418 Oljervailo7ii on Pumice Stone. 



Sicily; bnt in Sicily the heavy kind of pumice ftvine, wlitch 

 does not fvvim, is employed lor that purpofe. .It is worthy of 

 remark, that among the fo-called Etrufcan and other eartheil 

 ware, as well as among thofe which were formerly brought 

 from Japan and China oftener than at prefent, there were 

 veflTels much lighter and thinner than any that can be ma- 

 nufaftured in Europe. It is not improbable that Fabbroni 

 may have been fo fortunate as to difcover this preparation: 

 at any rate, he not long ago laid before the Economical 

 Society of Florence, for examination, a kind of brick, the 

 fpccific gravity of which was not greater than that of the 

 iighteft wood *. 



Mod authors, who give an account of pumice-ftone, fpeak 

 t)f it as if it were to be found in the neighbourhood of all 

 burning mountains. This, however, is falfe ; for it is not 

 found among the produftions of all volcanoes, but only near 

 tliofe, as the mincralogifts affert, the fire of which has arifen 

 in fuch ftrata as have intermixed with them a great deal of 

 feld fpar. It is found nowhere in (greater abundance than 

 in the Liparine iflauds, as already faid, though large quan- 

 tities of it arc found in Iceland; whereas it is very feldom 

 feen near Vefuvius, and never in the neighbourhood of 

 >'Etna. The ancients, however, fpeak of ^-Etncan pumice- 



• After I had wrisren t!>is article, I found in Grc-n's New Ph/ical 

 Jomual, Vol. IF. pnit i. p. 129. a paper tranflated from the Italian of 

 )-;;bbrt)ni, by which it appears, that he made his biick of a kind of earth 

 (hi^ up rear Santa Flora, in the territories of Sienna, which neither effi.r- 

 vefcea with acids nor is fufible in the fire, and which, according to his ex- 

 amination, confifls jf filiccous earth, magnefian earth, and aluminous 

 (•artb, in the proportions of 0"55, o'le;, and c-i2. This earth, therefore, 

 ft tms to coniirt of the lame component parts, and altrioft in the fame pro- 

 portions as the fo-cailed fes-froth. According to the prevailinii: mode of 

 cljaneing old names and making new opes, Fabbroni calls the above earth 

 y.trinafoJiUs, under which is uudcrftood, at prefent, an earth arifing from 

 tiflorefccd gvpfum. 



[For Fabbrn'ni's method of making floating biicks, fee Ibe. Philofofb.iul 

 h't»gttxine,^fA.\l. ^. \ho. Edii.] 



ftone ; 



