liser 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entirely superseded marine sponges for operative purposes.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