Remarks on Volcanoes. 277 



my professed object principally was that of enlisting the ser- 

 vices of chemists in an attempt to elucidate a series of phe- 

 nomena, which, although essentially chemical, had been 

 hitherto, in a great degree, abandoned to geologists. 



Indeed, since the time when Gay-Lussac published his 

 11 Remarks on Vesuvius," and that at which Sir Humphry 

 Davy paid a cursory visit to the same spot, no chemist of 

 European reputation appears to have made volcanoes a sub- 

 ject of study, excepting Abich, to whom we owe the first 

 lucid sketch of the chemical relations which volcanic and 

 plutonic rocks bear to each other ; and Professor Bischoff of 

 Bonn, whose researches were, however, confined to extinct 

 volcanoes, such as those of the Rhine and Eyfel. 



Hence it is not to be wondered at, that the subject should 

 be treated as though it were exclusively a mechanical pro- 

 blem, and theorized upon without any due appreciation of 

 the interesting chemical phenomena which it presents to our 

 notice. 



It was this consideration more especially which led me, in 

 my work on Volcanoes, to give a prominence to those points 

 which appeared to have been unduly neglected by others ; 

 and to advocate with more zeal than I might otherwise per- 

 haps have felt inclined to do, a theory which necessarily 

 brought before us the nature of the gaseous, saline, and 

 crystalline products which proceed from the internal focus of 

 its action. 



That this was my object, will appear from some remarks 

 which I made fifteen years ago, in my "Report on Mineral 

 and Thermal Waters," undertaken at the request of the Bri- 

 tish Association for the Advancement of Science, and pub- 

 lished in their Transactions : 



"We ought,'' I observed, " carefully to distinguish between 

 that which appears to be a direct inference from observed 

 fact, and what can at most advance no higher claim than that 

 of being a plausible conjecture. The general occurrence of 

 volcanoes in the neighbourhood of the sea, and the constant 

 disengagement of aqueous vapour, and of sea -salt from their 

 interior, are facts that establish in my mind a conviction that 

 water finds its way to the seat of the aqueous operations, 

 almost as complete, as if I were myself an eye-witness of an- 



