ON THE BORACIC ACID OF CENTRAL ITALY. 293 



Rotondo, Serrazzano, San Federigo, San Edoardo, and Castelnuovo. M. 

 Durval lias one establishment at the Lake of Monte Rotondo, and a new 

 company has just been established at Travale, near Volterra, All these 

 places are in close proximity to eruptions oigabbro or Miocene serpentine, 

 as at Monte Cerboli, Serrazzano, Monte Rotondo, and numerous other lo- 

 calities, where that rock has pierced the sedimentary strata. No one can call 

 in question the existence of deep-seated subterranean fire in this neighbour- 

 hood ; though during the present century no flames have been seen at 

 the surface. I cannot help thinking that these insignificant vents can 

 only be subsidiary to the more capacious craters of the volcanoes in the 

 .South of Italy, where more ample space is provided for the escape of 

 the gases produced by the decomposition of mineral matter. In support 

 of this theory I will presently give a comparison between the two 

 localities. 



The works are so similar that it will be cpiite sufficient to describe in 

 detail that of Lardarello, which is highly interesting. This thriving 

 little colony is entirely the creation of Count Lardarel, and is situated 

 on the torrent Possera, below the village of Monte Cerboli, three miles 

 from Serrazzano, and six from Pomarance. A group of half-a-dozen or 

 more lagoni are seen on the slope of the hill, about half a mile from the 

 main road, from which they are completely hidden by rising ground. 

 Some of these lagoni are those described by Targioni Tozzetti, but the 

 vapour-vents — the soffioni of which he speaks — no longer exist, as they 

 have been artificially converted into lagoni. 



Singularly enough, boracic acid has never been found here in the solid 

 state at any depth to which search has been made, with the exception of 

 such places in which it has sublimed ; it is probably either the result of 

 the double decomposition of water and a volatile salt of boron, accord- 

 ing to Dumas' theory ; sulphide of boron and water producing boracic 

 acid and sulphuretted hydrogen, thus : — 



BoS 2 + 2HO = Bo0 2 +2HS. 



or simply chloride of boron and water producing boracic and hydro- 

 chloric acids, thus : — 



BoCP + 2 HO = BoO 2 + 2 HC1. 



in support of which supposition we only find the boracic acid appear 

 when there is water present ; or it may be caused by the reaction of sul- 

 phuric acid on borates, such as tourmaline, the granite found not very 

 far off being so rich in this mineral as to bear the name of tourmalini- 

 ferous granite. The theory I advance is tenable, provided we assume the 

 heat to be very great. Though sulphuric acid is one of the most power- 

 ful, and boracic acid the weakest, next to carbonic acid, at ordinary 

 temperatures, they exhibit the reverse phenomena at very elevated 

 temperatures ; in fact, under such circumstances, boracic acid will 



