234 ELECTROCHEMISTRY 



not the case, and we must assume that two of the positive valen- 

 cies of the cation are neutralized and at the same time that two 

 of the negative valencies which the anions supply are also neu- 

 tralized. This immediately suggests that one of the two anions 

 neutralizes two of the valencies of the cation and that the true 

 constitution of the cation is either 



-CO++ v -CO+, H 



)Ca I \ I 



-CO.N- or Ca >N- 



/\ I / \ 



H OH -CO +/ OH 



or either of these formulae less the elements of water which are 

 attached to the nitrogen atom. If this be so then we must con- 

 clude that each molecule, of a diacid base gives rise to exactly 

 the same number of ions (apart from the question of the degree 

 of dissociation of the salt) and equivalents of protein salt as a 

 molecule of a monacid base, and that the molecule of a protein 

 salt of a diacid base must be twice as heavy as a molecule of a protein 

 salt of a monacid base. In this connection the following differ- 

 ences between the physical behavior of solutions of the caseinates 

 of the alkalies and those of the caseinates of the alkaline earths 

 may be recalled to the reader: The aqueous solutions of the 

 " neutral" or " basic" caseinates of the alkalies and ammonium 

 are clear, do not (except lithium caseinate) show any increase in 

 turbidity on warming, and are not precipitated by the addition 

 of finely divided insoluble substances or by passing through a 

 clay filter, while the aqueous solutions of the caseinates of the 

 alkaline earths are opalescent, show a marked turbidity on heat- 

 ing their solutions to 35-45 C., which disappears on cooling, 

 and are precipitated from their solutions by the addition of 

 finely divided insoluble substances or by passage through a clay 

 filter (5). Equally concentrated solutions of the hydroxides of 

 the alkalies and ammonium dissolve casein at approximately 

 the same rate. Solutions of the hydroxides of the alkaline earths 

 dissolve casein much more slowly (9) (13). 



The salts which casein forms with monacid bases at "satu- 

 ration" of the base with casein, that is, when the proportion of 

 base to casein is 11.4 X 10~ 5 equivalents per gram, are soluble 

 in water, while the corresponding salts which casein forms with 



