Mineral waters are usually obtained from springs which contain a considerable amount of saline matter. Those waters which abound in salts of iron are called chalybeate or ferruginous. Those containing salt are termed saline. Those in which contain sulphur are termed sulphurous. Water derives the quality of hardness from the salts of lime—chiefly the sulphates—which it contains. Hard water, being an imperfect solvent, is unsuitable for washing purposes. There are two varieties of hardness, one of which is temporary, being due to the presence of carbonic acid gas in the water which holds the salts in solution and may be removed by merely boiling the water and thus expelling the gas when the salts are deposited, while the other is permanent and can only be removed by the distillation of the water. It has been ascertained that twelve pounds of the best hard soap must be added to 10,000 gallons of water of one degree of hardness before a lather will remain and, consequently, 0.12 lb. to 100 gallons of water is a measure of one degree of hardness. Since hard water is not so useful in cooking and other domestic purposes, as soft water, causing a great waste of labor and material, it is often highly desirable to soften it, which is effected by the addition of lime in what is known as Clark's process. One ounce of quicklime should be added to 1000 gallons of water for each degree of hardness. It should be first slacked and stirred up in a few gallons and then thoroughly mixed with the entire quantity. Then it should be allowed to remain, and will become clear in about three hours, but should not be drunk for twelve hours.
The purity of drinking water is a matter of much importance. That which contains a minute quantity of lead will give rise to all the symptoms of lead poisoning, if the use of it be sufficiently prolonged. An account is given of the poisoning of the royal family of France, many of whom suffered from this cause when in exile at Claremont. The amount of lead was only one grain in the gallon. Care should therefore be taken to avoid drinking the water which has been contained in leaden pipes. It should always be allowed to run a few minutes before being used.
An excess of saline ingredients, which in small quantities are harmless, frequently produces marked disorders of the digestive organs. A small amount of putrescent matter habitually introduced into the system, as in the use of food, is productive of the most serious results, which can be traced to the direct action of the poison introduced. A case is recorded of a certain locality favorably situated with regard to the access of pure air, where an epidemic of fever broke out much to the astonishment of the inhabitants. Upon observation it was found that the attacks of fever were limited to those families who used water from a neighboring well. The disagreeable taste of the water which had been observed, was subsequently traced to the bursting of a sewer, which had discharged a part of its contents into the well. When the cause was removed, there was no recurrence of the evil effects.
Organic Impurities. "Water is liable to organic contamination from a multitude of causes, such as drainage from dwellings, dust, insects, the decaying of vegetable and animal matter. These impurities may be mechanically suspended or held in solution in the water. Although organic impurities, which are mechanically suspended in water, are poisonous, yet they are generally associated with animalculea, and these feed upon, and finally consume them. Good water never contains animalculæ. They are never found in freshly fallen rain-water, remote from dwellings, but abound, to a greater or less extent in cisterns, marshes, ponds, and rivers. These little workers serve a useful purpose since they consume the dead organic matter from the water, and, having fulfilled their mission, sink to the bottom and die. Water which contains organic matter is exceedingly dangerous to health, and its use should be carefully avoided.
In low lands where the current of streams is sluggish, and shallow pools abound, the water is apt to be more or less infected with decaying vegetable substances. Many people living in such localities, and wishing to obtain water with as little trouble as possible, dig a hole in the ground, a few feet in depth, and allow the stagnant surface water to accumulate. This water is used for drinking and cooking. The result is that ague prevails in such localities.
Care should be taken that wells, from which the water is used for household purposes, are located at a distance from barn-yards, privies, sinks, vaults, and stagnant pools.
