If any acne pustules or infected sinuses are present, they should be destroyed or purified by means of the thermo-cautery or pure carbolic acid, after the patient is anaesthetised.

#Appliances used at Operation.#—­Instruments that are not damaged by heat must be boiled in a fish-kettle or other suitable steriliser for fifteen minutes in a 1 per cent. solution of cresol or washing soda.  Just before the operation begins they are removed in the tray of the steriliser and placed on a sterilised towel within reach of the surgeon or his assistant.  Knives and instruments that are liable to be damaged by heat should be purified by being soaked in pure cresol for a few minutes, or in 1 in 20 carbolic for at least an hour.

Pads of Gauze sterilised by compressed circulating steam have almost entirely superseded marine sponges for operative purposes.  To avoid the risk of leaving swabs in the peritoneal cavity, large square pads of gauze, to one corner of which a piece of strong tape about a foot long is securely stitched, should be employed.  They should be removed from the caskets in which they are sterilised by means of sterilised forceps, and handed direct to the surgeon.  The assistant who attends to the swabs should wear sterilised gloves.

Ligatures and Sutures.—­To avoid the risk of implanting infective matter in a wound by means of the materials used for ligatures and sutures, great care must be taken in their preparation.

Catgut.—­The following methods of preparing catgut have proved satisfactory:  (1) The gut is soaked in juniper oil for at least a month; the juniper oil is then removed by ether and alcohol, and the gut preserved in 1 in 1000 solution of corrosive sublimate in alcohol (Kocher). (2) The gut is placed in a brass receiver and boiled for three-quarters of an hour in a solution consisting of 85 per cent. absolute alcohol, 10 per cent. water, and 5 per cent. carbolic acid, and is then stored in 90 per cent. alcohol. (3) Cladius recommends that the catgut, just as it is bought from the dealers, be loosely rolled on a spool, and then immersed in a solution of—­iodine, 1 part; iodide of potassium, 1 part; distilled water, 100 parts.  At the end of eight days it is ready for use.  Moschcowitz has found that the tensile strength of catgut so prepared is increased if it is kept dry in a sterile vessel, instead of being left indefinitely in the iodine solution.  If Salkindsohn’s formula is used—­tincture of iodine, 1 part; proof spirit, 15 parts—­the gut can be kept permanently in the solution without becoming brittle.  To avoid contamination from the hands, catgut should be removed from the bottle with aseptic forceps and passed direct to the surgeon.  Any portion unused should be thrown away.

Silk is prepared by being soaked for twelve hours in ether, for other twelve in alcohol, and then boiled for ten minutes in 1 in 1000 sublimate solution.  It is then wound on spools with purified hands protected by sterilised gloves, and kept in absolute alcohol.  Before an operation the silk is again boiled for ten minutes in the same solution, and is used directly from this (Kocher).  Linen thread is sterilised in the same way as silk.