174 ELECTROCHEMISTRY 



conductivity (calculated upon the basis of the potassium which 

 they contain) of over 120 X 10~^ or 30 per cent more than that 

 of the solution considered above. 



Hence we have no resource but to conclude that our initial 

 assumption was erroneous and that potassium caseinate dis- 

 solved in water does not yield 'potassium ions* 



Again, we may reach the same conclusion by quite a different 

 process of reasoning and from very different experimental data. 

 The conductivity of solutions of the caseinates and globulinates 

 of the alkalies and alkaline earths and of the salts which ovo- 

 mucoid forms with acids does not decrease in direct proportion 

 with the dilution, but more slowly, indicating a progressively 

 increasing dissociation of the caseinate on dilution. From the 

 curve expressing the relation between the equivalent-conduc- 

 tivity (calculated on the basis of the inorganic radical) and the 

 dilution we can, by exterpolation, estimate the maximum equiva- 

 lent conductivity, i.e., the equivalent conductivity at infinite 

 dilution of the salt; this we can do rather accurately, since at 

 readily attainable dilutions the equivalent conductivity already 

 increases very slowly with dilution and obviously tends to ap- 

 proach a constant maximum. Now, as is well known, this maxi- 

 mum bears a constant proportion to the sum of the equivalent 

 conductivities of the ions into which the salt dissociates. 



If the inorganic radical is dissociated as such, the equivalent 

 conductivity of these salts cannot be less than that of the inor- 

 ganic radical itself, but must exceed it by a quantity equal to 

 the equivalent conductivity of the protein ion or ions. In the 

 following table are compared the observed equivalent conduc- 

 tivities (at infinite dilution) of a number of protein salts at 30 

 degrees,! and those of the inorganic radicals which they contain, 

 calculated from the data given by Kohlrausch and Holborn (12). | 



* It may be mentioned in passing, that in the solutions investigated 

 potassium caseinate evidently does not form a double salt with potassium 

 chloride. Were such a double salt formed, and we have seen that in many 

 cases salts of this type may be formed in protein solutions, then, of course, the 

 KCl would not be without effect upon the conductivity of the caseinate. 



t Cf. data cited in Chap. X. 



X The migration-velocities of the ions at 18 degrees (p. 200) increased by 

 2 per cent per degree to reduce to the temperature employed and multiphed 

 by the proportionaUty between ionic velocity and reciprocal ohms per cc, i.e., 

 96.44. 



