160 NATURAL HISTORY. [NORTH 
negative metallic substances (metalloids), and their not 
oxidized combinations.— Tellurium and tellurets : the 
scarce native tellurium , which (like sulphur and sele¬ 
nium) has the property of mineralizing several metals, 
combining with them as electro-negative substance, viz.— 
with bismuth (formerly called molybdena-silver) from 
JBastnaes ; to which also belongs the tetradymite ;—with 
silver , from the Altai, Siberia;—with lead (foliated tel¬ 
lurium, or nagyag ore) ;—with silver and lead (white and 
partly yellow tellurium);—with silver and gold (graphic 
tellurium or schrift-ertz of authors), all from Transyl¬ 
vania.— Native antimony from Dauphiny, and antimonial 
silver or stibiuret of silver from the Hartz, &c. 
Case 4. Native arsenic (formerly called testaceous cobalt 
and scherben-cobalt) in reniform and botryoidal shapes, 
from Andreasberg, &c.; and its chemical combinations 
(arseniurets): with nickel (commonly called copper- 
nickel) ; with cobalt , comprising the grey and part of 
the white cobalt of some mineralogists, &c. 
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 tire passage into the rhombic dodeca¬ 
hedron ; varieties of the latter, giving rise to the six-sided 
prismatic and the tetrahedral forms ; cubes with truncated 
and bevelled edges; various hemitropic crystals or macles 
of diamonds ; an octahedral diamond, embedded in gold ; 
two others in hydrous oxide of iron, from Brazil; models 
of the largest diamonds ki-ow T n, &c. With these are 
placed specimens of the alluvial rock in which this pre¬ 
cious 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, &c.;— graphite (commonly called black-lead), 
massive, disseminated in porcelain earth, &c.— Seleniu¬ 
rets : lead seleniuret; copper and lead seleniuret; mer¬ 
cury and lead seleniuret, all from Tilkerode, Hartz ;— 
copper seleniuret; copper and silver seleniuret ( eukairiie ), 
