CHYMISTRY 



APPLIED TO 



AGRICULTURE 



CHAPTER I. 



GENERAL VIEWS OF THE ATMOSPHERE, CONSIDERED IN ITS 

 EFFECTS UPON VEGETATION. 



In order to judge of the influence which the atmosphere 

 exercises over vegetation, it is necessary to be acquainted 

 with the peculiar and characteristic properties of each of 

 the elements of which it is composed, and to study their 

 action upon terrestrial bodies. 



The gases, azote and oxygen, are the two fluids, of 

 which the atmosphere is essentially composed ; they are 

 found in uniform proportions, even in the highest regions 

 from which they have been brought. M. Gay-Lussac has 

 established this fact, by a comparative analysis of the air 

 taken from a height of twenty-three thousand feet, and of 

 that which is upon the surface of the earth. 



There are certain other fluids, which are uniformly 

 found in the atmosphere, but in very variable proportions ; 

 the principal of these are carbonic acid, water, the elec- 

 tric and magnetic fluids, light, and heat. The two last 

 mentioned exercise a very marked influence, not only on 

 vegetation, but on all the phenomena which terrestrial 

 bodies present to our notice ; and though they do not 

 enter essentially into the composition of the atmosphere, 

 their action is so closely united with that of its principal 

 constituents, as to be nearly inseparable from them. In 

 order that the action of the atmosphere may be better 

 understood, I propose to treat separately of all the fluids it 

 contains, and afterwards to show the phenomena which 

 the application of them to agriculture exhibits. 



