28 CASEIN. 



ing it over with wooden shovels towards the hotter end. 

 Unless erected indoors, the flue must be covered with a wide 

 roof to protect the plates from rain. By means of this simple 

 appliance, large quantities of casein can be dried in a short 

 time, the only precaution necessary being to protect it from 

 overheating by vigorous shovelling and breaking down the 

 lumps, the flow of steam being also checked if found desirable. 



By this means, 100 parts of skim milk will yield about 8^ 

 parts of damp or 3-J parts of dry casein. This is put on the 

 market as "technical casein " or " lactarin ". It is soluble in 

 alkalies but insoluble in water unless the latter receives an 

 addition of 10 per cent, of some alkali (e.g., soda, borax or 

 ammonia). The dry casein still contains about 10 per cent, 

 of moisture, which constitutes one of the factors determining 

 the quality of the product, though less important than the 

 appearance and smell. The latter must on no account be 

 ammoniaCc \ but recall that of fresh milk, and the colour 

 must be p re white. The purer the colour and the more 

 agreeable the smell, the higher the value. 



Soluble casein is obtained from the moist product by dis- 

 solving the same in an alkali (caustic potash or soda, ammonia, 

 lime water or baryta water), or in an alkali salt (carbonate of 

 potash or soda), and evaporating the solution at moderate 

 temperatures. This soluble casein is rarely prepared in 

 dairies, since the industrial consumers of the article can 

 make it more easily and cheaply themselves from the moist 

 or dry product. On this account they usually specify the 

 manner in which the moist casein is to be prepared. Con- 

 sequently, when these particulars are specified in the contract, 

 the casein-maker will do well to adhere to the instructions 

 given, and not to employ some other method of preparation 

 that may seem preferable to him, or he may conflict with the 

 objects and views of his customer. 



Another method of preparation, recommended by Just, is 



