TESTING ACIDITY OF MILK AND MILK PRODUCTS 95 



C.C. OF ALKALI SOLUTION Per ceiit. of acid 



(neutralizer) used in sample tested 



I 018 



2 036 



3 054 



4 072 



5 09 



10 18 



15 27 



20 36 



30 54 



40, etc 72, etc. 



By using the first formula above, similar tables can 

 be prepared wlTen the amount of sample taken is any 

 amount other than 50 cc. 



Using Babcock Pipette with Mann's Test. — If a 

 17.6 cc. pipette is used in measuring the liquid to be 

 tested, the percentage of acid may be found by divid- 

 ing by 2, the number of cubic centimeters of Mann's 

 alkali used, the result being expressed as tenths per 

 cent. Thus, if the liquid tested neutralizes 13 cc. of 

 alkali, the acidity is 13 divided by 2, which, expressed 

 as tenths, is .65 per cent. By diluting Mann's "neutral- 

 izer" with an equal volume of water, the number of 

 cubic centimeters gives directly the percentage of acid- 

 ity, expressed as tenths. 



FARRINGTON'S ALKALINE-TABLET TEST 



Apparatus and materials. — In this method the 

 same chemical principles are employed as in Mann's 

 test, but the alkali, in the form of a carbonate, and in- 

 dicator are mixed together in the form of solid tab- 

 lets. Each tablet contains enoug^h alkali to neutralize 



