( 339 ) 



Ampere's Theory of the Formation of the Globe, and of the 

 Pheiwmena of Volcmioes. 



In a former number of our Journal, we communicated to 

 our readers those important observations respecting the increas- 

 ing heat of mines and wells in proportion to their depth, which 

 seemed to demonstrate the existence of a temperature in the in- 

 terior of the earth surpassing that which prevails on its surface, 

 and which have thus disposed the minds of many distinguished 

 philosophers of the present day to adopt the notion of a central 

 heat, as supplying a ready explanation of the phenomena of vol- 

 canoes, hot springs, &c. 



This hypothesis, however, though sanctioned by such high 

 authority, can by no means be said to have commanded univer- 

 sal assent. Von Buch, for example, in many of his memoirs, 

 speaks of volcanic action as a process of oacidation ; and we have 

 ourselves inserted, in a former number of this Journal, an ar- 

 ticle by Professor Daubeny of Oxford, on Thermal Waters and 

 their connection with Volcanoes, in which it is contended, that 

 the known phenomena cannot be reconciled with the principles 

 assumed by Cordier, and must rather be referred to processes of 

 a chemical nature, kept up by the access of water and atmo- 

 spheric air to bodies capable of absorbing oxygen from both *. 



• In an article on Volcanoes, published in the 40th Part of the Encyclopae- 

 dia Jletropolitana, which has just appeared, Professor Daubeny has developed 

 his theory somewhat more at length, and has endeavoured to shew the fal- 

 lacy of some of the objections which have from time to time been alleged 

 against it. Thus he has proved, 1st, That a mass of matter composed of the 

 bases of the alkalies, earths, and metallic oxides, which exist in ordinary lava, 

 and in similar proportions, would possess a higher specific gravity than the 

 lava itself is found to have. 



2dly, That the basis of silica, and also that of alumina, combined either 

 with hydrogen or with an alkali, would enter into combustion at a red heat, 

 and therefore take a part in the chemical action which is manifested in vol- 

 canoes. 



3dly, That we might infer from the long continuance of the process, that 

 the substances which maintain the combustion are principally such as would 

 form with oxygen a fixed product, and disengage from water an inflammable 

 j)rinciple, both of which accord with the conditions of the theory. 



The rest ol' the article we need not insert, as its substance will be found in 

 the memoir already pubHshed in our Journal, and referred to above. 



