[108] Dr. Gotwald, formerly quoted, describes four varieties of carbuncles, the differences between which seem to be pretty distinctly marked. 1. “One kind rises pretty high, is of a dark brown colour, the cuticle appearing as if it were burnt, and it is surrounded with a lead-coloured circle. In the beginning it is no bigger than a pea, but, if not prevented, soon grows to the size of a crown piece; inwardly it is moister than the rest, and may be more easily separated. Its seat is generally in the fleshy parts, as on the shoulders, neck, hips, arms and legs. 2. The second lie a little deeper, and do not rise so high; the eschar in the middle is entirely dark and ash-coloured, full of small chops, as if it would burst by too great dryness: it has a strong lead-coloured circle, behind which the sound flesh looks red and shining. It eats into the flesh round about it, and takes deep root: it generally fixes in the most fleshy parts, as the buttocks, calves, &c. 3. The third is not very large at first; it appears like a blood swelling, not so dark as the former, with a wrinkled skin; as it increases, small blisters arise in the middle, and form an eschar, in little clusters, which, as an ingenious physician observed, were small carbuncles. They commonly are situated in membranous and tendinous parts about the knees, toes, and behind the ears, &c. 4. The fourth is the most curious, as Purman, in his treatise on the plague, has well observed. Sitonius calls them pale, livid, ulcerous papulae: they appear with a high, yellowish blister, which seems full of corruption: the circle round it is first red, then of an ash colour: the blister soon falls, and, with the carbuncle, appears scarce so big as a pepper corn, continually eating deeper and wider. They are seated upon the cartilaginous or gristly parts. Gotwald found them near the pit of the stomach, upon the cartilago ensiformis and short ribs. All the four take root and burn very violently at first, but the two former most of all.” Dr. Alexander Russel also describes another kind of pustule, which he says appeared in a small number of the sick, but which his brother Dr. Patrick had no opportunity of observing in 1760. It had no livid or discoloured circle surrounding it, but was filled with laudable pus; and, when dry, the crust fell off, as in the distinct small-pox. This was looked upon as a favourable symptom, all who had it happening to recover.