262 C H E M I 
tended with effervefcence, and a portion of the carbonic 
acid feparated from the alkali, appears to combine with 
the alumine, while another portion becomes diffolved in 
the fluid. It is likewife acknowledged, from the analyfis 
of many argillaceous earths, by modern chemifts, that 
they contain the carbonic acid; for they effervefce, when 
diflolved in the fulphuric or muriatic acids. 
Carbonat of Zircon. —This fait yet remains to be 
inveftigated by modern chemifts j its properties not being 
known. 
Of METALLIC SUBSTANCES. 
Before we proceed to the examination of each metallic 
fubftance in particular, it may be neceflary to confider, 
3. Their phyfical properties, 2. Their natural hiftory, 
3. The art of knowing their nature and quantity, called 
docimafia, or art of allaying. 4. The method of working 
them in the large way, or metallurgy. 5. Their chemical 
properties. 6. The manner of diltinguilhing one from 
another, and the diviftons neceflary to be eftablifhed 
amonglt them. 
The ancients fuppofed metals to be compofed of fome 
earthy fubftances, combined with phlogifton ; hence the 
denomination of perfect and imperfedt metals. The al- 
chemifts gave the name of folar metals to thofe which 
were coloured, and lunar to fuch as are white. But me¬ 
tals in general are Ample fubftances. At prefent there 
are reckoned twenty-one different fpecies of metallic fub- 
ftances, which Fourcroyhas defcribed under fi.ve divifions. 
I. Brittle and acidifiable metals, four kinds; arfenic, 
tungften, molybdena, and chrome. 
II. Brittle and Amply oxydable, feven fpecies : titane, 
nranite, nickel, cobalt, manganefe, bifmuth, antimony, 
and tellure. 
III. Metals femi-dudtile, and oxydiftable, two fpecies: 
mercury and zink. 
IV. Metals dudtile, and eafily oxydated, four fpecies; 
tin, lead, iron, and copper. 
V. Metals very dudtile, and not eaAly oxydated, three 
.fpecies : Alver, gold, and platina. 
Of ARSENIC. 
Native arfenic is often found ; it is in black mafles, 
little Alining, and very heavy; fom.etimes it has a metallic 
brightnefs, and refledts the colours of the rainbow. Pure 
arfenic has alfo been called regulus of arfenic ; but which 
denomination, fays Fourcroy, ought to be abandoned 
as improper. In breaking it appears more fhining, and 
deems compofed of a vaft number of little fca'les : when 
thefe fcales are viflble on the outflde of the pieces, it is 
called tefaceous arfenic , or, improperly, teflaceous cobalt, 
fcalj or laminated arfenic. It is alfo found in friable mall’es 
almoft without confidence. Arfenic, under thefe forms, 
is brought from Bohemia, Hungary, Saxony, St. Marie 
aux Mines, See. 
Arfenic is fometimes in the form of a white oxyd, hav¬ 
ing even a vitreous afpedtthis oxyd is often mingled 
with certain earths, or in the form of a fuperfleial pow¬ 
der. It is in the metallic ftate in its combinations with 
cobalt, in teftaceous cobalt, or with iron in mifpikel or 
arfenical pyrites. It is often combined in the mines with 
divers metals, as antimony, tin, iron, copper, and Alver. 
It is difengaged by calcining thefe metals. In many places 
they ufe long crooked chimnies which draw out the 
arfenical vapours, and detain them: the cruft which is 
formed on the walls or partitions of thefe chimnies is 
taken oft’; and this is what is known in commerce under 
the name of arfenic : this is the oxyd of white arfenic. 
This oxyd, or calx, is often combined with fulphur; it 
then forms or produces orpiment and realgar, or calxes 
of yellow and red lulphurated arfenic. When red it is 
called realgal, realgar , factitious rizigctl, or red arfenic. 
When yellow, it is called orpinum, or factitious orpiment. 
