mes a mere wire, and sometimes very large plates (1008.), and
also changing the terminal exciting plates Z and P, so that they were
sometimes wires only and at others of great size, still the results were
the same as those already obtained.

1025. In illustration of the effect of distance, an experiment like that
described with two exciting pairs and one intervening plate (1012.), fig.
93, was arranged so that the distance between the plates in the third cell
could be increased to six or eight inches, or diminished to the thickness
of a piece of intervening bibulous paper. Still the result was the same in
both cases, the effect not being sensibly greater, when the plates were
merely separated by the paper, than when a great way apart; so that the
principal opposition to the current in this case does not depend upon the
_quantity_ of intervening electrolytic conductor, but on the _relation of
its elements to the intensity of the current_, or to the chemical nature of
the electrodes and the surrounding fluids.

1026. When the acid was sulphuric acid, _increasing its strength_ in any of
the cells, caused no change in the effects; it did not produce a more
intense current in the exciting cells (908.), or cause the current produced
to traverse the decomposing cells more freely. But if to very weak
sulphuric acid a few drops of nitric acid were added, then either one or
other of those effects could be produced; and, as might be expected in a
case like this, where the exciting or conducting action bore a _direct_
reference to the acid itself, increasing the strength of this (the nitric
acid), also increased its powers.

1027. The _nature of the interposed plate_ was now varied to show its
relation to the phenomena either of excitation or retardation, and
amalgamated zinc was first substituted for platina. On employing one
voltaic pair and one interposed zinc plate, fig. 100, there was as powerful
a current, apparently, as if the interposed zinc plate was away. Hydrogen
was evolved against P in cell ii, and against the side of the second zinc
in cell i; but no gas appeared against the side of the zinc in cell ii, nor
against the zinc in cell i.

1028. On interposing two amalgamated zinc plates, fig. 101, instead of one,
there was still a powerful current, but interference had taken place. On
using three intermediate zinc plates, fig. 102, there was still further
retardation, though a good current of electricity passed.

102