:x, the
unknown volume, : :21 .5 :28 inversely; this gives

120X21.5 noi , ,. . ,
x= ~ = 92.143 cubic inches.

In these calculations we may either reduce
the height of the mercury in the barometer,
and the difference of level in the jar and basin,
into lines or decimal fractions of the inch; but
I prefer the latter, as it is more readily calculat-
ed. As, in these operations, which frequently
recur, it is of great use to have means of abbre-
viation, I have given a table in the appendix
for reducing lines and fractions of lines into dec-
imal fractions of the inch. -

LAVOISIER

In experiments performed in the water-ap-
paratus, we must make similar corrections to
procure rigorously exact results, by taking into
account, and making allowances for the differ-
ence of height of the water within the jar above
the surface of the water in the cistern. But, as
the pressure of the atmosphere is expressed in
inches and lines of the mercurial barometer,
and as homogeneous quantities only can be
calculated together, we must reduce the ob-
served inches and lines of water into corre-
spondent heights of the mercury. I have given
a table in the appendix for this conversion,
upon the supposition that mercury is 13.5681
times heavier than water. 1

SECTION VI Of the Correction Relative to the
Degrees of the Thermometer

In ascertaining the weight of gases, besides
reducing them to a mean of barometrical pres-
sure, as directed in the preceding section, we
must likewise reduce them to a standard ther-
mometrical temperature; because, ail elastic
fluids being expanded by heat and condensed
by cold, their weight in any determinate vol-
ume is thereby liable to considerable altera-
tions. As the temperature of 10 (54.5) is a
medium between the heat of summer and the
cold of winter, being the temperature of sub-
terraneous places and that which is most easily
approached to at all seasons, I have chosen that
degree as a mean to which I reduce air or gas
in this species of calculation.

M. de Luc found that atmospheric air was
increased }^i 5 part of its bulk, by each degree of
a mercurial thermometer, divided into 81 de-
grees, between the freezing and boiling points;
this gives }{ 1 1 part for each degree of Reaumur's
thermometer, which is divided into 80 degrees
between these two points. The experiments of
M. Monge seem to make this dilatation less
for hydrogen gas, which he thinks is only di-
lated }{%Q. We have not any exact experiments
hitherto published respecting the ratio of dila-
tation of the other gases; but, from the trials
which have been made, their dilatation seems
to differ little from that of atmospheric air.
Hence I may take for granted, till further ex-
periments give us better information upon this
subject, that atmospherical air is dilated >^io
part, and hydrogen gas #90 part for each de-
gree of the thermometer; but, as there is still
great uncertainty upon this point, we ought
always to operate in a temperature as near as

i The appendix is omitted in this edition.
EDITOR.

possible to the standard of 10 (54.5); by this
means any errors in correcting the weight or
volume of gases by reducing them to the com-
mon standard, will become of little moment.

The calculation for this correction is ex-
tremely easy. Divide the observed volume
of air by 210 and multiply the quotient by
the degrees of temperature above or below
10 (54.5). This correction is negative when
the actual temperature is above the standard
and positive when below. By the use of
logarithmical tables this calculation is much
facilitated.

SECTION VII Example for Calculating the Cor-
rections Relative to the Variations of Pressure
and Temperature

CASE

In the jar A (Plate iv, Fig. 3\ standing in a
water-apparatus, is contained 353 cubic inches
of air; the surface of the water within the jar
at EF is 4J/ inches above the water in the cis-
tern, the barometer is at 27 inches 9J^ lines,
and the thermometer at 15 (65.75). Having
burnt a quantity of phosphorus in the air, by
which concrete phosphoric acid is produced,
the air after the combustion occupies 295 cubic
inches, the water within the jar stands 7 inches
above that in the cistern, the barometer is at
27 inches 9J^ lines, and the thermometer at 16
(68). It is required from these data to deter-
mine the actual volume of air before and after
combustion and the quantity absorbed during
the process.

Calculation before Combustion

The air in the jar before combustion was 353
cubic inches, but it was only under a barometri-
cal pressure of 27 inches 9J^ lines, which, reduc-
ed to decimal fractions, gives 27.79167 inches;
and from this we must deduct the difference of
4J^ inches of water, which corresponds to
0.33166 inches of the barometer; hence the real
pressure of the air in the jar is 27.46001. As the
volume of elastic fluids diminish in the inverse
ratio of the compressing weights, we have the
following statement to reduce the 353 inches
to the volume the air would occupy at 28 inches
barometrical pressure.

353 :x, the unknown volume, ::27.46001:28.

353X27.46001 AQ . M ,. . ,
Hence, x = ^o 346.192 cubic inch-
es, which is the volume the same quantity of
air would have occupied at 28 inches of the ba-
rometer.

CHEMISTRY

The 210th part of this corrected volume is
1.65, which, for the five degrees of temperature
above the standard gives 8.255 cubic inches;
and, as this correction is subtractive, the real
corrected volume of the air before combustion
is 337.942 inches.

Calculation after Combustion

By a similar calculation upon the volume of
air after combustion, we find its barometrical
pressure 27.77083-0.51593 = 27.25490. Hence,
to have the volume of air under the pressure of
28 inches, 295: z::27.77083:28 inversely; or, x

this corrected volume is 1.368, which, mul-
tiplied by 6 degrees of thermometrical dif-
ference, gives the subtractive correction for
temperature 8.208, leaving the actual cor-
rected volume of air after combustion 278.942
inches.

Result

The corrected volume before combustion 337.942
Ditto remaining after combustion ..... 278.942

Volume absorbed during combustion 59.000.

SECTION VIII Method of Determining the Abso-
lute Gravity of the Different Gases

Take a large balloon A (Plate v, Fig. 10)
capable of holding 17 or 18 pints, or about half
a cubic foot, having the brass cap bcde strongly
cemented to its neck and to which the tube and
stop-cock fg is fixed by a tight screw. This ap-
paratus is connected by the double screw, rep-
resented separately at Fig. 12 to the jar BCD,
Fig. 10, which must be some pints larger in di-
mensions than the balloon. This jar is open at
top and is furnished with the brass cap hi and
stop-cock Im. One of these stop-cocks is repre-
sented separately at Fig. 11.

We first determine the exact capacity of the
balloon by filling it with water and weighing it
both full and empty. When emptied of water,
it is dried with a cloth introduced through its
neck de, and the last remains of moisture are
removed by exhausting it once or twice in an
air-pump.

When the weight of any gas is to be ascer-
tained, this apparatus is used as follows: fix
the balloon A to the plate of an air-pump by
means of the screw of the stop-cock fg, which
is left open; the balloon is to be exhausted as
completely as possible, observing carefully the
degree of exhaustion by means of the barom-

eter attached to the air-pump. When the vacu-
um is formed, the stop-cock fg is shut and the
weight of the balloon determined with the most
scrupulous exactitude. It is then fixed to the
jar BCD, which we suppose placed in water in
the shelf of the pneumato-chemical apparatus
(Fig. 1); the jar is to be filled with the gas we
mean to weigh, and then, by opening the stop-
cocks fg and Im, the gas ascends into the bal-
loon, whilst the water of the cistern rises at the
same time into the jar. To avoid very trouble-
some corrections, it is necessary, during this
first part of the operation, to sink the jar in the
cistern till the surfaces of the water within the
jar and without exactly correspond. The stop-
cocks are again shut, and the balloon being un-
screwed from its connection with the jar, is to
be carefully weighed; the difference between
this weight and that of the exhausted balloon
is the precise weight of the air or gas contained
in the balloon. Multiply this weight by 1728,
the number of cubic inches in a cubic foot, and ,
divide the product by the number of cubic
inches contained in the balloon; the quotient is
the weight of a cubic foot of the gas or air sub-
mitted to experiment.