Purification of Water. There are various methods of purifying water. It may be accomplished by distillation, which is the most perfect method; by filtration through sand, crushed charcoal, and other porous substances, which deprives it of suspended impurities and living organisms; by boiling, which destroys the vitality of all animal and vegetable matters, drives out the gases and precipitates carbonate of lime, which composes the crust frequently seen upon the inside of tea-kettles or boilers; by the use of chemical agents, which may be employed to destroy or precipitate the deleterious substances. Alum is often used to cleanse roily water, two or three grains in solution, being sufficient for a quart. It causes the impurities to settle to the bottom, so that the clear water can be poured or dipped out for use. One or two grains of the permanganate of potassium will render wholesome a gallon of water containing animal impurities.
How to Use Water. Very little if any water should be taken at meal time, since the salivary glands furnish an abundance of watery fluid to assist in mastication. When these glands are aided with water to "wash down" the food, their functions become feeble and impaired. The gastric juice is diluted and digestion is weakened. Large draughts of cold water ought never to be indulged in, since they cause derangement of the stomach. When the body is overheated, the use of much water is injurious. It should only be taken in small quantities. Thirst may be partially allayed, without injury, by holding cold water in the mouth for a short time and then spitting it out, taking care to swallow but very little. Travelers frequently experience inconvenience from change of water. If the means are at hand, let them purify their drinking water, if not, they should drink as little as possible. Persons who visit the banks of the Ohio, Missouri, or Mississippi rivers and similar localities, almost invariably suffer from some form of gastric or intestinal disease. Water standing in close rooms soon becomes unfit to drink and should not be used. A drink of cold water taken on going to bed, and another on rising are conducive to health, especially in the case of persons troubled with constipation. "Drink water" said the celebrated Dubois to the young persons who consulted him, "drink water, I tell you!" Du Moulin, the great medical authority of his time, wrote, just previous to his death, "I leave two great physicians behind me—diet and water."
Tea and Coffee. These substances are almost universally used as beverages, and when properly employed, serve a four-fold purpose: they quench thirst, excite an agreeable exhilaration, repress the waste of the system, and supply nourishment. In consequence of being generally used at meal times, their stimulant properties are employed to promote digestion, and consequently they are not so objectionable as they might otherwise be. The liquids introduced into the stomach at meal times should not be cold. Tea and coffee are drunk warm, while water, except in a few instances, is always drunk cold, the effects of which have already been shown. That their inordinate use may be injurious no body can deny, but this is equally true of other beverages, even pure, cold water. Scientific investigators inform us that the use of these agents as beverages, when judiciously employed, is not injurious. It has been urged that they are poisonous, but if they are, they are very slow in their operation.
When properly prepared, they are very agreeable beverages, and as man will drink more or less at meals, they are allowable; for if their use were excluded, some other beverage would be sought after, and quite likely one of an alcoholic character employed, so of two evils, if this be an evil, let us choose the least. Unlike alcoholic stimulants, they exhilarate without a depressing reaction after their influence has passed off. But one cup should be drunk at a meal, and it should be of moderate strength. The use of large quantities of drink at meals retards digestion by diluting the digestive fluids. The excessive use of large quantities of strong tea or coffee stimulates the brain and causes wakefulness, and produces irritability of the nervous system. When they are productive of such effects, their use is injurious, and should be considerably moderated or wholly discontinued. No criterion can be given by which the amount the system will tolerate can be regulated. What one person may take with impunity, may be deleterious to an other. Individuals differ greatly in this respect. There are some who cannot tolerate them at all, either because of some peculiarity of constitution, or on account of disease. And sometimes when tea is agreeable and beneficial, coffee disagrees with the individual and vice versa. Persons of nervous habits whether natural or acquired, are apt to find their wakefulness and irritability increased by the use of tea, particularly if strong, while coffee will have a tranquilizing effect. Persons of a lymphatic or bilious temperament often find that coffee disagrees with them, aggravating their troubles and causing biliousness, constipation, and headache, while tea proves agreeable and beneficial. Whenever they disagree with the system, the best rule is to abandon their use. We find many persons who do not use either, and yet enjoy health, a fact which proves that they are not by any means indispensable, and, no doubt, were it customary to go without them, their absence would be but slightly missed.