1913] Silver Xitkate Concentration Cells 47 



The Xernst formula for cells of this type is 



2v RT <:, 



u-\-v »F C2 



where c^ and Co refer to the concentration of silver ions and not 

 to the concentration of silver nitrate. It is necessary to know 

 the values of u and v, the migration ratios of Ag"" and jSTOg". 

 With solutions for which u and v are constant, values propor- 

 tional to the ionic concentrations are given by the conductivities 

 of the solutions, and these are inversely proportional to the re- 

 sistance of the solutions. Gumming and Abegg conclude "that 



conductivity seems to be an exact measure of ion concentration." 

 The preceding table contains the results of measurements of 

 the resistances of the above solutions. 



Measurements of the migration ratios at each concentration 

 were not made. The table given by Lehfeldt^ indicates that 

 the migration ratio for silver nitrate is fairly constant up to a 

 concentration of 0.2 mols per liter. Assuming this value to be 

 constant the above becomes 



E 2v RT 



. loare 10 = K. 



logio C1/C2 H + t/ »F 



E 



The values of K^ are given in the last column of 



logioCi/Co 



Table I and with the exception of cells 1 and 2, where normal 

 solutions were used, they are fairly constant. This confirms 

 the results of previous investigations, which show that the 



