THE PREPAEATION OF PLASTIC MASSES FROM CASEIN. 103 



This mass, whilst still in a plastic state, may be spread on a 

 network of wire, rushes or straw, so as to obtain a light, 

 unbreakable, insulating material. 



According to another process, milk is warmed to about 

 140 F., treated with a considerable addition of borax, and 

 heated further to about 190 F. in presence of barium 

 chloride or other mineral precipitant of casein. t The washed 

 precipitate is pressed and ground with an addition of acetic 

 acid, soda or other solvent, and the resulting mass is put 

 into a steam-heated press. The product is similar to bone 

 or celluloid. 



HORNY CASEIN MASS. 



According to P. Horn, dried casein is dissolved in dilute 

 caustic potash, and heated along with a quantity of sulphur 

 at least equal to the amount of alkali taken. The casein, 

 potash and sulphur are thereby dissolved to a clear liquid, 

 which is concentrated to the thickness of syrup, moulded 

 and dried, or made suitable for various technical purposes 

 by the addition of loading ingredients, driers or hardening 

 preparations. For example, a very elastic mass is obtained 

 from the following proportions : 



Water 200 parts by weight. 



Casein 100 



Potash 5 to 10 



Sulphur 10 to 30 



The elasticity increases with the proportion of sulphur 

 taken. The final product may be hardened by adding lead 

 hydroxide, zinc hydroxide and potassium or sodium silicate, 

 whilst wood, cork, sand or emery may be added to increase 

 the drying properties, or as fillers. 



In another recipe, 100 parts of skim milk are treated 

 with soda or potash, together with ^ of chemically pure 

 soda. The precipitated casein is separated from the mass, 

 and set aside for one to three days to ferment, whereupon it 



