This is a small blister, or vesicle, about the size of a chestnut, which at first contains a darkish fluid, which dries into a crust, falls off, and leaves an indolent ulcer. It is always connected with a vitiated constitution, and is dependent frequently upon imperfect diet, although chronic disease, such as syphilis, phthisis, dyspepsia, and poisonous mineral medicines, not unfrequently produce it.

TREATMENT. -- The digestive organs should be corrected, and the blood nourished and enriched by wholesome diet and tonics. The local applications should consist of emollient poultices, and kept constantly moist with the tincture of hydrastin, baptisin, or myrrh. A poultice of equal parts of bayberry, white pond lily and slippery-elm is very beneficial. The cause, however, is always to be ascertained before the treatment is interposed.