CONCENTRATION OF ALCOHOL 257 



Inserting the observed values of x in equations (ii) to (ix), we can 

 compute the "theoretical" values of m, that is, the equivalent 

 concentration of KOH neutralized by the casein which should, 

 provided the dilution-law holds good, correspond to the observed 

 conductivities. In Table II, on the following page, the observed 

 and calculated values of m are compared. 



It is evident that the correspondence between the experimental 

 results and those which are indicated by the Ostwald dilution- 

 law for a binary electrolyte is all that could be desired for the 

 solutions containing from to 60 per cent of alcohol. For the 

 solutions containing 75 per cent of alcohol the divergences be- 

 tween theory and experiment are, however, considerably greater 

 than could be accounted for by experimental error and probably 

 indicate that the law does not hold good for these solutions. The 

 sudden alteration in the relative values of the constants which 

 occurs when the percentage of alcohol attains this magnitude 

 indicates, whether the Ostwald law be considered as holding 

 good or not, a profound change in the molecular and ionic con- 

 dition of the protein. 



It would appear, however, that we are justified in concluding 

 that potassium caseinate dissociates in alcohol-water mixtures 

 containing from to 60 per cent of alcohol in the same manner 

 as it does in aqueous solutions. 



3. The Influence of the Concentration of Alcohol in the Solvent 

 upon the Conductivities of Solutions of Potassium Caseinate. — 

 I find (9) that the conductivity (= Xy) of a solution containing 

 any given concentration of casein combined with KOH in the 

 proportion requisite to secure neutrality to phenolphthalein, and 

 dissolved in an alcohol-water mixture containing y per cent of 

 alcohol by volume is connected with the conductivity {=x^ 

 of a similar solution in water by the formula 



where A is a constant which varies but slightly, if at all, with the 

 concentration of the caseinate. This constant is determined in 

 the following manner: If the logarithms to base 10 of a: corre- 

 sponding to y = 0, 10, 20, 30, 40, 50, and 60 per cent be tabulated 

 in that order and each successive value of log x be subtracted 

 from the one lying immediately above it, the differences thus 



