5- 



I 



o 



•1— « 



to 



C 



380 



360 



340 



3E0 



300 



280 



260 



240 



220 



200 



180 



160 



140 



120 



100 



80 



60 



40 



20 



^ 4096 20^1024 512 236 128 64 32 16 "8" 4 2 ^^^ 



Concentration 



Fig. 1. Initial rate of dififusion of pure water through a collodion membrane 

 into a solution containing an electrolyte. Abscissae are the logarithms of con- 

 centration, ordinates rise of level of water in manometer connected with solution 

 after 20 minutes. Solutions of salts were all rendered alkaline by enough KOH 

 to make the solution about 10~^n in regard to KOH. The water was positively 

 electrified. The curves show that the initial rate of diffusion of water into the 

 solution increases with increasing valency of the anion of the electrolyte, though 

 the membrane has the same sign of charge as the anion. The cations have a 

 depressing effect, increasing also with the valency. The drop in the curve 

 beyond a concentration of M/128 or m/64 is due to the fact that beyond this con- 

 centration the effect of the cation begins to prevail over that of the anion, until 

 at a concentration of m/8 or m/4 the gas pressure effect of the electrolyte begins to 

 prevail over the electrical effect.^- ^' ^ 



« Loeb, J., J. Gen. Physiol, 1919-20, ii, 273. 



394 



