THE 

 LONDON, EDINBURGH, ani. DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL 01^ SCIENCE. 



[SIXTH SERIE 



APRIL 191 



XXX. On the Surface Electric Double^i& 

 Liquid Bodies. By J. Frekkel, Postgi 

 University of Petrograd *. 



Part I. — Intrinsic Potentials. 



§ 1. TT has been assumed by many investigators on 

 JL contact electromotive forces that the latter -are 

 tine to the presence of electric double-layers on the surface of 

 metals. The existence of such layers has been conclusively 

 proved by experiments on the thermionic and photo-electric 

 effect. It has been shown by Richardson that the free 

 electrons, in escaping from a heated metallic body, perform a 

 perfectly definite amount of work at the cost of their kinetic 

 energy due to thermal agitation. This work is measured by 

 the constant iv in Richardson's formula 



w 



i = AVTe~**, 



where i is the thermionic current, T the temperature, tc the 

 gas constant. The fact that w is always positive shows that 

 the electric force near the surface of all metals is directed 

 outwards (thus tending to keep the electrons back), or in 

 other words, that the outer face of the electric double-layer 

 is always negative, and the inner positive. The eleetric 

 potential inside the metallic body must therefore exceed that 

 of its environment by a positive quantity V, connected with 



* Communicated by Prof. A. Yoffe. 

 Phil Mag. S. 6. Vol. 33. No. 196. April 1917. X 



