﻿Electrochemistry of Radioactive Bodies. 



637 



copper. The E.M.F.'s between gold or platinum and their 

 solutions are hardly comparable with those tabulated above, 





























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for the ions of the metals in these two cases are present as 

 complex anions. A further complication arises from the 

 so-called air-potential. 



4. The Function of the Salt Solution in the Electrolysis. 



Electrochemieally definite systems. 

 According to Nernst's theory, the single potential differ- 

 ence at any electrode is given by the expression 



E = RTloff -, 



* P 

 where P is the so-called solution-tension of a metal, a constant 

 characteristic of it, and p the osmotic pressure of the ions of 

 the metal present in the liquid surrounding the electrode. 

 p is proportional to the concentration of these ions, and 

 therefore the above expression may be written 



E=RT 



n 



loo- 



here C is a new constant. 



wner 



The difference of potential between a metal and an electro- 

 lyte depends, therefore, on the concentration of the ions of 

 the metal. The case when c=0 and therefore E infinite 

 cannot be realized ; on the contrary, dipping a metal into 



