152 



ISOELECTRIC POINTS OF PROTEINS 



o 



o 



o 

 o 



o 





0.320 

 0.300 



0.280 



0.260 



0.240 



0.220 



0.200 



0.180 



0.160 



0.140 



0.120 

 pH 2 



10 



Fig. 2. Solubility of protein in vegetable juices at different hydrogen ion 

 concentrations. 



The Compounds of Tuberin. — The changes in the solubility of 

 tuberin that have been described resulted, in part, from the combi- 

 nation with acids and bases of the basic and acid radicles in the juice 

 of the potato. The amount of such combination is calculable if 

 the hydrogen ion concentration is determined. It is equal to the 

 difference between the measured hydrogen ion concentration and 



