392 Dr. G. von Hevesy on the 



RTe 



Since the osmotic pressure P is — , we obtain, therefore, 

 i. n > 



n ax 



a ax 



The effect of the compensating electric forces is that 



N" K =— Uce -t- cations 

 ax 



and „,, _ r dyJr 



^ a = + Vc6 T l anions 

 ax 



traverse unit cross-section in unit time. ~- is the P.D. 



ax 



accelerating the slow ions, and retarding the fast ones, and 

 € is the charge borne by the gram-ion. 



The total number of cations and anions passing unit cross- 

 section in unit time are N K and N A respectively, where 



L n ax ax J 



N A =N' A+ N" A =-Vf^ f -eM]. 



L n ax ax J 



and 



Since the same number of anions and cations traverse the 

 cross-section, we get 



and therefore dyjr U — V RT dc 



dx "" U + V nee dx 



and ^ T AT 2UV nrr ^c 



A n(U + V) da? 



Now U = 1-036 u. 10- 5 , 



V= 1-036 ^.10" 5 



RT=8-61.10 13 T, 



and -.-^ , x I dc 



/ ax 



where u and v are the absolute velocities of the ions in cm. 

 per sec, and D the diffusion coefficient. If this last constant 



