Galvanic Pile, and Electromotive Forces. 507 



that contact electromotive force can be absolutely independent 

 of the chemical affinity between the substances which are in 

 contact with one another. 



Since, in order to explain the thermal phenomena in the 

 hydroelectric pile, we are compelled to assume that the elec- 

 tromotive force found in it consumes heat when a current 

 passes through in the same direction as that in which the 

 force acts, but generates heat if the current has the contrary 

 direction, we must also admit that the same thing must also 

 happen at the surface of contact between two metallic con- 

 ductors at which an electromotive force is present, and, there- 

 fore, that the explanation which I have given of Peltier's 

 phenomena *, may be the only true one. I will therefore not 

 dwell further upon the objections which were raised against 

 the correctness of that explanation. In connexion therewith 

 I have sought to prove that the thermoelectric force arises 

 from the dependence of the contact electromotive force on 

 temperature |. In consequence, however, of the reasons 

 alleged by Prof. Clausius f this view of mine has not met 

 with general recognition. I will therefore take leave here to 

 subject Prof. Clausius's arguments to a brief examination. 



1). In reference to the origin of thermoelectric currents, 

 Clausius urges, in the memoir cited, that it is in the 

 highest degree improbable that the attraction of the mate- 

 rial molecules for electricity should change with the tem- 

 perature ; and if this were not the case, the distribution of 

 heat would have no influence at all upon the distribution of 

 electricity. But, continues Clausius, even if it be conceded 

 that the attraction of matter for electricity is really dependent 

 on temperature, still no thermoelectric current can thence 

 arise ; for if material molecules at different temperatures pos- 

 sessed different amounts of attraction for electricity, variously 

 hot parts of the same conductor would behave like conductors 

 of different material at the same temperature. That is to 

 say, in other terms, a thermoelectric ring consisting of two 

 different metals, for example, the two soldering-p laces of 

 w T hich have different temperatures, would behave just like a 

 ring consisting of several different metals with all the contacts 

 possessing the same degree of heat. But it is known that 

 such a ring gives no current, because the electromotive forces 

 in it counteract one another. 



For my part, I cannot assent to this assertion of Professor 

 Clausius. On the contrary, according to my conviction, every 

 thing tends to show that the attraction of material for electrical 



* Oefversigt af Vetenskaps Ak. Fork. 1869, Vet. Ak. Handl. Bd. ix. 

 No. 14 



t Ibid. % Yogg. Ann. vol. xc. 



