leaving only the hydrogen and charcoal
remaining, which are the elements proper for producing fat or oil. This
observation 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 excrementitious matters, are
chiefly composed of charcoal and hydrogen, and approach considerably to
the nature of oil, of which they furnish a considerable quantity by
distillation with a naked fire; but the intolerable foetor which
accompanies 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 approximations in this Chapter upon the
composition of animal substances, which is hitherto but imperfectly
understood. We know that they are composed of hydrogen, charcoal, azote,
phosphorus, and sulphur, all of which, in a state of quintuple
combination, are brought to the state of oxyd by a larger or smaller
quantity of oxygen. We are, however, still unacquainted with the
proportions in which these substances are combined, and must leave it to
time to complete this part of chemical analysis, as it has already done
with several others.

FOOTNOTES:

[27] Binary combinations are such as consist of two simple elements
combined together. Ternary, and quaternary, consist of three and four
elements.--E.

[28] In the Third Part will be given the description of an apparatus
proper for being used in experiments of this kind.--A.

CHAP. XV.

_Of the Acetous Fermentation._

The acetous fermentation is nothing more than the acidification or
oxygenation of wine[29], produced in the open air by means of the
absorption 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 diminution 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 whi