CASEIN ! 229 



weight of water. This contains in solution 2| parts of 

 caustic soda per 100 parts of dry casein. This produces 

 a milky liquid, which may be cleared by adding a larger 

 quantity of 5-per-cent caustic soda. The clear solution 

 is treated with an acid to precipitate the casein, is dried 

 and then moistened with a Httle acid to restore its plas- 

 ticity. To prepare a hard casein mass (milk stone), the 

 casein is treated with formaldehyde, pressed or molded 

 into any desired form. Any desired coloring matter may 

 be added to the casein before its treatment with formalde- 

 hyde, to produce imitation ebony, marble, etc. The final dry- 

 ing must proceed very slowly in order to prevent cracking. 



Galahth, in a general way, resembles celluloid. The 

 specific gravities of the two substances are about the same. 

 Galalith is harder and less elastic than celluloid; it is hard 

 to cut, and inclined to chip; it takes a higher polish than 

 the celluloid; it cannot be made into so thin transparent 

 sheets, and it absorbs some water when soaked. 



Casein in the Textile Industry. — Casein is used largely 

 in calico printing, and more rarely in the finishing. Finish 

 refers to a glossy dressing like starch. The gummy am- 

 moniacal solution of casein is employed as a medium for 

 printing and fixing powdered pigments that will stand 

 alkali. Fairly well fixed colors are obtained, when the 

 ammonia has been driven off by vigorous drying and steam- 

 ing. Casein dissolved in lime water may be used for the 

 same purpose as the ammoniacal solution. In this case 

 the colors are fixed by the action of the carbonic acid in 

 the air, the products being calcium carbonate and insoluble 

 casein. 



Following are some of the casein products used in this 

 industry: caseo gum, to assist fibers in absorbing dyestuffs; 

 glutin, a glaze for dressing certain fabrics; and a product 



