Sampling Milk. 25 



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 fairly 

 satisfactory sample may generally be taken. The dilu- 

 tion of milk by the ether introduces an error in the 

 testing, and only the smallest quantity of ether neces- 

 sary to dissolve the lumps of butter should be used. If 

 desired, 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 

 increased 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 gave an average test of 4.2 per cent. The test must be in- 

 creased by r jj- (j .X4.2=.21 per cent., and the original milk there- 

 fore contained 4.2+.21=4.41 per cent, of fat. 



Milk containing ether must be mixed cautiously with 

 acid in making a test, so as to avoid a loss of the contents 

 of the bottle by the sudden boiling of the ether due to 

 the heat evolved in mixing the milk and the acid. 



Instead of adding ether to partially churned sam- 

 ples, the milk may be heated to about 110 F. for a 

 few minutes, so as to melt the butter granules; the 

 sample is now shaken vigorously until a uniform mix- 

 ture of milk and melted butter is obtained, and a pi- 

 petteful is then quickly drawn from the sample. 



