74 



GENERAL SCIENCE 



Experiment 14. Fit a bottle with a one-hole rubber stopper 

 and attempt to pour water into it through a thistle tube (Figure 



69). What property of matter is 

 demonstrated by this experiment? 

 Experiment 15. Place a cork 

 with a small piece of lighted candle 

 on it in a jar of water. Invert a 

 small jar over the cork and force 

 . it down into the water in the jar. 



FIG. 69. Impenetrability is one of 

 the general properties of matter. 



FIG. 70. 



The candle may be seen burning below the level of the water in 

 the first jar (Figure 70). 



Weight of the Atmosphere. The atmosphere is drawn 

 toward the center of the earth as all other substances are, 

 and since weight is the measure of this force, air has 

 weight. - 



Experiment 16. Exhaust the air from the hollow globe of a 

 Florence flask and weigh the flask carefully on a suitable balance. 

 Then admit air to the flask and weigh again (Figure 71). What is 

 the result? A cubic foot of air weighs a little more than one and 

 one quarter ounces. 



Air Pressure. Since air has weight, it must exert 

 pressure upon all bodies immersed in it. If a small 

 hand glass is placed on the receiver of an air pump and 



