116 Faraday's Researches

cases where a similar consequence might have been expected.
It may be said, that my own theory of electro-chemical decom-
position would lead to the expectation that all compound bodies
should give way under the influence of the electric current with
a facility proportionate to the strength of the affinity by which
their elements, either proximate or ultimate, are combined. I
am not sure that that follows as a consequence of the theory;
but if the objection is supposed to be one presented by the
facts, I have no doubt it will be removed when we obtain a
more intimate acquaintance with, and precise idea of, the
nature of chemical affinity and the mode of action of an electric
current over it (254, 260): besides which, it is just as directly
opposed to any other theory of electro-chemical decomposition
as the one I have propounded; for if it be admitted, as is gene-
rally the case, that the more directly bodies are opposed to each
other in their attractive forces, the more powerfully do they
combine, then the objection applies with equal force to any of
the theories of electrolysation which have been considered, and
is an addition to those which I have taken against them.

410. Amongst powerful compounds which are not decom-
posed, boracic acids stands prominent (144). Then again, the
iodide of sulphur, and the chlorides of sulphur, phosphorus, and
carbon, are not decomposable under common circumstances,
though their elements are of a nature which would lead to a
contrary expectation. Chloride of antimony (138, 426), the
hydro-carbons, acetic acid, ammonia, and many other bodies
undecomposable by the voltaic pile, would seem to be formed
by an affinity sufficiently strong to indicate that the elements
were so far contrasted in their nature as to sanction the expec-
tation that the pile would separate them, especially as in some
cases of mere solution (266, 280), where the affinity must by
comparison be very weak, separation takes place.1

411. It must not be forgotten, however, that much of this
difficulty, and perhaps the whole, may depend upon the absence
of conducting power, which, preventing the transmission of the
current, prevents of course the effects due to it. All known
compounds being non-conductors when solid, but conductors
when liquid, are decomposed, with perhaps the single exception
at present known of periodide of mercury (414, 426); and even
water itself, which so easily yields up its elements when the

1 With regard to solution, I have met with some reasons for supposing
that it will probably disappear as a cause of transference, and intend
resuming the consideration at a convenient opportunity.ttmuiE Ofhe surface were