DISINFECTION OF INFECTED CARRIERS, ETC. 51 
carbolic solution is not regarded as sufficient by the expe- 
rienced surgeon of today. Modern methods may be de- 
scribed under two headings.—first, by the use of heat, and 
second, with formaldehyde gas. 
Heat. Metallic instruments should be boiled for at least 
fifteen minutes in a I per cent. sodium carbonate solution, 
and when spread out for the operation they should be placed in 
a tray containing a 3 per cent. carbolic solution. As has 
been stated before this latter precaution is not considered 
necessary in human surgery, but the chances of instruments 
becoming contaminated during an operation is much greater 
in veterinary practice. Aftér the operation they should be 
carefully dried and replaced into the sterilizer, or in the ab- 
sence of such an equipment, in a dust-proof case. 
Sponges are, indeed, treacherous, and yet no other article 
can readily supplant them for baling blood from a wound 
during operations.. Cotton, gauze, oakum, etc., are very poor 
substitutes for this purpose in spite of the fact that they are 
less liable to carry infection into a wound. Sponges are here 
to stay, however, so far as veterinary operations are con- 
cerned, and therefore we should make the best of the situa- 
tion and adopt the best method of sterilizing them, which 
consists of boiling and then wringing them from a I to 500 
mercuric chlorid solution, or with formaldehyde gas, as de- 
scribed in the following paragraph. Bandages, wadding and 
ligatures are made entirely safe by soaking for fifteen minutes 
in mercuric solution of the same strength. Ligatures may 
be boiled, but this is not absolutely necessary in the case of 
bandages and wadding, as soaking them in such a concen- 
trated solution is certain to destroy any organisms they may 
carry. Even when these materials are boiled or subjected to 
dry heat the soaking should not be omitted, because it is an 
antiseptic bandage and not simply an aseptic one that is de- 
sired to cover veterinary operations. 
FoRMALDEHYDE Gas. The use of this gas for  sur- 
gical sterilization requires special apparatus, namely a for- 
maldehyde sterilizer, with which metallic instruments, wooden 
