VISCOSITY 



203 



ent from that of egg albumin, i.e., in the neighborhood of 1.4. 

 The values calculated in Table XL with Einstein's viscosity con- 

 stant 2.5 are from 20 to 40 times too low. Hence, the relative 



TABLE XL 



volume of gelatin in these solutions is far beyond the limit inside 

 which the formula of Einstein is applicable. The formula of 

 Arrhenius (2) leads to a fair agreement. According to this 

 formula the logarithms of the viscosity ratio when plotted 

 over the concentration of the gelatin should give a straight line. 

 The agreement of the values for 45 and 35 with this theory is 

 satisfactory (considering the limits of accuracy of the measure- 

 ments) the logarithms of the viscosity increasing practically in 

 direct proportion with the concentration (i.e., the relative 

 volume) of the gelatin in the solution (Table XLI). At 60 

 the agreement is not quite so good but still recognizable. At 

 25C., however, it is satisfactory only at the lowest concentra- 

 tions, but at the higher concentrations the viscosity grows more 

 rapidly than the concentration. The reason for this is, however, 

 obvious, since at this temperature the gelatin solution solidifies 

 so rapidly that the viscosity measurements were no longer 

 possible for a concentration of 3.5 per cent gelatin solution, and 

 for this reason the value of the viscosity of a 3 or a 2 per cent 

 solution is already too high on account of the mechanical hin- 

 drance of the flow of the solution through the viscometer owing to 

 partial solidification. 



