CASEINE AND LEGUMINE. 307 



Fibrine in its uncoagulated state is found in fresh-drawn 

 vegetable juices, from which, on standing, it is spontaneously 

 deposited. In its coagulated state, it is met with in the gluten 

 of wheat flour and in the seeds of the other grasses. 



Caseine. In milk, caseine exists to the extent of about three 

 per cent. The solutions of caseine do not coagulate by boiling, 

 but the hot liquid, by absorbing oxygen, forms on the surface 

 a pellicle which is insoluble in water. In solution, caseine is 

 at once coagulated by acids. With strong sulphuric, nitric, 

 and hydrochloric acids caseine produces the same reactions as 

 albumen ; and its solution in acetic acid gives a similar preci- 

 pitate with ferrocyanide of potassium. Soluble caseine is 

 sparingly soluble in cold alcohol, but more freely in hot alcohol. 

 Coagulated caseine is readily dissolved by solutions of the 

 alkalies and of the alkaline carbonates. Solutions of common 

 salt, of nitrate of potassa, and of hydrochlorate of ammonia, 

 readily dissolve caseine. Caseine forms insoluble compounds 

 with the alkaline earths. If a piece of poor cheese, which is 

 principally caseine, be reduced to a paste with water and mixed 

 with slaked lime, it forms a tenacious lute, which sets very 

 hard, and may be used for cementing pieces of broken earthen- 

 ware. The most remarkable property of caseine is its coagula- 

 bility by rennet, the dried and salted inner membrane of the 

 fourth stomach of the calf. 



According to some chemists caseine has not been detected 

 with certainty anywhere but in the milk of mammiferous 

 animals. Liebig, however, regards what has been called legu- 

 mine, a substance found in the seeds of leguminous plants and 

 in almonds both sweet and bitter, as identical with caseine. 

 Legumine at least so strongly resembles caseine that, after 

 coagulating it, like caseine, the Chinese make it into a kind of 

 cheese. Dried pease contain about a fourth part of their weight 

 of this caseine or legumine. 



