LABOEATORY EXERCISES 



EXERCISE 1 

 AIR TAKES UP ROOM 



Apparatus and Materials. Narrow-mouth bottle, water, thistle 

 tube or funnel, wide-mouth bottle (about 250 cu.cm.), two-hole rubber 

 stopper that fits the wide-mouth bottle, a glass plug or a round pencil, 

 biscuit cutter, oil-can used for sewing machine (or a carpenter's oil- 

 can), tin funnel. 



a. Fill a narrow-mouth bottle with water, and invert it over 

 a sink or a jar. Tell how the water comes out of the bottle. 

 Why does it not come out in a stream? 



6. Close the small end of the funnel or thistle tube tightly 

 with your finger (Fig. 1), and put the 

 large end into a deep pan or pail nearly 

 filled with water. Does water enter? 

 Remove your finger, and tell what 

 happens. Tell why it happens. 



N. B. You can carry out this ex- 

 periment with a piece of glass tubing 

 open at both ends. 



c. Now put the stem of the funnel 

 (or thistle tube) through one of the 

 holes of the two-hole rubber stopper 

 (Fig. 2). The glass slips through the 

 rubber easily if you wet the walls of the hole with water. 

 Do not force the glass tube into the hole roughly, but give it 

 a twisting motion. 



Put into the wide-mouth bottle a layer of water so deep that 

 the lower end of the funnel stem will reach just below the sur- 



1 



FIG. 1. 



