JACQUES LOEB 



75 



from the total volume of the suspension. Knowing the viscosity 

 we can calculate Einstein's constant c according to the formula 



{1-)t- 



where c should be 2.5 if V is sufficiently small. 



The values in Table I show that Einstein's formula gives the correct 

 values for viscosity when the volume, V, of the gelatin is small, since 

 in that case c is equal, or nearly equal, to 2.5, as his formula demands. 



When, however, the volume is larger, the value for c exceeds 2.5. 

 The fact that the value for c exceeds 2.5 when the relative volume 

 occupied by the particles in the solution is large, was found also by 



TABLE I. 



Hatschek,^ Smoluchowski,' and Arrhenius.* Hatschek replaced 

 the value 2.5 in Einstein's formula by a larger one, namely4.5. This, 

 however, meets in our case with the difficulty that the value c shows 

 a drift reaching a maximum when the volume of the gelatin particles 

 is a maximum. This difficulty is largely avoided in Arrhenius's 

 formula and we have to change from Einstein's formula to that of 

 Arrhenius whenever the relative volume of the particles in solution 

 or suspension exceeds the limits of the applicability of Einstein's 

 formula, as we shall see in the next chapter. 



- Hatschek, E., Kolloid Z., 1913, xii, 238; 1920, xxvii, 163. 

 ' Smoluchowksi, M., v., Kolloid Z., 1916, xviii, 190. 



* Arrhenius, S., Meddelanden from K. Velcnskapsakadetniens Nobelinstitut, 

 1917, iii. No. 21. 



