MATTER AND ITS PROPERTIES 



29 



bubbles in the bowl of water? Now close the delivery tube and 



pour more water into the funnel tube. Does the water go into 



the bottle as before? Is air matter? In this respect air is 



like all other matter. 



Air, however, has 



other properties 



which enable us to 



distinguish it from 



other gases, such as 



hydrogen or carbon 



dioxide. 



Other examples of 

 general properties of 

 matter are weight, 

 inertia, and porosity. F IG . 21. 



We can easily tell salt from sugar by the taste. If we 

 examine a piece of chalk and a piece of iron, we find tha,t 

 the chalk is more brittle than the iron. The iron is also 

 quite heavy and will scratch a stone, while the chalk is 

 light and will leave a white mark on the stone. Glass 

 and wood have quite different properties. Glass is heavier 

 than water, transparent, brittle, and very hard. Wood 

 on the other hand is lighter than water, opaque, not 

 so brittle as glass, and so soft that it may be cut easily 

 with a knife. These properties are special properties, 

 and we might make a long list of them, for there are 

 enough to enable us to distinguish all the thousands of 

 substances that are known. Many of these properties 

 are relative, as we may have observed from the illustra- 

 tions given above. We say that a substance is harder 

 than another, or that it is more elastic, or that its color 

 is a deeper shade of red, and thus by comparison dis- 

 tinguish one substance from another. 



Measurement. It is necessary in our discussion of 



