A CHYMISTRY APPLIED TO AGRICITLTTJKE, 



ARTICLE I. 



Of the Ponderable Fluids contained in the Atmosphere, 



The ponderable fluids contained in the atmosphere are 

 azote, oxygen, carbonic acid, and water. 



1. Azote constitutes nearly four fifths of the atmospher- 

 ic composition, and yet, by a singular caprice of nature, it 

 exercises less influence on the substances of the three 

 kingdoms, than any one of the other principles contained 

 in the atmosphere. This gas is found in small quantities 

 in some of the products of vegetables, and abundantly in 

 those of animals. The presence of azote in some of the 

 products of vegetation is to be accounted for by its pres- 

 ence in the water, which plants imbibe from the atmo- 

 sphere, and in those manures by which plants are nour- 

 ished, and of which it forms one of the principal constitu- 

 ents. 



In animals, in which azote is more abundant than in 

 plants, the food by which they are nourished, and the air 

 which is inhaled by respiration,^ concur equally to account 

 for its presence. The .experiments of Messrs. de Hum- 

 boldt and Proven9a} upon fish ; Spallanzani upon reptiles ; 

 and those of Messrs. Davy, Pfaff", Enderson, Edwards,^ 

 Dulong, &c. upon man, leave no doubt as to the absorp- 

 tion of azote during respiration ; but this absorption is 

 unequal and irregular, varying according to circumstances ; 

 this gas differing from oxygen in this particular, at least 

 in its effects upon animal and vegetable economy. The 

 action of azote is, so far as it is known, of such trivial im- 

 portance, that we are at a loss to account for the propor- 

 tion which nature has assigned it in the composition of 

 the atmosphere. It is supposed by some, that all the gas- 

 es, all the vapors, and all the exhalations which arise from 

 the surface of the earth, form in the atmosphere an im- 

 mense magazine of azote, which is returned thence as it 

 is needed, either for the support of animal and vegetable 

 life, or to produce those phenomena of composition and 

 decomposition, which are constantly renewing the surface 

 of the globe. The specific gravity of pure azote is to 

 that of the atmosphere in the proportion of 9,691 ta 

 10,000. 



2. Oxygen gas forms about one fifth of the atmosphere. 



