MATTER 3 



a glass jar. The water rises in the tumbler only 

 about iV of an inch. Evidently there is something within 

 the tumbler which prevents the water from rising to fill 

 it. The tumbler is then tilted sidewise until the mouth 

 comes just above the surface of the water. Bubbles of 

 air escape. If the tumbler is then again pushed into the 

 water, the water will rise into it. Evidently, in the first 

 instance^ it was air that kept the water from rising into 

 the tumbler. Since the water rose higher in the tumbler 



Fig. 2. A globe was balanced after part of the air was pumped 

 from it. It was found to be heavier after the air was again allowed 

 to enter it. 



after the air had escaped, this experiment proves that air 

 occupies space. In fact, air is present usually in spaces 

 which appear empty. 



A hollow brass globe fitted with a stop cock is accu- 



