A manual of practical hygiene : prepared especially for use in the medical service of the Army / by Edmund A. Parkes.

Date:
1864
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene : prepared especially for use in the medical service of the Army / by Edmund A. Parkes. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    CONTAMINATION OF DRINKING WATER. as 80 much more vegetable matter and animal excreta find their way into it. The water of a river may liave a very different constitution from that of the springs near its banks, A good example is given by the Ouse, at York ; the water of this river is derived chiefly from the millstone grit which feeds the Swale, the Ure, and the Xid, tributaries of the Ouse; the water contains only 9 grains per gallon of salts of lime, magnesia, soda, and a little iron. The ^rells in the neighbourhood pass dovra into the soft new red sandstone which lies below the millstone grit; the water contains as much as 64-96 grams, and even, in one case, 96 grains per gallon; in addition to the usual salts there is much chloride of calcium, nitrates of lime, soda, and magnesia. Shallow well water is always to be viewed with suspicion; it is the natural point to which the drainage of a good deal of surrounding land tends, and lieavy rains will often wash many substances into it. Distilled Water. This is now very largely used at sea, and it affords an easy way of getting good water from sea or brackish water. Almost any form of ap- paratus will suffice, if fuel can be procured, to obtain enough water to sup- port life, and if even the simplest appliances are not attainable, the mere suspension of clean woollen clotlung over boiling water will enable a large quantity to be collected. At sea, salt water is sometimes mixed with it from the priming of the boilers, and occasionally from decomposition of the clJoride of magnesium (ijrobably), a little free hydrochloric acid passes off. This can, if necessary, be neutralised by carbonate of soda. As distilled water is nearly free from air, and is therefore unpalatable to some persons, and it is supposed indigestible, it may be aerated by allo-\ving it to run through a cask, the bottom of which is pierced \nt]i fine holes, so as to expose the water to the air. A special apparatus for aerating the water distilled from sea water has been invented by the late Dr Normandy, and is in common use. Organic matter, at first offensive to taste and smell in dis- tilled Avater, can be got rid of by passing through a charcoal filter, or by keep- ing three or four days. Care should be taken that no lead finds its way into the distilled water. Many cases of lead-poisoning have occurred on board ships, partly from the use of minium in the apparatus, and partly from the use of zinc pipes con- taining lead in their composition. Sub-Section III.—Usual Sources of Contamination of Water, and Sanitary Precautions. In examining any water, it is necessary to consider whether, in any way, some special cause of impurity has been in operation. Eain water becomes contaminated by falling tlirough a foul atmosphere; also, by carrying away decaying leaves or other matters from roofs of houses; it dissolves also lead from lead coatings and pipes, and takes up enough zinc from zinc roofs to be injurious, (Tardieu, Diet, d^Hygiene, t. 11, p. 25.) Rivers may be rendered temporarily impure by heavy rain and floods bringing soils and vegetable debris from higher regions, or by irruptions of the sea, or by the overflow of marsh waters. Shallow weUs and springs are also sometimes altered in composition by the same causes, and, if situated near the sea, may be, in dry seasons, rendered brackish by the pressure of the salt water into the land. Deep springs and wells are, of course, less affected. The most common sources of contamination are found, however, in the B