The Ozone Plant in West Philadelphia is in operation and tests of its work in water purification have been made by Messrs. Rivas, Jackson and Hale. Raw Schuylkill River water contains as high as 2,500,000 bacteria per cubic centimeter. After rough straining this number is reduced to 250,000 to 700,000, and after the ozone treatment to 5 to 55. These few are all harmless varieties, and the water is also deoderized and freed from color. The process, which is controlled in this country by the United Water Improvement Co.» is substantially as follows: An electric current is taken from the city's wires to operate a motor generator, producing a current of 100 alternations, which is raised by transformers and condensers to a 10,000 voltage. By the operation of reactance coils and condensers, voltaic arcs are prevented and sparks are limited, and the current passes as a pencil of blue light from each of some millions of metallic discharge points across a short air-gap to nickel receivers. Atmospheric air is drawn across this gap by means of an air pump, and in so passing it is partially converted into ozone. The ozonized air is then forced through a stand-pipe, in which it meets a current of water flowing in the opposite direction. The contained bacteria are instantly destroyed by the ozone.