﻿66 Dr. C. V. Burton on the 



9. From these results we pass on to 



Theorem V. 



For any pair of metals at the absolute zero of temperature, 

 the Peltier effect vanishes. 



This is evidently true for our model, for when the molecules 

 are all reduced to relative rest, and there is permanent 

 instead of intermittent contact amongst their outer particles, 

 the conduction-potential will be uniform throughout both 

 metals, and at the junction there will be no Peltier effect. 

 But whatever view we take of the nature of the phenomenon, 

 the proposition is necessarily true. For if the Peltier effect 

 had a finite value for a pair of metals at the absolute zero of 

 temperature, we could cause an absorption of heat by sending 

 a current through the junction in the proper direction; and 

 this is impossible, since there is no heat to be absorbed. 



10. Volta E.M.F.'s. 



We must now consider a possibility suggested by our 

 model, and referred to in the opening sentence of §8. It is 

 not difficult to see that, with molecules constructed on the 

 plan of fig. 2, even when all measurements are made in vacuo, 

 the conduction-potential of a mass of metal is not in general 

 the same as the potential estimated by work done on an 

 external charged body, or by electrification induced on a 

 second mass of metal insulated from the first, — potential 

 measured in the latter way being called for distinction the 

 induction -potential. 



We may realize this most easily by considering the case of 

 two metals in contact at the absolute zero of temperature, for 

 then, in accordance with the last section, the Peltier effect at 

 the junction vanishes, and the conduc- . 



fo'cm-potential is the same through- 

 out both metals ; while on the other 

 hand the difference of induction- 

 potential may be finite. Let fig. 4 

 represent diagrammatically a very 

 large number of molecules which are 

 at rest with their outer conduc- 

 tive particles in electrical contact 

 throughout. Let the fixed central 

 charge of each molecule be positive. 

 Then, if the outer conductive par- 

 ticles of each molecule formed a 

 complete envelope around the central charge, the induction- 

 potential of the metal would be identical with its conduction- 

 potential ? and the same as if the fixed central charges did 



