Cautery, a surgical term given to substances which corrode or burn any solid part of the body: they are divided into two classes, actual, and potential. By the former are understood red-hot instruments, which were much in use among the ancients, and are still employed by several barbarous nations, as their almost only means of curing diseases; but, in the modern practice of Europe, they are seldom resorted to, except for the firing of horses and cattle.

Some practitioners, however, cauterize with burning tow, others with cotton, or mora (particularly the inflamed part of a toe, for preventing a fit of the gout) ; others again with live coals, Spanish wax, pyramidal pieces of linen, etc. But of ail actual cauteries, the most expeditious and least painful, is that of strewing on the wound a small quantity of the finest gun-powder, and then setting it on fire; a method which, particularly after the bite of a mad dog, has generally been attended with the happiest effect, while it always renders the operation with the knife unnecessary.

Potential cauteries are those which we have already explained under the head of Caustics. In this place, therefore, we shall only observe, that one of the most etfec-tual methods of cleansing foul, indolent ulcerations, and checking the progress of mortification, especially in the legs, is the cautious application of the following lotion : Take thirty grains of lunar caustic, dissolve it in a pint of the purest spring, or twice filtred water. If it produce a burning sensation which continues too long for sustaining the pain in the part affect-ed, wash the ulcer with pure water, and make the solution weaker every time it is applied. Although this, in general, proves an excellent remedy in those cases, yet as it is a powerful caustic, we do not advise an indiscriminate use of it, without consulting profes sional men. - See Ulcers, and Warts.