The Sun.
London, England, 1863-05-18 00:00:00

ROYAL INSTITUTION.

No science has undergone so many and such im-
portant changes as chemistry, not only in consequence
of the discoveries of new elementary bodies and the
decomposition of those that were supposed to be ele-
mentary, but in the theoreical views of the nature
of the actions of diffetent elements on each other,
and at the meeting of the members of the Royal In-
stitution on Friday evening another change that has
been recently made in the views of many chemists
was noticed and illustrated by Dr. Odling. Until
within the last 12 years there was no fact in chemi-
cal science that was considered to be more firmly
established than the composition of water. The de-
composition of distilled water by the voltaic battery
shows that it is composed of the two gases hydrogen
and oxygen in the proportions of one volume of oxy-
gen to two of hydrogen ; but as the latter ges is 16
times lighter than the former, the proportions by
weight are eight of oxygen to one of hydrogen.
Aceording to the atomic theory, which regards all
bodies as resolvable into ultimate indivisible atoms,
the molecule of water was considered to consist of
one atom of oxygen and one atom of hydrogen, and
that the weight of the oxygen atom was eight times
greater than that of the hydrogen atom. Nearly all
chemists were agreed on that point, though seme
doubts had been thrown on it by Gay Lussac, Sir
Humphrey Davy, and a few others. Recent con-
siderations of the well known combinations of hydro-
gen and oxygen in other substances have induced
many chemists to alter their opinions, and to con-
sider water to be composed of two atoms of hydrogen
and ore of oxygen, the weight of the oxygen atom
being thus raised to 16 times the weight of the atom
of hydrogen. Chemists are now nearly equally
divided in opinion respecting this change in the
relative weights of the two atoms; and Dr. Odling,
who is an active propagandist of the new theory,
endeavoured to support it by a variety of examples
and illustrative experiments, many of them exhi
biting remarkable and brilliant effects of chemi-
cal combinations. Two of the combinations
on which he relied for confirming his views were
those of hydrochloric acid gas and of phosphoretted
hydrogen. The latter gas is so inflammable that it
ignites the instant it comes in contact with the air,
and this effect was brilliantly exemplified by pass-
ing bubbles of the gas through water into a jar
containing oxygen. The evidence by which Dr.
Odling supported the new theory was entirely of a
technical character, and he introduced an array of
long terms with their accompanying chemical sym.
bols that was quite overpowering. The difference
between the new and the old theory of the compo-
sition of water, he contended, is not a mere matter
of form, but it,is a matter of fact that serves to ex-
plain many of the previously inexplicable chemical
combinations, and tends to remove those difficulties
of the atomic theory which arise from the necessity
of dividing indivisible atoms. It has been objected
to the new estimate of the weight of the atom o

oxygen that it would unnecessarily alter established
opinions, but that objection Dr. Odling thought
should have no force, for he considered it might be
desirable that nine-tenths of all established opinions
should be changed.