152 



CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



kinetic energy possessed by it; t is the time of flow through the capillary 

 tube of radius r and length I; v is the volume of fluid flowing in time t. 



The viscosity of fluids is, however, most commonly found by the method 

 recommended by Ostwald. 1 We find by this method the time of flow of a 

 fixed volume through a capillary tube, under the pressure due to the differ- 

 ence in level of the free surfaces of the fluid. The viscosity is found from the 

 ratio of the time of flow for the fluid in question to the time of flow for an equal 

 volume of water, multiplied by the specific gravity of the solution. This is 

 expressed by the formula 



iot 



in which r; is the coefficient of viscosity for water, S its specific gravity, and 



10- 



75 ;J 100-6 



Percentage of Acetone 



FIG. 71. CONDUCTIVITY OF COBALT CHLORIDE IN MIX- 

 TURES OF ACETONE AND METHYL ALCOHOL AT 25. 



t its time of flow, at a given temperature. The specific gravity and time of 

 flow of the liquid in question are given by S and t, respectively. 



1 Ostwald-Luther : Physiko-Chemische Messungen, Zweite Aufl., p. 259. 