Exact account must be kept of the baromet-
rical height and temperature of the thermom-
eter during the above experiment; and from
these the resulting weight of a cubic foot is
easily corrected to the standard of 28 inches
and 10, as directed in the preceding section.
The small portion of air remaining in the bal-
loon after forming the vacuum must likewise
be attended to, which is easily determined by
the barometer attached to the air-pump. If
that barometer, for instance, remains at the
hundredth part of the height it stood at before
the vacuum was formed, we conclude that one
hundredth part of the air originally contained
remained in the balloon and consequently that
only g %Q of gas was introduced from the jar
into the balloon.

CHAPTER III

Description of the Calorimeter, or Apparatus for
Measuring Caloric

THE calorimeter, or apparatus for measuring
the relative quantities of heat contained in
bodies, was described by M. de Laplace and
me in the Recueil de V Academic for 1780, p.
355, and from that essay the materials of this
chapter are extracted.
If, after having cooled any body to the f reez-

100

LAVOISIER

ing point, it be exposed in an atmosphere of
25 (88.25), the body will gradually become
heated, from the surface inwards, till at last it
acquires the same temperature with the sur-
rounding air. But, if a piece of ice be placed in
the same situation, the circumstances are quite
different; it does not approach in the smallest
degree towards the temperature of the circum-
ambient air but remains constantly at zero
(32), or the temperature of melting ice, till
the last portion of ice be completely melted.

This phenomenon is readily explained, as, to
melt ice, or reduce it to water, it requires to be
combined with a certain portion of caloric; the
whole caloric attracted from the surrounding
bodies, is arrested or fixed at the surface or ex-
ternal layer of ice which it is employed to dis-
solve, and combines with it to form water; the
next quantity of caloric combines with the sec-
ond layer to dissolve it into water, and so on
successively till the whole ice be dissolved or
converted into water by combination with ca-
loric, the very last atom still remaining at its
former temperature, because the caloric has
never penetrated so far as long as any inter-
mediate ice remained to melt.

Upon these principles, if we conceive a hol-
low sphere of ice at the temperature of zero (32)
placed in an atmosphere 10 (54.5), and con-
taining a substance at any degree of tempera-
ture above freezing, it follows, 1st, that the
heat of the external atmosphere cannot pene-
trate into the internal hollow of the sphere of
ice; 2nd, that the heat of the body placed in
the hollow of the sphere cannot penetrate out-
wards beyond it, but will be stopped at the in-
ternal surface and continually employed to melt
successive layers of ice, until the temperature
of the body be reduced to zero (32) by having
all its superabundant caloric above that tem-
perature carried off by the ice. If the whole wa-
ter, formed within the sphere of ice during the
reduction of the temperature of the included
body to zero, be carefully collected, the weight
of the water will be exactly proportional to the
quantity of caloric lost by the body in passing
from its original temperature to that of melting
ice; for it is evident that a double quantity of
caloric would have melted twice the quantity
of ice; hence the quantity of ice melted is a
very exact measure of the quantity of caloric
employed to produce that effect and conse-
quently of the quantity lost by the only sub-
stance that could possibly have supplied it.

I have made this supposition of what would
take place in a hollow sphere of ice for the pur-

pose of more readily explaining the method
used in this species of experiment, which was
first conceived by M. de Laplace. It would be
difficult to procure such spheres of ice and in-
convenient to make use of them when got; but,
by means of the following apparatus, we have
remedied that defect. I acknowledge the name
of calorimeter, which I have given it, as derived
partly from Greek and partly from Latin, is in
some degree open to criticism; but, in matters
of science, a slight deviation from strict ety-
mology, for the sake of giving distinctness of
idea, is excusable; and I could not derive the
name entirely from Greek without approaching
too near to the names of known instruments
employed for other purposes.

The calorimeter is represented in Plate vi. It
is shown in perspective at Fig. 1, and its inte-
rior structure is engraved in Figs. 2 and 3; the
former being a horizontal, and the latter a per-
pendicular section. Its capacity or cavity is di-
vided into three parts, which, for better dis-
tinction, I shall name the interior, middle, and
external cavities. The interior cavity//// (Fig.
4), into which the substances submitted to ex-
periment are put, is composed of a grating or
cage of iron wire supported by several iron
bars; its opening or mouth LM is covered by
the lid HG of the same materials. The middle
cavity bbbb (Figs. 2 and 8) is intended to con-
tain the ice which surrounds the interior cav-
ity, and which is to be melted by the caloric of
the substance employed in the experiment. The
ice is supported by the grate m m at the bottom
of the cavity, under which is placed the sieve
nn. These two are represented separately in
Figs. 5 and 6.

In proportion as the ice contained in the mid-
dle cavity is melted by the caloric disengaged
from the body placed in the interior cavity,
the water runs through the grate and sieve and
falls through the conical funnel ccd (Fig. 3),
and tube xy, into the receiver F (Fig. 1). This
water may be retained or let out at pleasure,
by means of the stop-cock u. The external cav-
ity a a a a (Figs. 2 and 3), is filled with ice, to
prevent any effect upon the ice in the middle
cavity from the heat of the surrounding air,
and the water produced from it is carried off
through the pipe ST, which shuts by means of
the stop-cock r. The whole machine is covered
by the lid FF (Fig. 7), made of tin painted with
oil colour to prevent rust.

When this machine is to be employed, the
middle cavity 6666 (Figs. 2 and 3), the lid
GH (Fig. 4) of the interior cavity, the exter-

CHEMISTRY

101

nal cavity aaaa (Figs. 2 and 3), and the gen-
eral lid FF (Fig. 7), are all filled with pounded
ice, well rammed so that no void spaces remain,
and the ice of the middle cavity is allowed to
drain. The machine is then opened, and the
substance submitted to experiment being placed
in the interior cavity, it is instantly closed.
After waiting till the included body is com-
pletely cooled to the freezing point, and the
whole melted ice has drained from the middle
cavity, the water collected in the vessel F (Fig.
1) is accurately weighed. The weight of the wa-
ter produced during the experiment is an exact
measure of the caloric disengaged during the
cooling of the included body, as this substance
is evidently in a similar situation with the one
formerly mentioned as included in a hollow
sphere of ice; the whole caloric disengaged is
stopped by the ice in the middle cavity, and
that ice is preserved from being affected by
any other heat by means of the ice contained
in the general lid (Fig. 7) and in the external
cavity. Experiments of this kind last from fif-
teen to twenty hours; they are sometimes ac-
celerated by covering up the substance in the
interior cavity with well drained ice, which
hastens its cooling.

The substances to be operated upon are
placed in the thin iron bucket (Fig. 8), the cov-
er of which has an opening fitted with a cork,
into which a small thermometer is fixed. When
we use acids, or other fluids capable of injuring
the metal of the instruments, they are con-
tained in the matrass (Fig. 10), which has a
similar thermometer in a cork fitted to its
mouth, and which stands in the interior cav-
ity upon the small cylindrical support RS (Fig.
10).

It is absolutely requisite that there be no
communication between the external and mid-
dle cavities of the calorimeter, otherwise the
ice melted by the influence of the surrounding
air, in the external cavity, would mix with the
water produced from the ice of the middle cav-
ity, which would no longer be a measure of the
caloric lost by the substance submitted to ex-
periment.

