Dr. Walter Flight — History of Meteorites. 405 



octahedron (221) and the cubic faces, viz. 70° 31' and 48° 11'. 

 Faces were noticed in the following positions : 



221, 212, 122, 221,. 212, 221 



the other six directions, although present, could not be traced on the 

 specimen which the author examined. Occasionally solid angles or 

 corners are protruded from the cleavage planes with faces at right 

 angles to each other and corresponding, as regards their position to 

 the cube, with the directions (221). Little step-like markings, such 

 as are seen on artificial iron, and fine lines, evidently sections of thin 

 plates, are likewise observed in positions that correspond with one 

 or other face of the triakis-octahedron (221). Tschermak shows 

 that the development of these faces is due to twinning, not by con- 

 tact, but by interpenetration, the normal on 111 being the axis of 

 twinning. Such twinning is met with on crystals of fluor-spar. 



By etching the Braunau iron two varieties of figures are developed : 

 with a moderate use of the corroding reagent an orientated sheen 

 is developed, the fine texture exhibiting what von Haidinger termed 

 crystalline damaskining (see page 75). As the author showed in the 

 case of the Ilimae iron this appearance is due to slight depressions 

 of the surface ; they are, in fact, little cubical hollows, the sides of 

 which are parallel to the cleavage faces. A second curious feature 

 brought to notice by etching are little furrows which make their 

 appearance on those parts of the cleavage-face where the fine lines 

 were previously seen, lines which owe their origin to the plates 

 parallel to (221). The twin-lamellas therefore are more readily 

 acted upon than the mass of the metal. 



On dissolving this iron in dilute nitric acid a residue remains 

 which consists of fine yellow metallic needles and excessively thin 

 yellow plates ; occasionally particles are met with exhibiting every 

 stage of transition from one to the other of these forms. The plates 

 are not unfrequently broken through, or imperfectly developed, in 

 the manner with which we are familiar in crystals of some varieties 

 of specular iron from volcanic localities. The needles, as Bose has 

 already shown, lie parallel to the edges of the cleavage-cube. 

 Tschermak believes both plates and needles to have the same com- 

 position, to be in fact schreibersite. He was not able to determine 

 the crystalline form of this meteoric mineral with the material pro- 

 vided by this meteorite, but he is of opinion that it will be found 

 to be either tetragonal or rhombic. 



1850, November 30th.— Shalka, Bancoorah, Bengal. 1 



The mineral characters of this meteorite were first described by 

 von Haidinger and Gr. Bose, and the chemical investigation under- 

 taken by C. von Hauer, who found the silicates, when analysed in the 

 mass, to give numbers the oxygen ratios of which were : BO to Si0 2 

 as 1 : 2-435. "While von Haidinger regarded the chief constituent 

 of the meteorite to be a silicate to which he gave the name of 



1 C. Rammelsberg. Monatsber. Ak. Wiss. Berlin, 1870, Ixx. 314. — N. Story- 

 Maskelyne. Philosophical Transactions, 1871, clxi. 359. 



