MILK 



r 



- 7 



- 6 



- 5 



-4 



flask and then drawn off, by means of a syphon provided with a 

 pinch-cock, into the test-bottles. In this way the test-bottles 

 are filled to the 7th or 8th division of the scale. 



In the new centrifuges which are heated by steam there is 

 a very practical arrangement for filling the bottles with hot 

 water. A reservoir of water placed above 

 the centrifuge is heated by the steam which 

 is used for warming up the centrifuge, and 

 from it, by means of a rubber tube, the test- 

 bottles can be filled without being taken out 

 of the centrifuge. The test-bottles are, of 

 course, in a vertical position when the centri- 

 fuge is not in motion. 



After adding the water, the test-bottles 

 are centrifuged for one minute and then 

 read. The fat ought to be a clear, well- 

 defined column in the graduated tube of the 

 test-bottle; if it is cloudy, then the bottles 

 must be slowly whirled again, the centrifuge 

 being heated. Generally the fat becomes 

 fairly clear after this. 



Both the upper and lower limits of the 

 column of fat are somewhat uneven. Each 

 division is equal to 0*2 per cent. fat. For 

 analysing cream by Babcock's method, speci- 

 ally constructed bottles are used. 



Ohlsson has also constructed a test-bottle 

 of special shape for determining the fat in 

 separated milk (see Fig. 28). 



As the column of fat is very short with 

 separated milk, the graduated part of the 

 test-bottle is made very narrow, so that a 

 longer and more easily-read column is ob- 

 tained. The milk, sulphuric acid, and water 

 are not filled in through the ordinary neck of 

 the bottle, but through a special side tube, 

 the scale represents 0'05 per cent, of fat. 



After the Babcock bottles have been emptied they are washed 

 in soda lye, rinsed in warm water, and allowed to drain upside 

 down. 



FIG. 26. Babcock 

 Test-bottle. 



Each division on 



