.500 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



showed much similarity with that of Zacatecas. It appeared possible to Burkart to assume that both aerolites origi- 

 nated from one fall. I think, however, that there is much against this assumption. In the meteorite of unknown 

 locality, which was examined by WShler and analyzed by Manross, granules of olivine and a granule of an apple- 

 green mineral were found. I found nothing of this sort in the Zacatecas iron, and while even the results of the analy- 

 ses of aerolites from one and the same find do not agree entirely, still the quantity of the individual constituents 

 differ so much in this case that it is not possible to assume that they are all from one fall. 



In the repetition of the investigation of the Zacatecas iron I found no terrestrial mineral. The insoluble residue 

 remaining after treatment with dilute muriatic acid was tested with the microscope at 200 diameters, but it appeared 

 entirely homogenous. It might be assumed that the small olivine particles were decomposed by the action of the 

 muriatic acid, since the iron solution contained a small quantity of magnesia; in that case, however, the presence of 

 silicic acid would also become apparent, but this was not found, and besides only dilute muriatic acid was used for 

 dissolving and the action of this was assisted only by slightly warming. 



In the determination of the essential constituents of this meteoric iron I obtained such a close approximation to 

 my own former results and such a wide divergence from Manross's published results, that I could not suppose that the 

 iron examined by the latter belonged to Zacatecas. 

 The second analysis gave: 



Fe 85. 42 



Ni 9. 73 



Co 44 



Schreibersite. . . 1. 05 



96.64 

 Muller 10 gave a description and analysis of a piece of the iron as follows: 



I made an examination of a specimen which was brought some years previous from Zacatecas, passing from M. F. 

 D' Arcais, a mining director of that region, to Mr. Brice Wright, of London, in order to determine whether it was identical 

 with a former acquisition from that country or whether it should be considered as a new one. 



The piece from which the material for the examination was taken was of irregular shape and was evidently a pro- 

 jection cut from a larger mass. It weighed about 20 ounces and those sides which from their black crust evidently 

 formed part of the exterior of the original were irregularly impressed and rounded at the edges. 



The iron is soft, tough, and difficult to break. The fractured surface shows a highly developed laminated structure. 

 The polished surface contains irregular and. circular spots, which are metallic and of a dark bronze color; when it is 

 tarnished or etched there appear bright points, which are generally arranged in lines, intersecting each other in various 

 directions. An oblique and intense illumination shows the intermixture of this bright substance throughout the mass 

 of the iron. 



The etched surface does not exhibit any Widmannstatten figures like the iron from Xiquipilco, Durango, and 

 others from Mexico, but presents the crystalline appearance of tinned iron when subjected to the action of an acid 

 (moir6 metallique), resembling in this respect the iron formerly brought from Zacatecas and analyzed by Bergmann. 



The iron is not passive and is dissolved with facility, even in diluted hydrochloric acid, when slightly warmed, 

 leaving a small insoluble residue which, however, dissolves entirely in aqua regia. 



The dark bronze-colored nodules embedded in the iron likewise dissolve with great ease in dilute acids, with evolu- 

 tion of sulphuretted hydrogen, and behave in every respect like monosulphide of iron. 



Three analyses yielded the following results: 



I. II. III. 



Fe '. 89.84 91.30 90.91 



Ni 5.96 5.82 5.65 



Co 0.62 0.41 0.42 



P 0.25 0.23 



S 0.13 0.07 



Si 0.50 



C trace. trace. trace. 



Mg trace. trace. trace. 



Insoluble... 3.08 2.19 2.72 



99. 63 99. 97 100. 50 

 The insoluble residue after treatment with dilute hydrochloric acid was further analyzed, with the following 



results: 



Fe 75.02 



Ni 14.52 



P... . 10.23 



99.77 



This analysis furnishes an additional proof that the substance termed schreibersite, and which forms a character- 

 istic component of almost every meteoric iron, is of very variable composition; the quantities of iron, nickel, and phos- 

 phorus which are the principal constituents, differ very materially in the schreibersite of different kinds of meteoric 



