did not seem to undergo decomposition in the latter
case.

415. 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 decomposition, 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, &c.; and from these it
might perhaps be assumed that decomposition is dependent upon 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[A].

[A] See 673, &c. &c.--_Dec. 1838._

416. The relation, under this law, of the conducting power for 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 hack to the solid state, it gains the
power of conducting 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 corpuscular condition of the substances
concerned.

417. The assumption of conducting power and a decomposable 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, &c. &c.,
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, &c. &c.,
and to obtain sodium, magnesium, boron, &c., in their separate states.

S 10. _On Conducting Power generally._[A]

[A] In reference to this S refer to 983 in series viii., and the
results connected with it.--_Dec. 1838._

418