614 TESTING FOR BUTTERFAT 



Cream Testing Scales. Sensibility reciprocal of 30 mgm., i. e. 

 the addition of 30 mgm. to the scales, when loaded to capacity, shall 

 cause a deflection of the pointer of at least one division on the gradu- 

 ation. 



Weights. 9 gram weights for 9 gram cream test bottles and 

 18 gram weights for 18 gram cream test bottles, preferably 

 stamped correct by the United States or State Bureau of Stand- 

 ards. 



Tester. Standard Babcock test centrifuge and speed in- 

 dicator. 



Dividers for measuring fat column. 



Water bath for cream samples, with proper arrangement for 

 regulating and recording temperature of samples. 



Water bath for test bottles, of sufficient size and with neces- 

 sary equipment to insure proper control of temperature. The fol- 

 lowing dimensions for a twenty-four bottle water bath are recom- 

 mended: Metal box, 14 inches long, 11 inches wide, and S 1 /^ inches 

 deep and equipped with a bottle basket 9 l / 2 inches long and 6 l /2 inches 

 wide, capacity twenty-four bottles, a steam and water inlet, a drain, 

 a thermometer holder with thermometer. 



Chemicals. Commercial sulphuric acid, specific gravity 1.82 

 to 1.83 ; glymol, or white mineral oil, high grade. 



OPERATION OF THE BABCOCK TEST 

 Milk Test 



Milk Samples. The sampling of milk is fully discussed in 

 Chapter VI on "Receiving Milk and Cream." 



Preparation of Milk Sample for the Test. Before testing, the 

 samples should be brought to the proper temperature; this may 

 range from 55 degrees to 70 degrees F. If the samples have been 

 exposed to summer heat or to temperatures near the freezing point, 

 the sample bottles are best set into a tank, sink, or tub and allowed 

 to stand in water at about 60 degrees F. until the temperature of the 

 milk is neither below 55 degrees F. nor above 70 degrees F. 



If to be transported by mail, express, or otherwise, the sample 

 bottle should be completely full and tightly stoppered and the sam- 

 ples should be preserved as previously directed, see Chapter VI. 



The contents of each bottle must be thoroughly mixed before 



