296 COLLOIDS AND ELECTROLYTES 



tion and the rate of diffusion of electrified particles of water. Since 

 the influence of the addition of electrolyte seems to be the same in 

 the case of solutions of metal gelatinate, the question arises whether 

 this influence of the addition of electrolyte cannot also be explained 

 in the same way, and, if this be true, the further question can be 

 raised whether this depressing effect necessarily depends upon the 

 colloidal character of the gelatin solution, or whether we are not 

 dealing in both cases with the same property of matter; namely, the 

 influence of ions on the electrification and rate of diffusion of water 

 through a membrane. 



4. It can be shown that the curve representing the influence of the 

 concentration of electrolyte on the initial rate of diffusion of water 

 from solvent into the solution through the membrane is similar to 

 the curve representing the permanent osmotic pressure of the gelatin 

 solution. The question which has been raised in (3) should then 

 apply also to the influence of the concentration of ions upon the 

 osmotic pressure and perhaps other physical properties of gelatin 

 which depend in a similar way upon the concentration of electrolyte 

 added; e.g., sweUing. 



5. When a 1 per cent solution of a gelatin-acid salt, e.g. gelatin 

 chloride, of pH 3.4 is separated from distilled water by a coflodion 

 membrane, water will diffuse into the solution with a certain rate. 

 When to such a solution acid or neutral salt is added — taking care 

 in the latter case that the pH is not altered — the initial rate with 

 which water will diffuse into the solution is diminished and the more 

 so the more acid or salt is added. Water diffuses into a gelatin 

 chloride solution through a collodion membrane in the form of 

 negatively charged particles. 



6. When we replace the gelatin-acid salt by a crystalloidal salt, 

 which causes the water to diffuse through the collodion membrane 

 in the form of negatively charged particles, e.g. m/512 AI2CI6, we 

 find that the addition of acid or of neutral salt will diminish the 

 initial rate with which water diffuses into the m/512 solution of 

 AI2CI6, in a similar way as it does in the case of a solution of a 

 gelatin-acid salt. 



