CHAPTER VII 

 SALTS OF ALBUMIN WITH BASES 



THE albumins undergo fundamental chemical changes in the 

 presence of high concentrations of acid at low temperatures ; 

 but with alkalis a much more marked sensitiveness is shown by 

 most proteins even at room temperature. It is therefore from 

 this point of view that work on the combination of alkalis with 

 such proteins has to be carried out. As is well known, the more 

 profound alteration of proteins by the action of strong acids 

 and bases, when the so-called acid albumins and alkali albu- 

 minates are formed, is an irreversible change which takes time 

 for completion. It can be recognised by the precipitation of 

 these products when the solutions are neutralised. The change 

 also proceeds further with a greater or less breaking down of 

 the protein. 



The electrometric method is the most important way of 

 investigating quantitatively the combination of proteins with 

 alkalis, in the same way as it has been found useful in the cor- 

 responding behaviour with acids. It was first applied to this 

 problem, as to the latter, by Bugarsky and Liebermann. The 

 procedure amounts to the determination of free hydrion, as 

 from the dissociation equation of water at the temperature of 

 experiment, K H2 o = C H . X COH, the concentration of hydroxyl 

 ions can be calculated, and from it the quantity of the alkali 

 that has combined with the albumin. 



In this way Bugarsky and Liebermann found that when 

 increasing quantities of albumin were added to 100 c.c. of 0-05 N 

 sodium hydroxide, complete combination with the alkali finally 

 took place. This was also shown by the falling off of the 

 depression of the freezing point of the solution, corresponding 

 to a decrease in the total molecular concentration. 



More recently Pauli and A. Spitzer * have carried out electro- 



* Carried out in 1913-14, but not yet published. 



