26 CHEMICAL STATICS 



H Cl 

 \ / 

 -COH.N. -COH++ ^N. 



/ R + 2 HC1 = -f ^ R (vi) 



-COH.N X -COH++ ^N x 



H Cl 



It is obvious that in reactions (iii) and (v) the molecules of 

 water may or may not participate in the reaction; also that the 

 anionic groups in reactions (iii) and (iv) may or may not be 

 united to form a single quadrivalent cation (derived from a 

 dicarboxylic acid group). As we shall see (Chapter X.), no evi- 

 dence has been found (at least among the compounds of casein 

 or of serum globulin with bases) of the occurrence of reactions 

 of the type represented by equation (iii). Equation (iv) faith- 

 fully represents, so far as the electrochemical data are concerned, 

 the mode of combination of bases with these proteins, and the 

 anionic groups are probably united to form one quadrivalent 

 union. The union of serum globulin and ovomucoid with acids 

 follows equation (v) (with or without the molecule of water) 

 when the concentration of acid is low; but at higher acidities 

 ovomucoid, at least, combines with hydrochloric acid in the 

 manner indicated by equation (vi). 



In the succeeding chapters of this work we shall see that this 

 hypothesis regarding the mode of union between the proteins and 

 acids and bases is supported by the following facts : 



(i) The compounds which the proteins form with acids and 

 bases, when dissolved in water, are excellent conductors of elec- 

 tricity, and true electrolytes (65) (55) (4), yet they do not, for 

 example, yield chlorine ions, when the compound in question is a 

 hydrochloric acid compound (8) (59), nor does the potassium 

 hydrate compound yield potassium ions, or the calcium hydrate 

 compound calcium ions (56). The equivalent conductivities of 

 the compounds at infinite dilution are such as would indicate 

 the presence only of bulky organic ions, travelling under a given 

 fall of potential at the constant minimal equivalent velocity of 

 about 20 X 10~ 5 cm. per sec. per volt per cm. fall in potential 

 at 30 C. which is characteristic for such ions (6). 



(ii) Edestin will displace NaOH from its combination with 

 hydrochloric acid (T. B. Osborne, Cf. Chapter V) and casein, 



