In the beginning of my trials of the treatment of the ulcers by the caustic, I was repeatedly betrayed by the smooth appearance of the eschar, to think that all was going on well, when in fact a scab was all along forming underneath. In these cases inflammation soon followed, and it was only by carefully and daily evacuating the fluid effused under the eschar that I at length succeeded in effecting an adherent eschar free from surrounding inflammation. This remark cannot be too often repeated. CASE XXIX. The peculiarity of the present case arose from neglect in evacuating the fluid effused under the eschar the day succeeding its formation, the consequence of which was that the edges of the eschar became raised all round, without however being entirely detached. Mr. Draper, aged 50, had a small irritable ulcer of the size of a horse-bean, upon the shin, of a month's duration, with surrounding inflammation to the extent of several inches. I applied the lunar caustic to form an eschar and protected it with gold-beater's skin. On the following day, it appeared from the flatness of the surface, that the eschar was adherent; the inflammation remained as before. On the next day the eschar was raised all round its borders, presenting the appearance of an elevated ring. I made an opening in one point of this ring by a penknife and evacuated the fluid, and I again applied the caustic all round in order to give firmness to the edges of the eschar. On the succeeding day an opening was made in the centre of the eschar and a little more fluid was evacuated. This mode of treatment was continued daily for about a week, the inflammation gradually subsiding and the eschar becoming adherent and corrugated. In about three weeks, the patient thinking the sore quite well detached the eschar; there was still, however, a minute ulcer left, which was touched with the caustic. CASE XXX. C. Cocking, aged 17, has an ulcer of the size of half-a-crown on the inner part of the knee, occasioned by an accident. He had been a month under surgical care in the country when he applied to me, but the ulcer continued without disposition to heal, and fungous; it had apparently been treated by a solution of sulphate of copper. I applied the lunar caustic over the surface of the sore and upon the surrounding skin. On the following day, the eschar was unadherent and puffy, and on piercing it a little fluid escaped. The incision into the eschar was repeated three or four successive days, but the eschar still retained its puffy character; I therefore directed a poultice to be applied to remove it.