Should this cause be admitted (indeed whether it is admitted or not) we see that it is in vain to attempt to solve the phenomena of pestilence by the doctrine of stimuli, excitement or debility. There is no degree of stimulus, fire exepted, which can convert part of the body into an hard eschar, neither can it be done by any degree of debility or exhaustion. Besides, the irregular manner in which these eschars are scattered up and down, shows that the cause has not acted from a regular diffusion all over the body, but in a number of insulated spots, between which the connexion can by no means be traced. In all pestilential eruptions indeed the action of fire seems to be very perceptible. Gotwald mentions his having observed in two patients what he calls _papulæ ardentes_ “burning pimples,” which Dr. Russel supposes to be a modification of carbuncular pustules. Gotwald calls them also _fire-bladders_, and says that they were as broad as a shilling, of an irregular shape, and the skin seemed as if _shrivelled with fire_. The carbuncle itself approaches much to the nature of the eschar, and is attended with violent heat in the adjacent parts. Gotwald, who gives an account of the plague at Dantzic, distinguishes the carbuncle into four kinds, (to be afterwards described.) Of these he says in general, that they all _burn_ very violently at first, &c. From all these accounts it seems plain, that in the plague there are partial discharges of heat, from _some_ cause, upon various parts of the body; and that, in many instances, this heat destroys the texture of the parts entirely. When this is done instantaneosly the patient feels no pain, but if more gradually, the pain is excessive, as in the case of buboes and carbuncles; which the Journalist of the plague year in London informs us were attended with such horrid pain as to make the patients cry out in a lamentable manner. This extraordinary heat must either come from without or within, and we have all the reason in the world to believe that it comes from within. Mr. Hunter, in his Treatise on the Blood, informs us that in a local inflammation there is always an increase of heat in the inflamed part. Should this heat arise, as it probably does, from an emission of part of the latent heat, we may conclude, that such a quantity might be emitted, as entirely to change the texture of the parts. Thus mortifications or destructions of those parts may ensue, of all kinds, from the mild _pus_ to the pestilential eschar.