Practical preventive medicine . Pig. 39. -Schematic view of a typical rapid sand filter of the pressure type.(Mason, Water Supply, John Wiley and Sons.). L Fig. 40.—Coagulant storage and feeding devices at Scranton. The coagu-lant solutions are stored in the tanks on the platform, and fed into the raw waterby means of the constant head device on the floor below. (Water Supply Paper315. U. S. Geological Survey.) WATER PURIFICATION 141 amount required is greater when the content of the water inorganic matter is high. Disinfection is probably accomplished

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Keywords: ., bookcentury1900, bookdecade1920, booksubjectprevent, bookyear1920