The Babcock Test. 



35 



bottles are whirled again at full speed for one minute, 

 and hot water added a second time, until the lower part 

 of the column of fat comes within the scale on the neck of 

 the test bottle, preferably to the 1 or 2 per cent, mark, so 

 as to allow for the sinking of the column of fat, due to the 

 gradual cooling of the contents of the bottle. By drop- 

 ping the water directly on the fat in the second filling, 

 the column of fat will be washed free from light floccu- 

 lent matter, which might otherwise be entangled therein 

 and render the reading uncertain or even too high. A 

 final whirling for one minute com- 

 pletes the separation of the fat. 



41. Measuring the fat. The amount 

 of fat in the neck of the bottle is 

 . measured by the scale or gradua- 

 tions on the neck. Each division 

 of the scale represents two-tenths of 

 one per cent, of fat, and the space 

 filled by the fat shows the per cent, 

 of butter fat contained in the sam- 

 ple tested. 



The fat is measured from the 

 lower line of separation between the 

 fat and the water, to the top of the 

 fat column, at the point ft, shown in 

 FIG. 11. Measuring the the figure 11, the reading being thus 

 cSckT s tbo f uie n a Bab " taken from a to 6, and not to c or to d. 

 Comparative gravimetric analyses have shown that the 

 readings obtained in this manner give correct results. 

 While the lower line of the fat column is nearly straight, 

 the upper one is curved, and errors in the reading are. 

 therefore easily made, unless the preceding rule is observed. 





