84 COLLOID CHEMISTRY OF THE PROTEINS 



Such a compound would first react with acids with its strongest 

 basic valency, and, when that was saturated, the weaker ones 

 would begin to come into play ; the hydrolysis also would be 

 very small in low acid concentrations, and would rise to a maxi- 

 mum with increasing addition of acid. 



The equilibrium of hydrolysis shows that hydrolytic dissocia- 

 tion increases with dilution. The table on p. 83 shows such 

 an increase in hydrolysis of the protein salt when it is subjected 

 to increasing dilution. 



Having thus found the degree of hydrolysis we have a way of 

 determining the mean * basic dissociation constant K 6 of the 

 albumin in the protein salt in question. The expression for 

 the hydrolysis constant is : 



-rr _ Kgait X K^O 

 Kacid X Kbase 



and in the case of the salt of a weak base and a strong acid the 

 dissociation constants of the salt and of the acid are practically 

 the same, hence 



K 

 = 



If x is the degree of hydrolysis, then i x is the non-hydrolysed 

 fraction, and the corresponding concentrations in a volume v 



IV T _ V 



are and - . Accordingly, the equilibrium equation of 

 hydrolysis is 



TT I X _ X X 

 V ~ V ' V 



TT K H2 o x 2 



or K _ _ 



KB (I x) . 



and hence K R = Kaofr-*)" 



* Albumin as a polyvalent base must exhibit a corresponding number 

 of basic dissociation constants. The values of these constants decrease 

 rapidly from that of the first, but it is not possible at present to deter- 

 mine the separate values. The mean value of K B for an albumin in its 

 combination with strong acid may be defined as that constant which a 

 univalent base would have which displays in like circumstances the 

 same hydrolytic dissociation as the collective available basic valencies 

 of the reacting protein. 



