2J93 SOUFFRIERE OF MONTSERRAT. 



by the eddy wind up the ravine, the breezes from any other 



quarter being shut out by the surrounding hills*. 



This evolved Admidst the loose stones and fragments of decomposed 

 irom fissures , ,. , . , 



rock are many fissures and crevices, whence very strong 



sulphureous exhalations arise, and which are diffused to a 



considerable distance ; these exhalations are t.o powerful as 



to impede respiration, and near any of the fissures are quite 



intolerable and suffocating. The buttons of my coat, and 



some silver and keys in my pockets were instantaneously 



with intense discoloured. An intense degree of heat is at the same time 

 evolved, which, added to the apprehension of the ground 

 crumbling and giving way, renders it difficult and painful 



Boilingritulet. to walk near any of these fissures. The water of a 

 rivulet, which flows down the sides t>f the mountain and 

 passes over this place, is made to boil with violence, and be- 

 comes loaded with sulphureous impregnations. Other 

 branches of the same rivulet, which do not pass immediately 

 near these fissures, remain cool and limpid, and thus you 

 may with one hand touch one rill which is at the boiling 

 point, and with the other hand touch another rill which is 

 of the usual temperature of water in that climate. The 



Fissures con- exhalations of sulphur do not at all times proceed fimthe 



ing/ same fissures, but new ones appear to be daily formed, other* 



* This peculiar decomposition of the surrounding rock has been 

 frequently observed in similar situations, and under analogous cir- 

 cumstances, and has I find been accounted for by other persons in the 

 same way : thus Dolomieu says, " The white colour of the stones in 

 the interior of all the burning craters is owing to a real alteration of 

 the lava produced by acid sulphureous vapours, which penetrate 

 them, and combine with the alumine that constitutes their base, thus 

 formiug the alum obtained from volcanic substances.'* Voy. aux Isle* 

 de Lipari. p. 18. 



And he afterward adds, " The alteration of lavas by acid sul- 

 phureous vapours is a kind of analysis of volcanic substances made 

 by Nature herself. There are lavas, on which the vapours have not 

 yet had sufficient time to act, so as to change their nature entirely ; 

 and then we see them in different states of decomposition, which we 

 know by the colour." 



Alum is doubtless formed at this place, as well as elsewhere under 

 similar circumstances : the potash necessary for the composition of 

 this salt being, as well as the argil, derived from the surrounding 

 rock. See Vuuouelin's Memoire. Journal des Mine*, vol x, p. 441. * 



becoming 



