ON MILK AND MILK-TESTING 45 



If the acid is too strong, how may it be corrected? 



1. By adding the acid to a small quantity of 

 water. 



2. By using less acid in testing. 



3. By cooling both milk and acid before mixing. 



If the acid is too weak, how may it be corrected? 



1. By using a larger quantity. 



2. By warming both acid and milk before test- 

 ing. 



3. If ^rnuch too weak, the acid should be dis- 

 carded. 



Will the acid weaken with age? 



Not if kept in tightly stoppered containers. It 

 will, however, absorb water from the air and be- 

 come weaker if left in open vessels. 



Why is it that acid which was of the proper 

 strength in winter will be apparently too 

 strong in summer? 

 During summer the acid, milk and apparatus has 



a higher temperature, so the acid appears stronger. 



The remedy is to cool both acid and milk. 



What kind of stoppers should be used in bottles 

 containing sulphuric acid? 

 Glass stoppers only. The acid and its fumes 

 destroy both cork and rubber. 



How may red spots, produced on clothing by acid, 

 be removed? 



If the acid has not been in contact with clothing 



