270 J. Lawrence Smith on Daubréelite. 
Art. XXX.—On the composition of the new Meteorie Mineral 
Daubréelite and its frequent, if not universal, occurrence in 
Meteoric Irons; by J. LAWRENCE SitTH, Louisville, Ky. 
WHEN I first announced the discovery of the mineral dau- 
bréelite,* the amount at my disposal was only sufficient for the 
determination of its specific characteristics. Since then I have 
made numerous sections of the first iron, which weighed about 
250 kilograms, and also sections of another iron of 200 kilograms 
from the same locality (Cohahuila), and in this last have found 
the nodules even more abundant than in the first. Of the 
second iron, I have a section with two polished surfaces of 
about 900 square centimeters each, which show twenty-five to 
thirty nodules, varying from three to sixteen millimeters 1n 
diameter, at least ten of which are from one to one and a half 
centimeters in diameter, and all of them exhibit to the eye 
daubréelite in angular segregations. 
The mineral used for my first analysis I obtained by break- 
ing it out from the nodules mixed with troilite and other 
impurities, depending on the eye to separate the impurities. 
Since then, I have found that chlorhydric or fluohydric acid 
will attack the troilite readily and not act on the daubréelite, 
and thus a method has been adopted by which the mineral is 
obtained more abundantly and quite pure. The shavings and 
cuttings procured in making the sections were used (several 
ilograms of which were at my command); the fragments of 
iron were separated by a large magnet, and the small particles 
left behind consisted essentially of troilite and daubréelite ; for 
the former is only feebly magnetic and the latter not at all so. 
Strong chlorhydric acid is next added to this last portion and 
gently warmed over a water bath; the troilite is readily at- 
tacked ; after a time the first acid is poured off, and a fresh 
rtion added, and the digestion continued over a water bath 
picked out. ; 
In this form it consists, as already described, of shining black 
fragments more or less scaly in structure, not altogether unlike 
fine particles of molybdenite. The fracture is uneven, except 
in one direction where there appears to be a cleavage. It is 
* This Journal, ITI, xii, 109, August, 1876. 
