f hydrogen; but
to have an affinity or attraction towards them, which, though it does not
at all approach in force, under ordinary circumstances, to that by which it
is combined with its own particle, can, under the electric influence,
exerted in a definite direction, be made even to surpass it. This general
relation of particles already in combination to other particles with which
they are not combined, is sufficiently distinct in numerous results of a
purely chemical character; especially in those where partial decompositions
only take place, and in Berthollet's experiments on the effects of quantity
upon affinity: and it probably has a direct relation to, and connexion
with, attraction of aggregation, both in solids and fluids. It is a
remarkable circumstance, that in gases and vapours, where the attraction of
aggregation ceases, there likewise the decomposing powers of electricity
apparently cease, and there also the chemical action of quantity is no
longer evident. It seems not unlikely, that the inability to suffer
decomposition in these cases may be dependent upon the absence of that
mutual attractive relation of the particles which is the cause of
aggregation.

524. I hope I have now distinctly stated, although in general terms, the
view I entertain of the cause of electro-chemical decomposition, _as far as
that cause can at present be traced and understood_. I conceive the effects
to arise from forces which are _internal_, relative to the matter under
decomposition--and _not external_, as they might be considered, if directly
dependent upon the poles. I suppose that the effects are due to a
modification, by the electric current, of the chemical affinity of the
particles through or by which that current is passing, giving them the
power of acting more forcibly in one direction than in another, and
consequently making them travel by a series of successive decompositions
and recompositions in opposite directions, and finally causing their
expulsion or exclusion at the boundaries of the body under decomposition,
in the direction of the current, _and that_ in larger or smaller
quantities, according as the current is more or less powerful (377.). I
think, therefore, it would be more philosophical, and more directly
expressive of the facts, to speak of such a body, in relation to the
current passing through it, rather than to the poles, as they are usually
called, in contact with it; and say that whilst under decomposi