* Spread the bright treasure. l. 520. The practice of flooding lands long in use in China has been but lately introduced into this country. Besides the supplying water to the herbage in dryer seasons, it seems to defend it from frost in the early part of the year, and thus doubly advances the vegetation. The waters which rise from springs passing through marl or limestone are replete with calcareous earth, and when thrown over morasses they deposit this earth and incrust or consolidate the morass. This kind of earth is deposited in great quantity from the springs at Matlock bath, and supplies the soft porous limestone of which the houses and walls are there constructed; and has formed the whole bank for near a mile on that side of the Derwent on which they stand.

The water of many springs contains much azotic gas, or phlogistic air, besides car∣bonic gas, or fixed air, as that of Buxton and Bath; this being set at liberty may more readily contribute to the production of nitre by means of the putrescent matters which it is exposed to by being spread upon the surface of the land; in the same manner as frequently turning over heaps of manure facilitates the nitrous process by imprisoning atmospheric air in the interstices of the putrescent materials. Water arising by land∣floods brings along with it much of the most soluble parts of the manure from the higher lands to the lower ones. River-water in its clear state and those springs which are called soft are less beneficial for the purpose of watering lands, as they contain less earthy or saline matter; and water from dissolving snow from its slow solution brings but little earth along with it, as may be seen by the comparative clearness of the water of snow-floods.

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