The water of deep wells is for the most part much harder than that of springs which overflow their channels.
277. RIVER WATER is a mixture of spring and rain water, which, from much agitation, and by long exposure to the air, in the course of its channel, becomes, in general, tolerably soft and free from earthy salts.
For washing, and other purposes of domestic economy, river water, from its softness and purity, is not only preferable to spring water, but also serves for many uses to which the latter cannot be at all applied. As a beverage, however, it is in general vapid and unpleasant.
The waters of some rivers, particularly where the beds, over which they flow, are sandy or stony, are remarkably pure. This is the case with several of those in Switzerland, Wales, Scotland, and the northern counties of England. The river Seine has great repute in France on this account: it has been found, on accurate examination, even more pure than Bristol water.
That of the river Thames, impregnated as it would appear to be with putrid remains, is soft and good, when taken up at low water; and, after rest and filtration, is found to contain but a small portion of any thing either noxious or unpleasant. It is preferred, by mariners, to most other water for sea store; but it soon becomes putrid, and undergoes a remarkable spontaneous change. When, after having been kept a month or two, a cask is opened, a quantity of inflammable air escapes, and the water is black and nauseous. If, in this state, it be racked off into large earthen vessels (oil jars it is said are commonly used for the purpose), and exposed to the air, it gradually deposits a portion of black slimy mud, and becomes perfectly clear, sweet, and fit for use.
278. STAGNANT WATER contains greater impurities than any other. In ponds and marshes particularly, it is filled with the remains of animal and vegetable matters, which are there undergoing a gradual decomposition.
The water of lakes is not, in general, so much contaminated as this; but from the same cause, it frequently has a slimy appearance, a brownish colour, and an unpleasant taste.
From the putrefying contents of stagnant water, nutriment is afforded to various living plants and insects which there supply the place of those that perish. Its taste is vapid, unpleasant, and wholly destitute of that agreeable freshness which is found in spring water. It is, however, generally soft, and, by filtration, it may be freed from many of its impurities.
The air which issues from marshes and stagnant pools is extremely noxious, and is the cause of agues and other distressing complaints, to such persons as reside in the neighbourhood of them or are much exposed to them; and the injurious effects of such air have also been considered to extend to the internal use of these waters.