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Percolation in colloidal soils, considered in relation to swelling and cohesiveness

Published online by Cambridge University Press:  27 March 2009

F. Hardy
Affiliation:
(Imperial College of Tropical Agriculture, Trinidad, B.W.I.)

Extract

(1) The results of experiments on the rate of horizontal flow, and on the rate of gain in mass, or kerosene and of water in fine and crumb fractions of certain West Indian colloidal soils, comprising three siliceous soils containing different amounts of calcium carbonate, and two lateritic soils, are described and tabulated.

(2) The methods of experimentation employed were those elaborated by Green and Ampt, whose equations were found, however, not to fit the values obtained, as is to be expected.

(3) The siliceous soils examined possess relatively high swelling coefficients, and their component particles, when wetted, cohere to a greater or lesser extent, depending on lime content. These properties appear to account for the relatively low rates of permeability to water in these soils. Lateritic soils, on the other hand, possess low swelling coefficients, and low cohesiveness; water percolates through them relatively very rapidly.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1925

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References

page 434 note 1 J. Agric. Sci. 1923, 13, pp. 243CrossRefGoogle Scholar and 340; 1925, 15, p. 420Google Scholar; J. Phys. Chem. (in press).

page 434 note 2 J. Agric. Sci. 1911, 4, p. 1.CrossRefGoogle Scholar

page 437 note 1 J. Phys. Chem. 1906, cited by green and Ampt, loc. cit. p. 10.

page 438 note 1 Leather, (J. Agric. Sci. 1911, 4, p. 303) has objected to the assumption made by Green and Ampt that a granular soil may be regarded as a system of capillaries, so that the Green and Ampt equations for horizontal percolation are not strictly applicable even to non-colloidal soils.CrossRefGoogle Scholar

page 438 note 2 No attempt has been made in this investigation to discover the possible significance of the factor “n” in the data recorded in Tables II and III. It is noteworthy, however, that its magnitude appears to depend largely on the degree of packing of colloidal soils, and that experiments with siliceous fine soils appear always to give values for “n” that are less than 2·00, when water flow is being measured.

page 439 note 1 It was noticed that the permeability of the siliceous soils, especially that containing a minimum amount of lime, decreased very rapidly during the passage of water through the soil tubes. This was doubtless due to the fact that swelling and cohesion were not complete at the end of the horizontal flow experiments. In certain cases, the soil tubes were cracked by the pressure developed during permeation. These effects were not produced by the lateritic soils.

page 442 note 1 See Fisher, , J. Agric. Sci. 1923, 13, p. 204Google Scholar

page 442 note 2 Trans. Roy. Soc. Canada, 1913, 7, p. 105;Google Scholar 1914, 8, p. 133Google Scholar; also J. Amer. Soc. Agron. 1915, 6, p. 283.Google Scholar

page 442 note 3 Mem. Dept. Agri. India, Chem. Ser. 1921, 6, 3, p. 155.Google Scholar

page 442 note 4 See the review by Stiles, , New Phytologist, 1921, 1922, 1923, 20, Nos. 2, 3, 4, 5; 21, Nos. 1, 2, 3, 4; 22, Nos. 1, 2, 3, 4, 5.CrossRefGoogle Scholar