MOLECULAR CONDITION 



269 



change in the refractive indices of the solutions, the proportion 

 between the percentage of casein in these solvents and the change 

 in the refractive index of the solvent, due to the protein, having 

 been previously determined (Cf. Chap. XIV). The volume of the 

 solution employed being always 25 cc, the actual amount of 

 casein deposited by the current was obtained by dividing the 

 alteration in percentage by 4. 



The results obtained are tabulated below, the figures in the 

 6th column being obtained from those in the 5th column through 

 multiplication by the Faraday constant. 



TABLE XII* 



50 X 10-^ Equivalents of KOH per Gram of Casein. Concentration of 

 KOH neutralized by Casein = 0.015 N 



Per 



cent of 

 alcohol 





 50 

 75 



Current in 

 amperes 



6.88 X I0-« 

 1.P4 X 10-< 



Time of passing 



3 hrs. 25 min. 



4 hrs. min. 



Grams casein 

 lost from solution 



0.2550 ±0.0170 

 0.1260 ±0.0200 



Electrochemical 

 equivalent in 

 grams per cou- 

 lomb 



0.0301 ±0.0020 

 0.0452 ±0,0072 



Grams of caseiii 

 carrying one ionic 

 charge 



2336 ±183 

 2906 ±193 

 4363 ±695 



* The weight of casein, in grams, which carries one atomic charge, in aqueous solution, is cited 

 after the determinations enumerated in Chap. VIII. The amount of casein lost from the anode 

 through resolution in electrolj'sis is not allowed for in the above estimates. In solutions con- 

 taining alcohol it is probably very small, since the rate of solution of casein in alkaline solvents 

 is much diminished by alcohol. 



The smallness of the current employed in the electrolysis of the solution containing 75 per cent 

 alcohol was due to the high resistance of the caseinate solution. The precipitate from the solution 

 containing alcohol is slimy and not spongy as it is from aqueous solution. Nor, in 75 per cent 

 alcohol, does it adhere well to the anode so that precipitation appears to take place in the body of 

 the anodal portion of the fluid, and the solution had to be filtered to remove the casein precipitated 

 by the electrolysis. 



There is evidently a very marked increase in the weight, or 

 decrease in the valency of casein ions in solution of potassium 

 caseinate when the added alcohol attains 75 per cent, leading 

 to a doubling of the weight of casein required to transport one 

 atomic charge of electricity. 



From these facts and from the failure of Ostwald's dilution- 

 law to adequately represent the behavior towards dilution of 

 solutions of potassium caseinate in 75 per cent alcohol, and the 

 opalescence of these solutions, it appears probable that they par- 

 take rather of the character of suspensions than of true solutions, 

 and that the transport of electricity by the caseinate in 75 per 



