364 



Mr. A. Frumkin on the 



According to this theory, the maximum surface-tension 

 corresponds to the zero of the potential difference between the 

 mercury and the solution. The experimental investigations 

 of Rothmund*, Smith f> and Gouy J have shown that this 

 relation cannot hold generally : solutions of electrolytes which 

 give complex salts with mercury show anomalies ; the 

 maximum of the electrocapillary curve is depressed and 

 displaced from its normal position so as to correspond to 

 greater values of -\jr (see fig. 1, where the electrocapillary 

 curves of n/1 KN0 3 and w/1 KI are drawn). 



Fig-. 1. 



too 



OS 



I.— n/1 KN0 3 . 



1,5 



II.— n/1 KI. 



Nernst § showed that equation (1) may also be deduced 

 from his " osmotic " theory of potential differences. To 

 explain the observed anomalies, Nernst conjectured that the 

 ions which form the double layer may have an influence on 



* Zeii. phys. Chem. xv. p. 1 (1894). 

 t Phil. Trans. A. cxciii. p. 83 (1900). 

 X Ann. chhn, phys. (7) xxix. p. 145 (1903). 



§ Wied. Ann. lviii. (1896), Beilage, Zeit. Electrochemie, vii, p. 253 

 (1900). 



