Condensed Milk- and Milk Powder 209 



butter fat 



The Babcock Test 

 standard glassware 1 



(a) Standard milk test bottles, graduated to 8 per cent, and 

 with sub-divisions of .1 per cent. 



(b) Pipette graduated to 17.6 c.c. 



(c) Acid measure graduated to 17.5 c.c. 



(d) Centrifuge-Babcock tester 



(e) Water 'bath for reading at 135 to 140 degrees F. 



(f) Calipers for measuring fat column 



(g) Sulphuric acid, specific gravity 1.82 to 1.83 



DETERMINATION 



Pipette 17.6 c.c. of the properly mixed sample of milk into the 

 milk test bottle. Add 17.5 c.c. of acid and shake until all the curd 

 is completely dissolved. Both milk and acid should have a temper- 

 ature of 55 to 70 degrees F. .If milk and acid are too warm, set 

 the sample bottles and the acid jar into a trough or tub of water at 

 55 to 70 degrees F. for thirty minutes before testing. The test 

 bottles containing the mixture of milk and acid are then whirled in 

 the Babcock tester for five minutes at about one thousand revolu- 

 tions per minute, in the case of a tester with a twelve inch diameter 

 wheel. Fill the test bottles to the bottom of the neck with hot 

 water. The water should be soft, preferably rain water or distilled 

 water. If hard tap water is used it should be boiled to precipitate 

 the carbonates, otherwise the test will be difficult to read, owing to 

 the presence of bubbles of gas on top of the fat column. Revolve 

 again at full speed for two minutes, fill the test bottles to near the 

 .top of the graduation with hot water. Whirl in the centrifuge for 

 one minute. Now set the test bottles in the water bath at 135 to 

 140 degrees F. for five minutes. The test is now ready to be read. 

 The figures on the test bottles represent per cent. In the case of 

 the 8 per cent, standard milk test bottle the sub-divisions represent 

 tenths per cent. Read from the bottom of the lower curve to the 

 top of upper curve of the fat column, including the meniscus in the 

 reading. 2 



1 Hunziker, Indiana Agricultural Experiment Station, Circulars 41 and 42, 1914 

 3 For correct reading see page 221 