When the temperature of the atmosphere is
only a few degrees above the freezing point, its
heat can hardly reach the middle cavity, being
arrested by the ice of the cover ( Fig. 7) and of
the external cavity; but, if the temperature of
the air be under the degree of freezing, it might
cool the ice contained in the middle cavity by
causing the ice in the external cavity to fall, in
the first place, below zero (32). It is therefore

essential that this experiment be carried on in
a temperature somewhat above freezing : hence,
in time of frost, the calorimeter must be kept
in an apartment carefully heated. It is likewise
necessary that the ice employed be not under
zero (32) ; for which purpose it must be pound-
ed and spread out thin for some time in a place
of a higher temperature.

The ice of the interior cavity always retains
a certain quantity of water adhering to its sur-
face, which may be supposed to belong to the
result of the experiment; but as, at the begin-
ning of each experiment, the ice is already sat-
urated with as much water as it can contain, if
any of the water produced by the caloric should
remain attached to the ice, it is evident that
very nearly an equal quantity of what adhered
to it before the experiment must have run down
into the vessel F in its stead; for the inner sur-
face of the ice in the middle cavity is very little
changed during the experiment.

By any contrivance that could be devised,
we could not prevent the access of the external
air into the interior cavity when the atmos-
phere was 9 or 10 (52 or 54) above zero. The
air confined in the cavity, being in that case
specifically heavier than the external air, es-
capes downwards through the pipe xy (Fig. $),
and is replaced by the warmer external air,
which, giving out its caloric to the ice, becomes
heavier and sinks in its turn ; thus a current of
air is formed through the machine, which is the
more rapid in proportion as the external air ex-
ceeds the internal in temperature. This current
of warm air must melt a part of the ice and in-
jure the accuracy of the experiment. We may,
in a great degree, guard against this source of
error by keeping the stop-cock u continually
shut; but it is better to operate only when the
temperature of the external air does not exceed
3, or at most 4 (39 to 41); for we have ob-
served that, in this case, the melting of the in-
terior ice by the atmospheric air is perfectly
insensible; so that we may answer for the ac-
curacy of our experiments upon the specific
heat of bodies to a fortieth part.

We have had constructed two of the above-
described machines; one, which is intended for
such experiments as do not require the interior
air to be renewed, is precisely formed according
to the description here given; the other, which
answers for experiments upon combustion, res-
piration, &c. in which fresh quantities of air
are indispensably necessary, differs from the
former in having two small tubes in the two
lids, by which a current of atmospheric air

102

LAVOISIER

may be blown into the interior cavity of the
machine.

It is extremely easy, with this apparatus, to
determine the phenomena which occur in op-
erations where caloric is either disengaged or
absorbed. If we wish, for instance, to ascertain
the quantity of caloric which is disengaged from
a solid body in cooling a certain number of de-
grees, let its temperature be raised to 80 (212) ;
it is then placed in the interior cavity ////
(Figs. 2 and 8) of the calorimeter, and allowed
to remain till we are certain that its tempera-
ture is reduced to zero (32); the water pro-
duced by melting the ice during its cooling is col-
lected and carefully weighed; and this weight,
divided by the volume of the body submitted
to experiment, multiplied into the degrees of
temperature which it had above zero at the
commencement of the experiment, gives the
proportion of what the English philosophers
call specific heat.

Fluids are contained in proper vessels, whose
specific heat has been previously ascertained,
and operated upon in the machine in the same
manner as directed for solids, taking care to de-
duct, from the quantity of water melted during
the experiment, the proportion which belongs
to the containing vessel.

If the quantity of caloric disengaged during
the combination of different substances is to be
determined, these substances are to be pre-
viously reduced to the freezing degree by keep-
ing them a sufficient time surrounded with
pounded ice; the mixture is then to be made in
the inner cavity of the calorimeter, in a proper
vessel likewise reduced to zero (32) ; and they
are kept inclosed till the temperature of the
combination has returned to the same degree.
The quantity of water produced is a measure of
the caloric disengaged during the combination.

To determine the quantity of caloric disen-
gaged during combustion and during animal
respiration, the combustible bodies are burnt,
or the animals are made to breathe in the in-
terior cavity, and the water produced is care-
fully collected. Guinea pigs, which resist the
effects of cold extremely well, are well adapted
for this experiment. As the continual renewal
of air is absolutely necessary in such experi-
ments, we blow fresh air into the interior cav-
ity of the calorimeter by means of a pipe des-
tined for that purpose and allow it to escape
through another pipe of the same kind; and
that the heat of this air may not produce errors
in the results of the experiments, the tube
which conveys it into the machine is made to

pass through pounded ice, that it may be re-
duced to zero (32) before it arrives at the cal-
orimeter. The air which escapes must likewise
be made to pass through a tube surrounded
with ice, included in the interior cavity of the
machine, and the water which is produced must
make a part of what is collected, because the
caloric disengaged from this air is part of the
product of the experiment.

It is somewhat more difficult to determine
the specific caloric contained in the different
gases, on account of their small degree of den-
sity; for, if they are only placed in the calorim-
eter in vessels like other fluids, the quantity of
ice melted is so small that the result of the ex-
periment becomes at best very uncertain. For
this species of experiment we have contrived to
make the air pass through two metallic worms,
or spiral tubes; one of these, through which the
air passes and becomes heated in its way to
the calorimeter, is contained in a vessel full of
boiling water, and the other, through which
the air circulates within the calorimeter to dis-
engage its caloric, is placed in the interior cav-
ity, ////, of that machine. By means of a small
thermometer placed at one end of the second
worm, the temperature of the air, as it enters
the calorimeter, is determined, and its temper-
ature in getting out of the interior cavity is
found by another thermometer placed at the
other end of the worm. By this contrivance we
are enabled to ascertain the quantity of ice
melted by determinate quantities of air or gas,
while losing a certain number of degrees of tem-
perature, and, consequently, to determine their
several degrees of specific caloric. The same
apparatus, with some particular precautions,
may be employed to ascertain the quantity of
caloric disengaged by the condensation of the
vapours of different liquids.

The various experiments which may be made
with the calorimeter do not afford absolute con-
clusions, but only give us the measure of rela-
tive quantities; we have therefore to fix a unit,
or standard point, from whence to form a scale
of the several results. The quantity of caloric
necessary to melt a pound of ice has been chos-
en as this unit; and, as it requires a pound of
water of the temperature of 60 (167) to melt
a pound of ice, the quantity of caloric expressed
by our unit or standard point is what raises a
pound of water from zero (32) to 60 (167).
When this unit is once determined, we have
only to express the quantities of caloric disen-
gaged from different bodies by cooling a cer-
tain number of degrees in analogous values.

CHEMISTRY

103

The following is an easy mode of calculation
for this purpose, applied to one of our earliest
experiments.

We took 7 Ib. 11 oz. 2 gros 36 grs. of plate-
iron, cut into narrow slips and rolled up, or ex-
pressing the quantity in decimals, 7.7070319.
These, being heated in a bath of boiling water
to about 78 (207.5), were quickly introduced
into the interior cavity of the calorimeter. At
the end of eleven hours, when the whole quan-
tity of water melted from the ice had thorough-
ly drained off, we found that 1.109795 pounds
of ice were melted. Hence, the caloric disen-
gaged from the iron by cooling 78 (175.5) hav-
ing melted 1.109795 pounds of ice, how much
would have been melted by cooling 60 (135)?
This question gives the following statement in
direct proportion, 78:1. 109795 ::60::z =0.8569.
Dividing this quantity by the weight of the
whole iron employed, viz. 7.7070319, the quo-
tient 0.1 10770 is the quantity of ice which would
have been melted by one pound of iron whilst
cooling through 60 (135) of temperature.

