Service chemistry : being a short manual of chemistry and metallurgy and their application in the naval and military services / by Vivian Byam Lewes and J.S.S. Brame.

  • Vivian Byam Lewes
Date:
1913
Catalogue details

Licence: In copyright

Credit: Service chemistry : being a short manual of chemistry and metallurgy and their application in the naval and military services / by Vivian Byam Lewes and J.S.S. Brame. Source: Wellcome Collection.

    134/622 page 112
    CHAPTER IX THE IMPUBITIES IN WATER Rain Water.—There is no such thing in Nature as pure water. In passing through the atmosphere the rain becomes highly charged with gases, taking up from 3 to 30 cubic centimetres per litre ; the oxygen is found in larger proportions than in air, reaching as much as 38 per cent, of the total amount of dissolved gas. It also contains about 3 per cent, of carbon dioxide and minute traces of carbonate and nitrate of ammonia, besides small particles of solid matter, such as dust (especially in very windy weather), salts, and organic matter. Li the countiy, where the air is fairly clean, rain water, owing to its purity and great aeration, is both wholesome and pleasant to drink, but in or near tovus the soot and dirt derived from the air and roofs make it unfit for drinking purposes. Spring Water.—Spring water contains most of the gaseous impurities present in rain water, and beside these all the mineral impurities it has dissolved in its passage through the ground. The most ordinary im]iurity of spring water is chalk or calcium carbonate, which gives the water those properties which we call “ hardness,” a hard water being a water containing calcium and magnesium salts in solution. Hardness.—Pure water cannot dissolve calcium carbonate to any appreciable extent, but when it filters through decomposing vegetable matter, it dissolves carbon dioxide, which is produced by decaying leaves, etc., and water containing carbonic acid dissolves chalk, owing to the formation of soluble calcium bicar- bonate ; lienee, when such water filters through or over chalk beds, some is dissolved, and the water becomes hard. There are two kinds of hardness in spring water ; “ temporary hardness,” due to calcium and magnesium carbonate dissolved by the carbonic acid in water, which can be got I’id of by any
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