362 S. F. Peckham on the probable origin 
3. I found that the mineral was powerfully magnetic, so 
much so, that a thin film would rise to the magnet, carrying 
with it a load of mica many times its weight. I also found that 
where the film of see was red or yellow it was destitute of 
magnetic propert 
4. I dcterstuiiad iy blowpipe tests that the mineral was an 
oxyd male iron yielding no reaction for titanium. 
eating the blackish brown mineral to redness out of 
contact of air it retained its color, but heated with access of 
air it became red. I a found that when the yellow mineral 
was heated it became 
From these Gliervations I concluded that the yel/ow mineral 
was hydrated oxyd of iron ; that the red substance was sesqui- 
oxyd of iron (hematite) ; and that the mineral varying from 
colorless to smoky and blackish-brown was magnetic oxyd of 
iron, or in other words magnetite; and further, that wherever the 
specimens were red this was due to oxydation, and the conse- 
quent formation of hematite ; and where they were yellow it 
was due to hydration as weil as oxydation. 
I have made a careful reéxamination of a large number of 
specimens and have not only confirmed my former veneer 
but have found that the red mineral when rubbed on white 
porcelain gives a red streak, the yellow mineral an oe yellow 
streak, while the blackish brown mineral gives a black streak. 
This is additional evidence that the red mineral is hematite, 
the yellow mineral hydrated oxyd of iron, and that the mag- 
netic mineral is in all probability magnetite. 
Art. XXXV.—On the probable origin of Albertite and allied 
minerals ; by 8. F. PEcKHAM. 
Iv a paper read at the meeting of the National Academy © 
eat — August,* I expressed the mpegs that solid fs 
aetitle in veins of igs extent, of wh ich t the Albert- 
ater containi Se aihas and very little nitrogen, like a 
those of Pennsylvania, were not rendered more dense by oxyda- q 
tion, but by inspissation. 4 
In 1863 Mr. J. P. Lesley expressed the opinion in reference 3 
o Grahamite, that, “there seems to be no escape from the 4 
Bokclusion, that the substance filling the vertical vein is 4 pro- q 
* Proc, Am. Phil. Soc., x, 457. a 
