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time to procure the sample is immediately after the milk 

 has been drawn from the cow and before the cream begins 

 to rise. Milk that has stood some time should be poured 

 from one vessel into another until the cream is evenly and 

 thoroughly distributed in the milk. It is impossible to secure 

 an average sample of the milk when the cream is partly 

 churned or small granules of butter appear on the surface of 

 the milk. It is not practicable to sample a large quantity of 

 curdled milk, but a small amount may be thoroughly mixed 

 if the curd be dissolved by slowly adding powdered soda. 



The sample should be thoroughly mixed just before the 

 pip3tte is filled. The pipette should be rinsed two or three 

 times with the milk before it is filled ; fill the pipette up to 

 the 17.6cc. mark; empty it into the graduated milk test bot- 

 tle, care being taken to let the milk flow from the pipette 

 slowly down the inside of the neck of the milk bottle. 



In order to get the best results the temperature of the milk 

 should be between 60 and 70 degrees F., especially if the acid 

 used has a specific gravity of 1.82. The milk may be cooler 

 if the acid is a little stronger. 



The acid measure is now filled up to the 17.5 c.c. mark with 

 sulphuric acid (not less than 1.82 or more than 1.83 sp. gr.); 

 the acid should be poured slowly down the inside of the neck 

 of the milk test bottle. Now thoroughly mix the acid and the 

 milk in the bottle by gently shaking the bottle with a circular 

 motion. The casein is precipitated and then dissolved, and 

 the solution soon becomes very dark brown in color, a result 

 of the charring of the milk sugar by the sulphuric acid. If 

 the acid is too weak, or there is not enough acid used, it will 

 not dissolve all of the casein ; if it is too strong, or there is too 

 much acid, the fat may be slightly charred and black specks 

 may collect at the bottom of the fat column. 



The bottles are now placed in a centrifugal machine in such 

 a position that the wheel will be evenly balanced ; then the 

 machine is turned at full speed for five minutes ; the bottles 

 are taken out, filled with hot water up to the graduated scale 

 point No. 7 ; they are then put back into the machine and 

 whirled at full speed for one or two minutes. Some author- 



