CHEMISTRY. 
ftate, Nitric acid is likewife formed during this procefs. 
See the fedtion on Ammoniac , page 226, for the manner 
of making this experiment with liquid ammoniac, rather 
than with muriat of ammoniac. 
By adding oxyd of manganefe to the materials ufed in 
making glal's, it is rendered of a clear white : the addi¬ 
tion of nitrat of potafh gives the glafs a violet-colour, 
which will be fo much the ftronger, in proportion as the 
oxydation of the metal by the nitric acid was the more 
complete. Thus the oxyd of manganefe is ufed in glal's- 
works, either to take away the yellow, green, or blue, 
tinge, from glafs intended to be of a clear white; or in 
other proportions to give the glafs a violet colour. The 
■affinity of manganefe for the principle of combuftion 
ferves likewife to guide modern chemifts in a great num¬ 
ber of cafes, and may lead to dilcoveries concerning the 
nature of many fubftances at prel'ent unknown. 
Of BISMUTH. 
Bifmuth is often found native in the bowels of the 
earth; or combined with fulphur, arfenic or oxygen. 
The primitive form of the metal is a regular odtahedron. 
To reduce, or fmelt, the ore of bifmuth, a cavity is made 
in the earth, which is covered with billets of wood 
placed one on the other; the wood is fet on fire, and 
the ore, being broken fmall, is thrown in it. The bif- 
rnuth melts, and runs into the cavity, where it takes an 
orbicular form. In other places the trunk of a pine tree, 
hollowed into the form of a gutter, is placed in the earth 
in an inclined pofition, and wood laid over it; the bif¬ 
muth is thrown on this combuftible matter, after it is fet 
on fire: the metal melts, falls into the channel, which 
conduits it into a cavity made in the earth, over which 
the extremity of the trunk is placed. The bifmuth, thus 
obtained, is poured into iron moulds. It is then of a 
light yellow colour, of a lamellous texture, and brittle; 
its metallic brilliancy is changed by expofure to the air, 
and it affumes a violet tinge ; and at length a white pow¬ 
der is formed on the furface, which is bifmuth in the 
oxyd date. 
Bifmuth is extremely fufible, and melts long before 
the red-heat commences. The following is the mode of 
obtaining it in crylials. Enclofe it in a crucible, and 
melt it; when melted, take the crucible off the fire, and 
let it ftand a fhort time to cool; then pour it off; the li¬ 
quid part runs off; but the congealed part, adhering to 
the crucible, fhews the metal in cryftals at the lower part 
and at bottom. Another mode of operation, according 
to Monges, is to ufe a crucible with a hole and Hopper 
at the bottom. When the metal is melted, let it co¬ 
agulate at the furface; when it begins to adhere, re¬ 
move the ftopper from the bottom, and the liquid part 
runs out; then the fides of the crucible, and the under 
part of the upper furface of congealed matter exhibit cry- 
-ftals, fometimes cubical, fometimes oftahedral. 
If bifmuth be kept in fufion with contaft of air, its 
furface becomes covered with a pellicle, which changes 
into an oxyd of a greenifh grey, or brown, named allies 
or calx of bifmuth, Nineteen drachms of bifmuth cal¬ 
cined in a capfule of glafs, afforded Baume twenty 
drachms thirty-four grains of oxyd. Bifmuth heated to 
rednefs, burns with a fmall blue flame, fcarcely fenfible. 
Its oxyd evaporates in the form of a yellowifli fmoke, 
which condenfes on the furface of cold bodies. The ex¬ 
periment is performed as follows : Put the bifmuth into a 
crucible, and urge it with a ftrong heat: as foon as the 
blue flame arifes, take the crucible off the fire, and fix 
over it a glafs funnel, in which the bifmuth will fublime 
in the oxyd ftate. When the bifmuth no longer fmokes, 
heat it again to the fame degree;.and repeat the experi¬ 
ment till the bifinuth will no longer volatilife : this was 
formerly called flowers of bifmuth. The oxyd of bifmuth 
is very fufible; it melts alone by the aftion of fire, and 
is converted into a yellow tranlparent glafs: this glafs 
corrodes and vitrifies the crucible. This oxyd may be 
VOL. IV. No. 195. 
