SALTS OF ALBUMIN AND ACIDS 



siderably dissociated and to an extent independent of the 

 strength of the acid. 



According to Arrhenius, if a strong acid is partly neutralised 

 by an alkali (by a protein in the case we are considering), the 

 portion of the acid which remains free has the same degree of 

 dissociation as that of the original acid in the same volume. 

 Thus, a mixture containing 0^05 N H 2 S0 4 and 0^05 N Na 2 S0 4 

 is dissociated to the same extent as O'l N H 2 S0 4 . If a is the 

 degree of dissociation of an acid in concentration n, and after 

 partial neutralisation without alteration in volume the con- 

 centration of free acid is ', the portion of the acid dissociated 

 is n'a.. A measurement of the hydrion concentration gives this 

 value C H = n'v., and thus the combined (or neutralised) part of 



j n CH 



the acid, n n ' = - . 



In this way it is possible to obtain a value for the combination 

 of albumin with strong acids from a knowledge of the original 

 concentration of acid, n, the corresponding degree of dissocia- 

 tion, a, and the hydrion concentration, C H , measured after addi- 

 tion of the protein. Thus Pauli and Hirschfeld found that the 

 quantity of sulphuric acid which entered into combination with 

 albumin and glutin was nearly the same as for hydrochloric 

 acid. It is, however, rather less than the latter in high con- 

 centrations. 



Table 26 (Fig. 15). 



Horse-serum Albumin (1*26 per cent.). 



