THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 101 



ARTIFICIAL HORN, ETC., FROM CASEIN. 



Pozzi and Tondell propose to treat skim milk with rennet 

 in the warm, leaving it to stand ten to fifteen minutes when 

 curdled, and expelling the whey by the aid of beaters. After 

 half -an -hour longer the whey is poured off and the curd is 

 drained on a sloping table, washed with water, squeezed to 

 remove fat and sugar, and bleached by washing with very 

 weak sulphuric acid, hydrochloric acid, or other suitable agent, 

 the surplus acid being removed by washing with lukewarm 

 water. The next step is to heat the curd in a jacketed pan 

 with twice its own weight of water, containing sufficient lactic 

 acid to replace that naturally present in the whey, the tem- 

 perature being slowly raised to 35 to 40 0. to facilitate the 

 ripening of the paste. The desired stage will have been 

 reached (in fifteen to eighteen hours) when a sample, plunged 

 into boiling water, changes to a tough, springy mass, where- 

 upon the temperature of the water jacket is raised to 70 to 

 75 C., and the contents of the pan are stirred with a spatula 

 until they unite to a compact, tenacious, and fibrous mass. 

 This is taken out of the pan and kneaded and rolled, at a 

 constant temperature of 50 to 55 C., until all the water 

 is removed. After cooling to 15 to 20 C., the mass is 

 chopped small in a machine and transferred to press moulds 

 or frames, in which it is subjected to pressure for twelve to 

 fourteen hours. The pressed sheets are then stained to re- 

 semble horn, ivory, mother-of-pearl, etc., either plain or in 

 fancy patterns, after which treatment they are spread out, one 

 above another, on thick sheets of cloth in an iron frame, and 

 placed in an autoclave charged with water containing glycerine 

 and formaldehyde in different proportions, according as the 

 product is desired to be more or less waterproof, flexible, 

 or hard, the operation of endosmosis being accelerated by 

 pumping air into the closed vessel until the pressure attains 



