JACQUES LOEB 733 



equal concentrations in Table IV mean equal normality and not 

 equimolecular concentration as in Table III for the neutral salts.) 



In order to compare two salts with univalent and bivalent anions, 

 m/128 NaCl and m/128 Na2 oxalate were chosen, since they vary con- 

 siderably in their attraction for water. In the m/128 Na2 oxalate 

 solution the liquid in the manometer rose in 30 minutes to a height 

 of 420 mm. and in the m/128 solution of NaCl to a height of 60 mm. 

 It might again be argued that this difference was due not to a more 

 rapid diffusion of water into the Na2 oxalate solution but to a more 

 rapid diffusion of the NaCl into the distilled water. Titration showed 

 that after 30 minutes the NaCl solution inside the bag had been 

 diminished by 3.6 cc. m/100 NaCl per 20 cc. solution, while the Na2 

 oxalate solution had been diminished by 3.8 cc. m/100 Nao oxalate. 

 Again the difference in the rate of diffusion of the two salts is small 

 and cannot explain the large difference in the osmotic behavior of the 

 two salts. We are therefore compelled to ascribe this difference to a 

 difference in the influence of the ions on the rate of the diffusion of 

 water into these solutions, as the rules expressed at the end of Chapter 

 I demand. 



While this is correct for solutions of electrolytes above a molecular 

 concentration of m/128, it is possible that for solutions of electrolytes 

 of a concentration below a certain limit the nature of the electrolyte 

 may modify the result. We intend to deal with this possibility in 

 a later paper. 



F. Measurements of the Approximate Value of the Electric Force 

 Influencing Di fusion. 



These experiments show that aside from the gas pressure of water 

 a second type of forces, namely electrical forces, influence the rate of 

 diffusion of water from solvent to solution of electrolyte through a 

 collodion membrane. If we denote these two t5^es of forces by p 

 and by e (for the osmotic pressure and the electrical attraction re- 

 spectively), the question arises whether we cannot arrive at an ap- 

 proximate determination of the value of e. This can be done in a 

 simple way. When we fill the coHodion bag with a solution, e.g. 

 of m/128 KCl, this solution has approximately the same osmotic 



