MATTER AND ENERGY 65 



We also might add that matter cannot be created by 

 man. If you think it can be created, make some salt, 

 or carbon dioxide, or a chair, without taking any material 

 out of which to make it. We can change the form of 

 matter, but we cannot create or destroy it. The law of 

 the conservation of matter is: Matter cannot be destroyed 

 or created, but can be transformed. 



48. States of Matter. There are three forms or 

 states in which matter exists, namely, solids, liquids, 

 and gases. The molecules of which all material is com- 

 posed are moving rapidly, and they are never perfectly 

 at rest. 



When matter is in the form called a solid, as ice and 

 iron are at ordinary temperatures, the molecules are held 

 within a given space by the force of attraction which 

 they have for one another. They cannot move enough 

 to change the shape of the solid, commonly speaking. 



When the molecules are made active by the application 

 of sufficient heat, their speed becomes so great that much 

 of the force of attraction which they have for one another 

 is overcome; then the molecules of matter form what is 

 known as a liquid. In liquids the molecules move over 

 or about one another with such speed and ease that the 

 liquid will take the shape of the vessel containing it. 

 The reason that liquids can be poured from one vessel to 

 another is because of the ease with which the molecules 

 move. 



If sufficient heat is applied to matter in the liquid 

 state, the molecules become so active and move about 

 with such speed that the force of attraction which they 

 have for one another is completely overcome, and they 

 continue to bounce about like a tennis ball batted by two 

 players. Matter in this state is called a gas. Any quantity 



