402 



ION SERIES AND PROTEINS, IH 



viscosity in the same way as the addition of KCl (Fig. 7) ; while the 

 addition of KOH to Na gelatinate of pH 4.8 to 8.0 increases the vis- 

 cosity and the addition of KCl to Na gelatinate always depresses the 

 viscosity. The depressing effect of salts on metal gelatinate is due to 

 the cation of the electrolyte added, that of bivalent cations being 

 greater than that of monovalent cations, while the valency of the 

 anion has no effect. 



CO 



8 



O 



o 



p. 



2.0 

 1.9 

 1.8 

 1.7 

 1.6 

 1.5 

 1.4 

 1.3 

 L2 

 LI 

 1.0 



" S^ 4096 2048 10Z4 51Z 256 128 64 32 16 8" 



Concentmtion 



Fig. 7. The depressing effect of KOH and KCl on Na gelatinate of pH 12.0 

 Is practically the same. 



The addition of neutral salt to isoelectric gelatin leaves the viscosity 

 and osmotic pressure of the solution practically unchanged. 



The cause of this difference in the action of acids, alkalies, and salts 

 is easy to understand on the basis of the purely chemical theory of 

 the behavior of proteins. When we add acid to isoelectric gelatin 

 we transform part of the latter into gelatin-acid salt and the propor- 

 tion of gelatin-acid salt formed increases with the amount of the acid 

 added. Near the isoelectric point the amount of gelatin-acid salt 

 formed increases very rapidly with the addition of acid, but when 



