Milk Sugar 321 
is sufficient. When the curd has formed, which 
will be as soon as the acid is thoroughly mixed 
with the milk, the whey is drawn off and _ the 
eurd washed two or three times with warm water. 
It is then taken out and pressed as dry as possible, 
after which it is ground rather fine in a peg mill 
and then dried in an oven till perfectly dry. The 
amount usually realized from the skimmed milk in 
this way is not more than may be realized when 
it is skilfully fed to animals. 
Milk sugar.—Milk contains between 4 and 5 per 
cent of milk sugar, and the manufacture of this sugar 
has come to be an important industry. In the manu- 
facture, whey is preferably used, or if skimmed milk 
the casein is first coagulated and removed. The 
water is then removed by evaporation until the erys- 
tals of sugar are formed. Various methods are used 
to rid the sugar of albumin and other materials con- 
tained in the whey. Formerly this was a somewhat 
difficult operation, and added considerably to the ex- 
pense of the manufacture, but recently improvements 
have been made in this respect, so that the cost of 
the manufacture of the sugar is much lessened. The 
growth of the industry has been very rapid, result- 
ing in a much lower price for the product and a very 
much increased consumption. Formerly, almost the 
only use of milk sugar was medicinal. Now, be- 
cause of its digestibility, it forms an important in- 
gredient of many of the so-called infants’ and inva- 
lids’ foods. It is usually prepared in the form of a 
white crystalline powder, only mildly sweet to the 
taste. 
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