In this place I have only to observe that I have in some cases completely succeeded, in others completely failed, in the cure of tinea capitis, by the lunar caustic. As I have not hitherto distinguished these cases from each other; and as I could only offer conjectures on the subject, I think it best to leave it for future inquiry. The same observation applies to some other cutaneous affections which I need not specify more particularly at the present. CHAPTER III. OF SOME CASES IN WHICH THE CAUSTIC IS INAPPLICABLE. It is by no means my intention to recommend the application of the lunar caustic as an infallible remedy for all local diseases. I am quite aware of the propensity, in recommending a favourite remedy, to extend its use beyond its true limits. The caustic, like all other remedies, requires to be employed with discrimination; and it is therefore my object in this little work, to state in which cases it is, and in which cases it is not, useful and successful. With this object, I have thought it not improper to add, in a concluding chapter, some observations on those cases in which I have found the lunar caustic to be inadmissible. It will, at the same time, be found that such cases, in the course of their treatment by the ordinary measures, not unfrequently become fit cases for the application of the caustic, with the view of more speedily completing the cure. This observation is particularly applicable to the cases of burns, of large ulcers, of fungous ulcers, &c. The caustic is inapplicable in extensive lacerations, for the same reason that it is so in extensive ulcers. I have found the caustic of little use in incised wounds, and should not employ it except in such wounds received in dissection. I have failed in my attempts to heal scrofulous sores by the adherent eschar; I would propose the trial with the lunar caustic and poultice. In erysipelatous inflammation, where vesicles are formed, the caustic does injury, as in recent burns. I have always found that the caustic has done injury in boils, aggravating rather than diminishing the affection. 1. _Of Burns._ The application of the lunar caustic in recent burns or scalds, has always appeared to me to increase the inflammation and vesication, even inducing blisters where there were none before. The caustic must not, therefore, be applied in these cases, until the inflammation has entirely subsided; but when there remains only a small superficial ulceration, the caustic may be passed lightly over the ulcerated surface to form an eschar which is to be defended by the gold-beater's skin; for the affection is then reduced to the state of a common superficial ulcer. An adherent eschar is generally readily formed, and no further application is required. If the ulceration be more extensive and deeper, the lunar caustic may be applied, and the eschar treated, exactly as in common ulcers. It may be well to illustrate these points, by the following cases. CASE XXXIII.