384 . Mr. A. Frumkin on the 



influence of osmotic and electrostatic forces, he calculated 

 the distribution of potential in the surface-layer and the 

 value of e for a given potential difference between mercury 

 and solution. The resulting equation of the electrocapillary 

 curve is 



2KT /Sp/S -^ 



where K is the specific inductive capacity of water, p the 

 osmotic pressure of the ions in the bulk of the solution, and 

 V = i|r — -^ Max As Chapman's reasoning involves the assump- 

 tion that the ions in the double layer behave like perfect 

 gases, equation (8) especially at higher concentrations can be 

 used only for small absolute values of V. It seemed to me 

 therefore of interest to test eq. (8) in the neighbourhood of 

 the maximum. Table III. contains the experimental values 

 of 7 Max> — y in c.g.s. units for KC1, KN0 3 , and Na 2 S0 4 , and 

 the values calculated by means of equation (8), assuming 

 K = 81, £ = 18°, and p = *cHT, where « is the degree of dis- 

 sociation of KN0 3 . Moreover, Table III. contains values 

 of 7 Max — 7 calculated by means of the classical formula 



y M a,-Y=«v 2 , (9) 



a being determined from the value of 7 Max# — 7 which corre- 

 spond to V=l volt. 



Table III. shows a very great discrepancy between the 

 calculated and the observed values : the influence of concen- 

 tration is much less pronounced, as it ought to be according 

 to (8); moreover, 7 Max — 7 is approximately proportional 

 to V 2 . Thus, the results of experiment are unfavourable to 

 Chapman's assumption concerning the conditions of the 

 equilibrium in the double layer. As Chapman's reasoning- 

 is thermodynamically correct, equation (8) must be in 

 agreement with" "(6). In fact, for great values of V, we have 



f yMax. _ " , y— ~^r\/ 2 e = const - Vce 2 —const. 6? 2RiV p ' 



With the help of equation (pa) we may calculate the 

 value of absorption of any ions, except those of mercury, as 

 we cannot vary their concentration without varying ijr. It 

 is easy to give to the equation of the electrocapillary curve 



