the Elementary Law of Hydrodiffusion. 495 



already, after the lapse of one day (£=1), had sunk below ^J^. 

 Moreover L^ was always made as nearly as possible = -5-, in 



1 • n. 1 • / 37rZ A -^Vl • t_. t 11 



order to bring the term q-sm( T fi L to vanishing. In all 



the experiments carried out, therefore, for every instant of 

 time t>l, was 



e r = -^ -sm 



and 



^ + -, 2 -l!i+a4-!fci!)« i ,,(|)«-S 



It/ 



From this results, as the expression of the electromotive force 

 E generated by the concentrations z" and z' of the boundary 

 layers between the two electrodes at the moment t ( > 1), 



E=A(/'-/([l + B(*'/ + *')] 



7T 



(%-^l) 



*■©•-*•)}■ 



If, therefore, Fick's law of hydrodiffusion is correct, then the 

 electromotive force between the two electrodes must be such a 

 function of the time that 



E=A 1 «""P*-B 1 *-"i?'**, 



where A x and B x are brief designations of certain constant 

 values. 



Since, according to the above-given measurements, the value 

 of the constant B is very small compared with the value of 

 the constant A, the expression of the electromotive force will 

 after a short time reduce to the first term, to 



The measuring of the electromotive force was accomplished 

 according to Dubois-Reymond's modification of the compen- 

 sation method. A Daniell element served as compensator, of 

 of which the electromotive force never varied more than y^m 

 of its value. The measuring-wire employed was perfectly 

 equal in value in each of its parts ; moreover care was taken 

 that the resistance of the Daniell and the other resistance of 

 the galvanic circuit in which the compensating Daniell was 

 included remained the same during all the measurements. If 



