222 



CRICA.M-RIPEXIXG AND STARTKRS 



quantity. For instance, it is not safe to develop as high a per 

 cent of acid in cream containing 40 per cent as could be devel- 

 oped in cream containing 25 or 30 per cent of fat. For this and 

 other reasons it is advisable to use a special test with which to 

 measure the amount of acid developed in the cream. There are 

 two acid tests in general use now in creameries, viz., " Mann's 

 Test " and the " Farrington Test." 



Mann's Test. — Mann's test consists of measuring the acid in 



Fig. 75. — A creamery equipped with glass enameled tanks and vats. 



the cream by means of an alkali of a deiinite strength. The kinfl 

 of alkali used is usually a tenth normal solution of caustic potash 

 (KOH) or caustic soda (NaOH). These solutions can be made 

 up very cheapl)' or bought from the supply houses. INIann's 

 test is based upon measuring out 50 c.c. of cream by means of a 

 pipette. While the test is based on 50 c.c. of cream a 25 c.c. 

 pipette can be used, and the reading multiphed by two, thus 

 avoiding the necessity of using so much cream. Even a smaller 

 pipette could be used, but 25 c.c. is preferable to a smaller quan- 

 tity, which would increase the danger of error. A few drops of an 



