266 ELECTROCHEMISTRY 



5. The Viscosities of Solutions of Potassium Caseinate in 

 Alcohol- Water Mixtures. — The striking resemblance between 



the formula — = -j- and the Arrhenius-Euler formula, — = a", 



Xq Ay rjo 



for the dependence of the viscosity of a solution upon its con- 

 centration (1), where ??„ is the viscosity of the solution, tjo that of 

 the solvent, n the concentration of the solution and a is constant, 

 forcibly suggests that the decrease in the conductivity of potas- 

 sium caseinate solutions due to the addition of alcohol between 

 alcohol-percentages of to 60 may be attributable for the greater 

 part to the hampering of the protein ions by the increased in- 

 ternal friction of the solvent.* 



Accordingly the following determinations were made: 



31.25 grams of casein were dissolved in 250 cc. of Ai''/10 KOH. 

 To 25 cc. portions of this were added 0, 10, 20, etc. cc. of alcohol, 

 the volume of each mixture being made up to 100 cc, the solution 

 containing 75 per cent alcohol being made up by adding 99.8 per 

 cent alcohol until the volume of the mixture was 100 cc. 



A series of exactly similar solutions were made up in which, 

 however, 25 cc. of A^/10 KOH were employed instead of 25 cc. 

 of caseinate solution. 



The viscosities of these solutions were determined at 30 degrees 

 in an Ostwald viscometer (5), for which the time of outflow, for 

 water, was 90 seconds. The times of flow were read with a stop 

 watch. The viscosities were calculated from the formula 



71 St 



= —7, where 770 is the viscosity of distilled water, rj that of the 

 Vo Soto 



solution under investigation, so and to are the density and the 

 time of outflow, respectively, of distilled water and S and t are 

 the density and time of outflow, respectively, of the solution. 

 The densities of the solutions were determined by means of a 

 normal hydrometer, reading the density to within 0.002. 



Taking the viscosity of water at 30 degrees to be 0.00798 

 dyne per cubic centimeter (13) and its density as 0.996, the 

 following were the results obtained : 



* In this connection the work of H. C. Jones and collaborators on the con- 

 ductivities of solutions of inorganic salts in alcohol-water and acetone-water 

 mixtures should be consulted (3). Cf. also Walden (14). 



