TO THE MOVEMENT OF MACfllXES. 9 



markable ex])eriments of M. Peltier on the calorific phaenomena 

 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 ther- 

 mo-electric cuiTcnt, whose power increases with the elevation of 

 the temperature, and especially with the heterogeneity of the 

 conducting mass, which may be regarded as w holly 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 che- 

 mical 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 cur- 

 rent 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 

 eflPect it exercises on the needle, nevertheless we shall not succeed 

 in producing a continued magneto-electric cuiTent by means of 

 latent magnetism. In fact, it Mould then be a state of equili- 

 brium, or a Umit of the magnetization. The uniform process of 

 the magnetic machine (18), and of almost all the magneto-electric 

 rotatory apparatus t, is owing, for the most part, to an analogous 

 state of equiUbrium between the voltaic and the magneto-electric 



• See Becquerel's Treatise on Electricity, vol. iii. Article 444. 



+ In the Treatises on Physics, the unifonnity of the movement of these appa- 

 ratus, of Barlow's wheel, &c., is attributed to the resistance of the air, and of the 

 mercury, which increase with the velocity. Since the grand discovery of Mr. 

 Faraday these have been shown to be not the only causes. 



