2 LABORATORY EXERCISES 



face of the water. Close the second hole in the rubber stopper 

 by means of a glass plug or a round pencil. See that the 



rubber stopper is pressed tightly into the mouth of 



the bottle; then pour water into the funnel, keeping 



the funnel full. 



Does any water run into the bottle? Does it 



continue to run in? Tell why. Now open the 



second hole of the stopper, and tell the result. 



Explain it. 



How do these experiments show that air takes 



up room? 



d. Examine a biscuit cutter. If you were making 

 FIG. 2. one out of a tin box cover, why would it be a good 



plan to make a hole in the top? 



Where is the faucet inserted into a vinegar or molasses 

 barrel? Why is a small hole (vent) drilled into the top of the 

 barrel? Is there any similar opening in the sewing-machine 

 oil-can or the oil-can used by carpenters? How is oil obtained 

 from such a can? Why? 



e. Simpler Form. You can carry out the 

 experiment of c with a small-mouth bottle, such 

 as a vinegar or ketchup bottle, and a kitchen 

 funnel (Fig. 3). Make the opening of the funnel 

 stem smaller by closing it partly by means of a 

 wooden plug, such as a pencil. Put the funnel 

 stem loosely into the mouth of the bottle, and 

 pour water into the funnel. How does the water 

 run into the bottle, in a stream or by spurts? 

 Now wind around the funnel stem a strip (about 

 1 cm. wide) of wet muslin, until the funnel 

 stem can be fitted tightly into the mouth of 

 the bottle. Then pour water into the funnel, 

 and tell how the water enters the bottle. FIG. 3. 



