have taken of the _quantity_ of electricity associated with the
particles of matter.

871. In this exposition of the law of the definite action of electricity,
and its corresponding definite proportion in the particles of bodies, I do
not pretend to have brought, as yet, every case of chemical or
electro-chemical action under its dominion. There are numerous
considerations of a theoretical nature, especially respecting the compound
particles of matter and the resulting electrical forces which they ought to
possess, which I hope will gradually receive their development; and there
are numerous experimental cases, as, for instance, those of compounds
formed by weak affinities, the simultaneous decomposition of water and
salts, &c., which still require investigation. But whatever the results on
these and numerous other points may be, I do not believe that the facts
which I have advanced, or even the general laws deduced from them, will
suffer any serious change; and they are of sufficient importance to justify
their publication, though much may yet remain imperfect or undone. Indeed,
it is the great beauty of our science, CHEMISTRY, that advancement in it,
whether in a degree great or small, instead of exhausting the subjects of
research, opens the doors to further and more abundant knowledge,
overflowing with beauty and utility, to those who will be at the easy
personal pains of undertaking its experimental investigation.

872. The definite production of electricity (868.) in association with its
definite action proves, I think, that the current of electricity in the
voltaic pile: is sustained by chemical decomposition, or rather by chemical
action, and not by contact only. But here, as elsewhere (857.), I beg to
reserve my opinion as to the real action of contact, not having yet been
able to make up my mind as to whether it is an exciting cause of the
current, or merely necessary to allow of the conduction of electricity,
otherwise generated, from one metal to the other.

873. But admitting that chemical action is the source of electricity, what
an infinitely small fraction of that which is active do we obtain and
employ in our voltaic batteries! Zinc and platina wires, one-eighteenth of
an inch in diameter and about half an inch long, dipped into dilute
sulphuric acid, so weak that it is not sensibly sour to the tongue, or
scarcely to our most delicate test-papers, will evolve more electricity in
one-twentieth of a minu