JACQUES LOEB 



731 



IV. The Rate of Diffusion of Electrolytes through the Collodion 



Membranes. 



We therefore see that no rise in the manometer occurs when a col- 

 lodion bag filled with a m/128 solution of MgCl2 or CaCl2 is dipped 

 into a beaker with distilled water, while a considerable rise occurs 

 when the bag is filled with a m/128 solution of NaCl or Na2 oxalate. 

 The writer was at first inclined to assume that salts of the type of 

 MgClo diffused so rapidly through the collodion membrane that no 

 osmotic effect had time to occur, while the diffusion of NaCl or Na2 

 oxalate was supposed to be much slower. In order to test this idea 

 the following experiments were made. 



Various concentrations of LiCl, NaCl, KCl, MgCl2, and CaBr2 were 

 put inside of the collodion bag and the latter was surrounded by a 

 beaker containing 350 cc. of H2O. Every half hour the amount of 

 CI or Br contained in 20 cc. of the liquid in the beaker was ascertained 

 by titration after Volhard's method. (Table III.) 



TABLE III. 



Quantity of 0.1 N CI (or Br) found in 20 cc. of the outside solution. 



After 30 minutes. 



LiCl.. 

 NaCl. 

 KCl.. 

 MgCl2 

 CaBro 



LiCl.. 

 NaCl. 

 KCl.. 

 MgCl2 

 CaBra 



M/64 



0.140 

 0.125 

 0.20 



After 60 minutes. 



0.22 



0.195 



0.28 



