A certain mixture of sulphur, steel-filings and water, buried a short depth from the ground, will exhibit a kind of miniature volcano; and hence some philosophers have concluded, that in the bowels of burning mountains there are various sorts of bodies which probably ferment by moisture, and being thus expanded, at last produce eruptions and explosions. The mouth or chimney of a burning mountain is, in many instances, upwards of a mile across! from which, in an eruption, are emitted torrents of smoke and flame, rivers of lava, (consisting chiefly of bitumen and melted metal,) and clouds of cinders, stones, &c. to an immense distance. The wonderful quantity of these materials thrown out from the orifice almost exceeds belief; the lava rushes like a fiery torrent at a very rapid pace,--ravages the labours of agriculture, overthrows houses, and in a few seconds utterly destroys the hopes of hundreds of families--the toils of hundreds of years. Nothing impedes its awful course; when interrupted by stone walls, or even rocks, it collects in a few moments to the height of eight or ten feet; its immense heat and violent pressure quickly batter down the obstacle, which is literally made rotten by the fire, and the whole mass seems to melt together into the lava, which again continues its progress until exhausted by the distance of its destructive march. An English traveller, who was at Naples during the eruption of Mount Vesuvius, on the 10th of September, 1810, thus describes the scene:--