Hygiene and public health / by B. Arthur Whitelegge.

  • Arthur Whitelegge
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Hygiene and public health / by B. Arthur Whitelegge. Source: Wellcome Collection.

    71/610 (page 59)
    the superficial strata it also receives organic matter, but the tendency of filtration through the soil is to remove this, or oxidise it with formation of nitrates. The nature and amount of the mineral matters in solution are determined by the soluble constituents of the various strata through which the water has passed, and the organic impurities are regulated by the facilities for pollution in the superficial soil and the completeness of purification by filtration lower down. Hence the water in shallow wells, especially if situated near dwellings or manured lands, is liable to contain much organic matter washed from the soil, with or without partial oxidation into nitrates or nitrites ; and also chlorides, which usually accompany organic impurities of sewage origin. In peaty districts the water acquires a brown tint due to vegetable matter. According to the depth of the strata from which it is derived, the water may be warm, or of the mean temperature of the locality, or varying in temperature according to the season. River-water is derived partly from springs, but chiefly from that portion of the rainfall which runs off the surface. Hence it contains a variety of mineral salts in solution, though in less amount than in spring or well water. All streams are inevitably polluted to a certain extent by organic matter. Moorland waters con- tain peaty matter, sometimes in sufficient quantity to produce diarrhoea. Even in rural districts, drainage from manured land and farmsteads finds its way to the river, and in times of heavy rain much impurity of animal and vegetable origin is washed into the watercourses. Such slight degrees of pollution are not regarded as rendering water unfit for drinking purposes, especially if the pre- caution is taken of filtering it. Some of the organic