202 



THEORY OF COLLOIDAL BEHAVIOR 



viscosity ratio, i.e., time of outflow of solution over time of 

 outflow of water. The volume occupied by the protein in 100 

 c.c. of solution is 



(n A 100 



<p= (^~ 



2.5 



By dividing the weight of albumin in solution by its volume we 

 should obtain the density of albumin. Determinations of the 

 density of albumin, by direct methods, give the value of 1.36 

 (Arrhenius). Table XXXIX shows that if we calculate the 



TABLE XXXIX 



density of albumin on the basis of Einstein's formula, we obtain 

 values which differ only inside the limits of accuracy from the 

 value 1.36 obtained by direct determination. The time of 

 outflow of water through the viscometer was in this case 227 

 seconds at 15C. These measurements show that the low order 

 of magnitude of the viscosity of solutions of crystalline egg 

 albumin is accompanied by a volume of albumin sufficiently low 

 to permit the application of Einstein's formula, with the constant 

 2.5. 



When we try to apply Einstein's formula in the same way to 

 the viscosity measurements of isoelectric gelatin solutions we find 

 that the relative volume of gelatin in the solution and its density 

 calculated on the basis of the constant 2.5 lead to impossible 

 results. Thus the density of gelatin is probably not very differ- 



