The Thermoelectric Circuit of Three Metals. 631 



electrodes at a lower potential than the minimum spark- 

 potential of the gas in which the discharge occurs, the dis- 

 charge is produced wholl}'- or in part by the metal ions. 



In conclusion I desire to thank Professor Michelson for 

 his kindly interest in my work and for several helpful 

 suggestions. 



I wish also to thank Professor Millikan for suggesting the 

 problem and for his valuable counsel throughout this work. 

 I can not adequately express my deep appreciation of his 

 efforts in my behalf. 



Ryerson Laboratory, * | 



University of Chicago. 

 April 1905. 



LXXI. The Thermoelectric Circuit of Three Metals. 

 By H. E. Schmitz, M.A., B.Sc* 



§ 1. Introduction. 



THE experiments described in the present paper were 

 undertaken at the instance of Professor E. Kiecke, 

 and were carried out in the Physical Institute of the 

 University of Gottingen during the months November 1904 

 to April 1905. 



Let a circuit be formed of three metals A, B, C ; and let 

 the junctions opposite these metals be at temperatures 

 (centigrade) represented respectively by t lt t 2i t B . If we 

 assume that the electromotive force E of such a circuit 

 depends only on the temperatures of the junctions, we may 

 suppose intermediate points to be at 0° C, and may therefore 

 write 



B=(B,O? + (0,A)«»+(A,B)?, . .... (1) 

 where (B, C)q is the electromotive force of a circuit formed 

 of the metals B, C when the junctions are at temperatures 

 0° C. and tx C, reckoned in the direction B to C through 

 the junction at t°, and E is reckoned in the direction ABC. 



If we farther assume that the electromotive force of the 

 circuit is zero when all the junctions are at the same 

 temperature t, we have 



(B,C)i+(C,A)«+(A,B) '=0 (2) 



By the use of this equation we may eliminate (C, A)o a 

 from equation (1), and may write 



E = (B, C)J-(B, C)'*+(A, B)J> -(A, B)fr. . . (3) 



* Communicated by the Author. A short abstract of this paper has 

 appeared in the Physikalische Zeitschrift (July 1905). 