Orpiment and realgar are found native or complete in 
certain places: cryftals of realgar are found at Salfaterra 
z 
S T R Y. 
near Naples, according to Ferber; in the mines of Nag.- 
yag in Tranfylvania; in the mines of Felfobanga in Up¬ 
per Hungary ; in thofe of Joachimfthal in Bohemia, in 
Marienburg,and in Saxony. Realgar is common in China, 
where it is made into vafes, pagodas, and other ornamen¬ 
tal works : the Indians ufe thefe vafes for purging, by 
drinking vinegar or lemon-juice which has flood in them 
fome hours. Orpiment is lefs fcarce than realgar : it al¬ 
moft always accompanies it. But the orpiment met 
with in commerce is lent to us from feveral parts of the 
Levant, in irregular mafles, folid, or lamellated, of a fine 
yellow colour. 
Arfenic, heated, with the admiflion of air, is quickly 
brought to an oxyd or calx: it flies off in a white -vapour, 
which has much the fmell of garlic. It is fufed and fub- 
limed in clofe veflels. It may be cryfta'llized in regular 
four-ftded prifms, if fublimed flowly. When red-hot, it 
burns with a blue flame. To fublime arfenic, flrft pul¬ 
verize it grofsly; All a long-necked matrafs with it half¬ 
way; place it in a fand-bath, covering the matrafs nearly 
up to the neck: proceed to lublimation with a gradual 
heat, and continue till all the arfenic is fublimed : leave 
it to get cold, 'and then break the matrafs. If the fire 
was fufticiently ftrong, the fublimed arfenic undergoes a 
kind of fufion ; but it becomes'tranfparent, and lies in 
a white colourlefs mafs, if the heat was weaker. This 
is what is known under the name of white oxyd, formerly 
called calx of arfenic, and white arfenic. 
If this oxyd be put into clofed veflels, it flies off, by 
a gentle heat, into a, white cryftalline powder called flow¬ 
ers of arfenic. For this purpofe reduce the arfenical oxyd 
to powder; take a glafs retort with a very fhort and large 
mouth ; fill it half or three parts full, and place it in the 
fand-bath of a furnace; lute on a globe to the mouth of 
the retort, and proceed as in common diftillation. The 
arfenic rifes in vapours, which are condcnfed inlide the 
globe, in the form of a white powder ; at the bottom of 
the retort remains a yellowifh matter, Amilar to that in 
the preceding operation. 
Arfenic, in the metallic ftate, does not adt fenfibly on 
combuftible bodies; yet it eafily diffolves in hydrogen gas; 
Expofed to the air, arfenic grows fenfibly blacker; but 
has no adtion with water. The adtion of faline earthy 
matters upon arfenic, is not known. Weak fulphuric 
acid has little adtion upon it; it mull be concentrated 
and boiling; then the folution is complete: it is tranfpa- 
rent, but of a light brown colour. This folution furnifhes 
in cooling a large quantity of fmall irregular cryftals r 
this is arfenic reduced to the ftate of an oxyd. 
Nitric acid dilfolves arfenic extremely well, even quick¬ 
ly ; but the acid mull be hot; for, when cold, it has no 
fenfible adtion. Strongly evaporated, it forms a fait with¬ 
out any regular fhape, according to Bucquet : Baume 
fays, on the contrary, that the folution produces cryftals^ 
fome nearly cubical, others diamond-fafiiioned : Walle- 
rius, in his Mineralogy, (vol. i. p. 404.) fays, that thefe 
cryftals are like thofe of lunar nitre. Thefe experiments 
therefore fliould be repeated, and the refults carefully 
examined, in order to afeertain the fact. 
Bayen and Charlard maintain, that muriatic acid, 
when cold, has no adtion upon arfenic; the adtion of fire 
is therefore required to diifolve arfenic in that acid-. 
Baume fays, that a yellow powder like fulphur is precipi¬ 
tated, which is infoluble,in water. Arfenic in powder, 
mixed with oxygenated muriatic acid, burns with a white 
flame. Mixed wilh fuper-oxygenated muriat of potafb, 
the mixture is ftrongly detonated by trituration and the 
ftroke of the hammer. It flames with extraordinary ra¬ 
pidity and brightnefs, by the contadt of fulphuric acid. 
Oxyd of arlenic, or the white arfenic of commerce, 
has properties very different from metallic arfenic, for¬ 
merly called regulus. To obtain arfenic in the metallic 
ftate, or tt) reduce the oxyd of arfenic, make a palte of 
the oxyd in powder and fioft foap, or linfeed-oil, or any 
other oil drawn out by expreffion : put this palte in a 
matrafs* 
