254 ELECTROCHEMISTRY 



solutions of strontium caseinate are less opalescent than equally 

 concentrated solutions of calcium or barium caseinate, and the 

 dissociation-constant of "basic" strontium caseinate is much 

 larger than those of barium or calcium caseinate, and is inter- 

 mediate in magnitude between these and the dissociation con- 

 stants of the "basic" caseinates of sodium and ammonium. 

 This, however, is not a general phenomenon where protein salts 

 of the alkaline earths are concerned, because the dissociation 

 constant for the strontium salt of "insoluble" serum globulin 

 is not very appreciably different from those of the calcium and 

 barium salts (Cf. previous chapter). 



The caseinates of the alkalies and alkaline earths dissolved in 

 various concentrations of alcohol afford, therefore, very favor- 

 able material for the investigation of the intimate nature of the 

 process of coagulation, since different caseinates, in the presence 

 of the same quantity of alcohol, may be, to all appearance com- 

 pletely soluble, or completely coagulated, and as we shall see, a 

 comparison of the behavior of these different caseinates towards 

 the presence of varying percentages of alcohol in their solutions 

 leads to a very considerable insight into the chemical mechanics of 

 protein-coagulation by alcohol. 



2. The Applicability of the Ostwald Dilution-Law to Solutions 

 of the Caseinates in Alcohol-Water Mixtures. — In the preceding 

 chapters it has been shown that the Ostwald dilution-law for a 

 binary electrolyte written in the form 



_ 1.037 X 10-^ 1.075 X 10-^ 2 n 



is applicable to many aqueous solutions of the salts which pro- 

 teins form with inorganic acids and bases, m being the equivalent 

 molecular concentration of the acid or base which is combined 

 with the protein, p the number of equivalents of protein salt 

 to which one equivalent of neutralized acid or base gives rise, 

 X the conductivity of the solution in reciprocal ohms per cubic 

 centimeter, K the dissociation constant of the salt and u -\- v 

 the sum of the equivalent specific migration-velocities of the 

 ions at infinite dilution. The same law applies to solutions of 

 potassium caseinate (80 X 10~^ equivalents KOH per gram) in 

 alcohol-water mixtures which contain up to and less than 60 

 per cent alcohol, as the following experimental results show (9). 



