the influence of the inductive forces
(1572.) to the next positive surface, and after discharge passes away, it
seems to me to represent exactly that particle of oxygen which, having been
rendered negative in the electrolyte, is urged by the same disposition of
inductive forces, and going to the positive platina electrode, is there
discharged, and then passes away, as the air or dust did before it.

1625. _Heat_ is another direct effect of the _current_ upon substances in
which it occurs, and it becomes a very important question, as to the
relation of the electric and heating forces, whether the latter is always
definite in amount[A]. There are many cases, even amongst bodies which
conduct without change, that at present are irreconcileable with the
assumption that it is[B]; but there are also many which indicate that, when
proper limitations are applied, the heat produced is definite. Harris has
shown this for a given length of current in a metallic wire, using common
electricity[C]; and De la Rive has proved the same point for voltaic
electricity by his beautiful application of Breguet's thermometer[D].

[A] See De la Rive's Researches, Bib. Universelle, 1829, xl. p. 40.

[B] Amongst others, Davy, Philosophical Transactions, 1821, p. 438.
Pelletier's important results, Annales de Chimie, 1834, lvi. p. 371.
and Becquerel's non-heating current, Bib. Universelle, 1835, lx. 218.

[C] Philosophical Transactions, 1824, pp. 225. 228.

[D] Annales de Chimie, 1836, lxii. 177.

1626. When the production of heat is observed in electrolytes under
decomposition, the results are still more complicated. But important steps
have been taken in the investigation of this branch of the subject by De la
Rive[A] and others; and it is more than probable that, when the right
limitations are applied, constant and definite results will here also be
obtained.

[A] Bib. Universelle, 1829, xl. 49; and Ritchie, Phil. Trans. 1832. p.
296.

* * * * *

1627. It is a most important part of the character of the current, and
essentially connected with its very nature, that it is always the same. The
two forces are everywhere in it. There is never one current of force or one
fluid only. Any one part of the current may, as respects the presence of
the two forces there, be considered as precisely the same with any other
part; and the numerous experiments which imply their possible separation,
as well