_same quantity_ of electricity may
pass in the _same time_, in at the _same surface_, into the _same
decomposing body in the same state_, and yet, differing in intensity, will
_decompose in one case and in the other not_:--for taking a source of too
low an intensity to decompose, and ascertaining the quantity passed in a
given time, it is easy to take another source having a sufficient
intensity, and reducing the quantity of electricity from it by the
intervention of bad conductors to the same proportion as the former
current, and then all the conditions will be fulfilled which are required
to produce the result described.

P iii. _On associated Voltaic Circles, or the Voltaic Battery._

989. Passing from the consideration of single circles (875. &c.) to their
association in the voltaic battery, it is a very evident consequence, that
if matters are so arranged that two sets of affinities, in place of being
opposed to each other as in figg. 73. 76. (880. 891.), are made to act in
conformity, then, instead of either interfering with the other, it will
rather assist it. This is simply the case of two voltaic pairs of metals
arranged so as to form one circuit. In such arrangements the activity of
the whole is known to be increased, and when ten, or a hundred, or any
larger number of such alternations are placed in conformable association
with each other, the power of the whole becomes proportionally exalted, and
we obtain that magnificent instrument of philosophic research, the _voltaic
battery_.

990. But it is evident from the principles of definite action already laid
down, that the _quantity_ of electricity in the current cannot be increased
with the increase of the _quantity of metal_ oxidized and dissolved at each
new place of chemical action. A single pair of zinc and platina plates
throws as much electricity into the form of a current, by the oxidation of
32.5 grains of the zinc (868.) as would be circulated by the same
alteration of a thousand times that quantity, or nearly five pounds of
metal oxidized at the surface of the zinc plates of a thousand pairs placed
in regular battery order. For it is evident, that the electricity which
passes across the acid from the zinc to the platina in the first cell, and
which has been associated with, or even evolved by, the decomposition of a
definite portion of water in that cell, cannot pass from the zinc to the
platina across the acid in the second cell, without the dec