y in the evidence is,
however, completely supplied by the former experiments on different-sized
electrodes; for with variation in the size of these, a variation in the
intensity must have occurred. The intensity of an electric current
traversing conductors alike in their nature, quality, and length, is
probably as the quantity of electricity passing through a given sectional
area perpendicular to the current, divided by the time (360. _note_); and
therefore when large plates were contrasted with wires separated by an
equal length of the same decomposing conductor (714.), whilst one current
of electricity passed through both arrangements, that electricity must have
been in a very different state, as to _tension_, between the plates and
between the wires; yet the chemical results were the same.

725. The difference in intensity, under the circumstances described, may be
easily shown practically, by arranging two decomposing apparatus as in fig.
67, where the same fluid is subjected to the decomposing power of the same
current of electricity, passing in the vessel A. between large platina
plates, and in the vessel B. between small wires. If a third decomposing
apparatus, such as that delineated fig. 66. (711.), be connected with the
wires at _ab_, fig. 67, it will serve sufficiently well, by the degree of
decomposition occurring in it, to indicate the relative state of the two
plates as to intensity; and if it then be applied in the same way, as a
test of the state of the wires at _a'b'_, it will, by the increase of
decomposition within, show how much greater the intensity is there than at
the former points. The connexions of P and N with the voltaic battery are
of course to be continued during the whole time.

726. A third form of experiment, in which difference of intensity was
obtained, for the purpose of testing the principle of equal chemical
action, was to arrange three volta-electrometers, so that after the
electric current had passed through one, it should divide into two parts,
each of which should traverse one of the remaining instruments, and should
then reunite. The sum of the decomposition in the two latter vessels was
always equal to the decomposition in the former vessel. But the _intensity_
of the divided current could not be the same as that it had in its original
state; and therefore _variation of intensity has no influence on the
results if the quantity of electricity remain the same_. The experiment, in