2 73 
reduced, orreftored to the metallic ftate, by being made 
into a pafte with black foap, and melted in a crucible. 
Hydrogen gas alters the colour of bifmuth, and gives 
it a violet tinge. Sulphur combines with this metal by 
fufion, and produces a fort of ore of bifmuth, fulphure- 
ous, artificial, blackifh, and porous, which, when melted 
again, becomes grey, fnining, ftriated, and is even fuf- 
ceptible of cryftallization. 
Bifmuth has, according to Pelletier, very little affinity 
for phofphorus. Of the experiments made for phofpho- 
rating bifmuth, the following lucceeded the belt: A lit¬ 
tle bifmuth was melted in a crucible ; when melted, fome 
little bits of phofphorus were thrown in, one after the 
other : the crucible was then taken off the fire, and the 
phofphorated bifmuth was found to adhere very ftrongly 
to it. . It is very brittle, like bifmuth; under the blow'- 
pipe, it emits a fmall green flame in theinftant of fufion; 
by expofure to the air, it affumes a varied colour; tin-ow¬ 
ing fome filings of it upon burning coals, fmall greenifh 
flames will arii’e with a pholphoric fmell. 
Concentrated and boiling fulphuric acid adts on bif¬ 
muth ; the acid is partly decompofed, and fulphureous 
gas is exhaled. The mars remaining in the veil'd, after 
the decompofition of a part of the acid, is white; that 
portion which is in the faline ftate may be feparated by 
means of water, from the other portion which is oxyd- 
ated, and does not contain any acid; the lixivium, by 
evaporation, affords a fulphat of bifmuth in fmall deli- 
quefeent needles. This fait is decompofable by fire, by 
the falino-terreftrial fubftances, by alkalis, and even by 
water alone, in large quantities. 
The nitric acid diffolves bifmuth with an aftonifhing 
rapidity; or rather this metal decompofes the acid, and 
very quickly takes from it a part of its oxygen ; the mix¬ 
ture becomes very ftrongly heated, and emits, denfe red 
Vapours. If the combination be made in the pneumatic 
apparatus, a large quantity of nitrous gas is obtained; 
and this procefs is one of the readied and mod conveni¬ 
ent for procuring this gas. During the folution, a black 
powder is precipitated, which Lemery fuppofed to be 
bitumen, and Pot confidered as calcined oxyd of bifmuth ; 
Baume fufpedted it to be fulphur; perhaps it may be 
charcoal. 
The nitric folution of bifmuth is without colour, and, 
when it is much faturated, it affords cryftals without 
evaporation. Evaporation, and cooling, afford a nitrat 
of bifmuth ; it is a white very firming fait, concerning 
the form of which chemifts differ. Fourcroy, by flow 
evaporation, obtained flattened rhomboids, very large, 
and perfedtly fimilar to the calcareous fpar of Iceland. 
The nitrat of bifmuth detonates feebly, and with reddifh 
fcintillations, after which it melts and fwells up, leaving 
an oxyd of a greenifh yellow, not reducible without ad¬ 
dition. This fait expofed to air, lofes its tranfparency, 
at the fame time that the w'ater of cryftallization is diiii- 
pated. If water be added, inftead of diflblving it, the 
fluid becomes white, milk}', and an oxyd of bifmuth 
is precipitated. The fame thing happens, if the nitric 
folution of bifmuth be poured into water, the greateft 
part of the oxyd of this metal being precipitated under 
the form of a white powder, called magifery of bifmuth. 
If it be defined to be very white and fine, diffolve the bif¬ 
muth in the nitric acid as mentioned before, dilute it in 
twice its weight of water, then let it fettle well, and 
draw it off to feparate the black precipitate. Pour the 
folution into a large quantity of frefh water, and a white 
precipitate will take place; when this has well fettled,. 
filtre the liquor; wafli the depofit remaining after filtra¬ 
tion in feveral waters, to feparate all the acid, and then 
dry it: this is what is called magifery of bifmuth , white 
paint, and pearl-powder. By the ladies it is ufed as a 
pigment for rendering the fkin white; but it h3s the in¬ 
convenience of becoming black when in contadt with 
odoriferous or combuftible matters. This property has 
occafioned many a painful ftruggle between black, white, 
4 A and 
