powers independent of the ice itself.

391. On one occasion I was surprised to find that after thawing much of the
ice the conducting power had not been restored; but I found that a cork
which held the wire just where it joined the platina, dipped so far into
the ice, that with the ice itself it protected the platina from contact
with the melted part long after that contact was expected.

392. This insulating power of ice is not effective with electricity of
exalted intensity. On touching a diverged gold-leaf electrometer with a
wire connected with the platina, whilst the tin case was touched by the
hand or another wire, the electrometer was instantly discharged (419.).

393. But though electricity of an intensity so low that it cannot diverge
the electrometer, can still pass (though in very limited quantities
(419.),) through ice; the comparative relation of water and ice to the
electricity of the voltaic apparatus is not less extraordinary on that
account, Or less important in its consequences.

394. As it did not seem likely that this _law of the assumption of
conducting power during liquefaction, and loss of it during congelation_,
would be peculiar to water, I immediately proceeded to ascertain its
influence in other cases, and found it to be very general. For this purpose
bodies were chosen which were solid at common temperatures, but readily
fusible; and of such composition as, for other reasons connected with
electrochemical action, led to the conclusion that they would be able when
fused to replace water as conductors. A voltaic battery of two troughs, or
twenty pairs of four-inch plates (384.), was used as the source of
electricity, and a galvanometer introduced into the circuit to indicate the
presence or absence of a current.