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Show PURIFICATION OF DRINKING WATER United States Geological Survey Issues Is-sues a Report Describing Practical Practi-cal Methods of Handling Public Water Supplies A Blmplo direct description ot moth ode of purifying water for drinking is given in a report by Ceorgo A. Johnson, John-son, Just published by the Unltod States Geological Survey. Tho report describes tho various types ot water supply systems used by cities in the United States sots forth the principal princi-pal advantages and disadvantages ot each, and gives a brief history ot the development ot waterworks systems and the effect ot their Installation on tho health ot communities. The necessity for purifying water for uso in cities is shown, not tho least important value of whter purification being tho Insurance it provides against disease. Mr. Johnson John-son shows by vory reasonable estimates esti-mates that tho uso ot puro water annually an-nually saves from tho rovnges ot wa-tprhorno wa-tprhorno typhoid fever nlone more thnn four times tho cost of purifying tho water. Tho substitution of puro for impure water supplies In tho United States would cavo annually somo 20,000 lives nnd fully $200,000.-000. Tho paper Includes a historical sketch of modes or systems of wntor purification, from tho storhgo works and clarification by alum used by tho ancient Chineso to tho present day mothods of nitration, coagulation nnd sterilization. Preparatory treatment. treat-ment. In which the water is pussed through scdlmontatlon tanks, coagulation coagula-tion basins, or roughing filters to remove a portion of Its color or turbidity, tur-bidity, Is discussed In detail. In slow sand filtration water is passed slowly through great beda of |