Fluid substances, such as sulphuric and ni-
tric acids, &c., are contained in a matrass (Plate
vi, Fig. 9) having a thermometer adapted to
the cork, with its bulb immersed in the liquid.
The matrass is placed in a bath of boiling wa-
ter, and when, from the thermometer, we judge
the liquid is raised to a proper temperature, the
matrass is placed in the calorimeter. The cal-
culation of the products, to determine the spe-
cific caloric of these fluids, is made as above di-
rected, taking care to deduct from the water
obtained the quantity which would have been
produced by the matrass alone, which must be
ascertained by a previous experiment. The table
of the results obtained by these experiments is
omitted, because not yet sufficiently complete,
different circumstances having occasioned the
series to be interrupted; it is not, however, lost
sight of; and we are less or more employed up-
on the subject every winter.

CHAPTER IV
Of Mechanical Operations for Division of Bodies

SECTION I Of Trituration, Levigation, and Pul-
verization

THESE are, properly speaking, only prelimi-
nary mechanical operations for dividing and
separating the particles of bodies and reducing
them into very fine powder. These operations
can never reduce substances into their primary,
or elementary and ultimate particles; they do

not even destroy the aggregation of bodies; for
every particle, after the most accurate tritura-
tion, forms a small whole, resembling the orig-
inal mass from which it was divided. The real
chemical operations, on the contrary, such as
solution, destroy the aggregation of bodies and
separate their constituent and integrant par-
ticles from each other.

Brittle substances are reduced to powder by
means of pestles and mortars. These are of
brass or iron (Plate i, Fig. 1 ) ; of marble or gran-
ite (Fig. 2} ; of lignum vitae (Fig. 3) ; of glass
(Fig. 4) ; of agate (Fig. 5) ; or of porcelain^i^.
6). The pestles for each of these are represented
in the plate, immediately below the mortars to
which they respectively belong, and are made
of hammered iron or brass, of wood, glass, por-
celain, marble, granite, or agate, according to
the nature of the substances they are intended
to triturate. In every laboratory, it is requisite
to have an assortment of these utensils, of var-
ious sizes and kinds. Those of porcelain and
glass can only be used for rubbing substances
to powder, by a dexterous use of the pestle
round the sides of the mortar, as it would be
easily broken by reiterated blows of the pestle.

The bottom of mortars ought to be in the
form of a hollow sphere, and their sides should
have such a degree of inclination as to make
the substances they contain fall back to the
bottom when the pestle is lifted, but not so per-
pendicular as to collect them too much togeth-
er, otherwise too large a quantity would get be-
low the pestle and prevent its operation. For
this reason, likewise, too large a quantity of
the substance to be powdered ought not to be
put into the mortar at one time; and we must
from time to time get rid of the particles al-
ready reduced to powder, by means of sieves
to be afterwards described.

The most usual method of levigation is by
means of a flat table ABCD (Plate 1, Fig. 7) of
porphyry or other stone of similar hardness,
upon which the substance to be reduced to pow-
der is spread and is then bruised and rubbed by
a muller M of the same hard materials, the
bottom of which is made a small portion of a
large sphere; and, as the muller tends continu-
ally to drive the substances towards the sides
of the table, a thin flexible knife or spatula of
iron, horn, wood, or ivory, is used for bringing
them back to the middle of the stone.

In large works, this operation is performed
by means of large rollers of hard stone, which
turn upon each other, either horizontally, in
the way of corn-mills, or by one vertical roller

104

LAVOISIER

turning upon a flat stone. In the above opera-
tions, it is often requisite to moisten the sub-
stances a little, to prevent the fine powder from
flying off.

There are many bodies which cannot be re-
duced to powder by any of the foregoing meth-
ods; such are fibrous substances, as woods;
such as are tough and elastic, as the horns of
animals, elastic gum, &c., and the malleable
metals which flatten under the pestle, instead
of being reduced to powder. For reducing the
woods to powder, rasps (Plate 1, Fig. 8) are
employed ; files of a finer kind are used for horn,
and still finer (Plate 1 , Figs. 9 and 1 0) for metals.

Some of the metals, though not brittle enough
to powder under the pestle, are too soft to be
filed, as they clog the file and prevent its oper-
ation. Zinc is one of these, but it may be pow-
dered when hot in a heated iron mortar, or it
may be rendered brittle, by alloying it with a
small quantity of mercury. One or other of
these methods is used by fire-work makers for
producing a blue flame by means of zinc. Met-
als may be reduced into grains, by pouring them
when melted into water, which serves very well
when they are not wanted in fine powder.

Fruits, potatoes, &c., of a pulpy and fibrous
nature may be reduced to pulp by means of the
grater (Plate 1, Fig. 11).

The choice of the different substances of
which these instruments are made is a matter
of importance; brass or copper are unfit for
operations upon substances to be used as food
or in pharmacy; and marble or metallic instru-
ments must not be used for acid substances;
hence mortars of very hard wood, and those of
porcelain, granite, or glass, are of great utility
in many operations.

SECTION II Of Sifting and Washing Powdered
Substances

None of the mechanical operations employed
for reducing bodies to powder is capable of pro-
ducing it of an equal degree of fineness through-
out; the powder obtained by the longest and
most accurate trituration being still an assem-
blage of particles of various sizes. The coarser
of these are removed, so as only to leave the
finer and more homogeneous particles by means
of sieves (Plate i, Figs. 12, 13, 14, 15) of differ-
ent finenesses, adapted to the particular pur-
poses they are intended for; all the powdered
matter which is larger than the interstices of
the sieve remains behind and is again submit-
ted to the pestle, while the finer pass through.
The sieve (Fig. 12) is made of hair-cloth, or of

silk gauze; and the one represented in Fig. 18
is of parchment pierced with round holes of a
proper size; this latter is employed in the man-
ufacture of gun-powder. When very subtile or
valuable materials are to be sifted, which are
easily dispersed, or when the finer parts of the
powder may be hurtful, a compound sieve (Fig.
15) is made use of, which consists of the sieve
ABCD, with a lid EF, and receiver GH; these
three parts are represented as joined together
for use (Fig. 14).

There is a method of procuring powders of
an uniform fineness, considerably more accur-
ate than the sieve; but it can only be used with
such substances as are not acted upon by wa-
ter. The powdered substance is mixed and agi-
tated with water, or other convenient fluid;
the liquor is allowed to settle for a few mo-
ments, and is then decanted off; the coarsest
powder remains at the bottom of the vessel,
and the finer passes over with the liquid. By
repeated decantations in this manner, various
sediments are obtained of different degrees of
fineness; the last sediment, or that which re-
mains longest suspended in the liquor, being
the finest. This process may likewise be used
with advantage for separating substances of
different degrees of specific gravity, though of
the same fineness; this last is chiefly employed
in mining, for separating the heavier metallic
ores from the lighter earthy matters with which
they are mixed.

In chemical laboratories, pans and jugs of
glass or earthen ware are employed for this op-
eration; sometimes, for decanting the liquor
without disturbing the sediment, the glass si-
phon ABCHI (Plate n, Fig. 11) is used, which
may be supported by means of the perforated
board DE, at the proper depth in the vessel
FG, to draw off all the liquor required into the
receiver LM. The principles and application of
this useful instrument are so well known as to
need no explanation.

SECTION III Of Filtration

A filtre is a species of very fine sieve, which
is permeable to the particles of fluids, but
through which the particles of the finest pow-
dered solids are incapable of passing; hence its
use in separating fine powders from suspension
in fluids. In pharmacy, very close and fine
woollen cloths are chiefly used for this opera-
tion; these are commonly formed in a conical
shape (Plate n, Fig. 2), which has the advant-
age of uniting all the liquor which drains through
into a point A, where it may be readily collect-

CHEMISTRY

105

ed in a narrow mouthed vessel. In large phar-
maceutical laboratories, this filtring bag is
stretched upon a wooden stand (Plate n, Fig . 1 ) .

