358 A?ialysis of Meteoric Iron from Tennessee. 



a microscope before their true character is detected.* If how- 

 ever, cross sections to the above surfaces are polished and etched, 

 we then see the dehcate, silver-white Hues, which are so common 

 in other meteoric irons. As this iron is cleavable into layers of 

 extreme tenuity, I selected a number of layers whose edges were 

 the brightest on these etched surfaces, for analysis ; my inquiry 

 being chiefly to ascertain whether the ratio of the iron to the 

 nickel was the same here, as in average portions of the mass. 

 I was satisfied that it contained no greater per cent, of nickel 

 than I had found in the analysis made at Charleston. 



In polishing some of the carbonaceous balls above alluded to, 

 minute grains of pyrites were rendered visible ; and others still 

 smaller, which had a more silvery whiteness.f A small fragment 

 was crushed under water in a mortar, and yielded white malle- 

 able grains, similar to tin. Portions of the mass were then acted 

 upon by the blowpipe along with carbonate of soda, when the 

 most satisfactory evidence of the presence of tin was afforded,. I 

 found also that (by treating these carbonaceous masses with nitric 

 acid and subsequently igniting with potassa) they contain sihcon 

 and magnesium in decided proportions, with traces of aluminium. 

 Their shape and mode of occurrence served to suggest an analogy 

 they sustain to the imbedded grains of olivin in the Pallas iron 

 of Siberia, and the Otumpa iron of South America, the difference 

 in the case being, that in the Tennessee iron no oxygen was sup- 

 plied for the combustion of the silicon, the magnesium, the alu- 

 minium, and the iron. 



It may not be out of place to add here, a mode of detecting 

 magnetic iron in meteoric irons, which was suggested by an obser- 

 vation of Mr. Abbot, the artisan who polished a face of the Texas 

 mass in the cabinet of Yale College. He inquired of me the rea- 

 son why, in the process of polishing, the dust abraded, especially 

 when rendered pasty by oil or water, should arrange itself in lines 

 so much resembling the outline of mountain ranges. Suspecting 

 the phenomenon to be due to lines of magnetic iron in the mass, I 

 scattered some pulverized magnetic iron ore on a slab of the pol- 

 ished iron, the half of whose area was etched, and found on giving 



* Similar results were obtained on a cleavage surface of the Guildford, N. C. 

 meteoric iron. 



1 Dr. Troost found their composition to be carbon 46.5, iron 3.0, and loss .5 in 

 50 parts. See this Journal, Vol. xxxviii, p. 253. 



