WATER

Water is in some form e ential to all forms of animal and vegetable life. Its consumption in liberal quantities 1s especially nece ary to civilized communities because of the generally dry character of the bulk of their diet. The human body requires an average of nearly 75% water, whereas bread, for example, has only 35% and bacon 20% liquid in its composition. The average individual would better his health if he drank a larger quantity—moderately cold—either with or between meals as best agrees with him. The world’s supply is obtained primarily from the ocean—the water being continuously drawn up into the atmosphere as vapor, leaving its salt behind, and later falling again condensed as rain or snow. Most of the rain and snow returns to the ocean, but part of it descends over the land surfaces of the earth to feed its rivers and lakes and thus becomes available for human use. Ocean water averages about 314% salinity—of which about three-fourths is common salt. The salt can be readily removed by distillation (following the example of natural evaporation) and ocean steamships thus customarily obtain their supply of fresh water. Chemically pure water is a compound resulting from the combination, by volume, of two parts of hydrogen and one part of oxygen (by weight, the proportion is two parts of hydrogen to sixteen parts of oxygen) without the addition of any other substance, but such water is obtainable only by careful filtration and distillation. The most nearly pure water naturally obtainable is (1) rain-water in places remote from regular human habitation, taken after the rain has been falling sufficiently long to clear the atmosphere; and (2) that obtained by melting snow that has fallen in the polar regions. Nearly as close to perfection is the water in some mountain lakes, when resulting chiefly from melting snow and resting on impermeable rocks. Such water—and all other in which the proportion of mineral matter is le than eight grains to the gallon—is known generally as ‘‘soft,’’ in contrast to ‘‘hard’’ water, which implies a mineral content of eight to ten, and more, grains to the gallon. Water from rivers running over calcareous and clayey rocks often averages fifteen to twenty grains to the gallon.. The minerals in waters vary greatly. Those as a rule most heavily present are lime and magnesia salts. The organic matter is partly animal and partly vegetable. Water becomes solid, or ice, at 32° Fahr. (0° Cent.), and, under normal air pre ure, is converted into steam at 212° Fahr. (100° Cent.), or the ‘‘boiling-point.’’ Under rarefied air conditions, as at high elevations or commercially in partial vacuums, the boiling-point is reached at various lower degrees. The mineral matter found in the average supply is not in any way detrimental to health. A little improves the flavor. The ‘‘pure water’’ that every community should provide is not nece arily chemically pure, but is water uncontaminated by sewage of any description or in any form, for such contamination is one of the most serious menaces to health. Spring water is frequently regarded as the highest type of pure water because of its ordinarily bright and more or le sparkling appearance. This appearance is, however, generally the result of its hardne —i.e., of the mineral ingredients it has absorbed in its pa age through the rocks. In cases where the mineral ingredients are im sufficiently large proportions to be of distinct, or supposed, medicinal value, the water is cla ed as a Minerat Water (which see). Distilled water is ‘‘ordinary water’’ filtered, boiled in vacuum boilers to remove volatile organic matter, converted into steam in stills (see DistmtLation), and finally condensed and aerated (aeration removing the otherwise objectionably ‘‘flat’’ taste of the distilled product). If these proce es are conducted with proper care, the water obtained is free both of salts and of all bacterial life. It must be remembered, however, that it remains pure only so long as it is kept from contact with the atmosphere, as in siphons or corked bottles. The same protection to health may, when nece ary, be obtained in the household by thorough boiling (.e., sterilization) —thus killing all organic matter. Similar care after boiling is also of course e ential.