and of the Phenomena of Volcanoes. S43 



time to time, very considerable and very sudden augmentations 

 of temperature, whenever the chemical actions alluded to were 

 produced. 



During the first stages of the formation of a planet, the li- 

 quid substances, which upon their deposition exerted chemical 

 action, might have been many and various, but now that the 

 only one which has continued in a hquid state is water, this alone 

 can, by its penetration into the interior, be supposed to bring 

 about similar convulsions to those which we have imagined to 

 have taken place antecedently. 



But experiment shews us that there are bodies in nature, upon 

 which water does produce a chemical action, capable, if proceed- 

 ing on a sufficiently large scale, to bring about very considerable 

 changes. 



M. Ampere illustrates this by observing, that, by pouring 

 water in very minute drops on a mass of potassium, a good imi- 

 tation of a volcano may be produced, the hydrogen liberated, 

 causing a little crater-shaped cavity in the centre, whilst the 

 oxide of potassium resulting will accumulate round its borders 

 into a little hillock. 



On the other hand, if water is made to fall in rather larger 

 quantities upon the same mass, its whole surface will be split 

 and rent asunder, so as to represent, on a minute scale, the great 

 valleys and chains of mountains with which the earth is chan- 

 nelled. 



Moreover, says M. Ampere, there remains an evidence of the 

 convulsions brought about by the decomposition of bodies de- 

 prived of their oxygen by these metallic bases, in the enormous 

 quantity of azote which forms the larger proportion of our at- 

 mosphere 



It seems most natural to suppose that this azote was once in 

 a state of combination with some substance or other, most pro- 

 bably with oxygen, existing perhaps in the form of nitric or ni- 

 trous acid. 



This compound would have required eight or ten times a* 

 much oxygen as the quantity existing in the atmosphere at pre. 

 sent. The disappearance of all this oxygen may be accounted 

 for by the oxidation of substances, at one time metallic, which 

 are now converted into silex, alumine, lime, oxide of iron, man- 



