blished 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 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.

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.

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.

I shall conclude this preface by transcribing, literally, some
observations of the Abbe 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.

'Instead of applying observation to the things we wished to know, we
have chosen rather to imagine them. Advancing from one ill