100 MANUAL OF GENEBAL AGRICULTURE. 



(b) A shorter meikod is by the use of an acid hydro- 

 meter. When an instrument of this kind is used it is only 

 necessary to lower jt into the acid and read off the specific 

 gravity. 



75. THE BABCOCK TEST OF MILK. 



Materials: Half pint of milk (enough for entire 

 class), 17.6 c.c. milk pipettes, milk test bottles, water- 

 white sulphuric acid of specific gravity between 1.82 and 

 1.83. Vessel for heating water, small beaker, dividers, 

 (the latter desirable but not necessary) and Babcock 

 tester, distilled or soft (rain) water. 



(a) Sampling the Milk. Be careful that the sample 

 represents a fair average to be tested. Any cream that 

 may rise on the milk should be thoroughly mixed with the 

 milk by cautiously pouring back and forth from one vessel 

 to another. 



(b) Measuring Milk. This is done with a milk pipette 

 which holds when filled to the mark on the stem, 17.6 cc. 

 Suck the milk up into the pipette above the mark and 

 place the finger quickly on the upper end of the pipette, 

 then press firmly down to keep the milk from running 

 out. Hold the pipette vertically with the mark on a 

 level with the eye and by gently relaxing the pressure of 

 the finger on the end of the pipette, air is admitted and 

 the milk is allowed to flow slowly out until the top of the 

 column of the milk is level with the mark of the pipette. 

 Read it to the lowest part of the curve or meniscus. The 

 pipette then holds 17.6 cc. of milk. 



(c) Filling the Test Bottles. Place the point of the 

 pipette into the mouth of the milk test bottle, holding 

 both milk test botle and pipette in an inclined position. 

 By removing the finger from the end of the pipette the 

 milk will flow out of the pipette and into the bottle. 



The object of inclining the test bottle and pipette is 

 to allow the milk to run down the side of the neck of 

 the test bottle, thus allowing the exit of the air in the 

 bottle. If this precaution is not observed, the air will 

 bubble out and cause some of the milk to overflow. 



