16 LAIET CBEMiaTEY 



in the cut. The second and third fingers are opposite 

 the thumb, wliile tlie little linger rests against the 

 stem. When held in this way, the pipette is pre- 

 vented by the little finger from swaying sidewise ; 

 while the thumb, with the second and third fingers 

 on the opposite sides, secures a good hold and leaves 

 the index finger free to properly control the flow of 

 milk from the pipette, and thus rapid measurements 

 can be made. If the pipette is wet, rinse it with a 

 little of the milk before using it. In passing from one 

 milk to another, clean the pipette by rinsing it with 

 the milk that is to be tested. The pipette should be 

 thoroughly cleaned, first with cold water, then with 

 hot water at the close of the work. The pipette 

 holds 17.6 CO. of water, and delivers 18 gm. of 

 milk. Hold the test bottle in the left hand at an 

 angle of about 60°. Let the tip of the pipette if 

 large just touch the inside of the neck of the test 

 bottle, in order to permit air to pass out of the test 

 bottle, otherwise the milk will spatter. Allow plenty 

 of time for the pipette to drain ; remove the last few 

 drops by blowing. 



17. Making the Test. — The test bottle (see Fig. 

 5) is provided with a neck which has a graduated 

 scale from 1 to 10. Each larger division is divided 

 into five smaller divisions, each representing .2 of a 

 per cent of fat. The test bottle is usually provided 

 with a copper collar bearing a number. Fill the 

 acid measure, Fig. 6, up to the 17.6 cc. mark with 

 sulphuric acid. The action of the sulphuric acid 



