672 DONNAN EQUILIBRIUM AND AIEMBRANE POTENTIALS 



stituted for NaCl. The two lower curves in Fig. 1 show that the 

 depressing effect of Na2S04 on the osmotic pressure and the p.d. of a 

 gelatin chloride solution is very similar and, moreover, that the 

 depressing effect of Na2S04 on both properties is more than twice (in 

 reality nearly eight times) as great as that of NaCl. This influence 



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Concentration o| salt solution 



Fig. 1. Depressing effect of NaCl and Na2S04 on osmotic pressure and p.d. 

 of gelatin chloride solutions. Abscissae represent the concentration of salt solu- 

 tion, ordinates the osmotic pressure and p.d. in millivolts respectively. The 

 depressing effect of neutral salts on osmotic pressure and p.d. is similar but not 

 identical. 



