366 Mr. A. Frumkin on the 



by the anomalies of the electrocapillary curves. But the 

 investigations of Paschen, and especially those of Smith and 

 Moss *, have shown that the potential of the dropping electrode 

 corresponds to the maximum of the electrocapillary curve 

 even in the case of anomalous curves of electrolytes forming 

 complex salts. The only attempt to explain quantitatively 

 this coincidence, which we shall call with Smith and Moss 

 Paschen's relation, was made by Krueger f. Krueger 

 assumes that on the mercury surface there occurs adsorption 

 of mercury salt and arrives at the following equation : 



|*= e + F(*-l),a, 



where F is 96541 coulombs, k the distribution coefficient of 

 mercury salt between the surface-layer and the bulk of the 

 solution, c the concentration of mercury salt in the solution,. 

 and 8 the thickness of the surface-layer. Let us compare 

 two solutions like KI and KC1 at equal values of ty : the 

 concentration of mercury in the KI solution will be much 

 higher on account of the complex salt which Hgl 2 gives 

 with KI ; the term F(k—l)cB will have a considerable 

 value and cause the observed anomaly of the electrocapillary 

 curve. 



The maximum corresponds to a value of ^ which makes e 

 equal to — F(/c — l)cS ; the quantity of mercury salt adsorbed 

 on unit surface therefore exactly corresponds to the quantity 

 of mercury which entered the solution in the form of ions 

 when the surface was increased by unity. It is obvious 

 that under these conditions surface increase does not produce 

 any change of concentration and the solution is a "null" 

 one. Further, the negative value of e increases with 

 increasing stability of the corresponding complex salts, and 

 accordingly the maximum corresponds to greater values 

 of ty, i. e. it is displaced to the ri<jht. 



Krueger's reasoning is quite correct, but, as we shall show 

 later, his supplementary term is probably much too small to 

 account for the anomalies observed; at any rate, Krueger's 

 theory is not applicable to the anomalous curves of organic 

 substances which Gouy t has discovered. A suitable 

 example of these curves may give the electrocapillary curve 



* Phil. Ma.g. (6) xv. p. 478 (1908). 



t Nachr. d. Ges. d. W'iss. Gottingm Math.-ph.ys. Klasse, 1904, p. 33 ;. 

 ZeiL Electr. xix. p. 68] (1913). 



X Ann. chim. phys. (8) viii. p. 291, and ix. p. 75 (1906). 



