oj Olivine, Peridot, Sj-c. 365 



creased oxidation of the metal. On fusing this mineral before 

 Marcet's lamp, all the protoxide of iron at length passes into 

 black oxide ; hence also the globule obtained assumes a dingy- 

 black colour. 



The analysis of the chrysolite succeeds to this. 

 Professor Blumenbach was so kind as to permit Professor 

 Stromeyer to avail himself of two rough chrysolites for that 

 purpose from his collection, which exhibited not only distinct 

 crystalline planes, but also possessed all the other charac- 

 teristics of pure chrysolite. Their specific gravity, according 

 to a mean of three weighings, was at 45* 5° F. and barom. 

 29-016 in. = 3-3514, which difters very insignificantly from the 

 specific gravity found in olivine. According to the experi- 

 ments made upon it, this mineral corresponds also in its com- 

 ponent parts and in its chemical properties with olivine, and 

 consists not only of the same integral parts, but contains these 

 also exactly in the same proportions as those of olivine. The 

 quantity of iron alone is in chrysolite somewhat greater than 

 in the two kinds of olivine that were examined. 



In 100 parts of chrysolite submitted to this analysis were 

 contained 



SiUca 39-73 



Magnesia 50-13 



Protoxide of iron 9*19 



Oxide of nickel 0-32 



Oxide of manganese 0-09 



Alumina 0-22 



99-68 

 With this result, as to the chief object, the analysis of the 

 chrysolite by Vauquelin also very well corresponds ; as, on 

 the contrary, Klaproth's differs from it very considerably. 



After the conclusion of the analysis of olivine and chry- 

 solite, the olivine-like mineral of Pallas was likewise submitted 

 to an equally careful examination. The opportunity of under- 

 taking an exact chemical analysis of this extremely rare fossil, 

 Professor Stromeyer owed to Dr. Blumenbach and Dr. Chladni, 

 who both, with a kindness that surpassed his wants, provided 

 him with this rare mineral substance. In order as much as 

 possible, to avoid all error in this investigation, only perfect 

 and pure grains of this fossil were used : they were all selected 

 with the utmost care with the help of a lens ; and neither par- 

 ticles from the mass of iron, nor from the rust into which the 

 iron had been partially converted, were permitted to contami- 

 nate them. The specific gravity of these pure grains was at 

 68"' F. and barom. 29-4-10 in. = 3-3404, which very exactly 

 corresponds with that of olivine and chrysolite. 



According 



