HOW SOILS ABE MADE 71 



the decay of plants and animals; the mineral matter 

 from the decay of rocks. 



/. \ n in unxT 



When the weather is sufficiently cold, fill some glass bottle of 

 convenient size with v at< r — an old ink bottle uill ansiccr. Stop 

 up the mouth of the bottle and set it out to freeze. By the ex- 

 pansion of the water in freezing the bottle xciil be broken. 



Questions 



, 1. What .!<> m moan by the term soil? 2. Is it proper to 

 speak of soil as dirt? Why? 3. To what part of the earth's 

 surface* does the word soil refer? 4. What is the difference 

 en a rock and n stone? 5. What sort of fragments make 

 up the greater part of all soils? f>. How aiv soils formed? 

 7. What substance la noat MtiVI in making soils? 8. Describe 

 the mechanical action of water in forming soils. 9. llow does 

 the chemical act inn <>f water help to form soils? 10. What 

 other agents bcsi.h- prater form soils? 11. From what sources 

 do soils draw their supply of organic matter? 



