=Pan-closets= (sometimes called _double-pan closets_) are essentially bad, though largely employed in the past. The construction is shown in Fig 22. Below the conical basin there is a metal pan capable of holding a certain amount of water, the lower end of the basin dipping into this water. By means of a pull-up apparatus the contents of the pan can be tilted into a second larger pan or _container_, and the bottom of the container is connected by means of a short pipe with a leaden [bowl-shaped symbol] shaped trap, from the side of which the soil-pipe passes out to be carried down to the drain. The arrangement insures the production of nuisance. The container and [bowl-shaped symbol] trap always arrest a certain amount of foul matter; and each time the handle of the closet is pulled up a puff of foul air comes into the operator’s face. Occasionally the [bowl-shaped symbol trap becomes corroded by the filth it contains, and foul gases from the drain escape into the house. [Illustration: FIG. 22. INSANITARY PAN CLOSET, SHOWING D TRAP BELOW.] =Valve Closets= differ from the last in having no container, but only a small box containing a movable water-tight valve, exactly fitting the lower edge of the basin (Fig. 23). They are much superior to the pan-closet, but require an overflow pipe in order to avoid accidental flooding of the closet. The overflow pipe should be made with a syphon bend in it, and the flushing of the closet should be so arranged that each time it is performed water enters the overflow pipe. (See Fig. 23.) The trap below the valve should be in the form of a syphon (see under traps, page 179), as this is not easily fouled. It is preferably made of lead, securely jointed to the soil-pipe and to the valve box of the closet. A lead tray or “safe” is required on the floor beneath a valve closet, in view of accidental spillings or overflow; and this should be provided with an overflow pipe discharging into the open air. [Illustration: FIG. 23. VALVE CLOSET. =A—Pan=. =B=—Overflow pipe with syphon trap. =C=—Valve shut. =C₁=—Valve open. =D=—Valve box. =E=—Floorline. =F=—Water-seal of trap.]