410 Drs. Noeggerath and Bischof on the largest Mass 



burg. The two latter resemble the former in colour, and in 

 containing nickel ; they are in like manner tenacious, and found 

 in isolated masses. That of Louisiana contains a trace of car- 

 bon ; and to judge from the hardness of a part of the Bitburg 

 mass, it must have contained some carbon also, like those of 

 South America, and Magdeburg. Those of Mexico and Peru 

 are found in volcanic districts like that of Bitburg, which lies in 

 the region of the extinguished volcanoes of the Rhine *. The 

 most striking difference is, that the masses in France (alluding 

 to Bitburg, which then belonged to France) and Louisiana ap- 

 pear compact, without any thing like a glassy substance or a 

 cellular texture ; yet they may have cavities within, like those 

 of South America, and are perhaps only compact on the sur- 

 face through attrition." 



On the vei-y small Octahedrons in the Scoria of the Smelted Me- 

 teoric Iron of Bitburg. By Dr. J. N<eggerath. 



Very small octahedral crystals were found in the above 

 scoria, and were considered by Professor Bischof and myself 

 as magnetic ironstone. Professor Hausmann, however, no- 

 ticed that these crystals were exactly similar to those which 

 he described in his treatise on crystallized iron scoria. [Vide 

 IVIoU's Journal of Mining and Smelting, vol. iii. page 39.) 

 M. Hausmann allows that he was at first deceived in the 

 nature of these crystals. " As magnetic iron constitutes a 

 principal part of the scoria, and the crystals of the latter are 

 also octahedral," observes M. Hausmann, " I considered them 

 as crystallized magnetic iron ore, as they had a black colour, 

 and 1 did not examine them very minutely." 



The same causes led me into error, especially as the crystals 

 in the scoria of the meteoric iron are but small, and scarcely 

 to be distinguished but by their prominence ; and on the dark 

 ground of the scoria they showed no appearance of being per- 

 vious to the light. 



The crystals are really of a vitreous nature, translucent, of 

 a dark-green colour, inclining to yellow, of a conchoidal frac- 

 ture. They scratch glass, and are not regular, but rectan- 

 gular octahedrons. I did not make any chemical experiments 

 with them, and cannot therefore decide whether they agree 

 with those examined by JNL Hausmann. I refer to that gen- 

 tleman's treatise ; and only observe that the analysis presented 

 oxide of iron, silica, lime, and alumina. 



• This is not exactly correct. Volcanic appearances are not found 

 •within a considerable distance of Bitburg, which lies among secondary rocks. 

 New red sandstone, gj'psum and muschelkalk, are the principal strata. 



Laugier'.s 



