Result of inquiries as to quantities of water required per acre for irrigated lands : and the supply of sewage obtainable from the metropolis. May, 1849.

  • London (England). Metropolitan Commission of Sewers.
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

Credit: Result of inquiries as to quantities of water required per acre for irrigated lands : and the supply of sewage obtainable from the metropolis. May, 1849. Source: Wellcome Collection.

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    Still, as the surface soil in most ordinary cases partakes very materially of the com¬ position of the substratum or rock on which it rests, it can hardly fail of producing useful practical results to the owner of lands, suitable for irrigation either by com¬ mon or sewer water, if we examine the quantity of moisture contained in various soils when saturated with water. Upon this question, M. Schubler, in a work trans¬ lated by Mr James Hudson, gives the results of a series of trials in which he evinced considerable skill and industry (Jour. R. A. S.} vol. i, p. 182). This distinguished German chemist thus explains the objects of the investigation, and the necessary precautions required for the experiments to determine what he denominates “ the power of the earths to contain water.” “ We understand” he observes, “by the power of the earths to hold or contain water, their property of receiving and retaining more or less water within their interstices, without allowing it again to flow away by dropping. It is of the greater importance to vegetation, as on it depends the quantity of the means of aqueous nourishment the soil is in a condition to receive and supply to the roots of plants.” The power of an earth to contain water may be found in the following manner :— We take 400 grains of the earth to be examined, and dry it at a temperature of about 144^ degrees Fahrenheit, until it ceases to lose weight. We put the dried earth on a round filter, consisting of unsized paper, and which had been previously weighed in its thoroughly moistened state and laid in a glass funnel or on a linen stretched over a frame. We now pour over the earth lying on a filter water, until it is fully moistened and saturated. We then bring it, while remaining in this wet state, to the balance. It was by this mode that the Professor determined the amount of water in the soils, as given in the following table*:— Real quantity of water in a cubic foot, when saturated. Weight of a cubic foot when dry. Weight of a cubic foot, when saturated with water. Calcareous sand . 31.81bs. 113.61bs. 141.31bs. Silicious sand 27.3 111.3 136.1 Sandy clay 38.8 97.8 129.7 Loamy clay 41.4 88.5 124.1 Stiff clay, or brick earth 45,4 80.3 119.6 Pure grey clay 48.3 75.2 115.8 Pipe clay 47.4 47.9 102.1 Garden mould 48.4 68.7 102.7 An Arable soil 40.8 84.5 119.1 Fine sUty marl 35.6 112.0 140.3 Gypsum powder 27.4 91.9 127.6 Fine carbonate of lime 47.4 53.7 103 5 Fine carbonate of magnesia 62.6 15.8 76.3 * The reason why the real quantity of moisture in a soil cannot be accurately determined by merely comparing the weight of a given measure when dry, with the same measure when wet, is that some soils when they are dried materially contract, and expand when wet.