OF PAPER Mercury-vapor quartz lamps are applied industrially for the production of ultra-violet rays for the sterilization of water. To obtain ultra-violet rays economically it is important to study the temperature of the luminous part of the lamp. There are different ways for measuring the ultra-violet power, based on physical, chemical or bacteriological reactions. Such reactions are compared between them. The paper refers to the historical development of mercury lamp water sterilizers and

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... development of pistol lamps for large sterilizing units. Different germs are of different sensitivity to ultra-violet light. It is important that the water should be clear when entering the sterilizer. Description is given of two typical installations, one in Europe, one in America. Data are given on the power consumption for the sterilization of water by ultra-violet rays. W ITHIN the last five years a new field for the application of electricity has been created in Europe based upon the electrical production of ultra-violet light for the sterilization of water and for other purposes. As this new industry is now being introduced into this country, it is of interest at this time to analyze its basis and principles.