The steam-safety valve on this sterilizer is set at seventeen pounds, but it can easily be regulated should a higher or lower pressure be desired. The door used on this apparatus has no packing of rubber or other soft material which wears or shrinks in time, a steam-tight joint being formed by the bringing together of two plane metal faces on the door and sterilizer head. The door hinge is so made that these parts are bound to come together properly, without the use of excessive caution. Springs on such doors are liable to get out of order or need replacing, and are avoided in this apparatus. All that is necessary to lock or unlock the door is to turn the large hand wheel on the front; the locking levers then work automatically. These sterilizers are arranged for both gas and steam heat. =Sterilizing Plant.=—For the ideal operating room the entire sterilizing plant can be had in combined form, as shown in Fig. 16. It consists of a dry-heat dressing apparatus, just described, water and instrument sterilizers, all mounted on a white enameled, tubular, wrought-iron frame. The chamber of the dressing sterilizer is 8½ by 19 inches. The water sterilizer has a capacity of six gallons in each tank and is fitted with natural stone filters, thermometer, water gauge, safety valve, etc. The size of the instrument sterilizer is 8 by 15 inches and 6 inches deep, with two trays. Each apparatus in the above can be used independently of the other, all being arranged for gas-heating. [Illustration: FIG. 16.—STERILIZING PLANT.] =Dressing Cases.=—All dressings should be sterilized immediately before operation, and not laid away for later use, as often done. As the aseptic material is taken from the sterilizer it is to be placed in glass cases provided therefor, from which they are removed, as needed, during the operation. A simple glass case, as shown in Fig. 17, may be used, or, better still, the same can be obtained in combination with an instrument table, as shown in Fig. 18. [Illustration: FIG. 17.—DRESSING CASE.] [Illustration: FIG. 18.—COMBINATION DRESSING CASE AND TABLE.] =Waste Cans.=—All soiled dressings and sponges should be immediately thrown into an enameled iron pail furnished for the purpose. At no time must soiled dressings or sponges be thrown upon the floor, where they are walked over, soiling the floor and, by drying, contaminating the air of the room. Cans for this purpose are made of steel, enameled, of the form shown in Fig. 19. The contents of the can must be taken from the room after each operation and burned. The can should be flushed with carbolic solution, and returned to the operating room. [Illustration: FIG. 19.—WASTE CAN.] SUTURES AND STERILIZATION (_Ligatures_)