Water : River Water

River water, which has previously percolated through soil, contains dissolved salts and suspended matter, both mineral (clay) and organic, from vegetable matter. Water which has flowed over peat, or peaty soil, contains dissolved organic acids (crenic, apocrenic and humic), some of which give it a yellow colour, and cause it to corrode lead or iron pipes.

River water flowing over cultivated land may contain, in addition to the above impurities, ammonium salts, nitrites, nitrates, sodium chloride, and organic matter of vegetable and animal origin containing nitrogen. The purity of the water depends on the nature of the soil. Thames water, flowing over soil rich in limestone, contains about 157 milligrams of calcium carbonate per litre. Trent water, Rowing over soil containing gypsum, contains 300 milligrams of calcium sulphate per litre. The calcium sulphate of the well water at Burton is of value in brewing. The waters of the Dee and Don, draining the Aberdeen granite area, contain only traces of dissolved calcium salts.

River water, like other natural waters, contains dissolved atmospheric gases, the oxygen of which is of importance to fish.

Spring, or deep well, water differs from river water only in having undergone filtration through porous strata. In this way the suspended matter may be largely removed, leaving the water clear. The organic matter, ammonia and nitrites may also have been more or less oxidised, but the dissolved mineral impurities usually increase. _ Of 100 parts of rain, only 36 flow to the sea in rivers; the rest is either evaporated, or penetrates into the earth's crust, to reappear to some extent in springs. This type of natural water is probably the best for drinking purposes.

Water for drinking purposes is purified by nitration through beds of gravel of varying degrees of coarseness, the upper parts, of fine gravel, being removed and washed from time to time. The water is freely exposed to air so as to take up oxygen. Filter beds remove most of the bacteria from water, but for safety the water may also be sterilised by adding small quantities of chlorine, or bleaching powder, or chlorine and ammonia (chloramine process), or by treatment with ozone.

Protein crystallography
Chemistry guide
Water
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