For the purposes of chemistry, as it is requi-
site to have the filtres perfectly clean, unsized
paper is substituted instead of cloth or flannel;
through this substance, no solid body, however
finely it be powdered, can penetrate, and fluids
percolate through it with the greatest readiness.
As paper breaks easily when wet, various meth-
ods of supporting it are^ used according to cir-
cumstances. When a large quantity of fluid is
to be filtrated, the paper is supported by the
frame of wood (Plate n, Fig. 8) ABCD, having
a piece of coarse cloth stretched over it by
means of iron hooks. This cloth must be well
cleaned each time it is used, or even new cloth
must be employed, if there is reason to suspect
its being impregnated with anything which can
injure the subsequent operations. In ordinary
operations, where moderate quantities of fluid
are to be filtrated, different kinds of glass fun-
nels are used for supporting the paper, as rep-
resented Plate n, Figs. 5, 6, and 7. When sev-
eral filtrations must be carried on at once, the
board or shelf AB, Fig. 9, supported upon stands
C and D, and pierced with round holes, is very
convenient for containing the funnels.

Some liquors are so thick and clammy as
not to be able to penetrate through paper with-
out some previous preparation, such as clari-
fication by means of white of eggs, which being
mixed with the liquor, coagulates when brought
to boil and, entangling the greater part of the
impurities of the liquor, rises with them to the
surface in the state of scum. Spiritous liquors
may be clarified in the same manner by means
of isinglass dissolved in water, which coagu-
lates by the action of the alcohol without the
assistance of heat.

As most of the acids are produced by distil-
lation, and are consequently clear, we have
rarely any occasion to filtrate them; but if, at
any time, concentrated acids require this oper-
ation, it is impossible to employ paper, which
would be corroded and destroyed by the acid.
For this purpose, pounded glass, or rather
quartz or rock-crystal, broken in pieces and
grossly powdered, answers very well; a few of
the larger pieces are put in the neck of the fun-
nel; these are covered with the smaller pieces,
the finer powder is placed over all, and the acid
is poured on top. For the ordinary purposes of
society, river-water is frequently filtrated by
means of clean washed sand, to separate its im-
purities.

SECTION IV Of Decantation

This operation is often substituted instead
of filtration for separating solid particles which
are diffused through liquors. These are allowed
to settle in conical vessels, ABODE (Plate n,
Fig. 10), the diffused matters gradually sub-
side, and the clear fluid is gently poured off. If
the sediment be extremely light, and apt to
mix again with the fluid by the slightest mo-
tion, the siphon (Fig. 11) is used, instead of de-
cantation, for drawing off the clear fluid.

In experiments where the weight of the pre-
cipitate must be rigorously ascertained, decan-
tation is preferable to filtration, providing the
precipitate be several times washed in a con-
siderable proportion of water. The weight of
the precipitate may indeed be ascertained, by
carefully weighing the filtre before and after
the operation; but, when the quantity of pre-
cipitate is small, the different proportions of
moisture retained by the paper, in a greater or
lesser degree of exsiccation, may prove a ma-
terial source of error which ought carefully to
be guarded against.

CHAPTER V

Of Chemical Means for Separating the Particles
of Bodies from Each Other Without Decompo-
sition, and for Uniting Them Again

I HAVE already shown that there are two meth-
ods of dividing the particles of bodies, the me-
chanical and chemical. The former only sepa-
rates a solid mass into a great number of small-
er masses; and for these purposes various spe-
cies of forces are employed, according to cir-
cumstances, such as the strength of man or of
animals, the weight of water applied through
the means of hydraulic engines, the expansive
power of steam, the force of the wind, &c. By
all these mechanical powers, we can never re-
duce substances into powder beyond a certain
degree of fineness; and the smallest particle
produced in this way, though it seems very mi-
nute to our organs, is still in fact a mountain
when compared with the ultimate elementary
particles of the pulverized substance.

The chemical agents, on the contrary, divide
bodies into their primitive particles. If, for in-
stance, a neutral salt be acted upon by these, it
is divided as far as is possible without ceasing
to be a neutral salt. In this chapter, I mean to
give examples of this kind of division of bodies,
to which I shall add some account of the rela-
tive operations.

106

LAVOISIER

SECTION I Of the Solution of Salts

In chemical language, the terms of solution
and dissolution have long been confounded and
have very improperly been indiscriminately em-
ployed for expressing both the division of the
particles of a salt in a fluid, such as water, and
the division of a metal in an acid. A few reflec-
tions upon the effects of these two operations
will suffice to show that they ought not to be
confounded together. In the solution of salts,
the saline particles are only separated from each
other, whilst neither the salt nor the water are
at all decomposed; we are able to recover both
the one and the other in the same quantity as
before the operation. The same thing takes
place in the solution of resins in alcohol. Dur-
ing metallic dissolutions, on the contrary, a de-
composition, either of the acid or of the water
which dilutes it, always takes place; the metal
combines with oxygen and is changed into an
oxide, and a gaseous substance is disengaged;
so that in reality none of the substances employ-
ed remain, after the operation, in the same
state they were in before. This article is entire-
ly confined to the consideration of solution.

To understand properly what takes place
during the solution of salts, it is necessary to
know that, in most of these operations, two
distinct effects are complicated together, viz.,
solution by water, and solution by caloric ; and,
as the explanation of most of the phenomena
of solution depends upon the distinction of
these two circumstances, I shall enlarge a little
upon their nature.

Nitrate of potash, usually called nitre or salt-
petre, contains very little water of crystalliza-
tion, perhaps even none at all ; yet this salt lique-
fies in a degree of heat very little superior to
that of boiling water. This liquefaction cannot
therefore be produced by means of the water of
crystallization, but in consequence of the salt
being very fusible in its nature, and from its
passing from the solid to the liquid state of ag-
gregation when but a little raised above the
temperature of boiling water. All salts are in
this manner susceptible of being liquefied by
caloric, but in higher or lower degrees of tem-
perature. Some of these, as the acetites of pot-
ash and soda, liquefy with a very moderate
heat, whilst others, as sulphate of potash, lime,
&c., require the strongest fires we are capable
of producing. This liquefaction of salts by ca-
loric produces exactly the same phenomena
with the melting of ice; it is accomplished in
each salt by a determinate degree of heat,

which remains invariably the same during the
whole time of the liquefaction. Caloric is em-
ployed and becomes fixed during the melting
of the salt, and is, on the contrary, disengaged
when the salt coagulates. These are general
phenomena which universally occur during the
passage of every species of substance from the
solid to the fluid state of aggregation, and from
fluid to solid.

These phenomena arising from solution by
caloric are always less or more conjoined with
those which take place during solutions in wa-
ter. We cannot pour water upon a salt, on pur-
pose to dissolve it, without employing a com-
pound solvent, both water and caloric; hence
we may distinguish several different cases of
solution, according to the nature and mode of
existence of each salt. If for instance, a salt be
with difficulty soluble in water, and readily so
by caloric, it evidently follows that this salt
will be with difficulty soluble in cold water,
and considerably in hot water; such is nitrate
of potash, and more especially oxygenated mu-
riate of potash. If another salt be little soluble
both in water and caloric, the difference of its
solubility in cold and warm water will be very
inconsiderable; sulphate of lime is of this kind.
From these considerations, it follows that there
is a necessary relation between the following
circumstances; the solubility of a salt in cold
water, its solubility in boiling water, and the
degree of temperature at which the same salt
liquefies by caloric, unassisted by water; and
that the difference of solubility in hot and cold
water is so much greater in proportion to its
ready solution in caloric, or in proportion to its
susceptibility of liquefying in a low degree of
temperature.

