a 
MILK AND ITS PRODUCTS. 
575,000 Ibs., valued at £12,564. The commercial value of casein depends 
on its solubility, adhesiveness, and swelling capacity. In Europe, this 
is tested by heating 20 gms. of casein in 120 c.c. of water with 3 gms. 
of borax. In five hours, the casein should be in solution. Another 
test is to heat 10 gms. of casein in 50 c.c. of water with 2 c.c. of 33 per 
cent. ammonia for two hours, at 140° F. The casein should then be in 
complete solution. ; 
Among other methods of preparing industrial casein, the following 
may be mentioned :— : 
(1) Casein is precipitated by leading SO, gas into milk warmed 
to 50° to 70° C. The process is complete in a few minutes, the 
time taken being so short that there is no danger of inversion 
occurring. (German Patent 184,300.) 
(2) A fat-free casein is obtained by mixing skimmed milk with 
alkali, warming, removing fat by centrifuging, and then preci- 
pitating casein in the ordinary way with acid. (German Patent 
135,745.) hold gears 
(3) The Bureau of Animal Industry, United States of America, 
has recently developed two good methods—(a) the “ ejector ” 
method, using natural souring; and (b) the grain curd method, 
using hydrochloric acid, producing a casein of exceptional purity. 
At the beginning of this year, only one large creamery had put it 
into operation. In (a) skim milk is soured until the acidity 
(using standard alkali and phenolphthalein) reaches -8 to -9 per 
cent. expressed as lactic acid. It is then allowed to run out of a 
tank through an ejector, where it is rapidly heated by introducing 
steam, and to fall into a second tank, where the curd collects on 
top of the whey. In (b) the method takes its name from the 
character of the curd when obtained from the milk, in which the 
hydrogen ion concentration is approximately that of the isoelectric 
point of casein Pu = 4-6. This is determined by testing: with 
methyl red small samples against stock solutions of known hydrogen 
ion concentration. . By the careful regulation of acidity .and 
temperature, the curd is easily freed. from impurities. 
The uses of casein are already numerous and varied, and are con- 
tinually extending. Omitting its use in cheese-making, for which 
easein is not separately prepared, the following are some of the commer- 
cial uses of the prepared product :— 
1. For administering medicinal agents, ¢.g., salicylates, alkaloids, 
lithium, mercury, silver, iron, bismuth, and others. 
2. As a mucilage, in adhesives and glues, in putties and cements. 
The ash and water:content of casein vary according to the 
method of manufacture. A determination of the ash makes it 
possible to use casein made by any method, and still obtain uniform 
results in making water-resistant glues. The equation W = 24 
Ash + (1:85) gives the ratio of the weight of water to be used 
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