

CASEIN ADHESIVES AND PUTTIES. 93 



9. Casein and Water-glass Cement for Glass and Porcelain. 



Casein, 10 parts, and water-glass, 60 parts, are mixed to- 

 gether. It is applied as quickly as possible, the cemented 

 articles being exposed to the air to dry. 



10. Vasein-Soda Cement. 



Casein is precipitated from milk with vinegar, then washed 

 and redissolved in a minimum quantity of caustic soda solu- 

 tion, the preparation being stored in well-closed bottles. 



WASHABLE CEMENT FOR DEAL BOARDS. 



Casein 18 oz. 



Water .7 pints. 



Ammonia *. . 



Quick-lime . . 9 oz. 



WENK'S CASEIN CEMENT. 



The casein is not used direct, but is first treated, so that 

 after the addition of some resinifying substance (e.g., tannin), 

 it acquires superior properties to those of cements prepared 

 in the usual way. The casein is rendered slightly alkaline 

 with soda or potash, and then heated for about twenty-four 

 hours at a temperature of about 140 F. It is next mixed 

 with lime or water-glass, and finally with some material 

 containing tannin, in order to ensure more rapid resinifica- 

 tion. The best results are obtained when the casein has 

 been prepared at the above-named temperature; otherwise, 

 it behaves less favourably. The tannin solutions to use are 

 preferably about 1 per cent, of gallic acid, cutch, quercitannic 

 acid or similar substances. The slaked lime, water-glass, 

 etc., which may be used in varying proportions, furnish the 

 requisite inorganic foundation for the organic mixture to be 

 resinified. The finished preparation may be used for gluing 

 wood in the ordinary way. 



