By these means, the sound part below assumes the ulcerative action, its connection with the diseased portion is then destroyed, and reparation takes place. The ulcer of the bone is red, and its surface covered with innumerable granulations, which rise up to the level of the surrounding parts, after which a cicatrice is formed. These granulations in the bone are absorbed, and others more perfect are deposited in their place, until at last they become completely osseous[38]. [37] If we use the solution, we must, if the bone be very porous, or spongy, apply only a little at once, otherwise it may sink down, and injure a part which we do not wish to act on. [38] There is a curious case of caries, which is frequently met with: The diseased part, instead of being cast off, is surrounded by a covering of new bone, (except at one portion, where a sinus and ulcer is formed in the soft parts) and may be felt rattling within it. In this case, there is necessarily a permanent enlargement of the part, from the additional bony matter; and this, together with the sinous openings, and the internal caries, being felt with the probe, form the character of the disease, which has been called necrosis, a term which formerly implied merely mortification. The cure of this complaint is to be accomplished by extracting the diseased part, when it becomes loose, if the opening in the case be sufficiently large; if not, it is to be enlarged with the trephine, &c. See the works of Ruysch, Default, &c.; and, more lately, the publication of Mr. Russel. The next point which merits our attention, is the situation of the bone, and the circumstances which attend the caries. When superficial, a fungous ulcer is produced, and the modification which this situation requires in the application of the general plan will come afterwards to be attended to; the modification in the treatment which is required in sinuses has been mentioned above. It may here only be remarked, that, where the sinuses are superficial, they may be laid open, which will induce the ulcerative action in their course, and allow us to apply the proper remedies to the bone; but where they run deep, we must either allow the disease to run its natural progress, and treat the constitution according to the effects produced, or, by means of a canula, convey a piece of caustic to the diseased part, in the same way as we treat obstinate strictures of the urethra, &c. When, with the probe, we feel the bone loose, we may assist its exit with the forceps, or by enlarging part of the sinus, according to circumstances.