Von Hoff o;i the Origin of Meteoric Stones. 289 



Magnesia occurs in abundance in many mountain rocks, and 

 silica is awanting in others, as well as the silicates of alumina 

 and of the alkalis. 



The oryctognostical character of the meteoric mineral com- 

 pound, when the latter is regarded as a mountain rock, is cer- 

 tainly different from all the rocks hitherto found on the earth. 

 But the structure exhibited by meteoric stones, the masses of na- 

 tive iron excepted, is the same as that presented by many terres- 

 trial rocks, viz. the granular-crystalline. But the same mixture of 

 the same simple minerals has not yet been observed on the earth. 



We find, therefore, in meteoric stones resemblances to inor- 

 ganic terrestrial masses, and also differences from them. The 

 similarity consists in all the simple ingredients, and some of the 

 mineral species resulting from their combination, being the same 

 in meteoric stones as those we find in the crust of the earth. The 

 difference is, that in meteoric stones the mineralogically simple 

 substances, resulting from the union of chemically simple ingre- 

 dients, form a compound which does not occur on the earth ; that 

 in this mixture iron occurs in a metallic condition, and that many 

 meteoric masses entirely consist of such iron, while the earth does 

 not afford any example of metallic iron. 



The difference of meteoric from terrestrial masses certainly 

 points to the conjecture, that meteoric stones previous to their 

 descent, have not belonged to the earth. But, as their characters 

 are not only those of a mineral, as in the masses of native iron, 

 but also of a mountain rock, as in meteoric stones, the conjecture 

 is admissible, nay natural, that formerly they belonged to bodies 

 constituted essentially like the solid portion of our globe. 



The moon is the nearest heavenly body to the earth to which 

 we can ascribe a composition of such materials. 



That a certain given power could project bodies so far from 

 the moon that they should be more powerfully attracted by the 

 earth than by the moon has been mathematically demonstrated 

 from physical laws. 



That in the moon volcanic action does occur, to whose agency 

 such a projectile power may be ascribed, is at least not impro- 

 bable, nay even indicated by some phenomena. 



The idea conceived by Berzelius is extremely ingenious, viz. 

 that most of the meteoric masses reaching the earth that is, 



