200

Faraday's Researches

evolution of electricity in cases of combination or decomposition,
it will be necessary, not merely to observe certain effects depen-
dent upon a current of electricity, but also their quantity: and
though it may often happen that the forces concerned in any
particular case of chemical action may be partly exerted in
one mode and partly in the other, it is only those which are
efficient in producing the current that have any relation to
voltaic action. Thus, in the combination of oxygen and hydrogen
to produce water,, electric powers to a most enormous amount
are for the time active (596, 608); but any mode of examining
the flame which they form during energetic combination,, which
has as yet been devised, has given but the feeblest traces.
These therefore may not, cannot, be taken as evidences of the
nature of the action; but are merely incidental results, incom-
parably small in relation to the forces concerned, and supplying
no information of the way in which the particles are active on
each other, or in which their forces are finally arranged.

696. That such cases of chemical action produce no current
of electricity, is perfectly consistent with what we know of the
voltaic apparatus, in which it is essential that one of the com-
bining elements shall form part of, or be in direct relation with,
an electrolytic conductor (656, 658). That such cases produce
no free electricity of tension, and that when they are converted
into cases of voltaic action they produce a current in which the
opposite forces are so equal as to neutralise each other, prove the
equality of the forces in the opposed acting particles of matter,
and therefore the equality of electric power in those quantities
of matter which are called electro-chemical equivalents (559).
Hence another proof of the definite nature of electro-chemical
action (518, etc.), and that chemical affinity and electricity are
forms of the same power (652, etc).

697. The direct reference of the effects produced by the
voltaic pile at the place of experimental decomposition to the
chemical affinities active at the place of excitation (626, 652),
gives a very simple and natural view of the cause why the bodies
(or ions) evolved pass in certain directions; for it is only when
they pass in those directions that their forces can consist with
and compensate (in direction at least) the superior forces which
are dominant at the place where the action of the whole is
determined. If, for instance, in a voltaic circuit, the activity of
which is determined by the attraction of zinc for the oxygen of
water, the zinc move from right to left, then any other cation
included in the circuit, being part of an electrolyte, or formingernd then