pper (1721.). It might have been supposed
that this mass would have allowed of the formation and discharge of almost
any quantity of currents in it, which the helix C was competent to induce,
and so in some degree have diminished if not altogether prevented the
effect in A: instead of which, though we can hardly doubt that an infinity
of currents are formed at the moment in the copper plate, still not the
smallest diminution or alteration of the effect in A appears (65.). Almost
the only way of reconciling this effect with generally received notions is,
as it appears to me, to admit that magnetic action is communicated by the
action of the intervening particles (1729. 1733.).

1736. This condition of things, which is very remarkable, accords perfectly
with the effects observed in solid helices where wires are coiled over
wires to the amount of five or six or more layers in succession, no
diminution of effect on the outer ones being occasioned by those within.

S _22. Note on electrical excitation._

1737. That the different modes in which electrical excitement takes place
will some day or other be reduced under one common law can hardly be
doubted, though for the present we are bound to admit distinctions. It will
be a great point gained when these distinctions are, not removed, but
understood.

1738. The strict relation of the electrical and chemical powers renders the
chemical mode of excitement the most instructive of all, and the case of
two isolated combining particles is probably the simplest that we possess.
Here however the action is local, and we still want such a test of
electricity as shall apply to it, to cases of current electricity, and also
to those of static induction. Whenever by virtue of the previously combined
condition of some of the acting particles (923.) we are enabled, as in the
voltaic pile, to expand or convert the local action into a current, then
chemical action can be traced through its variations to the production of
_all_ the phenomena of tension and the static state, these being in every
respect the same as if the electric forces producing them had been
developed by friction.

1739. It was Berzelius, I believe, who first spoke of the aptness of
certain particles to assume opposite states when in presence of each other
(959.). Hypothetically we may suppose these states to increase in intensity
by increased approximation, or by heat, &c. until at a certain point
combination occurs,