340 THE HANDBOOK FOR PRACTICAL FARMERS 



provided with swinging sockets to hold the bottles. At rest these 

 sockets allow the bottles to stand upright, but when in motion, 

 the centrifugal force causes the sockets to swing outward, bring- 

 ing the bottles to a horizontal position, Avith the necks toward the 

 center. AMiere steam pressure is available, a steam turbine 

 tester is strongly recommended for the reason that it maintains 

 a uniform motion under a definite pressure and at the same time 

 the steam keeps the bottles warm and supplies the hot water 

 required. "WHiatever kind of tester is used, it must be firmly 

 secured to a rigid support. There must be no shaking or 

 trembling of the tester when in motion. 



Acid. — The acid used in the Babcock test is the commercial 

 sulphuric acid, sometimes called oil of vitriol, and should have 

 a specific gravity of between 1.82 and 1.83. It should be kept 

 in glass bottles or jugs, preferably with glass stoppers. 



Sulphuric acid is an extremely corrosive liquid, which attacks 

 the skin, the clothing, wood, and most of the common metals. 

 Should the acid be spilled on the clothing, it should be imme- 

 diately washed off with plenty of water, and ammonia water 

 applied; this in turn must also be washed off. Unless the acid 

 is washed off immediately after contact Avith the skin, severe 

 burns will result. 



Testing strength of acid. — As already mentioned, the specific 

 gravity of the sulphuric acid used should be between 1.82 and 

 1.83. It is much better to purchase it guaranteed of the proper 

 strength than to bother with diluting the stronger acid. 

 Creamery supply houses handle acid guaranteed to be of the 

 proper strength, and if kept in well-stoppered containers it will 

 not change. 



DIRECTIONS FOR MAKING THE BABCOCK TEST WITH MILK 



Measuring the charge. — In preparing the sample for the test, 

 the milk is poured from one container to another two or three 

 times. The tip of the pipette is immediately inserted and the 

 milk sucked up Avith the mouth until it reaches a point Avell above 

 the graduation mark on the stem; the dry forefinger is then 

 quickly placed over the mouth of the pipette. By slightly relax- 

 ing the pressure of the finger the milk is alloAved to floAV doAvn 

 until it just reaches the mark. The tip of the pipette is noAV 

 placed in the neck of the test bottle and the milk alloAved to floAV 

 sloAvly down the side. If the bottle and pipette are held upright, 

 the neck of the bottle may clog up and some of the milk run over 

 the top. Care must be taken that none of the milk is lost during 



