In the type shown a single clamp arrangement is used (_a_). By the turning of the hand screw (_b_) two planed metal faces (the upper surface of the boiler and under surface of the cover) are brought together and sealed. When the cover (_c_) is removed the entire inside of the boiler is in sight and can be thoroughly cleansed, which should be done each time the apparatus is used. The pipes through which the formaldehyd gas passes after generation are arranged so that they can be taken off and cleaned. [Illustration: FIG. 3.—FORMALDEHYD DISINFECTING APPARATUS.] The gas is generated in the boiler (_d_) and passes out from the top, down through the pipe (_e_), and from thence through a series of pipes (_f_) underneath the boiler, which are subjected to direct heat from the lamp (_g_). By this means the gas becomes superheated, the polymerization of the formaldehyd is almost entirely prevented, and a dry gas is insured and given off at the pipe (_h_). The room should be left closed overnight and thoroughly aired thereafter. The bare floor must then be scrubbed with hot water and soda and flushed with a three-per-cent carbolic-acid solution. As little furniture as possible should be found in an operating room, and this preferably of undecorated enameled iron. =Instrument Cabinet.=—For the instruments and dressings there should be a dust-proof cabinet of iron and glass, such as is shown in Fig. 4. [Illustration: FIG. 4.—INSTRUMENT CABINET.] =Operating Table.=—The operating table should be of like construction and as plain as possible. Its top can be padded with sterilized felt, protected from moisture by rubber sheets. A surgical chair of plain construction might suffice, inasmuch as most plastic operations cover but a small area and are usually about the head and often performed under local anesthesia. A chair with head rest is much more comfortable, adding much to the moral and physical comfort of the then conscious patient. A very desirable chair is shown in Fig. 5. [Illustration: FIG. 5.—OPERATING TABLE.] =Instrument Table.=—An instrument table, such as is shown in the next illustration, is quite necessary, upon which dressings and instruments are laid during operation. In this the frame is of white enameled iron and the top and shelf of plate glass. [Illustration: FIG. 6.—INSTRUMENT TABLE.] =Irrigator.=—An irrigator is often of service, especially in washing out the fine pieces of bone resulting from chiseling or drilling. In skin-grafting it may be used with sterilized three-per-cent salt solution as described later. The best irrigators are those of germ-proof or ground-glass stopper type. They are suspended from the wall by means of an iron bracket or pulley service or placed upon a movable enameled stand as shown in Fig. 7. Irritating antiseptic solutions are to be avoided, their especial indication will be found under antiseptic care of wounds. CARE OF INSTRUMENTS [Illustration: FIG. 7.—IRRIGATOR.]