All the Pumices of the I sland of Melos are al so light and sandy and some Kinds there are which are produced, as was before ob served, in other Stones. The se are found in Heaps, many of them at lea st as big as can be gra sped in a Man’s Hand, and sometimes larger than that, when the superficial Part is taken off. The Pumices in the I sland of Ni suros seem an In stance of this, for they appear to have been formed by a slight Coale scence only of an arenaceous Matter: What is e steemed 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 Ma ss. On the whole, some Kinds of them, perhaps, may be formed by the Action of Fire on Stones of a proper Texture, and others in some other Manner: for there are in Nature many different Ways of Production. The Places, indeed, in which Ptimices are produced, seem to te stify the Manner of their Formation for they are principally found about the Craters of the burning Mountains. As al so the other, in regard to tho se formed in the Mouths, and different Openings of the burning Mountains, through which the Flames have made their way: and tho se made by burning the Lapis Arabicus, a Stone, which when it has pa s sed the Fire a s sumes the Form of the Pumice. Some are of opinion, that the Pumices have been entirely made what they are by burning that Kind excepted which they e steem formed by the Concretion of the Froth of the Sea This Opinion, as to the Sea kind, they take from the apparent Te stimony of their Sen ses. They seem not to burn, becau se they ab solutely and originally contain no Moi sture whereas tho se Sub stances do not kindle nor burn in the Fire, becau se their Humidity has been already evaporated.
The Power the se Stones have of re si sting the Force of Fire is not from the same Cau se with that of the Pumices, or of A shes.
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