40 BUTTER-MAKING. 



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 RusseU suggest to name it visco-milk, visco-cream, etc. 

 When this modification is made, then no objection can be 

 raised to its legitimate use. 



Fig. 6. — Microscopic appearance of milk, showing natural grouping of the 

 fat-globules. Single group in circle, highly magnified. (From Bui. 64, 

 Wis.1 



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 



