That the disinfection of water supplies is considered the most practical of the processes available at the present time is demonstrated by the rapid increase in the number of installations of chlorinators in North America, Central America, South America and Europe, as compared with the number of installations of equipment for the use of ozone and ultraviolet rays. Public health officials have taken into consideration that, given two practical processes of equal efficiency under identical conditions, the most economical one, from the standpoint of operation and maintenance will be selected for installation, except in the case of small filtration plants such as are used for swimming pools, club houses, hotels and bottling works.
I am of the opinion that the disinfection of water supplies by the application of liquid chlorine and calcium hypochlorite is established on such a firm basis that it is unnecessary to defend it against the attacks