as the inexhaustible nature of the current when
producing particular effects; for these effects depend upon transfer only,
and do not consume the power. Thus a current which will heat one inch of
platina wire will heat a hundred inches (853. note). If a current be
sustained in a constant state, it will decompose the fluid in one
voltameter only, or in twenty others if they be placed in the circuit, in
each to an amount equal to that in the single one.

1632. Again, in cases of disruptive discharge, as in the spark, there is
frequently a dark part (1422.) which, by Professor Johnson, has been called
the neutral point[A]; and this has given rise to the use of expressions
implying that there are two electricities existing separately, which,
passing to that spot, there combine and neutralize each other[B]. But if
such expressions are understood as correctly indicating that positive
electricity alone is moving between the positive ball and that spot, and
negative electricity only between the negative ball and that spot, then
what strange conditions these parts must be in; conditions, which to my
mind are every way unlike those which really occur! In such a case, one
part of a current would consist of positive electricity only, and that
moving in one direction; another part would consist of negative electricity
only, and that moving in the other direction; and a third part would
consist of an accumulation of the two electricities, not moving in either
direction, but mixing up together! and being in a relation to each other
utterly unlike any relation which could be supposed to exist in the two
former portions of the discharge. This does not seem to me to be natural.
In a current, whatever form the discharge may take, or whatever part of the
circuit or current is referred to, as much positive force as is there
exerted in one direction, so much negative force is there exerted in the
other. If it were not so we should have bodies electrified not merely
positive and negative, but on occasions in a most extraordinary manner, one
being charged with five, ten, or twenty times as much of both positive and
negative electricity in equal quantities as another. At present, however,
there is no known fact indicating such states.

[A] Silliman's Journal, 1834, xxv. p. 57.

[B] Thomson on Heat and Electricity, p. 171.

1633. Even in cases of convection, or carrying discharge, the statement
that the current is everywhere the same must