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518.  Passing to the consideration of electro-chemical decomposition, it appears to me that the effect is produced by an internal corpuscular action, exerted according to the direction of the electric current, and that it is due to a force either super to, or giving direction to the ordinary chemical affinity of the bodies present.  The body under decomposition may be considered as a mass of acting particles, all those which are 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 neutralized 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.

519.  In this view the effect is considered as essentially dependent upon the mutual chemical affinity of the particles of opposite kinds.  Particles aa, fig. 53, could not be transferred or travel from one pole N towards the other P, unless they found particles of the opposite kind bb, 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. 54, 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 combination, 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.

520.  As far as regards any single compound particle, the case may be considered as analogous to one of ordinary decomposition, for in fig. 54, a may be conceived to be expelled from the compound ab 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 (517.) superinduced by the current.  But as all the compound 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.