504 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



Schreibersite occurs as small plates, grains, and flakes. Larger crystals do not seem to have been present in the 

 plate investigated, but it may be that they were destroyed in the process of solution. The result of analysis of the 

 6chreibersite by Scherer follows under III. Ilia gives the composition calculated to 100 after removal of the chro- 

 mium reckoned as daubreelite and the chromite contained in the insoluble residue. The older analysis of Muller 

 is given (IV) for comparison. 



Substance taken 0. 5375 gr. 



P 15. 12 



Fe 68. 37 



Ni 10. 07 



Co 0.52 



Cr 0. 32 



S(calc) 0.39 



Chromite 4. 60 



99.39 100.00 99.77 



From Ilia: Fe : Ni (Co) : P=2.4992 : 0.3702 : 1 



Fe+Ni (Co) : P=2.869 : 1 

 The chromite occurs as highly lustrous grains with conchoidal fracture. It gave qualitative tests for iron, chro- 

 mium, aluminum, and magnesium. The taenite occurs in relatively small plates which were not obtained in suffi- 

 cient quantity for analysis. An analysis which I made of the solution gave the following results after deduction of 

 daubreelite (0.05 per cent) and schreibersite (0.69 per cent): 



Substance taken 0. 8703 gr. 



Fe 94.15 



Ni 5. 18 



Co 0. 61 



Cu 0.017 



Cr 0. 023 



P 0. 113 



100. 093 

 From this the total mineralogical composition would be as follows: 



Nickel-iron 94. 34 



Schreibersite 3. 54 



Troilite 26 



Daubreelite 10 



Chromite and silicate 21 



Carbon 03 



Nickel phosphide ? 1. 08 



Undetermined residue 44 



100 



As the above would not give the total composition on account of the lack of taenite, a mass analysis was made by 

 Scherer. The material employed for the analysis was cut from the plate previously mentioned. Scherer's analyses 

 follow under VI and VII. VIII gives the mean and Villa the analysis calculated to 100, after the deduction of 6.34 

 per cent of schreibersite and 0.41 per cent of daubreelite. The latter was calculated from the sulphur. Whether the 

 sulphur, as determined, is too low or whether the chromium may be present in some other soluble combination could 

 not be ascertained owing to lack of material. The total content of chromium reckoned as daubreelite, which amounts 

 to 2.4 per cent, is doubtless too high; also the calculation of the total phosphorus as schreibersite is, according to the 

 investigation of the nonmagnetic residue, of doubtful accuracy. Zacatecas seems to contain components which have 

 not been hitherto recognized in iron meteorites, and investigation should therefore be carried on with more abundant 

 material. 



The results given under Villa show nearly the composition of the nickel-iron. They also show that of the older 

 analyses only those by Muller apply to the meteoric iron now generally recognized as that of Zacatecas. 



The analyses by Bergemann probably were made on another meteoric iron. He stated that he obtained his 

 material from Burkart, but either a different iron must have been found near Zacatecas or some exchange of pieces 

 took place. This is the more probable since the percentages of nickel plus cobalt in his two analyses agree so well. 

 Of course, it is not impossible that different pieces of one iron meteorite may show such variation of chemical com- 

 position, but it is hardly likely. 



