Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy.

  • Davy, Humphry, Sir, 1778-1829.
Date:
1813
Catalogue details

Licence: Public Domain Mark

Credit: Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy. Source: Wellcome Collection.

    29/428 (page 15)
    ther in the exercise of their living functions, and to a certain ex- tent 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 temperature, and successively brought in contact with the surface of the earth, so as to exert their ferti- lizing influence. The modifications of the soil, and the applica- tion 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; but there is still much to be discovered with regard to the best methods of rendering animal and vegetable substances soluble; with respect to the processes of decomposition, how they may be accelerated or retarded, and the means of producing the greatest effects from the materials employed: these subjects will be attended to in the Lecture on Manures. Plants are found by analysis to consist principally of charcoal and aeriform matter. They give out by distillation volatile com- pounds, the elements of which are pure air, inflammable air, coally matter, and azote, or that elastic substance which forms a great part of the atmosphere, and which is incapable of supporting combustion. These elements they gain either by their leaves from the air, or by their roots from the soil. All manures from organized substances contain the principles of vegetable matter,