424 SCIENCE AND PRACTICE OF CHEESE-MAKING 



cock test finds occasion for use in connection with 

 cheese-making in the following ways : ( i ) Testing 

 milk of individual patrons when dividends are made 

 on the basis of the milk-fat; (2) testing milk to 

 ascertain if its fat content has been seriously affected 

 by skimming; (3) testing milk to use as a basis for 

 estimating the yield of cheese and regulating the 

 amount of salt used (p. 38) ; (4) testing whey 

 and press-drippings to ascertain if the loss of fat 

 is excessive, and (5) testing cheese for percentage 

 of fat. 



Apparatus and materials used. — The following list 

 includes the apparatus and materials used in making 

 this test: (i) Test-bottles, graduated from o to 10 

 per cent, so that each smallest division represents 0.20 

 per cent when 17.5 cubic centimeters (18 grams) of 

 milk are used; (2) pipette for measuring milk, hold- 

 ing 17.6 cubic centimeters to mark; (3) measure 

 for acid, holding 17.5 cubic centimeters to mark; 

 (4) centrifugal machine, having a wheel 12 to 20 

 inches in diameter, easily capable of being run at a 

 speed of 700 to 1,200 revolutions a minute; and (5) 

 commercial sulphuric acid having a specific gravity 

 between 1.82 and 1.83, preferably just 1.825 (Test- 

 ing Milk, etc., pp. 32-52). 



Sampling milk for testing. — Milk that has curdled, 

 or on the surface of which cream has risen and dried, 

 or milk the fat of which has partially churned, is- dif- 

 ficult to sample. These difficulties should not be com- 

 mon in cheese-factory work, but, when they arise, 

 careful attention should be given to the details pre- 

 scribed for such cases (Testing Milk, etc., pp. 22- 

 24). The samples to be tested must be thoroughly 

 mixed. 



