the test can be made a homogeneous mixture must be ob- 

 tained. This can best be obtained by pouring the milk 

 several times from one vessel into another. When the 

 sample is small, beakers are convenient for this purpose, 

 and if the sample has not remained in the container more 

 than a few hours, pouring back and forth four or five times 

 is sufficient. When, however, the sample haft stood for 

 some time in the container, the cream layer is liable to be 

 hard and to adhere to the. walls . This is particularly true of 

 preserved samples. In such event it is well to place the 

 container in warm water until the cream has become soft- 

 ened and can then be easily removed . Care must be taken 

 that none of the cream is left on the cover of the container; 

 if, however, any is left, a brush such as is used in cleaning 

 beakers is useful in dislodging it. 



The sample must always be well mixed immediately 

 before measuring out a charge for testing. If several 

 charges are to be measured out, the sample must be mixed 

 each time. Thorough mixing is absolutely necessary for 

 accurate work. 



Partially churned milk. Milk from some cows, notably 

 of the Jersey breed, churns very easily and sometimes a too 

 vigorous agitation in the mixing of such milk results in 

 some of the fat collecting in small granules which refuse to 

 emulsify again. This also frequently happens when the 

 milk is sent a long distance in partially filled containers. 

 These granules are easily recognized, and when they are 

 present special treatment is required to prepare the sample 

 for testing. A little ether equal in volume to 5 per cent 

 of the milk may be added, and the container stoppered and 

 vigorously shaken. The ether will dissolve the granules 

 and the solution will mix with the milk. A fairly accurate 

 charge may now be quickly removed, but the percentage 

 obtained must be corrected for the volume occupied by the 

 ether. 



Another and perhaps a better way to treat churned milk 

 is to place the container in hot water until the milk has 

 attained a temperature of about 110 F. In a few minutes 

 at this temperature the granules will have melted. The 

 container is then vigorously agitated and a charge for test 

 immediately measured out. 



