102 



THEORY OF COLLOIDAL BEHAVIOR 



anion acts like the bivalent SO 4 anion and not like the monovalent 

 Cl or NO 3 anion. Table VI shows that Na acetate also depresses 

 the hydrogen ion concentration more than NaCl or NaH 2 PO 4 ; 



M M M 



M M. H M M M M 

 512 256 128 64 32 16 



Concentration 



FIG. 34. When the pH is kept equal the depressing effect of equal concentra- 

 tions of NaCl and Na acetate on the relative viscosity of an 0.8 per cent gelatin 

 chloride or gelatin acetate solution of pH 3.3 is the same. 



M/64 Na acetate brings the gelatin solution practically to the 

 isoelectric point, and at the isoelectric point the viscosity of 

 gelatin solution is a minimum. This lowering of the hydrogen ion 



