Fused Chloride of Lead Conducts       35
it protected the platina from contact with the melted part long
after that contact was expected.
 128.	This insulating power of ice is not effective with elec-
tricity 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 elec-
trometer was instantly discharged (155).
 129.	But though electricity of an intensity so low that it
cannot diverge the electrometer, can still pass (though in very
limited quantities (155)) 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.
 130.	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 pro-
ceeded 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 electro-
chemical 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 (120), was
used as the source of electricity, and a galvanometer introduced
into the circuit to indicate the presence or absence of a current.         |
131.	On fusing a little chloride of lead by a spirit-lamp on a        -'
fragment of a Florence flask, and introducing two platina wires
connected with the poles of the battery, there was instantly
powerful action, the galvanometer was most violently affected,
and the chloride rapidly decomposed. On removing the lamp,
the instant the chloride solidified all current and consequent
effects ceased, though the platina wires remained inclosed in
the chloride not more than the one-sixteenth of an inch from
each other. On renewing the heat, as soon as the fusion had
proceeded far enough to allow liquid matter to connect the
poles, the electrical current instantly passed.
 132.	On fusing the chloride, with one wire introduced, and
then touching the liquid with the other, the latter being cold,
caused a little knob to concrete on its extremity, and no current
passed; it was only when the wire became so hot as to be able
to admit or allow of contact with the liquid matter, that con-
duction took place, and then it was very powerful.
 133.	When chloride of silver and chlorate of potassa were