100 GRADING AND TESTING MILK AND CREAM 



when the contents have reached a chocolate color some hot 

 water is added to the test bottle to check the action of the acid. 

 The sample is then centrifuged for five to six minutes, after which 

 hot water is added to float the fat into the neck of the bottle; 

 then the sample is again whirled for two minutes. The reading 

 is taken at a temperature of i3o-i4o F., after a few drops of a 

 colored reader, composed of a light mineral oil with suitable 

 coloring matter in it, have been added to flatten the meniscus. 

 Dividers are used for measuring the fat column in taking the 

 reading. 



There are three very common conditions which make it dif- 

 ficult to obtain a fat reading: (i) Black, charred, flocculent 

 matter is sometimes found at the bottom of the fat column. This 

 is commonly caused by using too much or too strong acid or by 

 mixing milk and acid at too high a temperature. The remedy 

 is to use less acid or to cool milk and acid before mixing. The 

 black charred matter may also be due to allowing the acid to 

 stand in contact with the milk too long a time before mixing or to 

 pouring acid through the center of the milk. (2) There may be a 

 layer of white flocculent 'matter at the bottom of the fat column. 

 In this case an insufficient quantity of acid may have been used, 

 the temperature of the milk and acid may be too low, or they 

 may not have been thoroughly mixed. The remedy is to use 

 more acid, to warm milk and acid before mixing, or to shake the 

 mixture thoroughly before whirling. (3) Occasionally there is a 

 layer of impure foam at the top of the fat column. This is gen- 

 erally due to the use of hard and impure water. The remedy is to 

 use pure distilled hot water. For more detailed information on 

 this subject see " Testing Milk and its Products," by Farrington 

 and Woll. 



Does the Babcock Test, as Ordinarily Applied to Cream, Give 

 too High a Reading? An investigation made by Harry B. Sieg- 

 mund, Analyst, Hendler Creamery Company, and R. Sewell 

 Craig, Senior Food Chemist, City Health Department, Balti- 

 more, resulted in a decision that the Babcock test of cream, as 

 ordinarily conducted, gives too high a reading. The following is 

 a brief summary of the results obtained: 



