C is 3 



It is shewn by various researches, that the constitu- 

 tion of the atmosphere has been always the same since 

 the time that it was first accurately analysed ; and 

 this must in a great measure depend upon the powers 

 of plants to absorb or decompose the putrifying or de- 

 caying remains of animals and vegetables, and the 

 gaseous effluvia which they are constantly emitting. 

 Carbonic acid gas is formed in a variety of processes 

 of fermentation and combustion, and in the respiration 

 of animals, and as yet no other process is known in 

 nature by which it can be consumed, except vegeta- 

 tion. Animals produce a substance which appears to 

 be a necessary food of vegetables ; vegetables evolve 

 a principle necessary to the existence of animals ; and 

 these different classes of beings seem to be thus con- 

 nected together in the exercise of their living functions 

 and to a certain extent made to depend upon each 

 other for their existence. Water is raised from the 

 ocean, diffused through the air, and poured down 

 upon the soil, so as to be applied to the purposes 

 of life. The different parts of the atmosphere are 

 mingled together by winds or changes of tempera- 

 ture, and successively brought in contact with the 

 surface of the earth, so as to exert their fertilizing in- 

 fluence. The modifications of the soil, and the ap- 

 plication of manures are placed within the power of 

 man, as if for the purpose of awakening his industry 

 and of calling forth his powers. 



The theory of the general operation of the more 

 compound manures may be rendered very obvious by 

 simple chemical principles j but there is still much 



