), mere wires of platina and zinc were immersed in the exciting
acid; yet, notwithstanding this change, those bodies were now decomposed
which resisted any current tending to be formed by the dilute sulphuric
acid. For instance, muriatic acid could not be decomposed by a single pair
of plates when immersed in dilute sulphuric acid; nor did making the
solution of sulphuric acid strong, nor enlarging the size of the zinc and
platina plates immersed in it, increase the power; but if to a weak
sulphuric acid a very little nitric acid was added, then the electricity
evolved had power to decompose the muriatic acid, evolving chlorine at the
_anode_ and hydrogen at the _cathode_, even when mere wires of metals were
used. This mode of increasing the intensity of the electric current, as it
excludes the effect dependent upon many pairs of plates, or even the effect
of making any one acid stronger or weaker, is at once referable to the
condition and force of the chemical affinities which are brought into
action, and may, both in principle and practice, be considered as perfectly
distinct from any other mode.

909. The direct reference which is thus experimentally made in the simple
voltaic circle of the _intensity_ of the electric current to the
_intensity_ of the chemical action going on at the place where the
existence and direction of the current is determined, leads to the
conclusion that by using selected bodies, as fused chlorides, salts,
solutions of acids, &c., which may act upon the metals employed with
different degrees of chemical force; and using also metals in association
with platina, or with each other, which shall differ in the degree of
chemical action exerted between them and the exciting fluid or electrolyte,
we shall be able to obtain a series of comparatively constant effects due
to electric currents of different intensities, which will serve to assist
in the construction of a scale competent to supply the means of determining
relative degrees of intensity with accuracy in future researches[A].

[A] In relation to this difference and its probable cause, see
considerations on inductive polarization, 1354, &c.--_Dec. 1838._

910. I have already expressed the view which I take of the decomposition in
the experimental place, as being the direct consequence of the superior
exertion at some other spot of the same kind of power as that to be
overcome, and therefore as the result of an antagonism of forces of the