CASEIN COMPOUNDS. 169 



term " argentumcasein ". This is able to form salts and 

 contains silver in complex combination, not as an ion. 



Compounds of arsenic and casein are prepared in the 

 same way as those of the heavy metals, and like them are 

 used medicinally. 



Alkali salts and the potassium salt of casein are obtained 

 as dry powders by concentrating, in vacuo, solutions of casein 

 in caustic alkalies, alkali carbonates, sodium phosphate or milk 

 of lime. According to Imray's patent, a solid silver-casein 

 compound of this kind, which does not furnish any precipi- 

 tate when its aqueous solution is treated with albumen or 

 salt, is obtained by mixing a solution of silver nitrate or 

 other salt of silver with a neutral solution of an alkali 

 caseate, and evaporating the mixture to dryness in vacuo. 



The Casein Company of America (U.S. patent 717,085) 

 prepares a casein compound that forms a thin solution 

 with a relatively small quantity of water. This is effected 

 by incorporating oxalates with casein, e.g., in the propor- 

 tion of 2 parts of potassium oxalate and 15 of powdered 

 borax to 100 of dry casein, the whole being thoroughly 

 mixed. 



A further patent relates to -the production of oxidised 

 casein by dissolving an oxidising agent in about its own 

 weight of water, and then rapidly stirring in the casein to 

 ensure intimate mixture. Ammonium persulphate is the 

 oxidising agent preferably used. 



An insoluble casein compound is prepared, according to 

 B. Dunham's patent, by mixing about 15 parts of borax and 

 85 of commercial casein, dissolving this in 400 parts of 

 water, treating the solution with about 15 parts of hexa- 

 methylene-tetramine and leaving the liquid to evaporate, the 

 dry product being then exposed to heat and moisture. The 

 preparation is suitable for replacing egg albumen. 



Kalle & Co. (Biebrich) have patented a process for pre- 



