CASEIX. 29* 



body without taste or smell ; it is practically insoluble in water, 

 dissolving in this menstruum to the extent of about O'l per cent. : 

 it is quite insoluble in alcohol and ether, ^'ery dilute acids seem 

 to diminish the solubility ; but it is soluble in stronger acids. 

 becoming, however, changed ; a solution of casein in acetic acid 

 has been used as glue ; it is completely soluble in caustic alkaline 

 solutions even when very dilute ; the solutions of the carbonates, 

 bi-carbonates, and phosphates oi the alkalies also dissolve it. and 

 from these solutions, as well as those of the alkalies, it is pre- 

 cipitated unchanged by the addition of sufficient acid to neut- 

 ralise the alkali. It has the property of forming an opalescent 

 solution when it is dissolved in the least possible excess of sodium 

 phosphate, and the addition of small quantities of calcium 

 chloride is made ; it gives then a solution having the appeaiancc 

 of milk. It is highly probable that milk contains casein in this 

 form. Casein has a peculiar affinity for calcium salts, especially 

 the phosphate. It is extremely difficult to free it from this 

 body, the purest preparations that have been prepared having 

 alwa)-s been contaminated with small amounts of this compound. 

 Casein yields a comparatively small amount of sulphide if boiled 

 with an alkali, and contains less of this element than citluT 

 globulin or albumin ; it also differs from these compounds l)y 

 containing phosphorus ; on analysis, like other proteins, it tli>r> 

 not yield very concordant results ; the most probable com- 

 position is as follows : — 



The composition of casein is variously stated by different 

 authorities. The following are the most reliable results : — 



Authority. 



The author has calculated the two follo^^'ing formulfe as possible 

 for casein ; the first agrees with the results of Hammarsten, 

 Chittenden and Painter, and Ellenberger, while the second 



