in effect be true (1627.); for
how, otherwise, could the results formerly described occur? When currents
of air constituted the mode of discharge between the portions of paper
moistened with iodide of potassium or sulphate of soda (465. 469.),
decomposition occurred; and I have since ascertained that, whether a
current of positive air issued from a spot, or one of negative air passed
towards it, the effect of the evolution of iodine or of acid was the same,
whilst the reversed currents produced alkali. So also in the magnetic
experiments (307.) whether the discharge was effected by the introduction
of a wire, or the occurrence of a spark, or the passage of convective
currents either one way or the other (depending on the electrified state of
the particles), the result was the same, being in all cases dependent upon
the perfect current.

1634. Hence, the section of a current compared with other sections of the
same current must be a constant quantity, if the actions exerted be of the
same kind; or if of different kinds, then the forms under which the effects
are produced are equivalent to each other, and experimentally convertible
at pleasure. It is in sections, therefore, we must look for identity of
electrical force, even to the sections of sparks and carrying actions, as
well as those of wires and electrolytes.

1635. In illustration of the utility and importance of establishing that
which may be the true principle, I will refer to a few cases. The doctrine
of unipolarity, as formerly stated, and I think generally understood[A], is
evidently inconsistent with my view of a current (1627.); and the later
singular phenomena of poles and flames described by Erman and others[B]
partake of the same inconsistency of character. If a unipolar body could
exist, i.e. one that could conduct the one electricity and not the other,
what very new characters we should have a right to expect in the currents
of single electricities passing through them, and how greatly ought they to
differ, not only from the common current which is supposed to have both
electricities travelling in opposite directions in equal amount at the same
time, but also from each other! The facts, which are excellent, have,
however, gradually been more correctly explained by Becquerel[C],
Andrews[D], and others; and I understand that Professor Ohms[E] has
perfected the work, in his close examination of all the phenomena; and
after showing that similar phenomena c