The above is a general view of solution; but,
for want of particular facts and sufficiently ex-
act experiments, it is still nothing more than
an approximation towards a particular theory.
The means of completing this part of chemical
science is extremely simple; we have only to as-
certain how much of each salt is dissolved by a
certain quantity of water at different degrees
of temperature; and as, by the experiments
published by M. de Laplace and me, the quan-
tity of caloric contained in a pound of water at
each degree of the thermometer is accurately
known, it will be very easy to determine, by
simple experiments, the proportion of water
and caloric required for solution by each salt,
what quantity of caloric is absorbed by each at
the moment of liquefaction, and how much is
disengaged at the moment of crystallization.

CHEMISTRY

107

Hence the reason why salts are more rapidly
soluble in hot than in cold water is perfectly
evident. In all solutions of salts caloric is em-
ployed; when that is furnished intermediately
from the surrounding bodies, it can only arrive
slowly to the salt; whereas this is greatly accel-
erated when the requisite caloric exists ready
combined with the water of solution.

In general, the specific gravity of water is
augmented by holding salts in solution; but
there are some exceptions to the rule. Some
time hence, the quantities of radical, of oxygen,
and of base, which constitute each neutral salt,
the quantity of water and caloric necessary for
solution, the increased specific gravity com-
municated to water, and the figure of the ele-
mentary particles of the crystals, will all be ac-
curately known. From these all the circum-
stances and phenomena of crystallization will
be explained, and by these means this part of
chemistry will be completed. M. Seguin has
formed the plan of a thorough investigation of
this kind, which he is extremely capable of
executing.

The solution of salts in water requires no
particular apparatus ; small glass phials of dif-
ferent sizes (Plate n, Figs. 16 and 17), pans of
earthern ware A (Figs. 1 and #), long-necked
matrasses (Fig. 14), and pans or basins of cop-
per or of silver (Figs. 13 and 15) answer very
well for these operations.

SECTION II Of Lixiviation

This is an operation used in chemistry and
manufactures for separating substances which
are soluble in water from such as are insoluble.
The large vat or tub (Plate n, Fig. 12), having
a hole D near its bottom containing a wooden
spiget and faucet or metallic stop-cock DE, is
generally used for this purpose. A thin stratum
of straw is placed at the bottom of the tub;
over this, the substance to be lixiviated is laid
and covered by a cloth, then hot or cold water,
according to the degree of solubility of the sa-
line matter, is poured on. When the water is
supposed to have dissolved all the saline parts,
it is let off by the stop-cock; and, as some of
the water charged with salt necessarily adheres
to the straw and insoluble matters, several fresh
quantities of water are poured on. The straw
serves to secure a proper passage for the water,
and may be compared to the straws or glass rods
used in filtrating to keep the paper from touching
the sides of the funnel. The cloth which is laid
over the matters under lixiviation prevents the
water from making a hollow in these substances

where it is poured on, through which it might
escape without acting upon the whole mass.

This operation is less or more imitated in
chemical experiments; but as in these, espe-
cially with analytical views, greater exactness is
required, particular precautions must be em-
ployed, so as not to leave any saline or soluble
part in the residuum. More water must be em-
ployed than in ordinary lixiviations, and the
substances ought to be previously stirred up in
the water before the clear liquor is drawn off,
otherwise the whole mass might not be equally
lixiviated, and some parts might even escape
altogether from the action of the water. We
must likewise employ fresh portions of water
in considerable quantity, until it comes off en-
tirely free from salt, which we may ascertain
by means of the hydrometer formerly described.

In experiments with small quantities, this
operation is conveniently performed in jugs or
matrasses of glass, and by filtrating the liquor
through paper in a glass funnel. When the sub-
stance is in larger quantity, it may be lixivi-
ated in a kettle of boiling water, and filtrated
through paper supported by cloth in the wood-
en frame (Plate n, Figs. 3 and 4) ; and in opera-
tions in the large way, the tub already men-
tioned must be used.

SECTION III Of Evaporation

This operation is used for separating two
substances from each other, of which one at
least must be fluid, and whose degrees of vola-
tility are considerably different. By this means
we obtain a salt, which has been dissolved in
water, in its concrete form ; the water, by heat-
ing, becomes combined with caloric, which ren-
ders it volatile, while the particles of the salt
being brought nearer to each other, and within
the sphere of their mutual attraction, unite
into the solid state.

As it was long thought that the air had great
influence upon the quantity of fluid evaporated,
it will be proper to point out the errors which
this opinion has produced. There certainly is a
constant slow evaporation from fluids exposed
to the free air; and, though this species of evap-
oration may be considered in some degree as a
solution in air, yet caloric has considerable in-
fluence in producing it, as is evident from the
refrigeration which always accompanies this
process; hence we may consider this gradual
evaporation as a compound solution made part-
ly in air and partly in caloric. But the evapora-
tion which takes place from a fluid kept con-
tinually boiling, is quite different in its nature,

108

LAVOISIER

and in it the evaporation produced by the ac-
tion of the air is exceedingly inconsiderable in
comparison with that which is occasioned by
caloric. This latter species may be termed va-
porization rather than evaporation. This proc-
ess is not accelerated in proportion to the ex-
tent of evaporating surface, but in proportion
to the quantities of caloric which combine with
the fluid. Too free a current of cold air is often
hurtful to this process, as it tends to carry off
caloric from the water and consequently re-
tards its conversion into vapour. Hence there
is no inconvenience produced by covering, in a
certain degree, the vessels in which liquids are
evaporated by continual boiling, provided the
covering body be of such a nature as does not
strongly draw off the caloric, or, to use an ex-
pression of Dr. Franklin's, provided it be a bad
conductor of heat. In this case, the vapours es-
cape through such opening as is left, and at least
as much is evaporated, frequently more than
when free access is allowed to the external air.

As during evaporation the fluid carried off
by caloric is entirely lost, being sacrificed for
the sake of the fixed substances with which it
was combined, this process is only employed
where the fluid is of small value, as water, for
instance. But, when the fluid is of more conse-
quence, we have recourse to distillation, in
which process we preserve both the fixed sub-
stance and the volatile fluid. The vessels em-
ployed for evaporation are basins or pans of
copper, silver, or lead (Plate n, Figs. 13 and 15),
or capsules of glass, porcelain, or stone ware
(Plate n, A, Figs. 1 and 2\ Plate in, Figs. 5 and
4) . The best utensils for this purpose are made
of the bottoms of glass retorts and matrasses,
as their equal thinness renders them more fit
than any other kind of glass vessel for bearing
a brisk fire and sudden alterations of heat and
cold without breaking.

As the method of cutting these glass vessels
is nowhere described in books, I shall here give
a description of it, that they may be made by
chemists for themselves out of spoiled retorts,
matrasses, and recipients, at a much cheaper
rate than any which can be procured from glass
manufacturers. The instrument (Plate in, Fig.
5), consisting of an iron ring AC, fixed to the
rod AB, having a wooden handle D, is employed
as follows: Make the ring red hot in the fire,
and put it upon the matrass G (Fig. 6), which
is to be cut; when the glass is sufficiently heat-
ed, throw on a little cold water, and it will gen-
erally break exactly at the circular line heated
by the ring.

