A type of sanitary privy in which the excrements are received directly into a water-tight receptacle containing chemical disinfectant is meeting with considerable favor for camps, parks, rural cottages, schools, hotels, and railway stations. These chemical closets,[4] as they are called, are made in different forms and are known by various trade names. In the simplest form a sheet-metal receptacle is concealed in a small metal or wooden cabinet, and the closet is operated usually in much the same manner as the ordinary pail privy. These closets are very simple and compact, of good appearance, and easy to install or move from place to place. In another type, known as the chemical tank closet, the receptacle is a steel tank fixed in position underground or in a basement. The tank has a capacity of about 125 gallons per seat, is provided with a hand-operated agitator to secure thorough mixing of the chemical and the excretions, and the contents are bailed, pumped, or drained out from time to time. [4] Among publications on chemical closets are the following: "Chemical Closets," Reprint No. 404 from the Public Health Reports, U. S. Public Health Service, June 29, 1917, pp. 1017-1020; "The Chemical Closet," Engineering Bulletin No. 5, Mich. State Board of Health, October, 1916; Health Bulletin; Va. Department of Health, March, 1917, pp. 214-219. [Illustration: Fig. 13.--Two-seat vault privy.] Chemical closets, like every form of privy, should be well installed, cleanly operated, and frequently emptied, and the wastes should receive safe burial. With exception of frequency of emptying, the same can be said of chemical tank closets. With both forms of closet thorough ventilation or draft is essential, and this is obtained usually by connecting the closet vent pipe to a chimney flue or extending it well above the ridge-pole of the building. The contents of the container should always be submerged and very low temperatures guarded against. [Illustration: Fig. 14.--Two-seat vault privy. Note the shallow, water-tight, easily cleaned concrete vault.]