#Sterilisation by Heat.#--The most reliable, and at the same time the most convenient and generally applicable, means of sterilisation is by heat. All bacteria and spores are completely destroyed by being subjected for fifteen minutes to _saturated circulating steam_ at a temperature of 130° to 145° C. (= 266° to 293° F.). The articles to be sterilised are enclosed in a perforated tin casket, which is placed in a specially constructed steriliser, such as that of Schimmelbusch. This apparatus is so arranged that the steam circulates under a pressure of from two to three atmospheres, and permeates everything contained in it. Objects so sterilised are dry when removed from the steriliser. This method is specially suitable for appliances which are not damaged by steam, such, for example, as gauze swabs, towels, aprons, gloves, and metal instruments; it is essential that the efficiency of the steriliser be tested from time to time by a self-registering thermometer or other means. The best substitute for circulating steam is _boiling_. The articles are placed in a "fish-kettle steriliser" and boiled for fifteen minutes in a 1 per cent. solution of washing soda. To prevent contamination of objects that have been sterilised they must on no account be touched by any one whose hands have not been disinfected and protected by sterilised gloves. #Sterilisation by Chemical Agents.#--For the purification of the skin of the patient, the hands of the surgeon, and knives and other instruments that are damaged by heat, recourse must be had to chemical agents. These, however, are less reliable than heat, and are open to certain other objections. #Disinfection of the Hands.#--It is now generally recognised that one of the most likely sources of wound infection is the hands of the surgeon and his assistants. It is only by carefully studying to avoid all contact with infective matter that the hands can be kept surgically pure, and that this source of wound infection can be reduced to a minimum. The risk of infection from this source has further been greatly reduced by the systematic use of rubber gloves by house-surgeons, dressers, and nurses. The habitual use of gloves has also been adopted by the great majority of surgeons; the minority, who find they are handicapped by wearing gloves as a routine measure, are obliged to do so when operating in infective cases or dressing infected wounds, and in making rectal and vaginal examinations.