STERILIZATION AND DISINFECTION. 113 surgeon which cannot well be rendered incandescent, exposed to dry heat at 150° C., steamed, or intermittently heated without injury. For these objects disinfection must be practised. Ever since Sir Joseph Lister intro- duced antisepsis, or disinfection, into surgery there has been a struggle for the supremacy of this or that highly- recommended germicidal substance, with two results— viz. that a great number of feeble germicides have been discovered, and that belief in the efficacy of all germi- cides has been somewhat shaken; hence the origin of the successful aseptic surgery of the present day, which strives to prevent the entrance of germs into, rather than their destruction after admission to, the wound. For a complete discussion of the subject of antiseptics in relation to surgery the reader must be referred to the large text-books of surgery, where much space is thus occupied. A short list of useful germicides of which the respective values are given, and a brief discussion of some of the more important measures, can alone find space in these pages. The antiseptic value of some of the principal substances used may be expressed as fol- lows, the figures indicating the strength of the solution necessary to prevent the development of bacteria : Pyoktanin (methyl violet) . i : 2,000,000—i : 5000. Formalin.........i 125,000—i 15000. Bichlorid of mercury . . . i: 14,300. Hydrogen peroxid.....i : 20,000. Formalin.........i : 20,000. Nitrate of silver......1:12,500. Creolin..........i: 5000 to i : 200 (does not kill anthrax). Chromic acid.......i: 5000. Thymol..........i : 1340. Salicylic acid.......i : 1000. Potassium bichromate . . . i: 909. Trikresol.........I : 1000—i : 500. Zinc chlorid........i : 526. Potassium permanganate . i : 285 ; not prompt in action. Nitrate of lead......i : 277. ...........i : 200.