Water
In a state of purity, at ordinary temperatures, water is a clear transparent liquid, perfectly neutral in its reaction, and devoid of taste or smell. Absolutely pure water is not to be found in nature, since water always finds something to dissolve even as it falls through the air in the form of rain. Rain water contains not only atmospheric air but also some ammonia and carbonic acid and traces of nitrates, together with salts derived from dust. Its chemical constitution, indicated by the formula H20 (molecular weight = 17.96), is 2 parts of hydrogen to 15.96 parts of oxygen by weight, or very nearly two volumes of hydrogen to one volume of oxygen, which upon combustion form by their combination two volumes of water – vapour. The question as to who was the discoverer of the composition of water – the great Water Question – takes rank in the history of chemistry as the controversy as to the discovery of the calculus and of the planet Neptune in other sciences. Brougham, Brewster, Kopp, Arago, Dumas and many others have maintained one or another of the theses and the claims of Cavendish, James Watt, Priestly, and Lavoisier have been canvassed and defended. Research seems inclined to give the priority to Cavendish, while allowing that Watt made independent experiments and came to similar results soon after. The principal tests to which water was subjected, then, in order to determine its impurities are examination of colour, taste, smell after being shaken up, analysis of the residue left after evaporation for silica, iron, alumina, lime and magnesia. Acidifying water with hydrochloric acid and estimating the sulphuric acid by means of barium chloride. Also the determination of the chlorine present and an estimation of nitrates and nitrites (these being of importance as indicating oxidised organic matter and showing that the water had passed through organic matter). Furthermore the determination of the free ammonia and of the total amount of ammonia producible by reductive processes from the organic matter present in the water (albuminoid ammonia) and lastly the estimation of the carbonic acid. |
Terminology like hard and soft water also came about. It was then generally recognised that on the score of health there is nothing to choose between these. Hard water is brisker and more agreeable to the taste, and has a better colour and appearance than soft water as derived from ordinary impounding reservoirs. For general manufacturing purpose the advantage is with the soft water (lime dissolved).
Water may be clear, bright and palatable or may resemble weak chicken-broth, flavoured with rotten eggs. It may give forth volumes of the carbonic acid with which we artificially impregnate waters for potable purposes or it may be accompanied by torrents of foul sulphuretted hydrogen. Having regard to the great solvent power of water, and to the variety of materials among which subterranean water passes and to the time it is in contact with these it is not surprising that when it comes to the surface it should contain some of these various matters in solution. But, then, though as a general rule springs and deep wells were relied on to produce water uncontaminated by any matter detrimental to health. That quality is dead today. Forever. Our love/respect for water – is it also dead? |
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