346 CONNECTION OF THERMAL SPRINGS IN VIRGINIA 



of the residuary nitrogen evolved. The carbonaceous matter* 

 also would h(>lj) to rob the air of oxygen, and aid in the produc- 

 tion of the carbonic acid, by which the nitrogen is uniformly ac- 

 companied, although it is to the calcination of calcareous rocks 

 that, in common with others, I would refer most of the carbonic 

 acid which our thermal waters contain. 



The conjectures thus thrown out, though, as I think, not en- 

 tirely useless, are offered with that disti'ust which must always 

 attach to speculations that cannot be brought to the touchstone 

 of actual observation, and more especially, too, from the fact, that 

 they do not appear to have suggested themselves with any force 

 to the able philosophers who have investigated this subject. 

 That I may not be misconceived, I here beg to remark, that I 

 have no disposition to clenij the hypothesis of the metallic bases, 

 as applied to volcanoes, or even to some thermal springs. On 

 the other hand, I would adopt it as a part of the general theory 

 of the causes concerned in the formation of the early crust of the 

 globe from a molten, and chiefly metallic mass. But, in this 

 later stage in the history of our earth, I would venture to doubt 

 the propriety of resorting to it in explaining the phenomena of 

 thermal waters in general, and more particularly of those to 

 which my own observations have been directed ; and I would 

 give a hearty welcome to any theory which, dispensing with the 

 necessity of penetrating to such enormous depths in search of 

 the unoxidated metals, would explain the chemical chai'acters of 

 these waters by the knoivn properties of the rocks, in connection 

 with a generally diffused irdernal heat. 



In considering the bearing of the preceding details respecting 

 the thermals of Virginia upon the doctrine of a general subterra- 

 nean heat, as compared with that of local foci of volcanic action, 

 there is one fact in the geology of our Appalachian region, par- 



* Quickly volatilized and combined with oxygen, its power to arrest the oxidation of 

 the protoxide, or to reduce the peroxide when formed, would not, I conceive, be called 

 into play. But even if it were, the difficulty would not be so great as where potassium 

 and sodium are regarded as among the chief oxidizing agents. For in this latter case, 

 what becomes of any carbonic acid which, evolved at the focus of activity, is brought in 

 contact with these metals? 



