Elements of agricultural chemistry: in a course of lectures for the Board of Agriculture; delivered between 1802 and 1812

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Página 4 - Chemistry has for its objects all those changes in the arrangements of matter connected with the growth and nourishment of plants ; the comparative values of their produce as food ; the constitution of soils ; the manner in which lands are enriched by manure, or rendered fertile by the different processes of cultivation.
Página 39 - I found that corn sprouted much more rapidly in water positively electrified by the Voltaic instrument than in water negatively electrified; and experiments made upon the atmosphere shew that clouds are usually negative ; and as when a cloud is in one state of electricity the surface of the earth beneath is brought into the opposite state, it is probable that in common cases the surface of the earth is positive.
Página 175 - Water, and the decomposing animal and vegetable matter existing in the soil, constitute the true nourishment of plants ; and as the earthy parts of the soil are useful in retaining water, so as to supply it in the proper proportions to the roots of the vegetables, so they are likewise efficacious in producing the proper distribution of the animal or vegetable matter...
Página 154 - The next process, however, after that of heating, should be their separation, which may be easily accomplished by the sieve, after the soil has been gently bruised in a mortar. The weights of the vegetable fibres, or wood, and of the gravel and stones, should be separately noted down, and the nature of the last ascertained ; if calcareous, they will effervesce with acids ; if siliceous, they will be sufficiently hard to scratch glass ; and if of the common aluminous class of stones, they will be...
Página 296 - It tends to diminish likewise the nutritive powers of albumen from the same causes; and always destroys to a certain extent the efficacy of animal manures, either by combining with certain of their elements, or by giving to them new arrangements. Lime should never be applied with animal manures, unless they are too rich, or for the purpose of preventing noxious effluvia, as in certain cases mentioned in the last Lecture. It is injurious when mixed with any common dung, and tends to render the extractive...
Página 267 - Fish forms a powerful manure, in whatever state it is applied ; but it cannot be ploughed in too fresh, though the quantity should be limited. Mr. Young records an experiment, in which herrings spread...
Página 25 - If a person journeying in the night wishes to avoid being led astray by the ignis fatuus, the most secure method is to carry a lamp in his own hand. It has been said, and undoubtedly with great truth, that a philosophical chemist would most probably make a very unprofitable business of farming ; and this certainly would be the case, if he were a mere philosophical chemist ; and unless he had served his apprenticeship to the practice of the art as well as to the theory. But there is reason to believe...
Página 167 - Of these soils the last was by far the most, and the first the least, coherent in texture. In all cases the constituent parts of the soil which give tenacity and coherence are the finely divided matters ; and they possess the power of giving those qualities in the highest degree when they contain much alumina.
Página 169 - In all cases, the ashes of plants contain some of the earths of the soil in which they grow; but these earths, as...
Página 24 - Nothing is more wanting in agriculture, than experiments in which all the circumstances are minutely and scientifically detailed. This art will advance with rapidity in proportion as it becomes exact in its methods.

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