40 Faraday's Researches

151. Again, there are many substances which contain elements
such as would be expected to arrange themselves at the opposite
poles of the pile,, and therefore in that respect fitted for de-
composition, which yet do not conduct. Amongst these are
the iodide of sulphur, per-iodide of zinc, per-chloride of tin,
chloride of arsenic, hydrated chloride of arsenic, acetic acid,
orpiment, realgar, artificial camphor, etc.; and from these it
might perhaps be assumed that decomposition is dependent
uoon conducting power, and not the latter upon the former.
The true relation, however, of conduction and decomposition in
those bodies governed by the general law which it is the object
of this paper to establish, can only be satisfactorily made out
from a far more extensive series of observations than those I
have yet been able to supply.1

152. The relation, under this law, of the conducting power
of electricity to that for heat, is very remarkable, and seems
to imply a natural dependence of the two. As the solid becomes
a fluid, it loses almost entirely the power of conduction for
heat, but gains in a high degree that for electricity; but as
it reverts back to the solid state, it gains the power of conduct-
ing heat, and loses that of conducting electricity. If, therefore,
the properties are not incompatible, still they are most strongly
contrasted, one being lost as the other is gained. We may
hope, perhaps, hereafter to understand the physical reason of
this very extraordinary relation of the two conducting powers,
both of which appear to be directly connected with the corpus-
cular condition of the substances concerned.

153. The assumption of conducting power and a decom-
posable condition by liquefaction, promises new opportunities of,
and great facilities in, voltaic decomposition. Thus, such bodies
as the oxides, chlorides, cyanides, sulpho-cyanides, fluorides,
certain vitreous mixtures, etc., etc., may be submitted to the
action of the voltaic battery under new circumstances; and
indeed I have already been able, with ten pairs of plates, to
decompose common salt, chloride of magnesium, borax, etc., etc.,
and to obtain sodium, magnesium, boron, etc., in their separate
states.

1 See 414, etc., etc.—December 1838.the manner necessary for decomposition ?