RECEIVING, SAMPLING, AND GRADING. 83 
practised to a considerable extent. This test is in common 
use in Canada. It consists of heating a small sample of the 
milk to be tested to 120° F. If it will stand this temperature 
without coagulating, it is considered to be good milk. If it 
Fic. 26.— Tortion cream test- ! 
ing scales. cock cream-testing scales. 
coagulates when heated to this temperature, it is too sour 
to be used for cheese. 
This heating may be considered an acid test. When milk 
contains about .39% acid, it usually coagulates when heated. 
It should be borne in mind in this connection that different 
samples of milk do not coagulate when containing exactly the 
same amount of acid, and at the same temperature. Some 
samples will coagulate upon heating when containing little 
