314 Dr. Walter Flight — History of Meteorites. 



examined by H.I.H. the Grand -Duke Nikolai Maximilianovitsch 

 von Leuchtenberg ; the mean numbers resulting from kis analyses 

 are given under I. Von Baumhauer, to wkose paper we skall im- 

 mediately turn our consideration, also publiskes a new analysis of 

 tkis silicate (II.), and gives in juxtaposition the tkeoretical numbers 

 (III.) corresponding to an olivine of tke formula : 

 2 FeO, Si0 2 + 7 (2 MgO, Si0 2 ). 



I. II. III. 



Silicic acid 40-24 40-87 40-70 



Magnesia 47"41 4693 47"17 



Iron protoxide 11-80 12-11 12-13 



Nickel protoxide trace ... , 



Manganese protoxide 0-29 trace 



Alumina 0-06 



Tin Oxide 08 



99-88 99-91 100 00 



Eumler found arsenic in tkis silicate, and Howard kalf a per cent, 

 of oxide of nickel. Tke Duke of Leucktenberg discovered none of 

 tkis oxide in tke specimens wkick ke examined. It is not improbable 

 that Howard may have fallen into error through the presence of 

 organic matter in the ammonia, employed in his analysis, having 

 rendered the precipitation of the iron oxide incomplete. 



Von Koksckarow finds the specific gravity of some very pure 

 crystals of the olivine to be 3*3372 ; of some brown fractured granules, 

 3-3415 ; the mean being 3-3393. 



Many terrestrial olivines contain nickel protoxide. Eammelsberg 

 found 2-35 per cent, in the variety of this mineral occurring in the 

 basalt of Petschau, in Bohemia ; Gentk determined its presence in 

 that from Tkjorsalava, of Hekla ; and Sartorius von Waltershausen 

 in the olivine of the Fiumara di Mascali, near Etna. It has also 

 been detected in the olivine of Langeac, Haute-Loire; it forms a 

 constituent of that mineral as met with in the lherzolite of the 

 Pyrenees, in the lava of the Isle of Bourbon, in the basalt of 

 Sneefels-Jockul, Iceland, in tke melapkyre of Oberstein, and in the 

 dunite of Mt. Dun, New Zealand. A knowledge of tkese facts in- 

 duced von Baumkauer to examine witk great care tke Pallas olivine 

 for nickel. 



Tkat portion of a meteorite wkick, after tke nickel-iron kas been 

 removed witk a magnet, dissolves in acid, is usually regarded as 

 olivine, 2 BO, Si0 2 . Small quantities of alumina, lime, manga- 

 nese, and nickel protoxide, and occasionally of alkalies, are, it is true, 

 also found in tke solution ; but witk tke exception of tke nickel oxide, 

 tke occurrence of wkick is ascribed to tke incomplete removal of the 

 nickel-iron by tke magnet, tke presence of tkese ingredients is attri- 

 buted to tke incipient decomposition, even in tke cold, of tke otker 

 silicates of tke meteorite. 1 Mercury ckloride, a reagent tke use of wkick 

 was proposed by Eammelsberg, enables us to separate by solution tke 

 nickel-iron from all tke silicates. The sublimate, however, does not 



1 It has been found that the enstatite of the Busti meteorite (which see) is slowly- 

 decomposed by hydrochloric acid. 



