HAMILTON ON THE GEOLOGY OF TUSCANY. 297 



evaporation, the boracic acid is at length obtained in numerous 

 vats, where it crystallises with great facility. 



The great difficulty formerly experienced in this process was 

 the expense of fuel required for the process of evaporation ; until 

 the happy idea at length suggested itself to the proprietor of 

 availing himself of the almost inexhaustible supply of heat pre- 

 pared by Nature herself in the numerous vents from which the 

 streams of boiling vapours were constantly emitted. Acting on 

 this suggestion, he built a sort of chamber over some of the vents, 

 and conducting the vapour by subterranean channels into the 

 evaporating houses, obtained without a farthing of additional out- 

 lay all the heat he could require. The consequence of this simple 

 application of natural power was, that the value of the works rose, 

 in one year, from a capital of one thousand pounds, for which the 

 fee simple was offered, to a rental of twenty thousand pounds per 

 annum. 



Similar vapours or " soffioni," as they are called, occur in several 

 other localities in the same district, or within a distance of 12 or 

 14 miles, as at Sarrezano, Castel Nuovo, Monte Rotondo, and 

 others ; and it is impossible not to be struck with the manner in 

 which they throw light on many of the geological phenomena in 

 this and other countries ; particularly with regard to the filling up 

 of cracks and fissures in rocks, and the local deposits of various 

 substances, such as calc spar, gypsum, sulphate of lime, sulphate 

 of soda, &c, many of which occur in this very neighbourhood. 

 It is highly probable that such emissions of gases and vapours 

 may have produced many of those local phenomena, which have 

 been so frequently attributed to the effect of springs, and are con- 

 sidered as aqueous deposits. That great connection exists between 

 them cannot be doubted, as the soffioni of Monte Cerboli do un- 

 questionably deposit much sulphate and carbonate of lime, and if 

 supposed to rise through water would most certainly deposit much 

 more. On the whole, therefore, whether we consider the remark- 

 able and almost terrific appearance of these vents, from hundreds 

 of which the vapours escape with the noise of a steam-boiler 

 blowing off its steam, or the importance they have in connection 

 with other geological problems to which they may offer a solution, 

 they must be considered as presenting to us some of the most 

 interesting, if not important geological phenomena which the 

 Tuscan States can afford to the pursuer of geological investi- 

 gations. 



November 20, 1844. 



Charles Faulkener, Esq., and John Bravender, Esq. of Ciren- 

 cester, were elected Fellows of this Society. 



