210 REACTION OF THE INTERIOR OF THE EARTH 



throw up small cones formed of liquid mud. They are 

 seen to rise in whitish whirls of vapour which disperse 

 themselves in the air. The boracic acids, which these 

 aqueous vapours bring up with them from the bosom of 

 the earth, cannot be secured when the vapours of the 

 soffioni are collected in vessels placed above the orifices ; 

 for they are so volatile that they escape into the atmo- 

 sphere. The acid is only successfully obtained in the 

 skilfully arranged establishments belonging to Count 

 Larderel, where the orifices of the soffioni are covered by 

 artificially formed reservoirs of water, which absorb the 

 vapours. ( m ) According to Payen's excellent analysis, 

 the gaseous exhalations contain 0'57 carbonic acid, 0'35 

 nitrogen, only 0-07 oxygen, and 0*001 sulphuric acid. 

 Where the boracic vapours penetrate the fissures of the 

 rock they deposit sulphur. According to Sir Eoderick 

 Murchison, the rock is partly cretaceous, and partly an 

 eocene formation containing nummulites; a "macigno," 

 broken through by upheaved serpentine, which shows 

 itself at the surface in the vicinity at Monte Eotondo.( 289 ) 

 May we not suppose, it is asked by Bischof, that here, 

 and in the crater of Vulcano, hot steam (aqueous 

 vapour) acts at a great depth on minerals containing 

 boracic acid, or on rocks containing datholite, arinite, 

 and tourmaline, and decomposes them ? ( 29 ) 



The system of soffioni in Iceland exceeds, both in 

 variety and magnitude, anything with which we are 

 acquainted on the continent. In the Fumarole-Field of 

 Krisuvek and Eeykialidh true fountains of mud break 

 forth out of greyish blue clay from small basins with 

 crater-shaped margins. ( 291 ) Here also definite di- 

 rections can be pointed out, along which fissures 

 marked by phenomena of this class can be traced. ( 2/)2 ) 



