METHODS OF SAMPLING MILK 23 



from top to bottom a hole one-eighth inch in diameter 

 or less. Finally, push a close-fitting plug of wood or 

 a glass rod into the hole in the stopper. 



SAMPLING FROZEN MILK 



Frozen milk is of very uneven composition in dif- 

 ferent portions of its mass. The crystals of ice con- 

 tained in it consist largely of water, while the liquid 

 portion contains most of the milk-solids. In such 

 cases it is necessary to melt the frozen portion by 

 warming, and then to mix well by gentle pouring 

 from one vessel to another, after which the sample is 

 at once taken for testing. 



SAMPLING MILK COAGULATED BY SOURING 



A sample of thickened, sour milk can not, without 

 special treatment, be taken so as to give reliable results 

 in fat determination. In ordinary curdled milk the 

 percentage of fat remains unchanged in amount, but 

 it is not evenly distributed through the milk. In or- 

 der to overcome this difficulty, the curdled casein 

 lactate must be dissolved before sampling. This is 

 done by adding to the milk a strong solution of caus- 

 tic soda or potash (lye), or strong ammonia water, 

 to the extent of 5 or 10 per cent, of the volume of the 

 milk used for sampling. The alkali is shaken with 

 the milk until the mixture becomes completely liquid, 

 after which the sample is at once drawn for testing. 

 It is necessary to make a correction by adding to the 

 results 5 or 10 per cent, of the amount of fat found, 

 according to the amount of alkali solution used. In 

 place of using a solution of alkali, one can add, in 



