46 A DAIRY LABORATORY GUIDE 



If five of the alkali tablets are dissolved in 97 cc. 

 of water each cubic centimeter of the solution will 

 neutralize .01 per cent of acid when 18 grams of 

 milk are used. This solution is often used by 

 creamerymen, as the per cent of acid may then be 

 read directly from the burette. Many devices for 

 testing- the acidity of milk are on the market, all 

 tending- to do away with computation and giving 

 the percentage of acid directly. One of these is 

 Publow's acidimeter. In this apparatus an n/io 

 alkali solution is used and 9 grams of milk are 

 tested. Each cc. on the burette equals .1 per cent 

 of acid and each I/TO of a cc. equals .01 per cent 

 acid. In testing for acid one should always try 

 and obtain the same degree of color each time. 

 This color should be permanent for at least one 

 minute. Great care should be taken not to run in 

 an excess of alkali. It will be much easier to detect 

 the color change if some water is added to the 

 sample after it is measured out before the alkali 

 is added. 



