358 Analysis 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 delicate, silver-white lines, 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.t 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 silicon 
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. Ansor, 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 piclialsiiee: 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 i iron, the half of whose area was etched, and found on giving 
Se ee 
' tals were obtained on a cleavage surface of the Guildford, N. C- 
+ tik Seales bce emma pede iron 3.0, and loss ic 
50 parts. Be ths Joura Vala p. 253, 
