154 COLLOIDS IN BIOLOGY AND MEDICINE 



sociation of the base, while in the latter, certain electrochemical 

 factors which may not be disregarded play a part. 



If dilute soda-lye (0.025 normal NaOH) acts for a long time on 

 serum albumin, the internal friction reaches a maximum, remains 

 constant for a while and then diminishes (K. SCHORR). Evidently 

 there occurs fixation of water, swelling. The cleavage of the albu- 

 min molecule is accompanied by the formation of less colloidal 

 disintegration products, and is characterized by a diminution of the 

 viscosity. 



If from these results we try to obtain an idea of the processes in- 

 volved, we shall find a useful guide in the theory of the amphoteric 

 nature of genuine albumin proposed by G. BREDIG* and extended by 

 Wo. PAULI. Let us think of albumin as built according to the 

 structure of a cyclic ammonium salt: 



R 



in which R represents a complicated organic complex and the ab- 

 sorption of water follows according to the scheme: 



xNH 3 OH 



R 



H 2 O <= R 



2OO X COOH 



This is an amphoteric electrolyte which unites with bases and acid, 

 which splits off H as well as OH ions and in which the 



K A (acid dissociation) > K B (base dissociation) 



in other words, it behaves like a very weak acid. Pure albumin 

 consists principally of electrically neutral particles but forms acid 

 and alkali salts which are strongly ionized. 

 There exist 



/ NHs H / NHlC1 / NHs H | 



\COOH N^OOH \COONa 



neutral albumin acid albumin alkali albumin 



That the albumin ions are responsible for the great internal friction 

 is to be assumed from the investigations of E. LAQUEUR and 0. 

 SACKUR* on alkali-caseinates. The cause of this phenomenon is 

 found in the strong hydration (water fixation, swelling) of the albu- 

 min ions. According to Wo. PAULI and M. SAMEC the existence of 

 polyvalent ions must be assumed in the case of acid and alkali albu- 



