370 Dr. Walter Flight — History of Meteorites. 



huge blocks of meteoric iron that from time to time have been met 

 with on many parts of the earth's surface, the record of the fall of 

 which is unknown, their descent having probably taken place at an 

 epoch long anterior to that of their discovery. While the stones 

 enclosing iron have not unfrequently been seen to fall, the descent of 

 purely metallic masses has been rarely witnessed. At present we 

 know of only the following few authentic cases : Agram (1751) ; 

 Braunau (1847) ; Victoria West, S. Africa (1862) ; and Nidigullam, 

 Madras (1870). To these few instances is to be added the one head- 

 ing this notice, of which a brief account was published by Troost, 

 of Nashville, in 1845. 1 The Tennessee iron fell from a cloudless 

 sky, near several persons who were working in the fields. A horse 

 which was harnessed to a plough close by took fright, and ran 

 round the field, dragging the plough with it. 



The iron has remained in the Troost Collection up to the present 

 time, when it passed into the hands of Dr. Lawrence Smith. It is a 

 reniform mass, and has a bright surface like that of soft cast- 

 iron. When etched it exhibits Widmannstattian figures in great 

 perfection, and the author states that in this respect he is acquainted 

 with only three or four irons which rival it. An illustration ac- 

 companying his paper, closely resembling the one given by Troost, 

 is a representation of the outer surface, magnified ; this is elaborately 

 reticulated, edges of thin laminae of metal, inclined at angles of 60°, 

 travei-sing the surface, the edges being separated from each other by 

 an apparently semi-fused slag-like material. The specific gravity of 

 the iron is 7*717, and its composition : 



Iron = 91-15; Nickel = 8-01 ; Cobalt = 0-72; Copper = 0"06. Total = 99-94. 



Sulphur is not present, and of phosphorus only a trace was 

 recognized ; and the author states that he has never before met with 

 so small a proportion of this element in a meteoric iron. The gas, 

 extracted from this iron by A. W. Wright, who has recently examined 

 the occluded gases of the irons of Texas, Arva, and Tazewell Co., 

 as well as that of the meteorite of West Liberty, Iowa (which see), 

 has nearly twice the volume of the metal operated upon, although 

 this is probably a portion only of that actually present. It is com- 

 posed of : 

 Hydrogen = 71-04- Carbonic oxide = 15-03 ; Carbonic acid = 13-03. Total = 100-00. 



A question of no slight interest in regard to the changes which 

 meteoric irons undergo during their passage through the atmosphere 

 is whether their surface becomes fused. From his study of the 

 Tennessee meteorite, Dr. Smith has decided it in the negative. The 

 fact of the delicate reticulated surface having been preserved is a 

 proof that the heat, instead of having been raised to a high tempera- 

 ture on the surface, has quickly been conducted away into the mass 

 of the metal. Had fusion of the superficial layer taken place, the 

 meteorite would have been coated with molten oxide. 



The author finds in this fact a confirmation of his theory that the 

 Ovifak masses are not of meteoric origin. 



1 G. Troost. Amer. Jour. Sc, xlix. 336. 



