ew pairs of
metals, &c., is resolved into its _ions_ the more readily as it is acted
upon by electricity urged forward by many alternations.

994. Both these effects are, I think, easily understood. Whatever
_intensity_ may be, (and that must of course depend upon the nature of
electricity, whether it consist of a fluid or fluids, or of vibrations of
an ether, or any other kind or condition of matter,) there seems to be no
difficulty in comprehending that the _degree_ of intensity at which a
current of electricity is evolved by a first voltaic element, shall be
increased when that current is subjected to the action of a second voltaic
element, acting in conformity and possessing equal powers with the first:
and as the decompositions are merely opposed actions, but exactly of the
same kind as those which generate the current (917.), it seems to be a
natural consequence, that the affinity which can resist the force of a
single decomposing action may be unable to oppose the energies of many
decomposing actions, operating conjointly, as in the voltaic battery.

995. That a body which can give way to a current of feeble intensity,
should give way more freely to one of stronger force, and yet involve no
contradiction to the law of definite electrolytic action, is perfectly
consistent. All the facts and also the theory I have ventured to put forth,
tend to show that the act of decomposition opposes a certain force to the
passage of the electric current; and, that this obstruction should be
overcome more or less readily, in proportion to the greater or less
intensity of the decomposing current, is in perfect consistency with all
our notions of the electric agent.

996. I have elsewhere (947.) distinguished the chemical action of zinc and
dilute sulphuric acid into two portions; that which, acting effectually on
the zinc, evolves hydrogen at once upon its surface, and that which,
producing an arrangement of the chemical forces throughout the electrolyte
present, (in this case water,) tends to take oxygen from it, but cannot do
so unless the electric current consequent thereon can have free passage,
and the hydrogen be delivered elsewhere than against the zinc. The electric
current depends altogether upon the second of these; but when the current
can pass, by favouring the electrolytic action it tends to diminish the
former and increase the latter portion.

997. It is evident, therefore, that when ordinary zinc is used in a vol