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.

    87/610 (page 75)
    Well aerated waters are bright, lustrous, and agreeable to the palate. This is especially the case with water from wells or springs, of medium depth, in calcic carbonate formations—the low temperature and greater pressure combining to increase the charge of carbonic acid. The absence of dissolved gases in dis- tilled water renders it flat, dull, and unpleasant to taste. Mineral ssftEts are derived from the strata with which the water has been in contact. They may include chlorides, sulphates, carbonates, silicates, nitrates, nitrites, and phosphates, the bases being lime, magnesia, soda, potash, alumina, or iron, and more rarely lead, zinc, copper, manganese, or arsenic. The proportion of salts present ranges from prac- tically nil in rain-water, or pure moorland water, to 3,000, or more, parts per million in mineral waters or brackish water from the coast. In water for drink- ing it should not exceed 400 parts per million, and a good water will not contain more than 100 parts. An excess of mineral salts in general leads to digestive disturbances, in the form of dyspepsia, diarrhoea, or constipation ; but this effect is largely dependent upon the nature of the salts present. Chlorides, estimated as chlorine, may reach the proportion of 100 parts per million in organically pure water from the New Red Sandstone, Greensand, and other saliferous formations. Brackish water also contains excess of clilorine. In general, however, good waters contain not more than about 20 or 30 parts per million, and rain-water and peaty waters little or none. Water from surfaces, shallow wells, or other sources open to contamination should be regarded with suspicion if it contains more than 100 parts of chlorine, especially if there is also excess of organic matter or oxidised nitrogen, all these being- significant of animal pollution. Tests.—T. Qualitative.—A solution of argentic