Temporary hardness is caused by a soluble lime compound which is precipitated by boiling. If the teakettle is incrusted inside by a layer of lime, the hardness is of this character. Such water should be boiled and cooled for drinking. Permanent hardness is due to other compounds of lime and magnesia which are not precipitated by boiling, but which can be counteracted for cleansing purposes by the addition of some substance like ammonia, borax, or soda. If the excess of salts has some undesirable physiological effect, this water should be distilled, or bottled water for drinking brought from elsewhere.
Of much greater importance is the question of the freedom of the water supply from harmful bacteria and organic matter. Never use a well without having the water tested by an expert. This will sometimes be done by the local or state Board of Health or Experiment Station. All water sources should be guarded from contamination. (See “Shelter and Clothing,” Chapter V.) Filters may be used, and are effective in straining out sediment, but the home filter is seldom to be relied upon to remove actual bacterial contamination. If used at all, the filter should be frequently cleaned and sterilized in boiling water. In case the supply is suspected, the water for drinking should be boiled for at least ten minutes, allowed to settle, if necessary, and poured off into bottles for cooling. This is a practice to be commended after a heavy rainfall, and especially in the autumn. These bottles may be placed on the ice.
Ice must be used with caution always in drinking water, and it is the safer way to cool the water beside the ice. The freezing of water in pond and river does not purify or sterilize it. Natural ice is usually questionable. Artificial ice, if properly manufactured, is much safer.
Always have a supply of water in covered pitcher or water bottle, with clean glasses at hand, where it may be taken freely when wanted. Remember that the individual cup or glass is an absolute necessity. The dipper or glass in common must not be countenanced. In a large family of many children it would save labor to use paper cups between meals.
Water should be swallowed slowly, and ice-cold water should not be taken when one is overheated. When one is overthirsty, control must be exercised in regard to quantity and rapidity of drinking.
Water in cooking.—Water is necessary to the softening of fiber, and the cooking of starch. It acts as a solvent for sugar and salt and for gelatin, and is the basis of meat soups, certain substances in the meat dissolving in the water. The flavors of tea and coffee are extracted by water.
As a medium in cooking it supplies heat in the steaming, boiling, and stewing processes, and in the form of melting ice with salt it acts as a freezing medium.
It is not necessary to lift the cover of a kettle to see if the water boils, if one is familiar with the action of water nearing and at the boiling point. A simple experiment with the boiling of water in a Florence flask is always interesting, and from it one gains practical knowledge.
Experiments with the boiling temperature of water.