MAKING THE TEST: DRAWING SAMPLE 305 



on the farm, the fat is commercially the most valuable. Fat is 

 also the element in which there is the greatest variation. Being 

 so variable in amount and so valuable on the market, it becomes 

 highly important that a test made shall be accurately done. 



Procuring the Sample. — If the milk of a single cow is to be 

 tested she must be milked dry and the milk thoroughly stirred, 

 preferably by pouring from one pail to another before a sample 

 is taken. This is necessary because the last milk, or strippings, 

 is anywhere from two to eight times as rich as the first milk 



Fig. 101. — Eight-bottle hand tester. Farm size. 



drawn. Merely drawing the milk into the bottle will not suffice 

 for the securing of an accurate sample. 



If a can or vat of milk is to be tested it must be 1 very thor- 

 oughly stirred before the sample is taken. Fat will rise in five 

 minutes sufficiently to show variation between the top and 

 bottom of a pail or can of milk. So small an amount of milk 

 as a single ten gallon canful will contain over 37,000 cubic 

 centimeters. In testing we use only 17.6 c.c, which is only one 

 part in 2162 parts of the whole. Where so small a quantity is 

 used to determine the value of so large a mass it is extremely 

 important, indeed, that the small amount be carefully taken. 



Making the Test: Drawing Sample. — With test bottle 



placed conveniently and safely and with pipette near at hand, 



mix again the sample of milk by pouring from one cup or dish 



to another, taking care that the milk flows down the side of the 



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