Milk Sugar. 205 
should be fed in connection with them, if they are 
used to the best advantage. When economically 
fed to young pigs and calves, skimmed milk and 
buttermilk may be made to return about fifteen cents 
per hundred weight, and whey about one-third less. 
These products are of value for food in proportion 
as the milk sugar has not been changed to lactic 
acid. They may be fed in unlimited quantities with- 
out ill results upon the health of the animal, ex- 
cept that occasionally when the milk is very sour, 
or when fermentations other than lactic have set 
in, derangements of the digestive organs, diarrhcea, 
etc., sometimes occur. It is, therefore, advisable that 
all of these products should be fed in as fresh a con- 
dition as possible, and it has been found in many 
instances that the eustom of sterilizing or partially 
sterilizing the skimmed milk or whey at the factory, 
by injecting a jet of steam into it until the whole 
is heated up to about 180° F., is practical, and is fol- 
lowed by beneficial results. 
Milk sugar.—Milk contains between 4 and 5 per 
eent 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 
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