OF AGRICULTURE. 191 



the effects of water, is a fact so well established, that 

 it needs only to be mentioned. There has been 

 an universal mingling of the loose materials of soil, 

 derived from the worn down rocks and decayed 

 vegetable matter. Great uniformity of the chemical 

 composition, characterizes soils, as, also, more or less ; 

 the rocks, from which they have been formed, 



CHAPTER II. 



THE CHEMICAL INGREDIENTS OP ROCKS AND SOILS, 



The geologist, mineralogist, and the chemist, eacri 

 view rocks with a different eye. The geologist regards- 

 the rocky mass ; the mineralogist, the simple minerals- 

 composing the rocks > the chemist, the simple elements 

 which compose the mineral. 



Elements are substances which as yet have not 

 been proved to be compound ; as oxygen and hydrogen 

 among the gases, iron and lead among the metals. 



The only point of view the farmer takes is that of 

 the chemist. His pole-star is fruit and progress; 

 and his mind, directed by the chemist, is taught the 

 nature and mode of action of the several elements of 

 the minerals, 



As 4 far as known, seven simple minerals compose 

 tho most important rocks, viz : quartz, mica, feldspar, 

 talc, hornblende, augite and carbonate of lime. Other 

 minerals are found in rocks, but the&e seven compose 



