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 presence 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 possible 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
attendant 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 philosophers and chemists: Indeed, it strongly
proves, that, in chemistry, as in moral philosophy, it is extremely
difficult to overcome prejudices 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 alkohol are burnt in an apparatus[21] 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
alkohol during its combustion; and I have already shown that this must
be oxygen, or the base of air. Thus alkohol 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 compound substance.
80