SAMPLING MILK. 177 



is not appreciably affected by an increase of any of the ingred- 

 ients of the ration. 



2. Under such circumstances fat cannot be fed into milk. 



Sampling' milk. The first consideration in the examination 

 of milk is the sampling. It is of the utmost importance that 

 a representative sample be taken and too much emphasis can- 

 not be placed on this point. Great care is called for in samp- 

 ling milk because, as previously stated, the fat of milk is not 

 in solution, but held in suspension, and forms an emulsion 

 with the milk serum. The little globules of fat commence 

 to rise very soon after milk is allowed to stand and, to the 

 uninitiated, surprisingly fast. The writer has analyzed three 

 different samples of milk from the same herd showing respect- 

 ively 2.9%, 9.1% and 3.6% fat. The variations were due en- 

 tirely to improper sampling. The sample should be taken and 

 the examination conducted while the milk is fresh and in normal 

 condition. If the samples are to be transported to any distance 

 previous to being tested, care should be taken to see that the 

 bottles are completely filled. This will avoid the tendency to 

 churn which might cause the fat to collect in lumps and pre- 

 vent, at times, an accurate determination of the fat. 



After a sample is properly taken it should be thoroughly 

 mixed before it is tested and the respective portions for the 

 different tests should be measured immediately after mixing. 

 If such a practice is not adopted, serious inaccuracies are liable 

 to occur, owing to the rapidity with which the fat globules will 

 rise toward the surface. By far the best way to mix a sample 

 is to pour it from one vessel to another, and the pouring should 

 be done on the side of the vessel and not in the center. If this 

 precaution is not taken an appreciable amount of air will be 

 incorporated in the milk, which will greatly interfere with the 

 accurate measuring of the milk for the Babccck test for fat. 



There are on the market several different devices for sam- 

 pling market milk, such as the Scovell, McKay, and Equity 

 sampling tubes, etc. These with full directions for use may 

 be obtained from dairy supply houses. 



Specific gravity. The specific gravity of a thoroughly mixed 

 sample may be most conveniently taken by means of the small 



