the Chemical Theory of Volcanos. 25 



rally on the same footing. Indeed, admitting this, it is the 

 same as if atmospheric air alone were to oxidise the metallic 

 principles of lava, viz. the same quantity of oxygen, formerly 

 furnished to them by water, must now be afforded to the hy- 

 drogen by the atmospheric air. 



To these considerations it may be added, that Sir Humphry 

 Davy could not, in any of the several instances in which he 

 experimented on lava, when freshly poured out, and in a liquid 

 ignited state, detect any traces of pure or uncombined alkaline 

 or earthy inflammable bases.* Dr John Davy properly adds that 

 the absence of iron in its metallic state amongst the products 

 of volcanos, so abundantly oxidated in the first degree of oxi- 

 dation, is very unfavourable to the idea that large quantities 

 of inflammable gas are evolved in volcanic eruptions, or even 

 disengaged. Were this oxide acted on by hydrogen at a high 

 temperature, what is there which could prevent its decompo- 

 sition 1 and if reduced, we might expect to discover it in this 

 state, at least occasionally, enveloped in and protected by lava. 



Before finishing my remarks, I cannot help asking the de- 

 fenders of the chemical theory, whether they suppose that the 

 volcanic actions by which the immense mountains of granite, 

 trachyte, basalt, porphyry, &c, have been elevated, resulted 

 from the same chemical processes ? The question is, did these 

 masses occur in the interior of the earth in a metallic condi- 

 tion, or as oxidised bodies ? In the latter case the advocates 

 of that theory would be obliged to embrace the very same 

 explanation of volcanic actions I am venturing to defend. On 

 the contrary, by assuming the former opinion, the very same 

 difficulties would be placed in opposition which 1 have esta- 

 blished above, but, as we cannot doubt, only much greater in 

 degree. It must be asked where are to be found the substances 

 separated by the oxidation of the metallic bases of the liquid 

 ignited masses that have arisen from the interior, whether it 

 was that atmospheric air or water was decomposed, whether 

 it was that nitrogen or hydrogen was separated, or that am- 

 monia, or sal-ammoniac, or sulphuretted hydrogen was pro- 

 duced ? These substances, the equivalents of the ejected liquid 



* Memoirs of the Life of Sir Humphry Davy, by his brother, vol. ii. p. 122 ; 

 unU Collected Works, vol. i. p. 259. 



