ckness, and exposing a surface on
each side equal to about half a square inch; these were placed upon platina
plates, one connected with the machine and electrometer (419.), and the
other with the discharging train, whilst a fine platina wire connected the
two pieces, resting upon them by its two points. On working the electrical
machine, it was possible to open the electrometer leaves about two-thirds
of an inch.

422. As the platina wire touched only by points, the facts show that this
salt is a far better conductor than ice; but as the leaves of the
electrometer opened, it is also evident with what difficulty conduction,
even of the small portion of electricity produced by the machine, is
effected by this body in the solid state, when compared to the facility
with which enormous quantities at very low tensions are transmitted by it
when in the fluid state.

423. In order to confirm these results by others, obtained from the voltaic
apparatus, a battery of one hundred and fifty plates, four inches square,
was well-charged: its action was good; the shock from it strong; the
discharge would _continue_ from copper to copper through four-tenths of an
inch of air, and the gold-leaf electrometer before used could be opened
nearly a quarter of an inch.

424. The ice vessel employed (420.) was half an inch in width; as the
extent of contact of the ice with the tin and platina was nearly fourteen
square inches, the whole was equivalent to a plate of ice having a surface
of seven square inches, of perfect contact at each side, and only one
fourth of an inch thick. It was retained in a freezing mixture during the
experiment.

425. The order of arrangement in the course of the electric current was as
follows. The positive pole of the battery was connected by a wire with the
platina plate in the ice; the plate was in contact with the ice, the ice
with the tin jacket, the jacket with a wire, which communicated with a
piece of tin foil, on which rested one end of a bent platina wire (312.),
the other or decomposing end being supported on paper moistened with
solution of iodide of potassium (316.): the paper was laid flat on a
platina spatula connected with the negative end of the battery. All that
part of the arrangement between the ice vessel and the decomposing wire
point, including both these, was insulated, so that no electricity might
pass through the latter which had not traversed the former also.

426. Under these circum