THE PROPERTIES OF PROTEINS 



the iso-electric point, and as a base if the [H - ] is greater than 

 that value. In other words, the ampholyte, like any acid, 

 increases [H-] in the first case quoted ; in the second, like any 

 base, it reduces the [H*]. If, however, the original [H-] is just 

 equal to that at the iso-electric point the added ampholyte pro- 

 duces no change in its value." It remains now to be shown 

 that these considerations do not hold good for strong acids and 

 albumins free from salts (Pauli and Samec*). These authors 

 found, in fact, that on addition of a strong acid a concentration 

 was reached at which a maximum of neutral particles was 

 present, which could be demonstrated both by viscosity 

 measurements and by the alcohol precipitation. This point, 

 however, unlike that obtained by the use of buffer solutions, 

 is largely dependent on the albumin concentration, and in less 

 degree on the nature of the acid. The examples given below 

 and on p. 43 demonstrate this. 



The determination of the osmotic pressure also shows the 

 existence of a minimum value. The osmotic pressure is mea- 

 sured against an aqueous solution of the same acid content as 

 the original mixture of acid and albumin put into the osmotic 

 cell. During the twenty-four hours required for the pressure 

 to become constant, acid enters the cell from the outer vessel, 



Table 10. 

 Viscosity of Glutin -f- Sulphuric Acid at 35. 



t __ Time of flow of the solution 

 T ~~ Time of flow of water 





* Unpublished researches during 1912-13. 



