HOT SPRINGS. 229 



cause of chemical attraction, by which salts, 

 rocks, and metals, are held in a state of intimate 

 combination with fluid menstruums. 



It may be objected, that caloric is not the 

 universal solvent of nature, because lime and 

 magnesia are more soluble in water at 60 F. 

 than at 212. But if it be true that lime and 

 magnesia, like all other bodies, are dissolved in 

 unlimited proportions by hot springs, such ex- 

 ceptions disappear, and therefore cannot invali- 

 date the general fact. 



It is stated by Mr. Lyell, to whom the science 

 of Geology is so largely indebted, that the warm 

 springs which supply the baths of San Filippo, 

 near Rome, contain in solution so large a quan- 

 tity of calcareous and magnesian rocks, that they 

 have been known to deposit in a pond, a mass 

 thirty feet thick in twenty years. (Principles of 

 Geology, vol. i. p. 204.) 



Mr. Lyell seems to suppose that the carbonic 

 acid contained in hot springs, is the chief cause 

 of their solvent power. But it is well known 

 that sulphate of lime, and many other rocks, are 

 dissolved by hot springs without the aid of car- 

 bonic acid. It is therefore evident, that the 

 solubility of lime and magnesia is augmented by 

 heat, as certainly as that the fusibility of all 

 other rocks and metals is augmented by it. It 

 is highly probable, that the carbonic acid found 

 in hot springs, has been driven off from a state 

 of combination with lime, during the process of 



