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 black colour, sometimes a little tranparent, (on the edges) but opaque in its general appearance, (when in a mass) and reflecting images, like mirrors, placed against a wall. Many make gems of it, and we have seen solid images of the divine Augustus cut out of this substance; who ordered four obsidian elephants to be placed, as curiosities, in the Temple of Concord, &c." It is evident from this description, that, though a fact now perfectly ascertained, it was not known to Pliny, that the obsidian stone itself is nothing more than glass thrown up by a volcano; notwithstanding that the exact resemblance between it and the manufactured glass had occasioned them, as he mentions, to be mistaken for each other; and hence it continued to retain the names of in Greek, and lapis obsidianus in Latin.

The learned Salmasius has ridiculed Pliny for his description of the obsidian, and has attempted to prove that he was wrong in calling it "obsidianus," or saying it was discovered by Obsidius in Æthiopia; but, with deference to such high authority, I still must think, that without better arguments than those he has given, Pliny is much more likely to be correct in his statement, especially as his description is now found to agree very accurately with the specimens of that very kind which is termed in the Periplus; whereas the description of the stone by Salmasius is extremely inaccurate. Dr. Vincent was the first person who suspected that the opsian stone might be found near this point, but, owing to the extreme incorrectness of the charts previously to Lord Valentia's survey of the coast, he was unable to find any bay from Massowa to Béloul, answering to the one described in the Periplus. As I have since had the