METHODS OF TESTING THE ACIDITY OF MILK 147 



(caustic soda), a 50 cc. burette and 50 cc. of the 

 sample to be tested. The operation is carried out in 

 the usual manner (p. 139). To calculate th results 



FIG. 39& MARSCHALL APPARATUS FOR ACIDITY-TESTING 



into percentage of lactic acid in the material tested, 

 multiply the number of cubic centimeters of alkali used 

 by 0.018. The method as originally given is inconve- 

 nient and much less used than formerly. The cost of 

 transportation of so dilute a solution of alkali is need- 

 lessly increased in comparison with tablets or normal 



