36 The Advantages of Chemical Science. 



culturist lived, however, sufficiently Ion? to alter his opinion. 

 The results of his later and most refined observations, led him 

 to the conclusion, that no single material afforded the food of 

 plants: the general experience of fanners had long before con- 

 vinced the unprejudiced of the truth of the same opinion, and 

 that manures were absolutely consumed in the process of vege- 

 tation. The exhaustion of soils by carrying off corn crops 

 from them, and the eifects of feeding cattle on lands, and of 

 preserving their manure, offer fapiilliar illustrations of the prin- 

 ciple ; and several philosophical inquirers, particularly Has- 

 aenfratz and Saussure,have shown by satisfactory experiments, 

 that animal and vegetable matters deposited in soils are ab- 

 sorbed by plants, and become a part of their organized matter. 

 But though neither water nor air, nor earth, supplies the whole 

 of the food of plants, yet they all operate in the process of 

 vegetation. The soil is the laboratory in which the food is 

 prepared ; no manure can be taken up by the roots of plants 

 unless water is present, and water or its elements exist in all 

 the products of vegetation. — The germination of seeds does not 

 take place without the presence of air or oxygen gas; and in 

 the sun-6hinc, vegetables decompose the carbonic acid gas of 

 the atmosphere, the carbon of which is absorbed, and becomes 

 a part of their organized matter, and the oxygen gas, the 

 other constituent, is given off, and, in consequence of a variety 

 of ugencics, the economy of vegetation is made subservient to 

 the general order of the system of nature. It is shown by 

 • various researches, that the constitution 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 atid gas 

 is formed in a variety of processes cf fermentation and com 

 bustion, and in the respiration of animals, and as yet no other 

 process is known in nature by which it can be consumed, ex- 

 cept vegetation. Animals pi oduce a substance which appears 

 to be a necessary food of vegetables ; vegetables evolve a prin- 

 ciple necessary to the existence of animals, and these different 

 classes of beings seem to be thus connected 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 up- 

 qp the soil so as to be applied to the purposes of life. The 

 different parts of the atmosphere 8re mingled together by 

 winds or changes of temperature, and successively brought in 

 contact with the surface of the earth, so as to exert their fer- 

 tilizing influence. The modifications of the soil ( and the npplfcj 



