Electro-Chemical Decomposition 69

included in the course of the electric current contributing to the
final effect; and it is because the ordinary chemical affinity is
relieved, weakened, or partly neutralised by the influence of
the electric current in one direction parallel to the course of the
latter, and strengthened or added to in the opposite direction,
that the combining particles have a tendency to pass in opposite
courses.

255. In this view the effect is considered as essentially de-
pendent upon the mutual chemical affinity of the particles of
opposite kinds. Particles a a, fig. 13, could not be transferred
or travel from one pole N towards the other P, unless they
found particles of the opposite kind b b, ready to pass in the
contrary direction : for it is by virtue of their increased affinity
for those particles, combined with their diminished affinity for
such as are behind them in their course, that they are urged
forward: and when any one particle a} fig. 14, arrives at the
pole, it is excluded or set free, because the particle b of the
opposite kind, with which it was the moment before in combi-

• @ r) 5 •

\L_X

Fig. 13. Fig. 14.

nation, has, under the superinducing influence of the current,
a greater attraction for the particle a, which is before it in its-
course, than for the particle a, towards which its affinity has
been weakened.

256. As far as regards any single compound particle, the case
may be considered as analogous to one of ordinary decomposi-
tion, for in fig. 14, a may be conceived to be expelled from
the compound a b by the superior attraction of a for b, that
superior attraction belonging to it in consequence of the relative
position of a b and a to the direction of the axis of electric
power (253) superinduced by the current. But as all the com-
pound particles in the course of the current, except those
actually in contact with the poles, act conjointly, and consist
of elementary particles, which, whilst they are in one direction
expelling, are in the other being expelled, the case becomes
more complicated, but not more difficult of comprehension. .

257. It is not here assumed that the acting particles must be
in a right line between the poles. The lines of action which may
be supposed to represent the electric currents passing through
a decomposing, liquid, have in many experiments very irregularich are