90 CASEIN. 



separation therefrom, is dissolved in alkalies or alkali salts in 

 the usual manner, and is then mixed with water-glass and 

 some other metallic compound such as calcium chloride, 

 barium chloride, or magnesium chloride in aqueous solution. 

 The casein combines with the metal of the chloride, and double 

 decomposition is set up between the chloride and the water- 

 glass, forming alkali chloride and the silicate of the other 

 metal. This product, e.g., magnesium silicate, is insoluble, and 

 would be precipitated in the absence of casein, but in presence 

 of that substance assumes the colloidal form, similar to that of 

 the casein solution, the mixture of the two augmenting the 

 adhesive properties of the casein. The following proportions 

 of the ingredients may be regarded as typical : 100 parts of 

 casein are mixed with 600 of water and dissolved by the 

 addition of 12 parts of carbonate of soda. To this solution 

 are added 100 parts of a 10 per cent, solution of magnesium 

 chloride and 80 parts of sodium silicate or potassium silicate, 

 the whole being stirred continuously. The dried product 

 swells up like ordinary glue in cold water, and dissolves in 



hot water. 



CASEIN GLUE FOR MATCH-MAKING. 



Casein forms a good substitute for glue or dextrin in 

 match-making, for the following reasons. It can be dis- 

 solved without heat, is neither hygroscopic nor inflammable, 

 and can also be made waterproof by suitable treatment. 



The preparation of the solution is simplified by using 

 sodium caseate or water-soluble casein instead of the variety 

 soluble in alkali. Water is heated to near boiling (190 F.), 

 and the casein powder is shaken in and stirred. 



'LEHNER'S CASEIN PUTTIES. 



1. 



Fresh curd is boiled with water until it has dissolved 

 to a ropy mass, and slaked lime and finely sifted wood ashes 

 are stirred into the solution. The proportions are : 



