1 88

Faraday's Researches

body capable of acting directly on the metal; and it also appears
to be essential that these two should merge into one, or that the
principle directly active on the metal by chemical action should
be one of the ions of the electrolyte used. Whether the voltaic
arrangement be excited by solution of acids, or alkalies, or
sulphurets,' or by fused substances (212), this principle has
always hitherto, as far as I am aware, been an anion (678); and
I anticipate,, from a consideration of the principles of electric
action,, that it must of necessity be one of that class of bodies.

660. If the action of the sulphuric acid used in the voltaic
circuit be considered, it will be found incompetent to produce
any sensible portion of the electricity of the current by its com-
bination with the oxide formed, for this simple reason, it is
deficient in a most essential condition: it forms no part of an
electrolyte, nor is it in relation with any other body present in
the solution which will permit of the mutual transfer of the
particles and the consequent transfer of the electricity. It is
true, that as the plane at which the acid is dissolving the oxide
of zinc formed by the action of the water is in contact with the
metal zinc, there seems no difficulty in considering how the
oxide there could communicate an electrical state, proportionate
to its own chemical action on the acid, to the metal, which is a
conductor without decomposition. But on the side of the acid
there is no substance to complete the circuit: the water, as
water, cannot conduct it, or at least only so small a proportion
that it is merely an incidental and almost inappreciable effect
(705); and it cannot conduct it as an electrolyte, because an
electrolyte conducts in consequence of the mutual relation and
action of its particles ; and neither of the elements of the water,
nor even the water itself, as far as we can perceive, are ions with
respect to the sulphuric acid (S83).1

661. This view of the secondary character of the sulphuric
acid as an agent in the production of the voltaic current, is
further confirmed by the fact, that the current generated and
transmitted is directly and exactly proportional to the quantity
of water decomposed and the quantity of zinc oxidised (603,
727), and is the same as that required to decompose the same
quantity of water. As, therefore, the decomposition of the
water shows that the electricity has passed by its means, there

1 It will be seen that I here agree with Sir Humphry Davy, who has
experimentally supported the opinion that acids and alkalies in combining
do not produce any current of electricity. — Philosophical Tram actions,
1826, p. 398.oxidising or othernd then