175 



CHAPTER XV. 



CONNECTED RECAPITULATION OF THE VARIOUS 

 TOPICS TREATED IN THE PRECEDING CHAP 

 TERS. 



We have now gone over nearly all of the ground 

 that I have thought it advisable to traverse, in a trea 

 tise of this character. It may be of advantage, in 

 closing, to give a condensed view of the whole sub 

 ject, recapitulating the main points that have been 

 illustrated and explained. 



This will serve as a species of index, and will, at 

 the same time, recall such arguments and facts rela 

 tive to the various divisions indicated, as may have 

 been forgotten. 



CHAPTER I. 



The art of cultivating the soil ; what this is, in its 

 proper meaning. 



Plants. Great division of them into organic and 

 inorganic substances. Organic bodies burn away ; 

 inorganic bodies incombustible. 



Names of organic bodies : carbon, hydrogen, nitro 

 gen, oxygen. 



Carbon, a solid, of which charcoal, plumbago, and 

 the diamond are forms. Hard, and combustible. 



Hydrogen, a gas, colorless, tasteless, inodorous, the 

 lightest body known. Inflammable, explosive when 

 mixed with air, extinguishes combustion, and will 

 not sustain life. n. / . 



