248 ELEMENTARY AGRICULTURE 



Follow these directions carefully : 



(a) Stir milk thoroughly before taking sample. This 

 is best done by pouring milk gently back and forth sev- 

 eral times between two vessels so the cream, or fat is 

 evenly mixed. 



(b) With the small end of a pipette suck up the milk 

 above the mark on the tube. Then close upper end with 

 your forefinger, releasing finger slowly to allow the milk 

 to fall until it stands just even with the mark 17.6 cc, 

 being careful to hold the pipette straight up and down. 



(c) Empty the pipette into the test bottle and blow 

 to drive out all the milk. 



(d) Fill the acid measure with sulphuric acid to the 

 mark shown and put this into the test bottle with the 

 milk. Remember the acid must be handled with care. If 

 any gets on hands or clothing it should be washed off 

 quickly with water. 



(e) Shake the bottle to mix milk and acid thoroughly. 



(f) Place bottles (several tests may be made at once) 

 in the machine and whirl five minutes. The bottles 

 should be hot when whirled; they may be placed in hot 

 water before being used. For whirling place boJ:tles op- 

 posite one another in the machine to keep balance. 



(g) With pipette or other means add hot water to 

 each bottle until filled to the bottom of the neck and 

 whirl two minutes. 



(h) Add more hot water to bring the contents nearly 

 to the top of the marks on the neck of the bottle, and 

 again whirl one minute. 



(i) Hold bottle upright on a level with the eye and 

 read the marks at the extreme top and bottom of the fat 



