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the Pumices, or of Aſhes^[1]. They ſeem not to burn, becauſe they abſolutely and originally contain no Moiſture; whereas thoſe Subſtances do not kindle nor burn in the Fire, becauſe their Humidity has been already evaporated.

XXXIV. Some are of opinion, that the^[2] Pumices have been entirely made

whether a coloured Diamond be not more beautiful even than a perfect clear one.

We talk of our vaſt Diamonds, the Tuſcan, the Sancy, and Pitt's; but what are theſe to that of the Mogul, which before cutting weighed very near eight hundred Carats? Foſſils arrang'd, p. 139, 140.

↑ The Author here explains upon the Manner in which theſe Stones reſiſt the Action of the Fire, which he declares to be by their containing naturally no Moiſture, which he has before declared to be eſſential to Fuſibility; not by their having already ſuffered all the Change they were liable to, from their having been before expoſed to that Element. He gives the very rational Opinion of ſome People in his Time, and which we ſhall eaſily perceive hereafter. was alſo his own, that ſome Subſtances, commonly ſuppoſed in their native State, had certainly been wrought upon by Fire; and had by that means been diveſted of whatever that Element could drive out of them: and brought into a Condition of not ſuffering any farther Changes by the ſame Means.
↑ The Author mentioning it but as the Opinion of ſome, that the Pumice had already paſſed the Fire, and by it been reduced into its preſent State; is a Proof that the general Opinion in his Time was, that it was in its native Condition. This ſeems to have been an Error of the later as well as the antient Writers of Foſſils, who have almoſt all given it a Place among the native foſſil Stones, as if Nature had formed it as we ſee it: Whereas there is all the Evidence that our Senſes can give, that it is no more than a Cinder; the Remainder of ſome other foſſile Body calcined by a violent Fire either ſubterranean unſeen, and perhaps ſince extinguiſhed, or that of the burning Mountains, on and about all which it is conſtantly found; and that in vaſt Quantities. The more violent Exploſions of theſe may have toſſed immenſe Quantities of it to Places ſo diſ-

[2] The Author here explains upon the Manner in which theſe Stones reſiſt the Action of the Fire, which he declares to be by their containing naturally no Moiſture, which he has before declared to be eſſential to Fuſibility; not by their having already ſuffered all the Change they were liable to, from their having been before expoſed to that Element. He gives the very rational Opinion of ſome People in his Time, and which we ſhall eaſily perceive hereafter. was alſo his own, that ſome Subſtances, commonly ſuppoſed in their native State, had certainly been wrought upon by Fire; and had by that means been diveſted of whatever that Element could drive out of them: and brought into a Condition of not ſuffering any farther Changes by the ſame Means.

[p83-3] The Author mentioning it but as the Opinion of ſome, that the Pumice had already paſſed the Fire, and by it been reduced into its preſent State; is a Proof that the general Opinion in his Time was, that it was in its native Condition. This ſeems to have been an Error of the later as well as the antient Writers of Foſſils, who have almoſt all given it a Place among the native foſſil Stones, as if Nature had formed it as we ſee it: Whereas there is all the Evidence that our Senſes can give, that it is no more than a Cinder; the Remainder of ſome other foſſile Body calcined by a violent Fire either ſubterranean unſeen, and perhaps ſince extinguiſhed, or that of the burning Mountains, on and about all which it is conſtantly found; and that in vaſt Quantities. The more violent Exploſions of theſe may have toſſed immenſe Quantities of it to Places ſo diſ-

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