338 



EXPERIMENTS EELATIVE TO METEORITES. 



tains, with the densities, the principal types of meteorites, wliilo the second col- 

 umn exhibits the principal terrestrial rocks : 



PEKIDOT CONSIDERED AS A UNIVERSAJL SCORIA. 



The idea to which we have thus been conducted, in order to explain the origin 

 of the planetary bodies from which meteorites proceed, illustrates' also the mode 

 of fonnation of that thick silicated mass which constitutes the external part of 

 the terrestrial globe. 



As early as the commencement of the century, Davy, after having made known 

 the results of his admirable discovery of the composition of the alkalies and 

 earths, supposed that the metals engaged in these oxides might exist in a free 

 state in the interior of the globe ; and he saw in their oxidation, by the access 

 of water and air, the cause of the heat and eruptions of volcanos. 



Subsequently this hypothesis has been enlarged by extending it to the origin 

 of the teiTestrial crust itself, which comprises, precisely in the state of silicates, 

 the oxides of the metals most avid of oxygen ; namely, potassium, sodium, cal- 

 cium, magnesium, aluminum, and by considering even the water of the seas as 

 the result of the combustion of the hydrogen in this general oxidation or confla- 

 gration. Sir Henry de la Beche, whose genius embraced all the great questions 

 of geology, was among the first to propound this idea,* for which the way had 

 been prepared by the important observations of Haussmann, Mitscherlicb, and 

 Berthier on the scoriae of manufactures,! and which M. Elie de Beaumont has, 

 with much justice, designated by the expression of yiatural cupcUatlon. % With- 

 out long explanations, it will be seen how this theoretic view is confirmed and 

 justified by the results which I have obtained in the synthesis of the meteorites. 

 • After what has been stated, it is natural to admit that the rocks of peridot, 

 whose importance has been recognized in the constitution of the deeper regions 

 of our globe, have the same origin with the similar silicates which form a part 

 of the meteorites. These peridotic rocks would thus be, in our planet, the most 

 direct product of a scorification which has been etFected at an extremely remote 

 epoch. 



* Researches in Theoretical Geology, 1834. The French translation of this work was pub- 

 lished in 1838, by M. de Collegno. 



t Among the numerous observations of Haussmann, which extend back as far as ISIP), I 

 would expressly mention his memoir entitled De usu Experientiarum Metallurgicarum ad 

 disquisitiones Geologicas luljuvandas, (Gosttingen gelehrte Aiizeigen, 1837.) It is proper 

 also to mention that as early as 1823, Mitscheriich recognized the forms of peridot and 

 pyroxene in the crystals of metallurgic scoriaB ( Abhandlungen der K. Academie der fVisscn- 

 schaften zu Berlin, 1823, p. 25.) 



t Bulletin Soc. Geologiqiie, 2d series, t. iv, p. 1326, 1847. 



