2(jfl s 
wards pours into this metallic lye a folulion of gold, 
drop by drop, taking care to ftir the whole with a glafs 
tube : wlicn the mixture becomes of a deep purple co¬ 
lour, he ceafcs dropping the Iblution of gold; and ini 
order to haflen tlie precipitation of the mineral purple, 
pours into tJie mixture a pint of fredi urine. Six or 
ieven hours after, the precipitate is colletled at the bot¬ 
tom of the vell’el : the Huid is then decanted; and the 
precipitate,, walked once or twice, is dried till it be¬ 
comes a brown powder for ufe.—2. Pour into a velfel of 
tine tin with a thick bottom four ounces of the folution 
of gold ; three minutes after add two pints of diftilled 
water. Let this mixture (land in the tin velfel during 
teven hours, taking care to ftir it every hour with a glafs 
tube; afterwards pour it into a conical glafs jug, and 
add to it a pint of frelh urine ; the mineral purple is 
foon precipitated, and then it is to be waflied and dried. 
—3. Diftil in a glafs cornute placed in a bath of allies, 
fomc gold dillblved in aqua regia, made with three parts 
nitrous and one part marine acid ; when the acid is palled 
over and the gold contained in the cornute appears dry, 
leave the velfel to cool, then pour into it fome new aqua 
regia, and proceed to diftil as before. Replace the aqua 
regia twice upon the gold, and diftil the fame. "After 
thefe four operations, pour by little and little into the 
cornute fome oil of tartar fie/' dcliquium, which will oc- 
calion a brilk efl'ervefcencc ; when this ceafes, diftil the 
mixture till it becomes dry, and then put fome warm 
water into the cornute. Shake the whole, and pour it 
into a cucurbit, when a precipitate is depolited, the co¬ 
lour ot which is fomeiimes brown and fometinies yel¬ 
low ; after having wallied this precipitate, dry it. 
jM . I'ontanieu fays, this mineral purple was much fupe- 
1 ior to the foregoing, fince two grains of it only were 
furticient to an ounce ot the bafe, whilft jt required of 
the other two a twentieth part of the bafe. And he 
adds, that he found a means of exalting the colour of 
the precipitate of Calfius, by putting to it a fixth part 
of its weight of glafs ot antimony finely powdered, and 
ot nitre in the proportion of a dram to eight ounces of 
the bafe. ° 
From Silver. —The calx of filver, being vitrified, 
produces a yelUiwith-grey colour. This calx enters 
only into the cornpolition of the yellow artificial dia¬ 
mond, and the opal, M. Fontanieu introduces it into 
the bafe in the form of lima cornea. In order to pre¬ 
pare it, he dirc6ls to dilfolve the filver in precipitated 
nitrous acid, and afterwards to pour into it a folution of 
lea-falt : a white precipitate is obtained ; which, being 
waftied and dried, melts very readily in the fire, and is 
foon volatilized it not mixed v/ith vitrifiable matters. 
T o make the yellow diamond, tw'enty-five grains of this 
luna cornea are put to an ounce of the fourth bafe above 
delcribed ; the dofe of filver may be diminiflied accord¬ 
ing to the fiiade ot yellow that one withes to procure. 
F rom Copper. —The calx of copper imparts to wliite 
pafte or glafs the fineft green colour ; but if this metal 
be not exabtly in a (fate of calx, it produces a brow nifli 
red colour. Mountain blue, v^rdegris, and the refidue of 
its diftillation, are the different preparations of copper 
which this artift employs to make the artificial emeralds. 
F'rom Iron. —Although it has been alferted, that the 
calces of iron introduce a very fine tranfparent red co¬ 
lour into white glafs, M. Fontanieu could only obtain 
from it a pale red a little opake. The calx of iron 
that he employed was in the proportion of the twentieth 
part of the bate.—There are feveral ways of preparing 
the calx of iron called crocus Martis, ox faffron of Mars. 
