PREFACE. Vll 



and the laws of organic chemistry in particular, in 

 their applications to agriculture and physiology ; 

 to the causes of fermentation, decay, and putre- 

 faction ; to the vinous and acetous fermentations, 

 and to nitrification. The conversion of woody 

 fibre into wood- and mineral-coal, the nature of 

 poisons, contagions and miasms, and the causes 

 of their action on the living organism, have been 

 elucidated in their chemical relations. 



I shall be happy if I succeed in attracting the 

 attention of men of science to subjects which so 

 so well merit to engage their talents and energies, 

 perfect agriculture is the true foundation of all 

 trade and industry it is the foundation of the 

 riches of states. But a rational system of agri- 

 culture cannot be formed without the application 

 of scientific principles; for such a system must 

 be based on an exact acquaintance with the 

 means of nutrition of vegetables, and with the 

 influence of soils and action of manure upon 

 them. This knowledge we must seek from che- 

 mistry, which teaches the mode of investigating 

 the composition and of studying the characters of 

 the different substances from which plants derive 

 their nourishment. 



