Spring water, from its filtration through earth rich in mineral deposits, usually contains a certain percentage of those minerals, as salt, sulphur, or iron, dissolved through the action of the carbon dioxid contained in the water. Some of these springs have become famous health resorts. The contained carbon dioxid gives spring water its pleasant, sparkling taste. Spring water is remarkably free from organic life. Water as used in cities usually needs careful filtration and purification to rid it of its contained sand and other impurities. The housewife whose water supply is derived from rivers does this on a small scale when she strains out the mud and sand from the water which she is often compelled to use when the river is in flood and full of impurities. Drinking water should be perfectly clear and without odor. Even a small amount of decomposing vegetable or animal matter can be detected by its odor, if the water is confined for a short time in a bottle or closed jar. The health of the body depends to a large degree on the purity of the water. Contaminated water is a menace to health. Water which appears perfectly clear may be badly contaminated with typhoid or other germs. For this reason no water should be used until it has been boiled if one is not sure of its purity. Water from wells near barns and cesspools is often impure. “Hard” water, as derived from wells, is usually rich in calcium and magnesium. When water contains a large percentage of these substances, it usually causes constipation and indigestion and may aid in the formation of gall-stones or gravel. The kidneys are especially the great eliminators of water and aid in maintaining the equilibrium of the blood. Except in conditions in which they need rest, water should be freely drunk in order to stimulate them to activity and to assist them in throwing off the body waste held in solution. One cannot form a better habit than that of drinking two or three glasses of water on first arising and then exercising the stomach and intestines by a series of movements which alternately contract and relax the walls of those organs, causing their thorough cleansing. This internal bath is as necessary as the cleansing of the skin. Often, in gastritis or a catarrhal condition of the stomach, a large amount of mucus will collect in the stomach over night, and the cleansing of the mucous lining of the digestive tract is then most important. If in good health, two or three glasses of cool water, vigorous exercises for the vital organs, and deep breathing of pure air, followed by a cold bath, will do more to keep the health, vigor, clear skin, and sparkling eye than fortunes spent on seeking new climates, mineral waters, or tonics. When cool water in the morning seems to chill one, a glass of hot water may be followed by a glass of cool. The free drinking of water aids the activity of the skin, keeping the tissues moist and the glands active.