in natural history, a flake or cinder of some fossil, originally bearing another form, and only reduced to this state by the action of the fire, though generally ranked by authors among the native stones. It is a lax and spungy matter, frequently of an obscure-striated texture in many parts, and always very cavernous and full of holes; it is hard and harsh to the touch; but much lighter than any other body that comes under the class of stones. It is found in masses of different sizes, and of a perfectly irregular shape, from the bigness of a pigeon's egg, to that of a bushel. We have it from many parts of the world, but particularly from about the burning mountains Ætna, Vesuvius, and Hecla, by whose eruptions it is thrown up in vast abundance; and being by its lightness supported in the air, is carried into seas at some distance by the winds, and thence to distant shores. The great use of the pumice among the ancients, seems to have been as a dentifrice, and at present it is retained in the shops on the same account.