The increasing use of chlorin in liquid form for the disinfection of water supplies was noted last year by The Journal.1 Continued experience has been highly favorable to this method. It is the natural outgrowth of the use of calcium hypochlorite which, since its introduction in this country, about 1908, has had a remarkable extension. Hundreds of cities have adopted temporarily or permanently the "hypochlorite" treatment, and the amount of typhoid fever prevented by this means is certainly large. At the Fifteenth International Congress of Hygiene in 1912, foreign visitors stated that the hypochlorite method, as developed in this country, was one of the most important contributions yet made to the water supply problem.
The practical application of calcium hypochlorite, however, seems beset with difficulties. The proper adjustment of the mixing and feeding devices by which the bleaching powder solution is added to the water is one of the