The substances belonging to this group are employed for the purpose of destroying the tissues to which they are applied. They differ in their mode of action, in the extent of the destruction which they effect, in their capacity for diffusion into the blood, and in the results which they severally accomplish.

They are prescribed for the purpose of cauterizing poisoned wounds —syphilitic ulcers, snake-bites, the bites of rabid animals—for the removal of gangrenous parts, foul or exuberant granulations, and especially for the destruction of malignant growths. When the diseased parts, to the destruction of which they are devoted, have been fully acted upon, the caustic action is ended; poultices are applied to favor the entire separation of the sloughs, and a healthy surface is finally left to heal by granulations.

The members of this group have, with one exception, been discussed elsewhere:

The mineral acids.

The chloride and sulphate of zinc.

Potassa fusa and potassa cum calce.

Arsenious acid.

The acid nitrate of mercury.

Bromine.