Page:Scientific Memoirs, Vol. 2 (1841).djvu/21

Rh experiments of M. Peltier on the calorific phænomena of electricity in a conductor composed of different metals. But if we collect all the isolated facts on this point, everything leads us to believe, that the resistance opposed by a conductor to the passage of voltaic electricity is nothing else than a reactive thermo-electric current, whose power increases with the elevation of the temperature, and especially with the heterogeneity of the conducting mass, which may be regarded as wholly composed of thermo-electric elements. According to this hypothesis, which must however be confirmed by experiment, this resistance would be null in a homogeneous body.—In general, matter opposes the transmission of physical forces, which tend to produce its disintegrations. It gives rise to, or generates of itself, forces which are frequently of the same nature, and tend to restore all molecular derangement occasioned by the primitive force. It is a struggle which terminates by the production of some state of equilibrium, or by the total destruction of the conducting body; but it would never end in producing any state of saturation.

That which is evident in regard to the electric force traversing any body whatsoever, cannot be admitted in regard to magnetism without some reserve; nor can it be supposed that soft iron can, without being affected, become the depository of a force not less extraordinary and not less energetic in producing thermal and chemical actions. In fact, soft iron possesses the power of generating a magnetism opposed to that which a current of induction tends to cause it to adopt, and I do not think that the magneto-electric current of Mr. Faraday can be otherwise conceived than as such a reaction. But, although the duration of this reactive current is not infinitely small, as has been sufficiently proved by the mechanical effect it exercises on the needle, nevertheless we shall not succeed in producing a continued magneto-electric current by means of latent magnetism. In fact, it would then be a state of equilibrium, or a limit of the magnetization. The uniform process of the magnetic machine (18), and of almost all the magneto-electric rotatory apparatus, is owing, for the most part, to an analogous state of equilibrium between the voltaic and the magneto-electric