100 
NATURAL HISTORY. 
£loxg 
Case 4. Native arsenic (formerly called testaceous or 
scherben cobalt) in reniform and botryoidal shapes, from 
Andreasberg, &c., and its chemical combinations (arse- 
niurets) : with nickel (commonly called copper-nickel) ; 
with cobalt, comprising the grey and part of the white 
cobalt of some mineralogists. See. 
The remainder of this Case contains the substances be¬ 
longing to the confined orders of Carbon and of Selenium. 
To the former are referred the diamond, anthracite, gra¬ 
phite ; to the latter the selenium metals or seleniurets. 
Among the specimens selected to illustrate the crystalline 
forms of the diamond are : —the primitive regular octahe¬ 
dron ; the same with solid angles truncated ; with edges 
truncated, forming the passage into the rhombic dodeca¬ 
hedron ; varieties of the latter, giving rise to the six-sided 
prismatic and the tetrahedral forms ; cubes w r ith truncated 
and bevelled edges; various hemitropic crystals or rnacles 
of diamonds; an octahedral diamond, embedded in gold ; 
another in its usual matrix; models of the largest diamonds 
known, &c. With these are placed specimens of the al¬ 
luvial rock in which this precious substance occurs in 
the East Indies and in Brazil.—Specimens of anthracite 
or kohlenblende (to which may be referred the Kilkenny 
coal), with native silver from Kongsberg, Sec.;—graphite 
(commonly called black-lead), massive, disseminated in 
porcelain earth, &c.— Seleniurets ,—only those of copper 
and silver (eukairite), those of lead and copper, and the 
selenium-sulphur, are at present in the collection. 
Case 5. The suite of specimens of sulphur (crystallized, 
massive, and stalactic, with selenite, sulphate of strontia. 
Sec.; and the same found sublimed near the craters of vol¬ 
canos, &c.) is succeeded by the Sidphurets , which occupy 
half of this and seven of the succeeding glass-cases. They 
begin with sulphuret of manganese or manganese-blende, 
from Nagyag in Transylvania and from Peru.—Among 
the numerous varieties of sulphuret of zinc, or zinc-blende, 
may be particularized those relative to colour, viz., the 
yellow, the brown, and the black blende of Werner; the 
hrst of which is generally most pure, while the others con¬ 
tain a portion of iron ; the fibrous blende of Przbram in 
Bohemia, in which cadmium was discovered by Stromeyer; 
the variety called testaceous or schaalen blende (the most 
