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WATER.
Water bears a very important part in relation to the human system and preservation of health. It combines with the tissues of the body, and forms a necessary part of its structure. In the case of a man weighing one hundred and fifty-four pounds, one hundred and eleven would consist of water. It enters very largely into the composition of our food. Although water is so important a factor in our existence, and although its vitiation often gives rise to that deadly pestilence, typhoid fever, yet, strange to say, there are comparatively few people who possess any trustworthy information respecting its primary sources and purest forms. The object of this paper will be to afford our readers some useful hints respecting the various kinds of water and their relative purity, also to mention certain wise precautions requisite in order to avoid impure water.
The first great source of water is the ocean; the sun shining upon the surface, its heating rays combine with and send out a certain amount of vapour. The atmosphere, like a sponge, absorbs the vaporous water, forming clouds, which are driven by the wind east, west, north, and south. When the clouds arrive in a cooler atmosphere, the vapour condenses, and descends in the form of rain or snow, being ultimately absorbed into the earth, giving rise to different varieties of water; or it pours down the mountains, and forms rivulets, and ultimately rivers. Thus we have rain, spring, and river water. We may here mention that Dr Normandy discovered a process by which sea-water can be distilled and rendered fit to drink. In nature, water is never found perfectly pure, as that which descends in rain is to a certain degree contaminated by the impurities contained in the air, as spring-water is by contact with various substances in the earth. These impurities are not always perceptible. Thus, the clearest and brightest waters, those of springs and pellucid rivers, even when filtered, are never pure. They all contain a greater or less percentage of saline matter, often so much so, indeed, as to form what are termed mineral waters. Amongst the purest natural waters hitherto discovered is that of the Loka in North Sweden. It contains only one-twentieth of a grain of mineral matter per gallon. The water supplied to the city of Edinburgh contains from seven to fourteen grains in the gallon; whilst that of the Thames near London contains about twenty-one. Rain-water, if collected in the country, is the purest; but when obtained in or near large cities, becomes impure from passing through a vitiated atmosphere.
It is, however, on spring and river water that we depend for our daily supply, and a due consideration of these waters is manifestly a matter of no small moment.
Well-water, as also that of some springs, especially when obtained in or near towns, although cool and clear, and at times sparkling, is to be avoided. The solvent power of water being so great, it takes up many impurities from the soil through which it passes. In the neighbourhood of dwellings and farmyards, the water often is impure, and unfit to drink. Wells in the vicinity of graveyards are particularly to be avoided. Mr Noad found a hundred grains of solid matter to the gallon of water taken from a well in the vicinity of Highgate Church, London. Besides mineral substances, decaying vegetable impurities are usually found in wells. The water that supplies the surface-wells of London is derived from rain, which percolates through the gravel and accumulates upon the clay. Now, this gravel contains all the soakage of London filth; through it run drains and sewers, the surface also being riddled with innumerable cesspools.
River-water being derived from the conflux of many springs with rain-water, unless close to large towns, is decidedly preferable to well-water; but it is liable to a certain amount of contamination, by holding in suspension a considerable quantity of animal, vegetable, and earthy matters. This, according to Dr Paris, is unquestionably the case in water supplied from the Thames by the Grand Junction Water Company. Be it known that Thames water is never used in London breweries, but Artesian-well water, brought up from a depth of several hundred feet.
Besides vegetable and animal impurities in water, there are two other substances which are usually considered foreign to pure water--namely, saline and mineral. The saline are often present in such large proportions as to render water medicinal, as illustrated by those of Cheltenham, Leamington, and Harrogate, numerous other varieties existing on the continent. Brighton water, although sparkling, contains a great deal of bi-carbonate of lime, which, being soluble, filtering is ineffectual to remove. When boiled, however, the carbonic acid is driven off and the chalk precipitated. Such water when boiled is fit for drinking purposes.
A simple but not infallible test for ascertaining animal or vegetable contaminations in water is to put fifteen or twenty drops of permanganate of potash solutions, or Condy's fluid, into a tumblerful of water. If the water is free from such impurities, the permanganate will retain its beautiful red colour. Should the water contain organic matter, the red hue soon disappears, and in proportion to its contamination will be the discoloration.
Bad water is far more dangerous than impure air; the air may be dispersed by ventilation and change of atmosphere; whilst water when vitiated is a constant source of mischief. Snow-water when collected in the open country equals rain-water in purity. It has been supposed by some to be unhealthy; but such belief is totally unsupported by any reliable evidence. The practical observations of Captain Cook on his voyage round the world demonstrate beyond all question its wholesomeness.
Lake-water is collected rain, spring, and occasionally river waters. Its transparency, however, is not to be relied on as evidence of purity. It is often contaminated by both vegetable and animal matter, which, owing to its stagnant nature, have become decomposed. According to Dr Paris and other authorities, endemic diarrhoea often arises from drinking lake-water, a circumstance which tourists would do well to bear in mind.
Should much lime be present in water, as in that supplied by the Kent Water Company, boiling alone will not soften it; but by the addition of a little soda during the boiling, the lime of the gypsum is precipitated. Marsh-water is certainly the most impure of all water, being loaded with decomposing vegetable matter. Many diseases have without doubt been occasioned by its use.
The receptacles in which even the purest water is kept are of the utmost importance in a hygienic point of view. The noted colic of Amsterdam was believed by Tronchin--who wrote a history of that epidemic--to have been occasioned by leaves falling into leaden cisterns filled with rain-water and there putrefying. Van Sweiten also mentions an instance where a whole family were affected with colic from a similar cause. The acidity arising from decomposing leaves in water dissolves part of the leaden receptacle, and such water ofttimes thus induces lead-colic.
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