MILK 



73 



whereby substances insoluble in ether (chiefly amylene, C 5 H 10 ) 

 were formed. 



After the sulphuric acid, milk, and amyl alcohol have been 

 brought together, a rubber stopper, which must not be damaged, 

 is fitted into the mouth of the test-bottle, and then the contents 

 well shaken, the thumb being kept on the stopper to prevent it 

 coming out. As a considerable amount of heat is generated by 

 the action of the sulphuric acid on the milk, the test-bottle should 

 be wrapped in a cloth, or the aluminium 

 sheath designed by Dr. Baechler, of Zurich, 

 may be used. 



The shaking of the sample must be done 

 thoroughly and quickly, and the test-bottle 

 inverted several times, so that the liquid in 

 the neck becomes thoroughly mixed. By 

 pressing in the rubber stopper, the height 

 of the liquid can be brought to about the 

 zero point on the scale. 



If only a few samples have to be analysed 

 and the room is warm, the test-bottles can 

 be put into the centrifuge without any 

 preliminary heating, otherwise the test- 

 bottles must be warmed for a few minutes 

 (not longer) in the water-bath at a tem- 

 perature of 60-65 C. When the tempera- 

 ture rises higher than this, say above 70 C., 

 the rubber stopper is liable to be blown out 

 of the test-bottle. After the test-bottles 

 have been heated they are arranged symmetrically in the 

 centrifuge and whirled for 3-4 minutes at a speed of about 

 1,000 revolutions per minute. When the centrifuge has a 

 heating arrangement attached to it, the preliminary warming 

 is not, of course, necessary. 



When the test-bottles are taken out of the centrifuge they 

 are again placed in the water-bath at a temperature of 

 60-65 C., and left there for several minutes before being read ; 

 where the centrifuge is heated, the tubes can be read off as 

 taken from the centrifuge. 



By carefully screwing in the rubber stopper, or even by pressing 

 it, the lower limit of the fat column is brought on to one of the 



FIG. 38. Amyl Al- 

 cohol Measurer. 



