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for they appear to have been formed by a ſlight Coaleſcence only of an arenaceous Matter: What is eſteemed a Proof of this is, that ſome of the Pumices found there crumble in the handling into a kind of Sand, as if they never had been thoroughly concreted or bound into a Maſs.
XXXVII. Theſe are found in Heaps,
ner of writing in thoſe early Times, had given Occaſion to be ranked among them. What they really were is not eaſy, at this diſtance of Time, to determine; but the moſt probable Conjecture is, that they were Pyritæ; Specimens of which I have at this Time, that bear ſome rude external Reſemblance of the Pumice Kind; and we ſhall preſently ſee this Author deſcribing a Pumice, which he ſays is ſomething like one Species of the Pyritæ, called Molaris; it may give ſome Light into this Caſe to obſerve, that Strabo, mentioning this Iſland, ſays, Saxoſa eſt & molaris lapidis copia prædita. De Laet imagines the Stone deſcribed by our Author muſt have been very different from that of Strabo's, becauſe it was liable to crumble to pieces in the Fingers; but as I have already obſerved, that the Molaris of the Antients was a Species of the Pyrites, and as no Stone is ſo liable to crumble in pieces as the Pyrites, when it has lain ſome time expoſed to the Air, and the Salts have ſhot and got looſe, I am ſo far from being of his Opinion, that I look upon it as a Certainty, that the Niſura Pumice of our Author, and Molaris of Strabo, are the very ſame Subſtance; and that Strabo's Words are a great Confirmation of my Conjecture; as is alſo the Size our Author allots the Stone, and its Property of crumbling in pieces, which he alſo obſerves was not univerſal, but only happened to ſome of them, thoſe, I imagine, which had lain moſt expoſed, and the Salts of which had been let looſe by the Humidity of the Air, while the others continued firm and ſolid, as thoſe in England and other Places do, while lodged in the Strata they were originally depoſited amongſt. This I take to have been the Occaſion of the different Degrees of Hardneſs of this Subſtance which our Author has deſcribed, though the Philoſophy of his Times
