66 COLLOID CHEMISTRY OF THE PROTEINS 



In connection with the above viscometric measurements, 

 C. Schorr * has made the important observation that the 

 quantity of the precipitate produced by alcohol in acid 

 albumin solution passes through a minimum value when 

 increasing quantities of acid are added. The point of minimum 

 precipitate coincides with the maxima of viscosity and of 

 ionisation, and still larger quantities of acid cause the quantity 

 precipitated to increase again. The following table gives the 

 results of work on a i-i per cent, ox-serum. The mixture of 

 albumin and acid was precipitated by the addition of ten times 

 its volume of alcohol. 



Table 24. 



Measurements of the depression of the freezing point, due to 

 Bugarsky and Liebermann,t lead to the result that addition of 

 albumin to solutions of hydrochloric acid causes a decrease in 

 the lowering of freezing point, showing that the molecular 

 concentration has become less. The molecules of the albumin 

 salt formed on combination of the albumin with the acid 

 cause a diminution in the total number of molecules of albu- 

 min plus acid. Further, by working out the results of these 

 authors it is clear that when increasing quantities of albumin 

 are added to a constant quantity of acid, the depression caused 

 per gram of albumin first of all increases and then falls off 



* Biochem. Zeitsch., 1911, 37, 424. 

 f Loc. cit. 



