118 MANUAL OF MILK PRODUCTS 



Whirl for five minutes at the proper speed. A tester with a 

 twelve-inch wheel requires one thousand revolutions and a tester 

 with an eighteen-inch wheel requires eight hundred revolutions 

 a minute. 



Fill the bottles to the bottom of the neck with hot, soft 

 water; whirl again for two minutes and fill the bottles with 

 hot, soft water to about the 7 per cent mark ; whirl for one 

 minute. The temperature of the water added should be not 

 lower than 140 degrees F. and preferably near that of boiling 

 water (212 degrees F.). 



Reading the test (Fig. 22) 



Place the test bottles in a water bath at 135 degrees to 140 

 degrees F. for five minutes. Measure the fat column with a 



pair of dividers, including the menis- 

 cus or curve, both at the bottom and 

 at the top of the fat column. Each 

 __ B -^ subdivision represents .1 per cent; 



each main division represents 1 per 

 cent. Record the percentage of fat 

 thus found on the test sheet. 



Read from A to D 



Abnormal appearance of the fat column 



When the test is made properly and 

 in accordance with above directions, 

 the fat column is perfectly clear, has 

 a golden yellow color, and the top and 

 bottom curves are sharply defined. 



Fl0 ' ^hTufd" k ^ The presence of whitish curd in or 



immediately below the fat column is 



the result of excessively cold milk and acid, or the use of too 



little or too weak acid. 



The presence of charred and dark curdy masses in the fat 





