306 



Common Science 



FIG. 165. Filling a bottle with oxygen. 



first, then put the cork into the test tube. Put one end of a 

 2-foot piece of rubber tubing over the glass tube and put 

 the other end into a pan of water. 



Fill a flask or bottle to the brim with water, letting it 

 overflow a little; hold a piece of cardboard firmly over 

 the mouth of the bottle; turn the bottle upside down 

 quickly, putting the mouth of it under water in the pan; 

 take the cardboard away. The water should all stay in the 

 bottle. 



Now shove the rubber tube into the neck of the bottle 

 until it sticks up an inch or two. During this experiment, 

 be careful not to let the neck of the bottle or flask pinch the 

 rubber tubing; small pieces of wood or glass tubing laid 

 beside the rubber tubing where it goes under the run of the 

 neck will prevent this. 



Hold the test tube, tightly corked, over the flame of a 

 burner, keeping the tube at a slant and moving it slightly 

 back and forth so that all the material in it will be thoroughly 



