BORACIC ACID LAGOONS. 79 



(called Suffioni) in the hard crust, partly out of the 

 midst of the little pools, agitating the liquid, and 

 hurling mud and water into the air. These vapour- 

 jets have become very important to the arts, from 

 the boracic acid, a substance contained in borax, 

 which they bring up from below and leave behind 

 in the water of the Lagoons. This boracic acid is 

 recovered from the water by artificial evaporation. 

 There are ten manufactories, established for this 

 purpose, scattered about the neighbourhood ; these 

 yielded altogether in the year 1846 about a thou- 

 sand tons of crystallised boracic acid. The evapora- 

 tion goes on in pans, which, are kept hot by the jets 

 of steam from the ground, which have, it is said, 

 a temperature of from 97° to 100° C. (206°*6 to 

 212° P.) 



In certain other districts the vapours issuing 

 from the ground are mixed with (besides carbonic 

 acid) sulphuretted hydrogen, sulphurous acid, and 

 even with the vapour of sulphur : the quantity of 

 this latter, thus brought up, is certainly but 

 small, yet easily recognised by the peculiar smell, 

 and by the masses of it that are deposited in 

 the course of time. These are the Solfataras. 

 Among those best known is the Solfatara of 

 Puzzuoli, which is covered with sulphurous 

 fumeroles; but precisely similar features are met 

 with in other volcanic districts. Bunsen says of 

 the Solfataras of Krisuvick and of Reykjahlid, 



