256 ELECTRIFICATION OF WATER 



Such bags seemed to retain the effect of the gelatin treatment for a 

 long time, and continued use and subsequent washing did not seem 

 to remove this after effect of the gelatin treatment. 



When collodion bags which had received this gelatin treatment 

 were filled with solutions of electrolytes (of the theoretical osmotic 

 pressure of that of a m/64 sugar solution) and were dipped into beakers 

 with distilled water, the influence of the nature of the electrolyte 

 upon the initial rate of diffusion of water into the bag could be 

 expressed by the following two rules.^ 



1. Solutions of neutral salts possessing a univalent or bivalent 

 cation influence the rate of diffusion of water through a collodion 

 membrane, as if the water particles were charged positively and were 

 attracted by the anion and repelled by the cation of the electrolyte; 

 the attractive and repulsive action increasing with the number of 

 charges of the ion. The same rule applies to solutions of alkalies. 



2. Solutions of neutral or acid salts possessing a trivalent or tetra- 

 valent cation influence the rate of diffusion of water through a collodion 

 membrane as if the particles of water were charged negatively and 

 were attracted by the cation and repelled by the anion of the elec- 

 trolyte; the attractive and repulsive action increasing with the 

 number of charges of the ion. Solutions of acids obey the same 

 rule. 



When the same experiments were repeated with collodion bags 

 which had not come in contact with gelatin, the influence of the 

 electrolytes mentioned in Rule 1 on the diffusion of water was the 

 same as when the membrane had been treated with gelatin. Rule 2, 

 however, was not vahd when the collodion membranes had not been 

 treated with gelatin. It was of interest to discover the cause of this 

 difference. 



The curves in Figs. 1 and 2 show that Rule 1 holds also for collodion 

 membranes not treated with gelatin. The solutions of salts used 

 were neutral or slightly alkaline (in the case of Nas citrate). The 

 abscissae in the figures are the logarithms of the concentration, the 

 ordinates the height to which the level of liquid in the manometer 

 rose in the first 20 minutes. The curves in Fig. 1 show that the levels 



»Loeb, J., J. Gen. Physiol., 1918-19, i, 717. 



