In treating of the cure of caries, the first thing is, to determine by what means the disease of the bone may be removed; and, secondly, what modification our treatment must undergo, in consequence of the caries belonging to the first or second species. From the very earliest periods, we find the application of stimulating and corrosive remedies recommended in this disease. The actual cautery, euphorbium, mineral acids, scalding oil, the essential oils, and warm balsams, have been universally employed, and frequently alternated with rasping and perforating the bone. This proceeded from observing, that, on the one hand, mild applications had no effect, and, on the other, that the natural slowness of exfoliation was overcome by the use of these more powerful remedies. A caries of a bone is correspondent to a mortification of a soft part; and, therefore, it is impossible to restore the diseased part to health, or life. Our chief object, then, must be to prevent the disease from spreading, and to procure a speedy separation of the dead portion. The first is much less under our power than the second; for, it is most probable, that, in the majority of instances, at least of those of a simple nature, the disease, from the first, extends a certain length, affecting a portion of the bone, and that it afterwards makes very little progress. There is, however, a specific disease which affects the bone in common with the soft parts. The bone becomes rough, and suppurates; and the soft parts have a fiery appearance: This has been called the phagedenic caries. Cancer, scrophula, lues, and other specific actions, also spread after they are once induced. The second object is to be effected by such means as operate upon the vitality and action of the part, and those which act mechanically. Those which tend mechanically to remove the dead portion, are perforations down to the sound part, which we know has happened, by the bleeding which ensues; or, we may saw down this length with a trephine. We thus, by cutting off the communication of part of the diseased surface with the adjacent parts, kill it completely, sooner than could otherwise happen, and likewise stimulate the parts below to assume the ulcerative action, and throw it off. We may also sometimes be able to turn out these portions with a levator. Those which act more exclusively, by affecting the action of the part, are stimulating applications; such as heat, acids, &c. The actual cautery is so terrifying to the patient, that it is now laid aside; and it is likewise liable to this objection, that it may, by its operation on the neighbouring parts of the bone, produce disease in them. The potential cautery is more useful, and may frequently be employed with advantage, either in a solid form, as to callus, &c. or dissolved in water, and applied with a pencil[37]. M. Sue, in his notes to Ravaton’s Practique, &c. recommends l’eau mercurielle, or solution of mercury, in nitrous acid.