PROPORTION OF INORGANIC RADICAL 



247 



In the following table the experimental and calculated values 

 of X X 10 5 are compared: 



TABLE XXXV 



The relation does not, however, hold good for solutions of 

 casein in HC1. Doubtless it would hold good for these solutions 

 also were it possible to obtain solutions of casein in dilute HC1, 

 without at the same time introducing the chloride of the base 

 employed to dissolve the dry casein. But, as I have explained 

 in Chap. V, dry casein is not readily dissolved by dilute acids, 

 and in order to secure a solution of casein in acid it is necessary 

 to first dissolve the casein in dilute alkali, and then add acid in 

 excess of that necessary to neutralize the base and sufficient 

 to redissolve the wet, freshly precipitated casein. Now casein, 

 dissolved in acids is very markedly influenced in its solubility 

 by the presence of salts; the departure of the conductivities of 

 these solutions, therefore, from the regularity indicated in equa- 

 tion (vii) is sufficiently explicable. 



The physico-chemical significance of this relation is, at the 

 present stage of our knowledge, not at all clear. It is possible 

 that equation (vii) is merely an interpolation-equation and that 

 the relation is of purely empirical significance.* It is chiefly of 

 use, at present, as we shall see, in throwing light upon questions 



* It should here be noted that any relationship of this type must involve 

 the mutual dependence of the following factors: 



(i) The variation of m, the amount of acid or base bound by the protein 

 with variation in ai or 61, the concentration of acid or alkali in which 

 the protein is dissolved. 



(ii) The variation of K (the dissociation-constant of the salt) and possibly 

 of (u + t>) with the quantity of acid or alkali bound by the protein, 

 (iii) The effect of dilution upon the conductivities of the protein salts. 



