302 
THE CAUTERY AND THE SETON. 
eight or ten seconds, for at the expiration of that time it will have 
lost a great deal of its heat, especially if it has been plunged into 
any vascular texture : it will then only act as an excitant; the 
surrounding parts with which it was in contact will begin to ad- 
here to it, and will not be separated from it without considerable 
force, and very annoying blemishes will be produced. If it is 
thought that the first incision by the iron is not sufficiently deep, 
a second should be applied as soon as possible, and, in some 
cases, a third. 
When the iron is carried deeply across certain muscles, in or- 
der to reach a portion of bone affected with caries or necrosis, 
it will be necessary to make a previous incision, with a common 
scalpel, down to the bone, and then to hold the edges of the wound 
apart, and conduct the heated iron to the bottom by means of 
a canula contrived for this purpose. It should be the especial 
care of the operator that the iron, brought to a blood-red heat, shall 
not be brought into the immediate neighbourhood of any of the 
great vessels, or nervous trunks, or any important articulation. 
This deep mode of firing causes at the moment excessive pain, 
but which soon calms down, and produces an exfoliation, the 
thickness of which depends on the degree of heat, the force with 
which the cautery was applied, the repetition of the application, 
and the soft or hard texture of the parts. The fluids, sound or 
diseased, which were in the cauterized part are evaporated or de- 
composed, the bloodvessels and the nerves are destroyed, and 
the sensibility and the circulation cease. The neighbouring 
parts are highly irritated, and immediately and powerfully con- 
tracted ; but at the expiration of a few days a discharge com- 
mences, which is followed by a separation of the burned and 
charred parts, and a more or less abundant suppuration. 
It can be easily conceived that such a mode of cauterization is 
indicated in envenomed wounds, the bites of rabid animals, 
farcy, and gangrenous and malignant affections. It is useful to 
arrest haemorrhages which will not yield either to the ligature or 
the styptic. It is often applied to destroy portions of fungous or 
cancerous tumours, which cannot be got at by the bistoury ; and 
also the secreting membrane of encysted tumours ; also warts, 
and polypous tumours ; and to remove the scirrhosities of certain 
fistulae, and to excite a laudable suppuration ; and, finally, to 
produce exfoliation in caries of the bones, the cartilages, or the 
ligaments. 
THE SETON. 
The seton consists of a piece of linen, or tape, or riband, or 
cord, or leather, introduced into the subcutaneous or other tis- 
