M 2 Metals. M I N E R A 
alloy in fome of the varieties, it has been called white 
gold; and, as at firlt there were great doubts refpe&ing 
the nature of the ore altogether, and the ftate hi which 
the gold exifted in it, or whether it was to be regarded 
as a chemical conftituent part, it has alfo been called 
ourum problematicum , and durum paradoxum. 
i. Tellurium nativum, or native tellurium: foft, heavy, 
fomewhat ductile, with metallic luftre. Found in the 
mine of Mariahilf in the Facebay-mountains of Tran¬ 
fylvania ; maffive and difl'eminated: contains tellurium 
92-55, iron 7-2, gold 0-25. 
2: Tellurium graphicum, or graphic tellurium: tin- 
white, or inclining to yellow ; foft, brittle, llaining a 
little; in fmall prifmatic cryllals, often grouped in fuch a 
manner as to refemble written characters. Found in the 
Francifcus-mine at Offenbanga in Tranfylvania, with 
metallic luftre. Contains tellurium 60, gold 30, filver 10. 
3. Tellurium album, or white tellurium : filver-white 
pafling into brafs-yellow; foft, heavy, fomewhat duftile, 
with metallic luftre. Found in the Nagyag-mine of Tran¬ 
fylvania, difl'eminated or cryftallized in fmall four-fitted 
prifms: frafture in one direction foliated, in the other 
uneven. Contains tellurium 4475, gold 2675, lead i 9'5j 
filver 8-5, fulphur o - 5. 
4. Tellurium braCteatum, or foliated tellurium: be¬ 
tween lead grey and iron-black, in flexible plates or fix- 
fided tables, with very little metallic luftre. Found at 
Nagyag in Tranfylvania; it is loluble in acids with eft’er- 
vefcence. Contains lead 54, tellurium 32, gold 9, and a 
little filver and copper. Specific gravity, on account of 
the great quantity of lead it contains, as high as 8-918. 
Arsenicum, Arfenic.—Bluifh-white, loon becoming 
black, and falling to powder in the air; foft, extremely 
brittle; fpecific gravity, 871 : fubliming, without melt¬ 
ing, in a moderate heat, in a white powder emitting a 
ftrong fmell refembling garlic; its fublimed oxyd giving 
an acrid tafte to water, and turning vegetable blues red ; 
when diflolved in muriatic acid, and a watery folution of 
fulphurated hydrogen poured into it, precipitating a fine 
yellow powder. 
1. Arfenicum nativum, or native arfenic : uncombined, 
with metallic luftre. There are three varieties. Native 
arfenic occurs in Great Britain, various parts of Ger¬ 
many, Norway, Saxony, See. accompanying fpar, barytes, 
or felfpar; maflive, rarely difl’eminated, often compofed 
of hemifpherical layers, corroded, branched, perforated, 
botryoidal, or ftalaClitical: colour lead-grey, but its fur- 
face foon tarnifhing and becoming black by expofure to 
the air: fometimes a little fonorous when ftruck againft 
a hard body, and fo foft as to be eafily cut with a knife : 
before the blowpipe it immediately emits a white fmoke, 
diffufing its peculiar and liighly-poifonous vapours to a 
great diftance, burning with a blue flame and gradually 
vanifliing, depofiting a white oxyd in the form of a pow¬ 
der: fpecific gravity, 57. It is always alloyed with iron, 
and often contains cobalt, bifmuth, filver, and fometimes 
a little gold. 
2. Arfenicum calciforme, or white oxyd of arfenic: 
white, foluble in 80 times its weight of water. There are 
three varieties: they are found in various parts of Great 
Britain, Germany, Hungary, Saxony, Bohemia, See. either 
in powder or maflive, or cryftallized in prifmatic needles. 
Colour white or grey, with often a tinge of red, yellow, 
green, or black: before the blowpipe it fublimes, but 
does not inflame, and tinges borax green: fpecific gra¬ 
vity, 37. 
3. Arfenicum auripigmentum, yellow arfenic, or orpi- 
ment: ponderous, yellow, curved or undulately foliated, 
of a waxy internal luftre, evaporating almoft entirely be¬ 
fore the blowpipe. 
