Preface from The Elements of Chemistry
Antoine-Laurent Lavoisier
Preface of the Author
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
Science in the month of April 1787, on the necessity of reforming and completing
the Nomenclature of Chemistry. While engaged in this employment, I perceived,
better than I had ever done before, the justice of the following maxims of the
Abbé de Condillac, in his System of Logic, and some other of his works.
2 "We think only through the medium of words. --Languages are true analytical
methods. --Algebra, which is adapted to its purpose in every species of
expression, in the most simple, 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."
3 Thus, while I thought myself employed only in forming a Nomenclature, and
while I proposed 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.
4 The impossibility of separating the nomenclature 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 necessarily 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,
without 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.
5 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
essentially 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.
6 It is a maxim universally admitted in geometry, 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, observations, and analyses, a
successive train of ideas arises, so linked together, that an attentive observer
may trace back to a certain point the order and connection of the whole sum of
human knowledge.
7 When we begin the study of any science, we are in a situation, respecting
that science, similar 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 necessary consequence, and immediate effect, of an
experiment or observation. Besides, he that enters upon the career of science,
is in a less advantageous situation than a child who is acquiring his first
ideas. To the child, Nature gives various means of rectifying any mistakes he
may commit respecting the salutary or hurtful qualities of the objects which
surround him. On every occasion his judgments are corrected by experience; want
and pain are the necessary consequences arising from false judgment;
gratification 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.
8 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 necessity to correct them. Imagination, on the contrary,
which is ever wandering beyond the bounds of truth, joined to self-love and that
self-confidence we are so apt to indulge, prompt us to draw conclusions which
are not immediately 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.
9 The only method of preventing such errors from taking place, and of
correcting them when formed, is to restrain and simplify our reasoning 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 nothing but facts: These are
presented to us by Nature, 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 observation. 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.
10 Thoroughly convinced of these truths, I have imposed upon myself, as a law,
never to advance but from what is known to what is unknown; never to form any
conclusion which is not an immediate consequence necessarily flowing from
observation and experiment; and always to arrange the fact, and the conclusions
which are drawn from them, in such an order as shall render it most easy for
beginners in the study of chemistry thoroughly to understand them. Hence I have
been obliged to depart 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 almost 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 phenomena of chemistry into view at the very outset: They make use
of terms which have not been defined, and suppose the science to be understood
by the very persons they are only beginning to teach. It ought likewise to be
considered, that very little of chemistry can be learned in a first course,
which is hardly sufficient to make the language of the science familiar to the
ears, or the apparatus familiar to the eyes. It is almost impossible to become a
chemist in less than three or four years of constant application.
11 These inconveniencies 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 arrangement of chemistry, which appeared to me more
consonant to the order of Nature. I acknowledge, however, that in thus
endeavouring to avoid difficulties of one kind, I have found myself 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 labours. 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
complete science, the parts of which are all closely connected together: Its
actual progress, however, is so rapid, and the facts, under the modern doctrine,
have assumed so happy an arrangement, 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 susceptible.
12 The rigorous law from which I have never deviated, of forming no conclusions
which are not fully warranted by experiment, and of never supplying the absence
of facts, has prevented 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 body.
Messrs Geoffroy, Gellert, Bergman, Scheele, De Morveau, Kirwan, and many others,
have collected a number 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 defined, or not sufficiently
proved, to become the foundation upon which to build so very important a branch
of chemistry. This science of affinities, or elective attractions, holds the
same place with regard to the other branches of chemistry, as the higher or
transcendental geometry 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.
13 Perhaps a sentiment of self-love may, without my perceiving it, have given
additional force to these reflections. Mr de Morveau is at present engaged in
publishing the article Affinity in the Methodical Encyclopedia; and I had
more reasons than one to decline entering upon a work in which he is employed.
14 It will, no doubt, be a matter of surprise, that in a treatise upon the
elements of chemistry, there should be no chapter on the constituent 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 elements, which, by the variety of their
proportions, compose all the known substances in nature, 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 or 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.
15 It is very remarkable, that, notwithstanding of 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, considered sulphur and salt as elementary substances entering into the
composition of a great number 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 succeeding 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 admitted as proofs the slightest degrees of probability, unsupported by
that strictly rigorous analysis required by modern philosophy.
16 All that can be said upon the number and nature 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 all probability, is consistent with nature.
I shall therefore only add upon this subject, that if, by the term elements, we mean to express those simple and indivisible atoms of which
matter is composed, it is extremely probable we know nothing 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 or 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 substances we consider as simple may not be compounded 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.
17 The foregoing reflections upon the progress of chemical ideas naturally apply
to the words by which these ideas are to be expressed. Guided by the work which,
in the year 1787, Messrs de Morveau, Berthollet, de Fourcroy, and I composed
upon the Nomenclature of Chemistry, I have endeavoured, as much as possible, to
denominate 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
received the sanction of the public; and, secondly, when the names which had
been adopted, whether by the ancients or the moderns, appeared to us to express
evidently false ideas, when they confounded the substances, to which they were
applied, with others possessed of different, 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 language. We
endeavoured to frame them in such a manner as to express the most general and
the most characteristic quality of the substances; and this was attended with
the additional 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.
