﻿320 The Kinetics of the Process of Coagulation. 



Table XV. 

 Electrolyte : Strontium Nitrate. 



Temperatures. 

 Concentrations. Standards. '77^ ^ 50°~^ 



N/1000 Y 3 77/^xlO 6 '565 1-65 2-1 



B 3 ri/tBxlO 1 '80 3"3 377 



Ratio between f V 3 100 : 291 : 371 



nltB 1 B 3 ... 100 : 410 : 430 



Since 7] = t6 is a constant for a definite electrolyte con- 

 centration and temperature according to Smoluchowski's 

 equation, the ratios should be independent of the standard 

 used. This is true within the limits of experimental error 

 with -852 N/1200 Barium Chloride. In the other two cases 

 the variations are not great considering that we are com- 

 paring the ratios. A slight variation in each value will be> 

 magnified in the ratio. Taking into account the probable 

 experimental error, it can be said that e is roughly constant 

 in each experiment. 



On the other hand, the variation in e with temperature is 

 considerable. We have already seen that the irregularity 

 in the variation of e means that the precipitating power of 

 the ions changes with the temperature (Mukherjee, Trans. 

 Chem. Soc. vol. cxvii. p. 358, 1920). 



Further experiments with arsenious sulphide are in 

 progress on similar lines. 



Summary. 



(1) It has been shown that the equations of Smoluchowski 

 on the rate of coalescence of the particles of gold sols agree 

 with the results obtained by the writers. 



(2) It has been suggested that the disagreement of the 

 ultramicroscopic measurements with this theory may in part 

 be due to the difficulties inherent in them. 



Our best thanks are due to Professor F. Gr. Donnan for 

 his kind interest and encouragement, and also to our friend, 

 Professor J. 0. Ghosh. 



Physical Chemistry Department, 



University College, London. 



