A geological inquiry respecting the water-bearing strata of the country around London, with reference especially to the water-supply of the metropolis

J. Van Voorst, 1851 - 240 pages

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Page 164 - DEGREES OF HARDNESS AND DEGREES OF ALKALINITY EXPLAINED. Degrees of Hardness. — Each degree of hardness indicates as much hardness as would be produced by one grain of chalk per gallon held in solution in the form of bicarbonate of lime, free from any excess of carbonic acid. The degree of hardness caused by a lime salt depends, not on the state of combination of the calcium it contains, but on the quantity of the calcium.

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