Proceedings of the Yorkshire Geological Society, Band 1


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Seite 347 - ... feet. They are covered by a wide mantle of perpetual snow, and numerous cascades pour their waters through the woods into the narrow channel below. In many parts magnificent glaciers extend from the mountain side to the water's edge. It is scarcely possible to imagine anything more beautiful than the beryl-like blue of these glaciers, and especially as contrasted with the dead white of the upper expanse of snow.
Seite 4 - The animal tribes are exposed to many severe sufferings ; and we know that, as " the world which once was, being overflowed with water, perished," so " the heavens and the earth which are now...
Seite 98 - The first colonists of Virginia found a country, the soil of which was similar to that mentioned above; harvests of wheat and tobacco were obtained for a century from one and the same field without the aid of manure, but now whole districts are converted into unfruitful pasture land, which without manure produces neither wheat nor tobacco. From every acre of this land, there were removed in the space of one hundred years 1,200 Ibs. of alkalies in leaves, grain, and straw...
Seite 409 - Professor of Botany in King's College, London, as follows:—" The office of ferns and the other plants of the coal formation, and the final cause of their predominance in that period, would seem from numerous facts to be, that by their assimilation of the carbon, and liberation of the oxygen with which it was combined, they might purify the atmosphere, and bring it into a condition in which it would become respirable by reptiles, beasts and man. That such was the primitive condition of the atmosphere,...
Seite 108 - ... nitrogen of the atmosphere takes part in the processes of assimilation of plants and animals ; on the contrary, we know that many plants emit the nitrogen, which is absorbed by their roots, either in the gaseous form, or in solution in water. But there are on the other hand numerous facts, showing, that the formation in plants of substances containing nitrogen, such as gluten, takes place in proportion to the quantity of this element which is conveyed to their roots in the state of ammonia, derived...
Seite 113 - The proportion of this salt does not vary perceptibly in the soil of corn-fields, because it is again conveyed to them as manure in the form of putrefying straw. But this is not the case in a meadow, and hence we never find a luxuriant crop of grass * on sandy and calcareous soils, which contain little potash, evidently because one of the constituents indispensable to the growth of the plants is wanting.
Seite 98 - The property on which this depends is that of its invariably containing potash and soda. Alumina exercises only an indirect influence on vegetation, by its power of attracting and retaining water and ammonia ; it is itself very rarely found in the ashes of plants,* but silica is always present, having in most places entered the plants by means of alkalies.
Seite 99 - Again, how does it happen that wheat does not flourish on a sandy soil, and that a calcareous soil is also unsuitable for its growth, unless it be mixed with a considerable quantity of clay?* It is because these soils do not contain alkalies in sufficient quantity, the growth of wheat being arrested by this circumstance, even should all other substances be presented in abundance.
Seite 112 - Most plants, perhaps all of them, contain organic acids of very different composition and properties, all of which are in combination with bases, such as potash, soda, lime or magnesia. These bases evidently regulate the formation of the acids, for the diminution of the one is followed by a decrease of the other : thus, in the grape, for example, the quantity of potash contained in its juice is less, when it is ripe, than when unripe ; and the acids, under the same circumstances, are found to vary...
Seite 98 - From every acre of this land there were removed, in the space of one hundred years, 12,000 pounds of alkalies in leaves, grain, and straw. It became unfruitful, therefore, because it was deprived of every particle of alkali which had been reduced to a soluble state, and because that which was rendered soluble again in the space of one year was not sufficient to satisfy the demands of the plants.

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