METEORITES OF NORTH AMERICA. 237 



maintained, if we assume, as is very probable, that the concentric stripes and markings are to be regarded as merely 

 secondary phenomena, sequences of mechanical and chemical alteration, which the rounded lump underwent after 

 the rounding. 



Iron sulphide plays an important part in the composition of the Iowa stone. It seems to be distributed in small 

 irregular patches as if forced in between the other ingredients. By treating the pulverized stone with hydrochloric 

 acid, hydrogen sulphide is developed, without the separation of sulphur. This iron sulphide may therefore be regarded 

 as troilite. The meteoric iron grains of the stony mass appear to be abundantly compacted in jagged, angular lumps, 

 frequently running out into fine points which cling as closely to the nonmetallic portions as if the iron was first sepa- 

 rated by reduction on the place where it originated (?). This meteoric iron contains nickel and some sulphur, is very 

 malleable, as it can be readily hammered out into thin leaves; is active, as proved by the fact that when a shaving 

 is immersed in blue vitriol, the iron surface is quickly coated with a copper deposit. Whether Widmannstatten figures 

 appear upon etching can not be determined definitely on account of the smallness of the iron grains. Yet darker 

 and brighter specks do appear. 



That the stone contains water, requires no proof beforehand, since this is demonstrated already by the presence 

 of rust specks, hydroxide of iron. 



The specific gravity of the stone in the interior is 3.75; that of the crust portion 3.55 (at 20° C). 



I had at my disposal for the chemical analysis of this meteorite something over 1.5 grams of material. From the 

 finely pulverized portion the meteoric iron was first carefully abstracted with the magnet, and this was then freed as 

 carefully as possible by repeated treatment from all adhering stony matter and examined by itself. One portion 

 served for the determination of the sulphur, the remainder was first treated with boiling hydrochloric acid, the por- 

 tion dissolved in this way and likewise the undissolved portion isolated by means of barium hydrate, and further 

 analyzed. The analysis gave the following results. 



The stone consisted of: 



Meteoric iron 12. 32 



Troilite 5. 25 



Soluble in hydrochloric acid 48. 11 



Insoluble in hydrochloric acid 34. 32 



100. 00 

 The nickel-iron contained — besides traces of copper and sulphur, the latter evidently from adhering troilite: 



Iron 83. 381 



Nickel (containing some cobalt with sulphur and ^Approximating Fe 6 Ni. 



phosphorus) 16. 62j 



100. 00 

 The soluble portion (without reckoning the meteoric iron and iron sulphide) contained : 



Oxygen. 



Silicic acid 38. 38 19. 76' 



Iron protoxide 28. 58 6. 33 



Manganese protoxide 0. 53 0. 12 >19. 51 



Magnesia 31.49 12.59 



Alumina 1.01 0.47 



Lime alkalies, water , [Trace. 



99.99 

 The insoluble portion contained : 



Oxygen. 



Silica 53. 96 28. 74 



l20. I 



Alumina 2.01 0.94|" 



Iron protoxide •. 25. 18 5. 571 



Magnesia 8. 91 3. 56U0. 29 



Lime 4.04 1. lej 



Manganese protoxide Trace 



Chrome oxide 1.42 1.16 



Soda 2.39 0.591 



Potash 1.67 0.291 



>■ 



As to the meteoric iron and pure iron sulphide, it requires no further place here. 



In the portion soluble in hydrochloric acid there was an oxygen proportion of the base and the acid of nearly 1: 1, 

 and it also requires no further demonstration to show that this portion is certainly derived from an olivine rich in iron 

 protoxide. The explanation of the insoluble residue is much more difficult, as its constituents and oxygen propor- 

 tion agree with no definite mineral. This agrees perfectly with the optical analysis according to which, after the 

 removal of the soluble portion, it contained, besides the spherical chondri in various characters, a bright mineral, much 

 cracked, and small black granules. That the latter consisted of chrome iron is, according to the results of the analysis, 



