288 Von Hoff on the Origin of Meteoric Stones. 



siderablexjuantity of silicates of alumina and the alkalies, cha- 

 racterise meteoric mineral masses. On the earth the case is re- 

 versed ; here the silica predominates, and silicates of alumina and 

 the alkalies are every where the chief component ingredients: 

 magnesia occurs rarely. 



5. Meteoric stones do not seem, like our terrestrial volcanic 

 products, to have been ejected in a melted condition, but to 

 have been quietly and slowly formed ; for they appear to have 

 been fractured, and to have had the fissures so produced filled 

 in some places with a dark coloured mineral substance. 



6. Berzelius does not think that olivine is a volcanic product, 

 on account of its difficult fusibility ; but regards it as a pre-exist- 

 ing mineral which was only enveloped in the liquid lava. 



7. The meteoric stone of Alais is a rock which has been wea- 

 thered and decomposed in its place of origin. 



8. The meteoric stones of Stannern, Jonzac, and Juvenas, 

 were derived from a different part of the moon from the others, 

 and possess very distinct characters. They contain no native 

 iron, and are aggregates of easily distinguishable minerals ; 

 magnesia occurs in them in very inconsiderable quantity. But 

 on the other hand, besides a little sulphuret of iron, silicates of 

 lime, alumina, and oxide of iron, they contain also chrome, &c. 



The chemical investigations of Berzelius are of such extreme 

 value, that, even to praise them, would, in me at least, be un- 

 pardonable presumption. 



But the question may be asked, Whether the composition and 

 constitution of meteoric stones as ascertained by chemical exa- 

 mination ; whether further their oryctognostical characters and 

 physical properties ; whether, finally, the phenomena accom- 

 panying their descent to the earth, furnish a ground for be- 

 lieving them" to be derived from the moon ; or render it neces- 

 sary for us to adopt such an opinion, and at the same time to 

 reject every other view of the question. 



The component parts of meteoric stones exhibited as well by 

 their empirical and physical characters, as by the analysis of 

 their simple chemical constituents, are not exclusively peculiar 

 to them, but all occur in the masses of which the crust of the 

 earth is composed. 



The metallic iron is the only exception, for it has not yet been 

 found in any hitherto examined portion of the globe. 



