TESTING ACIDITY OF MILK AND MILK PRODUCTS IOO, 



acidity than the truth. It has also the disadvantage of 

 requiring a calculation to obtain the results in the 

 form of per cent., and any other form of statement 

 ought not to be used. 



The alkaline-tablet test has the advantage of giving 

 the results directly in percentages. The tablets do not 

 change if kept dry, and the use of a fresh solution 

 avoids all uncertainity of strength. The cost of trans- 

 portation is insignificant compared with that of the 

 neutralizer. The tablets are not always absolutely 

 uniform in strength of alkali, but the variations are 

 not sufficient to make serious differences in results. 



In the Purdue modification, the small bottles of al- 

 kali do not lose strength so long as they are kept 

 properly stoppered, and therefore any number can be 

 ordered at a time. Being more concentrated than 

 Mann's neutralizer, the cost of transportation is less. 

 The solution is more quickly and conveniently prepared 

 than the tablet solution. The strength of the small 

 bottles of alkali is said to be more strictly uniform than 

 in the case of tablets. By high dilution of the alkali 

 solution when used, the chance of error is reduced. 



TESTING THE ACIDITY OF WHEY 



Whey may be tested by any of the methods de- 

 scribed. Owing to the comparatively low acidity of 

 whey in the operation of cheese-making, it is desirable 

 either to have the alkali dilute ( i cc. of alkali equal to 

 .01 per cent, acid), or else to take twice as much whey 

 for testing as in the case of cream, the final results 

 being corrected by dividing by 2. The whey should 

 be free from particles of curd, since curd has the 



