JACQUES LOEB 295 



These facts, then, show that the depressing effect of the addition 

 of electrolyte upon the osmotic pressure of gelatin solutions (or 

 colloidal solutions in general) is paralleled by the effect the addition 

 of electrolyte has upon the initial rate of diffusion from water into 

 solution through a collodion membrane, when we substitute a 

 crystalloidal electrolyte for the gelatin salt. 



SUMMARY. 



1 . When a 1 per cent solution of a metal gelatinate, e.g. Na gelatinate, 

 of pH = 8.4 is separated from distilled water by a collodion mem- 

 brane, water will diffuse into the solution with a certain rate which 

 can be measured by the rise of the level of the liquid in a manometer. 

 When to such a solution alkali or neutral salt is added the initial 

 rate with which water will diffuse into the solution is diminished and 

 the more so the more alkali or salt is added. This depressing effect 

 of the addition of alkali and neutral salt is greater when the cation 

 of the electrolyte added is bivalent than when it is monovalent. 

 This seems to indicate that the depressing effect is due to the cation 

 of the electrolyte added. 



2. When a neutral m/256 solution of a salt with monovalent cation 

 {e.g. Na2S04 or K4Fe(CN)6, etc.) is separated from distilled water by 

 a collodion membrane, water will diffuse into the solution with a 

 certain initial rate. When to such a solution alkali or neutral salt is 

 added, the initial rate with which water will diffuse into the solution 

 is diminished and the more so the more alkali or salt is added. The 

 depressing effect of the addition of alkaH or neutral salt is greater 

 when the cation of the electrolyte added is bivalent than when it is 

 monovalent. This seems to indicate that the depressing effect is 

 due to the cation of the electrolyte added. The membranes used in 

 these experiments were not treated with gelatin. 



3. It can be shown that water diffuses through the collodion mem- 

 brane in the form of positively charged particles under the conditions 

 mentioned in (1) and (2). In the case of diffusion of water into a 

 neutral solution of a salt with monovalent or bivalent cation the 

 effect of the addition of electrolyte on the rate of diffusion can be 

 explained on the basis of the influence of the ions on the electrifica- 



