Whenever a bone is injured, it is either corrupted, or fissured, or fractured, or perforated, or contused, or dislocated. A corrupted bone generally turns first oily, and afterwards either black or carious. These cases happen from large ulcers, or fistulas over them, when they have either grown antient, or have been seized with a gangrene. First of all it is necessary to lay bare the bone, cutting out the ulcer, and if the disorder extends farther than the ulcer was, to pare away the flesh below, till the sound part of the bone be exposed all round; then it is sufficient to cauterize the part that is oily, once or twice, by the application of an iron instrument, that so a scale may cast off; or to scrape it, till some blood appear, which is the mark of a sound bone: for whatever is vitiated must necessarily be dry. The same method must also be pursued in a cartilage that is injured; for that too must be scraped by a knife, till what remains be sound. And then what is thus scraped, whether bone or cartilage, must be sprinkled with nitre well powdered. And nothing else is to be done, where a caries or blackness is in the surface of the bone: for in that case, the cautery or the scraping must only be continued a little longer. A person, that scrapes these, ought to press the instrument boldly, that he may both do it effectually, and have the sooner done. The operation is finished, when we come to the white or firm bone. It is evident, that when the defect is a blackness, it ends in the white, and that where there is a certain degree of solidity, there the caries terminates. We have already observed, that there is also some blood in a sound bone: But when either of these happen to go in pretty deep, it is uncertain where they end.

It is easy to form a judgment in a caries, if a small probe is introduced into the foramina, which by penetrating more or less, shews that the caries is either in the surface, or of greater depth. The same may be collected(11) even from the pain and fever; for when these are moderate, it cannot have penetrated deep. A greater certainty is obtained however by the application of the perforator: for the disease ends, where the dust of the bone ceases to be black. Therefore if the caries has gone deep, several holes must be made in it by the perforator, as deep as the disease goes; then into these holes must be put hot irons, till the bone become entirely dry. For the consequences of this operation will be, that whatever is spoilt will be separated from the bone below; and the cavity will be filled up with flesh; and afterwards either no humour at all, or a small quantity will be discharged.

But if the blackness goes through(12) to the other side of the bone, it ought to be cut out. The same may be done also in a caries, that penetrates to the other side of the bone. But where the whole is spoilt, the whole must be taken away. If the inferior part is sound, so far as is corrupted, ought to be cut out. Likewise if the skull or pectoral bone, or a rib be carious, the actual cautery is needless, but there is a necessity for excision. Neither does the opinion of these people deserve our attention, who defer the excision to the third day after the bone is laid bare, before they cut it out; for in all cases it is safer to perform an operation, before an inflammation come on. Therefore both the skin is to be cut, and the bone laid bare, and freed from every fault, as far as possible, in the same moment. Now a disease in the pectoral bone is far the most pernicious of any; because though the operation have succeeded well, it hardly ever restores a perfect soundness.