204 



THEORY OF COLLOIDAL BEHAVIOR 

 TABLE XLI 



These experiments lead to the following two conclusions. 



(a) Since the viscosity measurements of solutions of crystalline 

 egg albumin and of gelatin agree fairly well with Einstein's and 

 Arrhenius's formula respectively, it seems that the viscosity of 

 the solutions of proteins is primarily a function of the relative 

 volume occupied by the protein in solution. 



(6) Since the measurements were made at (or near) the iso- 

 electric point of the two proteins the difference in the viscosity 

 of solutions of gelatin and of crystalline egg albumin cannot be 

 ascribed to differences in the degree of hydration of the individual 

 protein ions, since at the isoelectric point the protein is not 

 ionized. 



It follows from these results, that the difference in the order 

 of magnitude of the viscosity of the two proteins must be due to 

 the fact that gelatin possesses a mechanism for increasing its 

 relative volume in solution which is lacking in the case of egg 

 albumin (in not too high a concentration, at not too high a tem- 

 perature a*nd a pH above 1.0), and this mechanism seems to be 

 connected, in the case of gelatin solutions, with their tendency 

 to set to a gel. 



Zsigmondy (p. 98) states that Smoluchowski has explained 

 the increase in the viscosity of a solution of aluminium oxide 

 upon coagulation by the assumption of an occlusion of liquid 

 between the particles. Smoluchowski calculates from the 



