THE BABCOCK TEST SI 



(2) Clean the inside walls of the neck of the bot- 

 tle from adhering liquid before testing, 



(3) No air-bubbles should be allowed to adhere to 

 the tester when it is below the liquid. 



(4) The tester should be dry each time before using. 



(5) The temperature of the instrument, liquid and 

 bottle tested should be the same. 



(6) While making the test, do not hold the bottle 

 in the hand, because the heat of the hand will produce 

 expansion in the liquid and thus make the results in- 

 correct. 



Testers of the same form are made for cream-bot- 

 tles. Some difficulties are met in their use. In test- 

 ing bulb-necked bottles, the plunger does not enable 

 one to learn whether the bulb itself has the exact ca- 

 pacity it should. The wire which forms a part of the 

 instrument may interfere with the correct reading of 

 the meniscus. In cream-bottles with narrow necks, 

 it has been found necessary to have the first addition 

 of water reach one-half of the meniscus above the 

 zero mark in order to bring the bottom of the menis- 

 cus in the top of the neck on a level with the highest 

 mark of graduation, after the plunger is inserted. In 

 the case of wide-necked bottles, the water should be 

 run into the bottle at the start so that the meniscus is 

 on a level with the zero mark, which then brings the 

 bottom of the meniscus at the top of the neck on a 

 level with the highest mark of graduation, after the 

 plunger is inserted. 



(3) Testing with mercury. From an accurately 

 graduated burette measure 2 cc. of clean mercury 

 into the bottle to be tested. Then push down into 



