810—Ci A. B. Tyler and C. U. Shepard on 
“The fragments of the mineral which afforded material for 
the following analysis appeared to be composed of crystals, but 
so interwoven and indistinct that a determination of their form 
was impossible. 
The mineral possesses a hardness of 3°5; specific gravity, 4128 
(mean of three trials which gave respectively 4:07, 4126 and 
4188); light reddish-brown streak; metallic luster; and is of an 
iron-black color. 
Before the blowpipe, on charcoal, it melts, with the appear- 
ance of effervescence, and coats the charcoal with oxyd of zine. 
With carbonate of soda melts to a bead; which, if moistened and 
brought in contact with silver, blackens the latter, showing sul- 
phur to be present. A coating of oxyd of zine is also formed 
upon the coal, and metallic particles remain in the soda, of iron 
and copper. ith microcosmic salt, in the oxydizing flame, 
after being strongly ignited on charcoal, it gives a bead which is, 
- and which, if 
Ww 
filter, dried at 100° C., and weighed with the filter. The sulphur 
which had been oxydized in the process of solution to sulphuric 
acid was precipitated with chlorid of barium. After the excess 
of the latter had been removed by adding sulphuric acid, the 
copper was precipitated by means of sulphuretted hydrogen, and 
determined as sulphid of copper (Cu?S) by Rose’s method, viz: 
heating with a little sulphur, to redness, in a current of hydro- 
en gas. The iron was then precipitated, after neutralization, 
with acetate of soda as basic acetate of iron, ignited and weighed 
as oxyd of iron. Sulpbid of ammonium was added to precipitate 
the zinc, which was determined as sulphid (ZnS) in the same 
manner as the copper. 
‘5935 grm. of the mineral gave 0675 S; 9505 BaOSO®, con- 
taining 1805 S; 1041 Cu’S, containing -0831 Cu; -0552 Fe?0*, 
containing 0366 Fe; 4238 ZnS, containing -2840 Zn. 
' Per cent as follows: 
Found. Ratio of equivalents. Formula. Calculated. 
Ss 33°36 27085 10 1 33°36 
Cu 14°00 0°441 2 ¥eCu 13°22 
Fe 618 0-220 1 1 asFe > S. 5°84 
Zn 47°86 1468 7 agit 47°58 
101-40 <oou0" 
2. Marcylite——Marcylite is described on page 405 of my Min- 
eralogy ; but from less pure specimens ian thoes sobuntied to 
Mr. Tyler. Mine appears to have contained an intermixture of 
