22 



CHEMISTRY OF SOIL. 



CHAPTER II. 



CHEMICAL CONSTITUTION OF ROCKS 

 AND SOIL. 



34. The geologist, the mineralogist, the chemist, 

 each views rocks with a different eye. The geolo- 

 gist regards the rocky mass ; the mineralogist, the 

 simple minerals composing the rock ; the chemist, 

 the simple elements which compose the minerals. 



35. Elements are substances which have not as 

 yet been proved to be compound, as oxygen and hy- 

 drogen among the gases, or iron and lead among 

 metals. Minerals are called simple which have cer- 

 tain definite, external, physical characters, though 

 they may be composed of several elements. Rocks 

 are called compound, which consist of several sim- 

 ple minerals, as granite which consists of quartz, fel- 

 spar, and mica. 



36. The only point of view which the farmer 

 takes is, that of the chemist ; his pole-star is " fruit 

 and progress ;" and his philosophy, guided by this, 

 teaches the nature and mode of action of the several 



