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 can take place with good conductors, proves that with soap, &c. many of the effects are the mere consequences of the bodies evolved by electrolytic action.

  [A] Erman, Annales de Chimie, 1807. lxi. p. 115.  Davy’s Elements, p.
  168.  Biot, Ency.  Brit.  Supp, iv. p. 444.  Becquerel, Traite, i. p. 167. 
  De la Rive, Bib.  Univ. 1837. vii. 392.

  [B] Erman, Annales de Chimie, 1824. xxv. 278.  Becquerel, Ibid. xxxvi.
  p. 329

  [C] Becquerel, Annales de Chimie, 1831. xlvi. p. 283.

  [D] Andrews, Philosophical Magazine, 1836. ix. 182.