140 Mr Forbes's Physical Notices of the Bay of Naples. 



Mines^'' by Dupuget,* and in the Geological Transactions. In 

 the first we have an account of one of the active eruptions of 

 the principal mountain in the island in the middle of last cen- 

 tury, which appear to take place from the sides, leaving a 

 plain on the top in the form of a Solfatara. In 1797 an 

 eruption took place at the height of 4800 feet. Dupuget is 

 most particular in his account of the sulphureous part, which 

 he describes as extremely active and filled with vapours. He 

 describes minutely three caverns he observed on the moun^ 

 tain, the first of which is 45 feet by J:i5, and of difficult access, 

 through which vapour rises of a temperature of 32° R. = 104° 

 Fahr. and the walls are abundantly lined with green and white 

 crystals, thus presenting phenomena apparently identical with 

 those which we have been endeavouring to describe. In the 

 plain at top springs occur, having a temperature of 73° R. 

 = 198° Fahr. 



Another of the most remarkable of these islands is St Vin- 

 cent, the great mountain of which is called Le Souffrier, a 

 name which it probably received before 1718, when it changed 

 its character and became an active volcano, and again in 1812 

 desolated the island by a most awful eruption. In Martinique, 

 though the volcanic formations are overlaid by limestone, yet 

 in some places form lofty hills, particularly La Montagne Pelee, 

 which is a Solfatara, and 736 toises high. There has been no 

 eruption of the Peak, at least since America was discovered ; 

 but there are several craters on the side, one of which opened 

 January 22, 1792, and discharged much sulphur and black 

 sulphuretted water. Hot springs occur in different parts of 

 the island, -f- 



Several other Solfataras occur in the same group ; but the 

 particulars which have reached us serve only to confirm the 

 general fact of the similarity of this volcanic phase wherever 

 it occurs. Montserrat is mentioned as possessing beautifully 

 crystaUized porphyritic rocks which have in many places suf- 

 ferred decomposition from sulphureous vapours, as we have 

 explained in the Solfatara of Pozzuoli. 



I have not even mentioned the Solfatara in the Campagna 

 di Roma near Tivoli, nor the Lagunes of Tuscany. The for- 



• Vol. iii. p. 44, &c. t Annales des Mines, vol. iii. 



