74 Br Daubeny on Thermal Springs, 



whereby the combustion is kindled, the constituents of those 

 salts which are held by it in solution will of course be detected 

 among the ejected substances, but no one has ever supposed the 

 latter to exert any influence upon the character of the pheno- 

 mena thereby produced. 



The writer of the above article seems also to go so far, when 

 he asserts, that the position of volcanos near the sea furnishes 

 no proof of the chemical theory, as being explicable, from the 

 circumstance of the elevated portion of the earth's crust having 

 suffered most in former ages from the exertion of subterra- 

 nean energy, and therefore being least exposed to it at present. 

 Has the elevation of the Apennines, I may ask, exempted the 

 Italian Peninsula from such effects, or did that of the Car- 

 pathians appear to exhaust the volcanic materials in Hungary, 

 so long as large fresh- water lakes existed in that country to ex- 

 cite their action ? 



The very idea, too, of an exhaustion of the materials seems 

 inconsistent with the views of those, who imagine with Cordier, 

 that the ejections of a volcano constitute part of the general 

 fluid contents of the globe, which, therefore, under such circum- 

 stances, ought to be every where alike present. 



Neither does the existence of volcanos in certain continuous 

 lines only, and not generally along the coasts of all regions, ap- 

 pear consistent with this notion, since there is no reason why the 

 pressure exerted, and the resistance opposed, should not, on an 

 average, be the same along the coasts of Germany or Scandina- 

 via, as of Italy and South America. 



It would seem, then, that if we were to estimate the relative 

 probability of the above theories by their capability of explain- 

 ing the various phenomena, which form the aggregate of our 

 knowledge on this subject, the lowest place must be assigned to 

 that mechanical hypothesis, which, on the authority of some 

 great names, seems in the greatest repute at present. 



It applies indeed only to one phenomenon, and that neither 

 the most constant nor the most essential of the concomitants of 

 volcanic action, — namely, the emission of lava-currents ; whilst 

 the explosive force by which the ejections of loose materials are 

 brought about, no less than the chemical nature of the ejections 



