434 PROCEEDLNGS OP THE AMERICAN ACADEMY 



The expression ordinarily obtained for the electromotive force of a 

 thermo-electric cu'cuit is 



E 



J T' 



The only assumption made in obtaining this equation was that the 

 heat effects obey tlie two laws of thermodynamics. 



It is thus seen that the same form of i'undaniental equation can be 

 obtained in an entirely different way, by considering the energy of a 

 thermo-electric current as part of the energy which resides upon every 

 surface. 



The last case is, in every respect, identical with the ordinarj- thermo- 

 electric circuit between a solid and liquid. And if tiie results of Lipp- 

 mann are accepted it has been shown that even the existence of neutral 

 points can be explained. 



If, as Maxwell says, there is for all bodies a coelTicient of superficial 

 energy, the energy of every thermo-electric circuit may be accounted 

 for by changes in the potential energy of superficial tension. 



