488 LEGUMIN. 



line phosphates), when exactly neutralized, in the form 

 of a flocculent, fibrous, non-gelatinous mass. In an 

 alkaline solution and in the milk, it is not coagulated 

 by boiling ; the solution only forms a skin of coagu 

 lated casein on the surface, which, when removed, is re 

 formed. When a slightly alkaline solution of casein 

 is poured into an excess of an acid, a flocculent pre 

 cipitate is formed, which is soluble in pure water. 

 This is a compound of casein with the acid employed. 

 The real coagulation of casein is brought about in a 

 peculiar manner, as yet not satisfactorily explained : 

 i. e., by contact with the internal mucous membrane 

 of the stomach of the calf. Skimmed milk, warmed 

 with a small piece of such a stomach (rennet) at 

 50-60, coagulates so thoroughly, that only very small 

 quantities of casein remain in a state of solution in 

 the whey. The coagulum formed in this way, mixed 

 with fat, forms cheese, when dried. 



In a coagulated condition casein resembles coagu 

 lated albumen in nearly all its properties. 



3. Legumin. In leguminous and many other seeds, 

 a protein compound, very similar to casein, is con 

 tained. In order to prepare it, beans or lentils are 

 softened with warm water and triturated to a paste. 

 This paste is then diluted with water and the skins 

 sieved off. Legumin, in a state of solution, is con 

 tained in the liquid that passes through the sieve ; 

 starch, in a state of suspension, is also contained in it, 

 but the latter is deposited if the liquid is allowed to 

 stand quietly. By adding a very little acetic acid, the 

 legumin is thrown down as a gelatinous mass ; to 

 purify it, it is washed out with water, alcohol, and 

 ether. The crude solution soon becomes acid, if left 

 alone, on account of the formation of lactic acid ; and 

 thus coagulates spontaneously. It does not coagulate 

 when boiled, but, as in the case of milk, a skin is 

 formed on the surface, which is always reformed when 

 removed. The dissolved condition of legumin ap 

 pears, as in the case of casein, to be caused by the 

 presence of alkalies. When oily seeds (e. g., shelled 