It is called auripigmentum from its golden-yellow co¬ 
lour, and the ufe to which it is commonly applied. This 
fubftance, which is the arfenic of the ancients, differs 
from the fubftance commonly cal led-arfenic at the prefent 
day, in containing a portion of fulphur 5 and in being 
LOGY. Metals.* 
confequently of a yellow colour: whereas our arfenic is 
perfectly white. That the arfenic of Theophraftus and 
Pliny was of a yellow colour is evident from the particu¬ 
lar defeription which they give of it. -Pliny fays that 
the beft arfenic is, “ coloris in aura excellentis:” Theo¬ 
phraftus fays that, on account of its refemblance in co¬ 
lour, ochre is ufed inftead of arfenic: but the 
term u^st itfelf is apparently derived from its yellow co¬ 
lour; and that it was of this colour appears further pro¬ 
bable, from its being changed to a red by calcination, 
which is mentioned by Theophraftus, and being thus 
converted into the fubftance called which anfwers 
exaftly to our red ochre. The term agc-eny.ov, from which 
our word arfenic is derived, was an epithet applied by the 
ancients to thofe natural fubftances the properties of 
which were found to be of a ftrong, and as it were maf- 
culine, character: and, as the poifonous quality of arfenic 
was foon found to be remarkably powerful, the term was 
efpecially applied to that form of it which was moft com¬ 
monly met with. The arfenic of commerce of the pre¬ 
fent day is in fome inftances of a yellow colour; and, as 
the ores from which white arfenic may be obtained very 
commonly contain fulphur, the prefence of this yellow 
colour is eafily explained : for the orpiment of commerce, 
which is valuable on account of its yellow colour, is 
obtained by fubliming together either a mixture of white 
arfenic and fulphuret of iron, or of fulphuret of iron 
and any mineral containing a confiderable proportion of 
arfenic. 
Orpiment is met with in the cavities of many volca¬ 
noes ; and in the fubftance of many primitive rocks. It 
occurs in great abundance in Saxony, Bohemia, and Hun¬ 
gary. Orpiment is diftinguiflied from native fulphur by 
its laminated ftrufture, and by the garlic fmell which it 
emits upon the application of the blowpipe: the laft pro¬ 
perty ferves alfo to diftinguilh it from yellow mica. 
4. Arfenicum fandaraca, red arfenic, realgar, or fan- 
darac : fomewhat ponderous, red with an orange-yellow 
ftreak, in ftraight foliations, melting eafily before the 
blowpipe, burning with a blue flame and white arfenical 
vapours. Found in Sicily,' Naples, Hungary, Bohemia, 
China, Japan, See. maflive, difl’eminated, fuperficial, or 
cryftallized in fmall acutangled quadrangular or acicular 
prifms. Colour aurora-red, ruby, fcarlet, crimfon, or 
blood-red, often variegated with yellow. Texture la¬ 
mellar, with the foliations a little flexible, and fo foft as 
to be cut with a knife, and frequently exhibiting a bril¬ 
liant luftre: ftreak yellowifli-red, powder Icarlet: in nitric 
acid it loles its colour. Realgar is diftinguiflied from red 
filver ore, and chromat of lead, by its inferior fpecific 
gravity, 3*338; from cinnabar, by the yellow’ifh-red co¬ 
lour of its powder; that of cinnabar being a bright red. 
The ftrong fmell of garlic, and the white fumes which it 
emits upon the application of the blowpipe, are in them- 
felves ftrong diftin&ive marks between this fubftance 
and others with which it is liable to be confounded by 
the eye. 
5. Arfenicum fulphuratum, arfenical pyrites, or mar- 
cafite: hard, bluifh-grey with metallic luftre, before the 
blowpipe emitting white arfenical vapours and blue ful- 
phurous flames. Found in various parts of Great Britain, 
Germany, Sweden, Bohemia, Saxony, &c. in irregular 
mafi'es, difl’eminated, inverting, or cryftallized in Cubes or 
four-fided prifms. Colour greyifh-white, often a little 
variegated: texture uneven, fometimes granular, fome¬ 
times lamellar or radiate: when rubbed, it gives the 
odour of garlic. Specific gravity, 6-522. Contains arfenic 
53, iron 19-7, fulphur 15 3, filex 12. 
6. Arfenicum albicans, .ferruginous arfenic, or mif- 
pickel: of a fteel-white colour and luftre, hard, emitting 
white arfenical vapours before the blowpipe, but no ful- 
phurous flame or vapour. T his form of arfenic is very 
common in the tin-mines of Cornwall. The white oxyd 
of arfenic, which is the white arfenic of commerce, is 
often obtained from it, by fubmitting the ore to the prq- 