By digelling filings of fteel with diftilled vinegar, then 
evaporating and replacing the vinegar ten or twelve 
times upon thefe filings and drying them alternately, a 
cal.'c of iron is obtained, whicli muft befifted through a 
filk lieve, a.tjd then calcined. The calx of iron tluis 
obtained by the vinegar, introduces into the bafes a 
green colour, inclining to a yellow. By the following 
E M. 
procefs a faffron of Mars of the fineft red colour is ob¬ 
tained : Let an ounce of iron filings be dilfolved in ni¬ 
trous acid in a glafs cornute, and diftilled over a fand- 
bath to drynefs. After having replaced the acid or the 
dry calx, and re-diftilled it a fecond and a third time, 
it is then edulcorated with fpirits of wine, and after¬ 
wards waftied with diftilled water. 
From tlte Mag NET. —It is neceffary to calcine the 
magnet before it be introduced into the vitrifications : 
having therefore torrified the magnet during two hours, 
it muft be waftied and dried. It is only employed in 
compofitions of the opal. . 
From Cobalt. —The calx of cobalt is only proper 
to introduce a blue colour into glafs gems ; but this me¬ 
tal is rarely found free from iron and bifmuth, and there, 
tore it is firft neceffary to feparate them from it. This 
is done by calcining the ore of cobalt in order to diten- 
gage the arfenic : afterwards the calx muft be diftilled 
in a cornute with fal ammoniac, and the iron and the 
bifmuth are found fublimed with this fait. The diftil¬ 
lation muft be repealed with the fal ammoniac till this 
fait is no longer coloured yellow. The cobalt which 
remains in the cornute is then calcined in a potftierd, 
and becomes a very pure calx ; which being introduced 
into the bale, in the proportion of a nine-hundredth part, 
gives it a very fine blue colour, the intenfity of which 
may be increafed at diferetion by the addition of calx of 
cobalt. In order to prepare black enamel relembling that 
which is called black agate of Iceland ; melt together a 
pound and a half of one of the bafes, two ounces of the 
calx of cobalt, two ounces of crocus Martis, prepared 
with vinegar, and two ounces of manganefe. 
From Tin.—T he calx of tin is not vitrifiable alone, 
and when deprived of its caloric is of a white colour; 
it renders opake the glafs with which it is melted, and 
forms white enamel. For this purpofe, calcine the putty 
of tin; then walh and dry it, and lift it through a filk 
fieve. Take fix pounds of tlie lecond bale, the fame 
qutintity of the calcined putty of tin, and forty-eight 
grains of manganefe. 
From Antimony. —Antimony is only fufceptible of 
vitrification when its calx contains caloric, and then it 
produces a reddifti or hyacinth coloured glafs ; but if 
the antimony be in a ftate of abfolute calx, fuch as the 
diaphoretic antimony, then it is no longer vitrifiable, 
and may be fubllituted for calx of tin to make white 
enamel. M. Fontanieu introduces the glafs of anti, 
mony in the compofition of artificial topazes. For the 
oriental topaz, he takes twenty-four ounces of the firft 
bafes and five drams of the glafs of antimony. To imi¬ 
tate the topaz of Saxony, he adds to each ounce of the 
bafe five grains of the glafs of antimony. For the topaz 
ot Brazil, he takes twenty-four ounces of the firft bafe, 
one ounce twenty-four grains of glafs of antimony, and 
eight grains of the precipitate of Caffius. 
From Manganese. —This mineral, employed in a 
fmall quantity, renders the glafs whiter ; a larger quan¬ 
tity produces a very fine violet colour, and a ftill larger 
proportion renders the glafs black and opake. 
1 here are two ways of preparing manganefe: i. The 
moft fimple confifts in expofing it to a red heat, and then 
quenching it with diftilled vjinegar ; it is afterwards 
dried and powdered, and palfed through a filk lieve. 
2. Haudiquer de Blancour deferibes the fecond manner 
of preparing the manganefe, proper to furnilh a red co¬ 
lour, and names it fujible manganefe. Take of manganele 
of Piedmont one pound ; torrify and pulverize it; then 
mix it with a pound of nitre, and calcine the nuxture 
during twenty-four hours ; afterwards walh it repeat¬ 
edly in warm water, till the water of the lyes has no 
longer any tafte; dry the manganefe, and mix with it 
an equal weight of fal ammoniac; levigate this mix¬ 
ture on a llab of porphyry with oil of vitriol diluted 
with water to the ftrength of vinegar. Dry the mixture, 
and introduce it into a cornute; diftil by a graduated 
