The Meaning of Thirst. None of us who has ever been a mile or more away from a well, or brook, on a hot summer's day needs to be told how necessary water is, for comfort as well as for health. The appetite which we have developed for it—thirst, as we call it—is the most tremendous and powerful craving that we can feel, and the results of water starvation are as serious and as quick in coming as is the keenness of our thirst. Men in fairly good condition, if they are at rest, and not exposed to hardship, and have plenty of water to drink, can survive without food for from two to four weeks; but if deprived of water, they will perish in agony in from two to three days.
We should Drink Three Pints of Water a Day. Although all our foods, either as we find them in the state of nature, or as they come on the table cooked and prepared for eating, contain large quantities of water, this is not enough for the needs of the body; to keep in good health we must also drink in some form about three pints, or six glassfuls, of water in the course of the day. Part of this goes, as you will remember (p. 16), to dissolve the food so that it can be readily absorbed by our body cells in the process of digestion.
Water is Always in Motion. The part of our water supply which we take directly, in the form of drinking water, is, however, unfortunately anything but free from danger of impurities. The greatest difficulty with water is that it will not "stay put"—it is continually on the move. The same perpetual circulation, with change of form, but without loss of substance, which is taking place in the engine and in our bodies, is taking place in the world around us. The water from the ocean, the lakes, and the rivers is continually evaporating under the heat of the sun and rising in the form of vapor, or invisible steam, into the air. There it becomes cooler, and forms the clouds; and when these are cooled a little more, the vapor changes into drops of water and pours down as rain, or, if the droplets freeze, as snow or hail.
The rain falls upon the leaves of the trees and the spears of the grass, or the thirsty plowed ground, soaks down into the soil and "seeps" or drains gradually into the streams and rivers, and down these into the lakes and oceans, to be again pumped up by the sun. All we can do is to catch what we need of it, "on the run," somewhere in the earthy part of its circuit.
Why our Drinking Water is Likely to be Impure. Every drop of water that we drink or use, fell somewhere on the surface of the earth, in the form of rain or snow; and if we wish to find out whether it is pure and safe, we must trace its course through the soil, or the streams, from the point where it fell. Our drinking water has literally washed "all outdoors" before it reaches us, and what it may have picked up in that washing makes the possibilities of its danger.
As it falls from the skies, it is perfectly pure—except in large cities or manufacturing centres, where rain water contains small amounts of soot, smoke-acids, and dust, but even these are in such small amounts as to be practically harmless. But the moment it reaches the ground, it begins to soak up something out of everything that it touches; and here our dangers begin.
Risks from Leaf Mould. Practically the whole surface of the earth is covered with some form of vegetation—grass, trees, or other green plants. These dying down and decaying year after year, form a layer of vegetable mould such as you can readily scratch up on the surface of the ground in a forest or old meadow; this is known as leaf mould, or humus. As the water soaks through this mould, it becomes loaded with decaying vegetable matter, which it carries with it down into the soil. Most of this, fortunately, is comparatively harmless to the human digestion. But some of this vegetable matter, such as we find in the water from bogs or swamps, or even heavy forests, will sometimes upset the digestion; hence, the natural dislike that we have for water with a marshy, or "weedy," taste.
We should Drink Three Pints of Water a Day. Although all our foods, either as we find them in the state of nature, or as they come on the table cooked and prepared for eating, contain large quantities of water, this is not enough for the needs of the body; to keep in good health we must also drink in some form about three pints, or six glassfuls, of water in the course of the day. Part of this goes, as you will remember (p. 16), to dissolve the food so that it can be readily absorbed by our body cells in the process of digestion.
WHERE OUR DRINKING WATER COMES FROM
Water Contained in our Food is Pure. Seeing that five-sixths of our food is water, it is clearly of the greatest importance that that water should be pure. That part of our water supply which we get in and with our foods is fortunately, for the most part, almost perfectly pure, having been specially filtered by the plants or animals which originally drank it, or having been boiled in the process of cooking. THE SPOUTING FOUNTAIN Where no lips need touch the cup.
The rain falls upon the leaves of the trees and the spears of the grass, or the thirsty plowed ground, soaks down into the soil and "seeps" or drains gradually into the streams and rivers, and down these into the lakes and oceans, to be again pumped up by the sun. All we can do is to catch what we need of it, "on the run," somewhere in the earthy part of its circuit.
Why our Drinking Water is Likely to be Impure. Every drop of water that we drink or use, fell somewhere on the surface of the earth, in the form of rain or snow; and if we wish to find out whether it is pure and safe, we must trace its course through the soil, or the streams, from the point where it fell. Our drinking water has literally washed "all outdoors" before it reaches us, and what it may have picked up in that washing makes the possibilities of its danger.
As it falls from the skies, it is perfectly pure—except in large cities or manufacturing centres, where rain water contains small amounts of soot, smoke-acids, and dust, but even these are in such small amounts as to be practically harmless. But the moment it reaches the ground, it begins to soak up something out of everything that it touches; and here our dangers begin.
Risks from Leaf Mould. Practically the whole surface of the earth is covered with some form of vegetation—grass, trees, or other green plants. These dying down and decaying year after year, form a layer of vegetable mould such as you can readily scratch up on the surface of the ground in a forest or old meadow; this is known as leaf mould, or humus. As the water soaks through this mould, it becomes loaded with decaying vegetable matter, which it carries with it down into the soil. Most of this, fortunately, is comparatively harmless to the human digestion. But some of this vegetable matter, such as we find in the water from bogs or swamps, or even heavy forests, will sometimes upset the digestion; hence, the natural dislike that we have for water with a marshy, or "weedy," taste.
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