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ORE than two-thirds of the weight of the body consists of water. An adult requires five pints daily, and is furnished with this supply from the food he eats and the beverages he drinks. The outgo is even greater than the income, owing to the chemical changes which are constantly taking place in the body.

Pure water is composed of hydrogen and oxygen, there being two parts of hydrogen to one part of oxygen. The symbol of water is H2O.

Water as found in nature is never chemically pure. It not only contains many mineral substances, but decaying animal and vegetable matter, and often pathogenic germs. From this statement it may be seen that a water supply cannot be too carefully guarded.

The clear, colorless, tasteless fluid furnishes the average person with sufficient evidence of its purity; while if lacking in any of these qualities he seems to be equally assured of its unfitness for consumption. These tests are entirely useless, and scientific investigations are the only safeguards to a proper water supply.

Filters, as used to render drinking water pure, are a delusion and a snare. The bed of a filter furnishes a desirable soil for the growth of bacteria, and while some of the larger organic particles are removed by filtration, the rapidity with which the micro-organisms increase render it less fit for use.

Distilled water, prepared for medicinal purposes, is chemically pure. It is flat and insipid to the taste, having been deprived of its atmospheric gases. When used as a