40 BUTTER-MA KING. 
nitrogenous constituents in such a way as to aid in the resto- 
ration of the body of the cream or milk. 
Nearly all dairy laws forbid the addition of any foreign 
substances to milk or cream. If viscogen is added, Babcock 
and Russell suggest to name it. visco-milk, visco-cream, etc. 
When this modification is made, then no objection can be 
raised to its legitimate use. 
Fic. 6.—Microscopic appearance of milk, showing natural grouping of the 
Naas Single group in circle, highly magnified. (From Bul. 64, 
3. Drives off Gases.—When milk is heated, taints, and 
gases of different kinds pass off to some extent. This is facili- 
tated by heating and stirring in an open vessel. Many of 
these gases also escape when milk is aerated and cooled in a 
pure atmosphere. 
4. Imparts a Cooked Taste.—When milk is heated to 160° F. 
or above, it assumes a distinctly cooked taste, which makes it 
disagreeable as a food for many people. On this account, 
milk for city supply in America is generally not heated. 
In a few cities where milk is consumed directly, heating and 
cooling (pasteurization) has been generally introduced. It 
is said that people can become accustomed to this cooked 
flavor and acquire a liking for it. When milk is not heated 
higher than 180° F., nor exposed to the heat very long, and 
