﻿03* 



Dr. (I. von Hevesv 



a 



water results in an immediate production of some ions at the 

 surface separating them and E assumes a finite value. This 

 variation of potential difference is a phenomenon depending 

 on many factors, and we can, therefore, have definite po- 

 tential differences between a metal and an electrolyte, only 

 when the latter contains a known quantity of a salt of the 

 former. 



One of the chief causes of the elucidation of the relation- 

 ship mentioned in the last paragraph between the E. M. F. 

 Metal/Electrolyte, and the composition of the mixture of B 

 and C deposited, was the fact that in every case only electro- 

 chemically definite systems were employed. In what follows, 

 a definite system will be used to denote a system in which 

 an electrode dips into a solution of one of its salts, an 

 indefinite system, one in which a metal dips into any other 

 liquid. 



Fig. G shows the difference between an indefinite poten- 

 tial difference, e.g., Xickel/water, and a definite one 



ZSB zu Set 



Xickel/XiCl 2 . In the former case a rise-curve is obtained 

 (denoting excess of B over (_•), corresponding to a negative 

 potential difference Metal/indefinite Electrolyte, and in the 

 latter case, a decay-curve (C present practically in the pure 

 state). These differences are complicated in the case of 

 to its passivity, which causes it to act as 



