ii4 ALTERATIONS IN STATE OF THE 



Table 63. 



Variation in combination of Alkali and Albumin 

 with Lapse of Time. 



The alkali caseinates also show changes in physico-chemical 

 properties with lapse of time, the viscosity variations being 

 particularly interesting. Laqueur and Sackur made the 

 far-reaching generalisation, which later work has shown to 

 be unexceptionable, that the ions of the protein are respon- 

 sible for high viscosity. It is based on two observations : 

 first, the increase in viscosity of caseinates on addition of 

 alkali, and secondly, the decrease when sodium chloride is 

 added to sodium casemate. These authors explained the latter 

 effect by the action of the common ion of the sodium chloride 

 in suppressing the ionisation of the sodium caseinate. This 

 loses its cogency since it has been shown by Pauli and 

 Handovsky (loc. cit.) that any salt, whether it contains a 

 common ion or not, produces this result with alkali proteins. 

 Further, investigation has also shown the viscosity of the 

 alkali caseinates to be less simple than this, and in particular 

 to be complicated by changes with lapse of time. The 

 experimental results * in Table 64 show this behaviour clearly. 



The viscosity of the caseinate actually passes through a 

 maximum value as the concentration of alkali is increased, but 

 the high viscosity falls off with progress of time, and in five to ten 



* Biochem. Zeitsch., 1915, 70, 489. 



