EXERCISE No. 32 

 BABCOCK TEST 



Object: To determine the per cent of butterfat in milk. 



Material : Babcock Tester, milk testing bottles, pipette, 

 a sample bottle of whole milk, an acid measure, and a bottle 

 of sulphuric acid. 



Method : After the sample of milk has been well shaken, 

 insert the pipette in it and with the mouth suck the milk up 

 until it has risen above the 17.6 cc. mark. Then quickly 

 place the soft part of the index finger over the end of the 

 pipette. The column of milk can be easily controlled and 

 allowed to flow out until it is on a level with the 17.6 cc. 

 mark. The pipette should always be so held that the 17.6 

 cc. mark is on a level with the eye. Transfer the milk in 

 the pipette to the bottle, holding the latter in a slanting posi- 

 tion, so that the milk will run down the lower inside of the 

 bottle neck and will not be forced out by the outcoming air. 



After transferring the milk into the bottle, add to it 17.5 

 cc. of sulphuric acid (H^SCU) of a specific gravity of 1.82 

 to 1.83. The milk and the acid should be thoroughly mixed 

 at once. The acid burns up (by moist combustion) every- 

 thing in the milk except the fat. The same precautions 

 should be observed in adding the acid as in inserting the milk, 

 namely, to slant the bottle, and the bottle should be revolved 

 as the acid is poured in, so that all of the milk adhering to 

 the neck of the bottle will be washed down. If the acid is 

 too weak, more than 17.5 cc. is used, and if too strong, less 

 than 17.5 cc. is used. Good acid is colorless, although it may 

 be quite dark and contain undissolved foreign particles. 



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