Small flasks or phials of thin glass are exceed-
ing good vessels for evaporating small quantities
of fluid ; they are very cheap, and stand the fire
remarkably. One or more of these may be
placed upon a second grate above the furnace
(Plate in, Fig. #), where they will only experi-
ence a gentle heat. By this means a great num-
ber of experiments may be carried on at one
time. A glass retort, placed in a sand-bath, and
covered with a dome of baked earth (Plate in,
Fig. 1), answers pretty well for evaporations;
but in this way it is always considerably slow-
er, and is even liable to accidents; as the sand
heats unequally, and the glass cannot dilate in
the same unequal manner, the retort is very
liable to break. Sometimes the sand serves ex-
actly the office of the iron ring formerly men-
tioned ; for, if a single drop of vapour, condensed
into liquid, happens to fall upon the heated
part of the vessel, it breaks circularly at that
place. When a very intense fire is necessary,
earthen crucibles may be used ; but we gener-
ally use the word evaporation to express what
is produced by the temperature of boiling wa-
ter or not much higher.

SECTION IV Of Crystallization

In this process the integrant parts of a solid
body, separated from each other by the inter-
vention of a fluid, are made to exert the mutual
attraction of aggregation, so as to coalesce and
reproduce a solid mass. When the particles of
a body are only separated by caloric, and the
substance is thereby retained in the liquid state,
all that is necessary for making it crystallize is
to remove a part of the caloric which is lodged
between its particles, or, in other words, to cool
it. If this refrigeration be slow, and the body be
at the same time left at rest, its particles as-
sume a regular arrangement, and crystalliza-
tion, properly so called, takes place; but, if the
refrigeration is made rapidly, or if the liquor
be agitated at the moment of its passage to the
concrete state, the crystallization is irregular
and confused.

The same phenomena occur with watery so-
lutions, or rather in those made partly in water
and partly by caloric. So long as there remains
a sufficiency of water and caloric to keep the
particles of the body asunder beyond the sphere
of their mutual attraction, the salt remains in
the fluid state; but, whenever either caloric or
water is not present in sufficient quantity, and
the attraction of the particles for each other
becomes superior to the power which keeps
them asunder, the salt recovers its concrete

CHEMISTRY

109

form, and the crystals produced are the more
regular in proportion as the evaporation has
been slower and more tranquilly performed.

All the phenomena we formerly mentioned
as taking place during the solution of salts, oc-
cur in a contrary sense during their crystalliza-
tion. Caloric is disengaged at the instant of
their assuming the solid state, which furnishes
an additional proof of salt being held in solu-
tion by the compound action of water and ca-
loric. Hence, to cause salts to crystallize which
readily liquefy by means of caloric, it is not
sufficient to carry off the water which held
them in solution, but the caloric united to them
must likewise be removed. Nitrate of potash,
oxygenated muriate of potash, alum, sulphate
of soda, &c., are examples of this circumstance,
as, to make these salts crystallize, refrigeration
must be added to evaporation. Such salts, on
the contrary, as require little caloric for being
kept in solution, and which, from that circum-
stance, are nearly equally soluble in cold and
warm water, are crystallizable by simply car-
rying off the water which holds them in solu-
tion, and even recover their solid state in boil-
ing water; such are sulphate of lime, muriate
of potash and of soda, and several others.

The art of refining saltpetre depends upon
these properties of salts, and upon their differ-
ent degrees of solubility in hot and cold water.
This salt, as produced in the manufactories by
the first operation, is composed of many differ-
ent salts; some are deliquescent and not sus-
ceptible of being crystallized, such as the nitrate
and muriate of lime; others are almost equally
soluble in hot and cold water, as the muriates
of potash and of soda ; and, lastly, the saltpetre,
or nitrate of potash, is greatly more soluble in
hot than it is in cold water. The operation is
begun by pouring upon this mixture of salts as
much water as will hold even the least soluble,
the muriates of soda and of potash, in solution ;
so long as it is hot, this quantity readily dis-
solves all the saltpetre, but, upon cooling, the
greater part of this salt crystallizes, leaving
about a sixth part remaining dissolved, and
mixed with the nitrate of lime and the two mu-
riates. The nitre obtained by this process is
still somewhat impregnated with other salts,
because it has been crystallized from water in
which these abound. It is completely purified
from these by a second solution in a small quan-
tity of boiling water, and second crystallization.
The water remaining after these crystallizations
of nitre is still loaded with a mixture of salt-
petre, and other salts; by further evaporation,

crude saltpetre, or rough-petre, as the work-
men call it, is procured from it, and this is pur-
ified by two fresh solutions and crystallizations.

The deliquescent earthy salts which do not
contain the nitric acid are rejected in this man-
ufacture; but those which consist of that acid
neutralized by an earthy base are dissolved in
water, the earth is precipitated by means of
potash, and allowed to subside; the clear liquor
is then decanted, evaporated, and allowed to
crystallize. The above management for refin-
ing saltpetre may serve as a general rule for
separating salts from each other which happen
to be mixed together. The nature of each must
be considered, the proportion in which each
dissolves in given quantities of water, and the
different solubility of each in hot and cold wa-
ter. If to these we add the property which some
salts possess, of being soluble in alcohol, or in a
mixture of alcohol and water, we have many
resources for separating salts from each other
by means of crystallization, though it must be
allowed that it is extremely difficult to render
this separation perfectly complete.

The vessels used for crystallization are pans
of earthen ware A (Plate n, Figs. 1 and 2) and
large flat dishes (Plato in, Fig. 7). When a sa-
line solution is to be exposed to a slow evapora-
tion in the heat of the atmosphere, with free
access of air, vessels of some depth (Plate in,
Fig. 3) must be employed, that there may be a
considerable body of liquid; by this means the
crystals produced are of considerable size, and
remarkably regular in their figure.

Every species of salt crystallizes in a peculiar
form, and even each salt varies in the form of
its crystals according to circumstances, which
take place during crystallization. We must not
from thence conclude that the saline particles
of each species are indeterminate in their fig-
ures. The primitive particles of all bodies, es-
pecially of salts, are perfectly constant in their
specific forms; but the crystals which form in
our experiments are composed of congeries of
minute particles, which, though perfectly equal
in size and shape, may assume very dissimilar
arrangements and consequently produce a vast
variety of regular forms, which have not the
smallest apparent resemblance to each other
nor to the original crystal. This subject has
been very ably treated by the Abbe* Hatiy, in
several Mimoires presented to the Academy
and in his work upon the structure of crystals.
It is only necessary to extend generally to the
class of salts the principles he has particularly
applied to some crystallized stones.

110

LAVOISIER

SECTION V Of Simple Distillation

As distillation has two distinct objects to ac-
complish, it is divisible into simple and com-
pound; and, in this section, I mean to confine
myself entirely to the former. When two bodies,
of which one is more volatile than the other, or
has more affinity to caloric, are submitted to
distillation, our intention is to separate them
from each other. The more volatile substance
assumes the form of gas, and is afterwards con-
densed by refrigeration in proper vessels. In
this case distillation, like evaporation, becomes
a species of mechanical operation, which sep-
arates two substances from each other without
decomposing or altering the nature of either.
In evaporation, our only object is to preserve
the fixed body, without paying any regard to
the volatile matter; whereas, in distillation,
our principal attention is generally paid to the
volatile substance, unless when we intend to
preserve both the one and the other. Hence,
simple distillation is nothing more than evap-
oration produced in close vessels.

