OP ARTS AND SCIENCES. 



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Furthermore, since the specific gravity of olivine only varies from 

 3.33 to 3.56, it is not surprising that the specific gravity of the Kiowa 

 County and Prehistoric olivines should be so nearly alike ; but it will 

 be seen by the above table that it differs from the Prehistoric more 

 widely than the latter differs from the other volcanic olivines. The 

 above table could be largely extended, but enough is given to show 

 that the olivine from the Kiowa County meteorite more closely re- 

 sembles some modern volcanic products and the original Pallas me- 

 teorite, than it resembles the Prehistoric. Furthermore, when the 

 difficulty of obtaining an average sample of meteoric material for 

 analysis is borne in mind, it will be seen how useless it is to compare 

 the analyses as a proof of the identity of any meteorites, and particu- 

 larly the olivine ones. But the same difficulties lie in the way of 

 giving undue weight to the etched figures or structure of a small speci- 

 men. For instance, the well known meteorite that fell at Esther- 

 ville, Emmet County, Iowa, is made up largely of olivine, the iron in 

 most specimens not forming a continuous network ; yet portions can be 

 selected almost entirely free from iron, and others where iron forms 

 much the larger part. Figure 5, Plate IL, is pi-inted directly from an 

 iron nodule taken from the Estherville meteorite, and placed here for 

 comparison with the similar mass shown in the Kiowa County slab. 

 It will be seen at once that the etched surfaces of the two irons show 

 utterly different Widmanstiittian figures. Yet the Estherville speci- 

 men does not exhibit any of the peculiar characteristics which we are 

 in the habit of associating with that iron, and the slab from which 

 Figure 5 is printed might be mistaken by an expert for at least half 

 a dozen typical Widmanstattian irons, while the olivine iron to which 

 it really belongs would be one of the last to be compared with it. 



A similar feature appears even more strikingly on comparing the 

 specimens found in Kiowa County. The largest of these has through- 

 out the structure typical of the pallasites, but several of the smaller 



