ON MILK AND MILK-TESTING 4I 



How may cream-testing bottles be calibrated by 

 the use of a plunger? 



In the same manner as milk-testing bottles, ex- 

 cepting thSt a larger plunger is used. Each c. c. 

 of space occupied by the plunger equals 5 per cent 

 in the neck of the bottle. 



What precautions should be taken in calibrating 

 with a plunger? 



1. Have the surface of the liquid level with the 

 zero mark. 



2. Remove any liquid adhering to the walls of 

 the neck above zero mark. 



3. The plunger should be dry before inserting. 



4. There should be no air bubbles in the neck 

 during calibration. 



5. The temperature of the plunger should be the 

 same as that of the liquid. 



6. While calibrating do not allow heat from the 

 hand to cause the liquid to expand. 



How may testing bottles be calibrated by use of 

 scales ? 



Fill the bottle to the zero mark with water and 

 balance it on the scales. Add i gram of water. The 

 surface of the liquid should then be exactly on the 

 5 per cent mark. On addition of another gram of 

 water the surface should be level with the 10 per 

 cent mark. Each two-tenths of a gram equals i 

 per cent in the neck of the bottle. By this means 

 any part of the neck of milk or cream bottles may 

 be calibrated. 