The most simple distilling vessel is a species
of bottle or matrass A (Plate in, Fig. 8), which
has been bent from its original form BC to BD,
and which is then called a retort ; when used, it
is placed either in a reverberatory furnace
(Plate xin, Fig. 2} or in a sand bath under a
dome of baked earth (Plate in, Fig. 1). To re-
ceive and condense the products, we adapt a
recipient E (Plate in, Fig. 9), which is luted to
the retort. Sometimes, more especially in phar-
maceutical operations, the glass or stone ware
cucurbit, A, with its capital B (Plate in, Fig.
12) or the glass alembic and capital (Fig. 18)
of one piece, is employed. This latter is man-
aged by means of a tubulated opening T, fitted
with a ground stopper of crystal; the capital,
both of the cucurbit and alembic, has a furrow
or trench, rr, intended for conveying the con-
densed liquor into the beak RS by which it
runs out. As, in almost all distillations, expan-
sive vapours are produced, which might burst
the vessels employed, we are under the neces-
sity of having a small hole T (Fig. 9) in the
balloon or recipient, through which these may
find vent; hence, in this way of distilling, all
the products which are permanently aeriform
are entirely lost, and even such as with diffi-
culty lose that state have not sufficient space to
condense in the balloon. This apparatus is not,
therefore, proper for experiments of investiga-
tion, and can only be admitted in the ordinary
operations of the laboratory or in pharmacy.

In the article appropriated for compound dis-
tillation, I shall explain the various methods
which have been contrived for preserving the
whole products from bodies in this process.

As glass or earthen vessels are very brittle,
and do not readily bear sudden alterations of
heat and cold, every well regulated laboratory
ought to have one or more alembics of metal
for distilling water, spiritous liquors, essential
oils, &c. This apparatus consists of a cucurbit
and capital of tinned copper or brass (Plate in,
Figs. 15 and 16), which, when judged proper,
may be placed in the water bath D (Fig. 17).
In distillations, especially of spiritous liquors,
the capital must be furnished with a refrigera-
tory, SS (Fig. 16), kept continually filled with
cold water; when the water becomes heated, it
is let off by the stop-cock, R, and renewed with
a fresh supply of cold water. As the fluid dis-
tilled is converted into gas by means of caloric
furnished by the fire of the furnace, it is evi-
dent that it could not condense, and, conse-
quently, that no distillation, properly speak-
ing, could take place, unless it is made to de-
posit in the capital all the caloric it received in
the cucurbit; with this view, the sides of the
capital must always be preserved at a lower
temperature than is necessary for keeping the
distilling substance in the state of gas, and the
water in the refrigeratory is intended for this
purpose. Water is converted into gas by the
temperature of 80 (212), alcohol by 67
(182.75), ether by 32 (104) : hence these sub-
stances cannot be distilled, or, rather,they will
fly off in the state of gas, unless the tempera-
ture of the refrigeratory be kept under these
respective degrees.

In the distillation of spiritous and other ex-
pansive liquors the above described refrigera-
tory is not sufficient for condensing all the
vapours which arise; in this case, therefore, in-
stead of receiving the distilled liquor immed-
iately from the beak, TU, of the capital into a
recipient, a worm is interposed between them.
This instrument is represented Plate in, Fig.
18, contained in a worm tub of tinned copper;
it consists of a metallic tube bent into a con-
siderable number of spiral revolutions. The
vessel which contains the worm is kept full of
cold water, which is renewed as it grows warm.
This contrivance is employed in all distilleries
of spirits, without the intervention of a capital
and refrigeratory, properly so called. The one
represented in the plate is furnished with two
worms, one of them being particularly appropri-
ated to distillations of odoriferous substances.

CHEMISTRY

111

In some simple distillations it is necessary
to interpose an adopter between the retort
and receiver, as shown (Plate in, Fig. 11). This
may serve two different purposes, either to
separate two products of different degrees of
volatility, or to remove the receiver to a
greater distance from the furnace, that it may
be less heated. But these, and several other
more complicated instruments of ancient con-
trivance, are far from producing the accuracy
requisite in modern chemistry, as will be
readily perceived when I come to treat of
compound distillation.

SECTION VI Of Sublimation

This term is applied to the distillation of sub-
stances which condense in a concrete or solid
form, such as the sublimation of sulphur, and
of muriate of ammonia, or sal ammonia. These
operations may be conveniently performed in
the ordinary distilling vessels already described ,
though, in the sublimation of sulphur, a species
of vessels, named alludels, have been usually
employed. These are vessels of stone or porce-
lain ware, which adjust to each other over a
cucurbit containing the sulphur to be sublimed.
One of the best subliming vessels, for substances
which are not very volatile, is a flask, or phial
of glass, sunk about two thirds into a sand
bath; but in this way we are apt to lose a part
of the products. When these are wished to be
entirely preserved, we must have recourse to
the pneumato-chemical distilling apparatus,
to be described in the following chapter.

CHAPTER VI

Of Pneumato-chemical Distillations, Metallic
Dissolutions, and Some Other Operations
Which Require Very Complicated Instruments

SECTION I Of Compound and Pneumato-chemi-
cal Distillations

IN the preceding chapter, I have only treated
of distillation as a simple operation, by which
two substances, differing in degrees of volatil-
ity, may be separated from each other; but dis-
tillation often actually decomposes the sub-
stances submitted to its action and becomes
one of the most complicated operations in
chemistry. In every distillation, the substance
distilled must be brought to the state of gas in
the cucurbit or retort, by combination with ca-
loric. In simple distillation, this caloric is given

out in the refrigeratory or in the worm, and
the substance again recovers its liquid or solid
form, but the substances submitted to com-
pound distillation are absolutely decompound-
ed; one part, as for instance the charcoal they
contain, remains fixed in the retort, and all the
rest of the elements are reduced to gases of dif-
ferent kinds. Some of these are susceptible of
being condensed and of recovering their solid
or liquid forms, whilst others are permanently
aeriform; one part of these are absorbable by
water, some by the alkalies, and others are not
susceptible of being absorbed at all. An ordi-
nary distilling apparatus, such as has been de-
scribed in the preceding chapter, is quite insuf-
ficient for retaining or for separating these di-
versified products, and we are obliged to have
recourse, for this purpose, to methods of a more
complicated nature.

The apparatus I am about to describe is cal-
culated for the most complicated distillations,
and may be simplified according to circum-
stances. It consists of a tubulated glass retort
A (Plate iv, Fig. 1), having its beak fitted to a
tubulated balloon or recipient BC; to the up-
per orifice D of the balloon a bent tube DE/gr
is adjusted, which, at its other extremity g, is
plunged into the liquor contained in the bottle
L, with three necks xxx. Three other similar
bottles are connected with this first one, by
means of three similar bent tubes disposed in
the same manner; and the farthest neck of the
last bottle is connected with a jar in a pneu-
mato-chemical apparatus, by means of a bent
tube. A determinate weight of distilled water
is usually put into the first bottle, and the other
three have each a solution of caustic potash in
water. The weight of all these bottles, and of
the water and alkaline solution they contain,
must be accurately ascertained. Every thing
being thus disposed, the junctures between the
retort and recipient, and of the tube D of the
latter, must be luted with fat lute, covered
over with slips of linen, spread with lime and
white of egg; all the other junctures are to be
secured by a lute made of wax and rosin melted
together.

When all these dispositions are completed,
and when, by means of heat applied to the re-
tort A, the substance it contains becomes de-
composed, it is evident that the least volatile
products must condense or sublime in the beak
or neck of the retort itself, where most of the
concrete substances will fix themselves. The
more volatile substances, as the lighter oils,
ammonia, and several others, will condense in

112

LAVOISIER

the recipient GC, whilst the gases, which are
not susceptible of condensation by cold, will
pass on by the tubes, and boil up through the
liquors in the several bottles. Such as are
absorbable by water will remain in the first
bottle, and those which caustic alkali can
absorb will remain in the others; whilst suc