230 Dr Daubeny on the Spring at Torre del Annunziata. 



do not furnish direct confirmation of the connexion between vol- 

 canic processes and the evolution of nitrogen, I contend, on the 

 other hand, that they suggest no facts, which can set aside the 

 evidence in favour of that position, which the production of am- 

 monia within the volcano itself appears to furnish *. 



It seems to me also, that an examination into the thermal 

 springs of a volcanic district, with reference to this point, name- 

 ly, as to whether they do or do not afford a channel for any 

 gaseous emanations, may perhaps be a means of determining, 

 either that the igneous action is at the time going on underneath, 

 or that it has been transferred to some other quarter. 



The former I take to be the case at Castellamare, at Torre, at 

 the Solfatara ; the latter, I should conclude, from the absence of 

 gaseous exhalations, with respect to Ischia, notwithstanding the 

 continuance of a high degree of heat pervading the rocks of that 

 island, which is evidenced by the abundance of thermal waters, 

 and by other phenomena, — a heat imparted to them probably at 

 a period as remote as that of the latest eruption which has oc- 

 curred in that island, that, namely, of 1502. 



* See my paper in the Philosophical Transactions for 1835 on the late erup- 

 tion of Vesuvius. 



