METHODS OF TESTING THE ACIDITY OF MILK 151 



3. The alkali solution, in whatever form used, must 

 be kept from contact with the air as much as possible 

 to prevent changing strength. 



4. When alkaline tablets are used, prepare a fresh 

 solution in order to be sure of its strength, if there is 

 any reason for uncertainty. 



5. The alkaline tablets should be kept dry in well- 

 stoppered bottles. 



6. The tests should be made in a good light so that 

 one can easily see the appearance of the longer-lasting 

 pink color at the end of the reaction. 



7. The appearance of the pink color at the end of 

 the test can usually be more sharply seen by diluting 

 the material examined with three or four times its vol- 

 ume of distilled water. 



