I must however confess, that Galen says the opocalpasum was so far from being an innocent drug, that it was a mortal poison, and had produced very fatal effects. But as those Troglodytes, though now more ignorant than formerly, are still well acquainted with the properties of their herbs and trees, it is not possible that the savage, desiring to increase his sales, would mix them with a poison that must needs diminish them. And we may therefore without scruple suppose that Galen was mistaken in the quality ascribed to this drug, and that he might have imagined, from tenderness to the profession, that people died of the opocalpasum who perhaps really died of the physician: First, Because we know of no gum or resin that is a mortal poison: Secondly, Because, from the construction of its parts, gum could not have the activity which violent poison has; and considering the small quantities in which myrrh is taken, and the opocalpasum could have been but in an inconsiderable proportion to the myrrh, to have killed, it must have been a very active poison indeed: Thirdly, these accidents from a known cause must have brought myrrh into disuse, as certainly as the Spaniards mixing arsenic with bark would banish that drug when we saw people die of it. Now this never was the case, it maintained its character among the Greeks and the Arabs, and so down to our days; and a modern physician, Van Helmont, thinks it might make man immortal if it could be rendered perfectly soluble in the human body. Galen then was mistaken as to the poisonous quality of the opocalpasum. The Greek physician knew little of the Natural History of Arabia, less still of that of Abyssinia, and we who have followed them know nothing of either. This gum being put into water, swells and turns white, and loses all its glue; it very much resembles gum adragant in quality, and may be eaten safely. This specimen came from the Troglodyte country in the year 1771. The Sassa, the tree which produces the opocalpasum, does not grow in Arabia. Arabian myrrh is easily known from Abyssinian by the following method: Take a handful of the smallest pieces found at the bottom of the basket where the myrrh was packed, and throw them into a plate, and just cover them with water a little warm, the myrrh will remain for some time without visible alteration, for it dissolves slowly, but the gum will swell to five times its original size, and appear so many white spots amidst the myrrh.