Sampling Milk. 25 



sticking to the glass. This churning of the milk can be 

 easily prevented by completely filling the bottle or the 

 can. If there is no space left for the milk in which to 

 splash around, the fat will not be churned out in transit. 



31. Approximately accurate results may generally be 

 obtained with a partially churned sample of milk, if a 

 teaspoonful of ether be added to it. After adding the 

 ether, cork the bottle and shake it until the lumps of 

 butter are dissolved. This ether solution of the butter 

 will mix with the milk, and from the mixture a uniform 

 sample may generally be taken without difficulty. The 

 dilution of milk by the ether introduces an error in the 

 testing, and only the smallest quantity of ether necessary 

 to dissolve the lumps of butter should be used. If de- 

 sired, a definite quantity of ether, say five per cent, of 

 the volume of the sample of milk to be tested, may be 

 added; in such cases the result of the test must be in- 

 creased by the per cent, of ether added. 



EXAMPLE. To a 4-oz. sample (120 cc.) of partially churned 

 milk, 5 per cent., or 6 cc., of common ether are added: the mix- 

 ture gives an average test of 4.2 per cent. The test must be in- 

 creased by j X 4.2 .21, and the original milk therefore con- 

 tained 4.2-f.21=4.41 per cent, of fat. 



Instead of adding ether to partially churned samples, 

 the milk may be heated to about 110 F. for about ten 

 minutes, so as to melt the butter granules; the sample is 

 now shaken vigorously until a uniform mixture of milk 

 and melted butter is obtained, and a pipetteful then 

 quickly drawn from the sample. 



32. Sampling sour milk. When milk becomes sour, the 

 casein is coagulated and the mechanical condition of the 



