344 DOMAIN IV. TALCOUS. 



" In the magnetic parts of this hill certain 

 rocks are also observed, which have no action, 

 by the side of similar rocks, which have a very 

 strong one. Some affect the needle at the dis- 

 tance of 22 feet. 



" Thi^ mountain not only exerts its action on 

 the magnetic needle in its whole mass, like some 

 other mountains, but it is manifest in even very 

 small pieces. Humboldt has observed, that frag- 

 ments, scarcely visible, are briskly moved, upon 

 presenting to them, one after the other, the poles 

 of the weakest magnet: and it is remarkable, 

 that a substance possessing such a decided po- 

 larity, has not the least attraction on iron not 

 magnetised. 



" Humboldt convinced himself that this ser- 

 pentine does not contain an atom of magnetic 

 iron ; all which it contains, and which colours 

 it, is in the state of oxyd. It is for naturalists 

 to explain the cause of so remarkable a pheno- 

 menon. 



cc The specific gravity of this serpentine is 

 much less than that of others; it only extends 

 from 1 900 to 2000, while the ordinary weight 

 of this rock is 2700, and even reaches, as Saus- 

 sure has observed, tcr 3000, in certain varieties 

 which he found in the vicinity of the lake of 

 Geneva, 