18 To those bodies which are formed by the union 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 individuals: The
name of the species, on the contrary, expresses a quality peculiar to certain
individuals only.
19 These distinctions are not, as some may imagine, merely metaphysical, but are
established by Nature. "A child," says the Abbé de Condillac, "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 of chemistry.
20 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 substance, 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 species. But, in
the greatest number of acids, the two constituent elements, the acidifying
principle, and that which it acidifies, may exist in different proportions,
constituting all the possible 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.
21 Metallic substances which have been exposed to the joint action of the air
and of fire, lose their metallic lustre, increase in weight, and assume an
earthy appearance. In this state, like the acids, they are compounded of a
principle which is common to all, and one which is peculiar to each. In the same
way, therefore, we have thought proper to class them under a generic name,
derived from the common principle; for which purpose, we adopted the term oxyd; and we distinguish them from each other by the particular name of
the metal to which each belongs.
22 Combustible substances, which in acids and metallic oxyds are a specific and
particular principle, are capable of becoming, in their turn, common principles
of a great number of substances. 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 Berthollet, that charcoal may be combined with
iron, and perhaps with several other metals; and that, from this combination,
according to the proportions, 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.
23 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
principles 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; 2d, The acidifiable principle
which constitutes their peculiar acid; 3d, 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 individuals of that class; and distinguished each species by the name of the
saline, earthy, or metallic basis, which is peculiar to it.
24 A salt, though compounded of the same three principles, may, nevertheless, by
the mere difference 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 chiefly by changes of termination
uniformly applied to the same state of the different salts.
25 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 principle,
and in what proportion; what is the state of the acid; with what basis it is
united; whether the saturation be exact, or whether the acid or the basis be in
excess.
26 It may be easily supposed that it was not possible to attain all these
different objects without departing, in some instances, from established 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 connected with a general and rational system. The names, besides, which were
formerly employed, such as powder of
algaroth, salt of
alembroth, pompholix,
phagadenic water, turbith
mineral, colcothar,
and many others, were neither less barbarous nor less uncommon. It required a
great deal of practice, and no small degree of memory, 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 suggested false
ideas: For, in the whole mineral kingdom, and particularly in the metallic
class, there exists no such thing as butters, oils, or flowers; and, in short,
the substances to which they give these fallacious names, are nothing less than
rank poisons.
27 When we published our essay on the nomenclature of chemistry, we were
reproached for having changed the language which was spoken by our masters,
which they distinguished by their authority, and handed down to us. But those
who reproach us on this account, have forgotten that it was Bergman and Macquer
themselves who urged us to make this reformation. In a letter which the learned
Professor of Upsala, 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
always be learned, and those who are ignorant will thus learn sooner.
28 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 the opinion of
those who have gone before me; that I have stated only my own opinion, without
examining that of others. By this I have been prevented from doing that justice
to my associates, and more especially to foreign chemists, which I wished to
render them. But I beseech the reader to consider, that, if I had filled an
elementary work with a multitude of quotations; 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 human mind, that
we are to attend in an elementary treatise: Our only aim ought to be ease and
perspicuity, and with the utmost care to keep every thing 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,
present 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
fist 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
experiments 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 with my
own, it is owing to the circumstance, that frequent intercourse, and the habit
of communicating our ideas, our observations, 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.
29 The remarks I have made on the order which I thought myself obliged to follow
in the arrangement 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 doctrine
I have adopted, and to which I wished to give a form completely elementary.
30 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 nothing 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.
31 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
method of performing experiments, and particularly those of modern chemistry, is
not so generally known as it ought to be; and had I, in the different memoirs
which I have presented to the Academy, been more particular in the detail of the
manipulations of my experiments, it is probable I should have made myself better
understood, and the science might have made a more rapid progress. The order of
the different matters 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 operations which are most connected
with one another. 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 any thing but the experiments which I have made
myself.
32 I shall conclude this preface by transcribing, literally, some observations
of the Abbé 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 subject; but they will not, on this account, have less
force, if the application of them be thought just.
33 "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 errors.
These errors becoming prejudices, are, of course, adopted as principles, and we
thus bewilder ourselves more and more. The method, too, by which we conduct our
reasonings is as absurd; we abuse words which we do not understand, and call
this the art of reasoning. When matters have been brought this length, when
errors have been thus accumulated, there is but one remedy by which order can be
restored to the faculty of thinking; this is, to forget all that we have
learned, to trace back our ideas to their source, to follow the train in which
they rise, and, as my Lord Bacon says, to frame the human understanding anew.
34 "This remedy becomes the more difficult in proportion as we think ourselves
more learned. Might it not be thought that works which treated of the sciences
with the utmost perspicuity, with great precision and order, must be understood
by every body? The fact is, those who have never studied any thing will
understand them better than those who have studied a great deal, and especially
those who have written a great deal."
35 At the end of the fifth chapter, the Abbé de Condillac adds: "But, after all,
the sciences have made progress, because philosophers have applied themselves
with more attention to observe, and have communicated to their language that
precision and accuracy which they have employed in their observations: In
correcting their language they reason better."
|
