A f EAR IX SCIENCE 



Definition of matter. 



all its forms and with the changes and processes to which 

 it is subject. Some of the physical sciences are Chem- 

 istry, Physics, and Physical Geography. Chemistry deals 

 with changes in substances which result in the formation 

 of new substances. For instance, the burning of wood 

 is a chemical process. Physics treats of changes and 

 processes that do not result in the formation of other 

 substances. In Physical Geography a study is made of 

 weather, climate, and land forms, and their relation to 

 man. 



For the substance dealt with 

 in this general science 

 the term matter is 

 used. According to 

 most authors, matter 

 is anything which oc- 

 cupies space or has 

 weight. Thus it will 

 be seen at once that 

 wood is matter, and 

 that water is matter. 

 Matter, however, does 

 not exist in visible 

 form only, for gases, 

 too, are matter. 



Is air matter? An 

 empty tumbler, that is, a tumbler which does not 

 contain anything that can be seen, is pushed mouth 

 downward half under the surface of the water in 



Fig. 1. If an inverted tumbler is 

 pushed mouth downward into water, 

 the air within the tumbler keeps the 

 water from entering it. 



