ring into qualifications
for which we lack space, we believe no chemist will deny it to be a
general law of these inorganic combinations that, _other things equal_,
the stability decreases as the complexity increases.

And then when we pass to the compounds of organic chemistry, we find
this general law still further exemplified: we find much greater
complexity and much less stability. An atom of albumen, for instance,
consists of 482 ultimate atoms of five different kinds. Fibrine, still
more intricate in constitution, contains in each atom, 298 atoms of
carbon, 40 of nitrogen, 2 of sulphur, 228 of hydrogen, and 92 of
oxygen--in all, 660 atoms; or, more strictly speaking--equivalents. And
these two substances are so unstable as to decompose at quite ordinary
temperatures; as that to which the outside of a joint of roast meat is
exposed. Thus it is manifest that the present chemical heterogeneity of
the Earth's surface has arisen by degrees, as the decrease of heat has
permitted; and that it has shown itself in three forms--first, in the
multiplication of chemical compounds; second, in the greater number of
different elements contained in the more modern of these compounds: and
third, in the higher and more varied multiples in which these more
numerous elements combine.

To say that this advance in chemical heterogeneity is due to the one
cause, diminution of the Earth's temperature, would be to say too much;
for it is clear that aqueous and atmospheric agencies have been
concerned; and, further, that the affinities of the elements themselves
are implied. The cause has all along been a composite one: the cooling
of the Earth having been simply the most general of the concurrent
causes, or assemblage of conditions. And here, indeed, it may be
remarked that in the several classes of facts already dealt with
(excepting, perhaps, the first), and still more in those with which we
shall presently deal, the causes are more or less compound; as indeed
are nearly all causes with which we are acquainted. Scarcely any change
can with logical accuracy be wholly ascribed to one agency, to the
neglect of the permanent or temporary conditions under which only this
agency produces the change. But as it does not materially affect our
argument, we prefer, for simplicity's sake, to use throughout the
popular mode of expression.

Perhaps it will be further objected, that to assign loss of heat as the
cause of any changes, is to attribut