BASIC AND ACID PROPERTIES OF PROTEINS 29 



required by similar preparations of edestin. Owing to the fact that 

 legumin, when thus neutralised, is soluble in water, neither the presence 

 nor the nature of the combined acid has yet been demonstrated, but there 

 is little doubt that these legumin salts are similar to those of edestin. 

 It has been shown that the slightest excess of alkali added to edestin, 

 beyond the quantity needed to neutralise the combined acid, produces 

 a red colour with phenolphthalein, through hydrolytic dissociation of 

 the potassium edestinate, and it is in the highest degree improbable 

 that if legumin were dissolved by forming a soluble potassium salt, the 

 latter would be so stable as to yield a solution neutral to phenol- 

 phthalein under the conditions given. 



In view of these facts there is little doubt that legumin, in the free 

 state, is soluble in water, but when combined with acids, forms salts 

 that are insoluble therein, and the idea that it is a strong acid, in- 

 soluble in water in the free state, but forming water-soluble salts with 

 alkalies, is no longer tenable. 



