316 Milk and Its Products 
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, diarrhea, 
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 custom 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. 
Condensed milk.—In 1856 a patent was granted 
to Gail Borden, Jr., on a process for “concentrating 
sweet milk by evaporation in vacuo, having no sugar 
or other foreign matter mixed with it.” From small 
beginnings the business has grown to enormous pro- 
portions, and is still largely in the hands of the 
descendants of the original patentee. 
There are two classes of condensed milk, namely, 
sweetened and unsweetened. 
Sweetened condensed milk.— Sweetened condensed 
milk was the first condensed milk to successfully reach 
