514.  The view of M. de la Rive to a certain extent agrees with that of M. Hachette, for he considers that the two electricities decompose separate portions of water (490.)[A].  In one passage he speaks of the two electricities as two influences, wishing perhaps to avoid offering a decided opinion upon the independent existence of electric fluids; but as these influences are considered as combining with the elements set free as by a species of chemical affinity, and for the time entirely masking their character, great vagueness of idea is thus introduced, inasmuch as such a species of combination can only be conceived to take place between things having independent existences.  The two elementary electric currents, moving in opposite directions, from pole to pole, constitute the ordinary voltaic current.

  [A] Annales de Chimie, 1825, tom, xxviii. pp. 197, 201.

515.  M. Grotthuss is inclined to believe that the elements of water, when about to separate at the poles, combine with the electricities, and so become gases.  M. de la Rive’s view is the exact reverse of this:  whilst passing through the fluid, they are, according to him, compounds with the electricities; when evolved at the poles, they are de-electrified.

516.  I have sought amongst the various experiments quoted in support of these views, or connected with electro-chemical decompositions or electric currents, for any which might be considered as sustaining the theory of two electricities rather than that of one, but have not been able to perceive a single fact which could be brought forward for such a purpose:  or, admitting the hypothesis of two electricities, much less have I been able to perceive the slightest grounds for believing that one electricity in a current can be more powerful than the other, or that it can be present without the other, or that one can be varied or in the slightest degree affected, without a corresponding variation in the other[A].  If, upon the supposition of two electricities, a current of one can be obtained without the other, or the current of one be exalted or diminished more than the other, we might surely expect some variation either of the chemical or magnetical effects, or of both; but no such variations have been observed.  If a current be so directed that it may act chemically in one part of its course, and magnetically in another, the two actions are always found to take place together.  A current has not, to my knowledge, been produced which could act chemically and not magnetically, nor any which can act on the magnet, and not at the same time chemically[B].

  [A] See now in relation to this subject, 1627-1645.—­Dec. 1838.

  [B] Thermo-electric currents are of course no exception, because when
  they fail to act chemically they also fail to be currents.

517. Judging from facts only, there is not as yet the slightest reason for considering the influence which is present in what we call the electric current,—­whether in metals or fused bodies or humid conductors, or even in air, flame, and rarefied elastic media,—­as a compound or complicated influence.  It has never been resolved into simpler or elementary influences, and may perhaps best be conceived of as an axis of power having contrary forces, exactly equal in amount, in contrary directions.