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neceflary to be employed. If the, enamel, however, be 
very fufible, the colours may all penetrate it. This man¬ 
ner of painting gives no thicknefs of colour; on the con¬ 
trary, the colours fink into the enamel at the places where 
the tints are drongeft. To make them penetrate, and 
give them ludre, a ftrong fire will be neceffary to fofren 
the enamel, and bring it to a date of fufion. This" me¬ 
thod cannot be praftifed but on enamel compofed with 
fand. It will be readily conceived, that the colours and 
enamel capable of enduring the greated heat, are the 
mod folid, the mod durable, and the lead liable to be 
changed by the air. A mixture of thefe different enamels 
produces a great variety of intermediate colours, accord¬ 
ing to their nature and proportion. In this branch of the 
art, the coloured enamels are fometimes mixed with each 
other, and fometimes the calces are mixed before they 
are added to the vitreous bafes. 
The enarnciler, however, though provided with a fet 
of good colours, is very far from being in a dtuation for 
pradtifing the art, unlefs he be fkilled in the methods of 
applying them, and the nature of the grounds upon which 
they are to be laid. Many of the metals are too fudble 
to be enamelled, and almoft all of them are corroded by 
the aftion of the fufedglafs. For this reafon, none of 
the metals are tiled btitgold, diver, and copper. Platina 
has indeed been ufed; but of its effects and habitudes 
with enamels, very little can yet be faid, for want of a 
fufficieiit number of experiments. The pored gold of 
twenty-four carats is calculated to produce the bed eftefit 
with enamel; becaufe it -entirely preferves the metallic 
brilliancy, without undergoing any calcination in the dre. 
Being alfo lefs fufible, it admits of a more refractory, and 
confequently a harder and more beautiful, enamel. It is 
not ufual, however, to enamel upon dner gold than twen¬ 
ty-two carats ; and the operation would be very defec¬ 
tive, if a coarfer kind than that of eighteen carats were 
ufed. For in this cafe more alkali mud be adde'd to the 
enamel, to render it more fufible; and this addition would 
at the fame time render it fofter and lefs brilliant. 
Theartid begins his operation, by breaking the enamel 
into frnall pieces in a deel mortar, and afterwards pulveri- 
fing it in a mortar of agate. He is careful to add water in 
this part of his- procefs, which prevents the fplinters of 
glafs from flying about. There are no means of explain¬ 
ing the point at which the trituration Ought to be given 
up, as this can be learned only by experience. Some 
enamels require to be very flnely triturated; but others 
may be ufed in the form of a coarfe powder. As foon as 
he apprehends that his enamel is fufliciently pounded, he 
wadies it by agitation in very clear water, and pouring off 
the fluid as it becomes turbid. This operation, which is 
made for the purpofe of carrying'off dud and every other 
impurity from the enamel, is continued until the water 
comes off as clear as it was poured on. The workman 
puts his enamel, thus prepared, in a white china or ear¬ 
then faucer, with water poured on it to the depth of about 
one tenth of an inch. He afterwards takes up this ena¬ 
mel with an iron fpatula, as equally,as podible. As the 
enamel here fpoken of is tranfparent, it is ufual to orna¬ 
ment the Airfare of the gold with rofe-work, or other 
kinds of work, calculated to produce a good effect through 
the enamel. The thicknefs of this drd layer depends 
entirely upon its colour; delicate colours, in general, re¬ 
quire that it diould have no great thicknefs. The moid 
enamel, being thus placed, is dried by applying a very 
clean half-worn linen cloth to it, which mud be very care¬ 
fully done, to avoid removing the enamel by any adlion 
of wiping. In this date the piece is ready for the dre. 
If it be enamelled on both ddes, it is placed upon a tile, 
hollowed out in Arch a manner, that the uncovered edges 
of the piece alone are in contact with the iron. But if it 
be enamelled on one fide only, it is fimply laid upon the 
plate, or on a tile. Two things, however, require to be 
attended to. i. If the vvoik be very fmall, or not capa¬ 
ble of being enamelled on its oppodte fide, the iron plate 
L L I N G. 
mud be perfectly flat, in order that the work may not 
bend when foftened by heat, 2. If the work be of cond- 
derable fize, it is always counter-enamelled if podible ; 
that is to fay, .an enamel is applied on the back Atrface, in 
Order to countera6t the effedd which the other coating of 
glafs might produce on the foft metal, when it caine to 
contraft by cooling. < 
The.enamellers furnace is fquare, and built of bricks, 
bedded in an earth proper for the purpofe. It may be 
conddered as confiding of two parts, the lower part, which 
receives a mufFel, reding on the floor of the furnace, and 
open on both ddes. The upper part of the furnace con- 
fids of a dre-place, rather larger and longer than the di- 
menfions of the mufFel. This dre-place contains the 
charcoal, which mud furround the mufFel on all ddes, 
excepting at the bottom. The charcoal is put in at a 
door above the mufFel, and which is clofed when the dre 
is lighted. A chimney proceeds from the fummit of the 
furnace with a moderate aperture, .which may be clofed 
at the pleaftire of the artid, by applying a cad iron plate 
to it. This furnace differs from that of the affayer in the 
circumdance that it is fupplied with air through the muf- 
fel itfelf; forif the draught w-ere beneath the mufFel, the 
heat would be too drong, and could not be dopped when 
requidte. As foon as the dre is lighted, and the mufFel 
has obtained the requidte degree of ignition, the charcoal 
is difpofed towards the lower part of the mufFel in fuch a 
manner as that it 1 hall not fall upon the work, which is 
then conveyed into the muff'd with thegreated care upon 
the plate of. iron or earthen ware, which is taken up by 
long fpring pinchers. The work is placed as near as pof- 
dble at the further.extremity of the mufFel ; and as foon 
as the artid perceives a commencement of fufion, lie turns 
it round wdth great delicacy, in order that the fufion may 
be very uniform. And as foon as he perceives that the 
fufion has completely taken place, lie indantly removes 
it out of the furnace : for the fufion of gold happens fo 
very near that of the enamel, that a negledt of a few feconds 
might be attended with confiderable lofs. When thq 
work is cooled, a fecond jcoaf'of, enamel is applied in the 
fame manner as thefird, if neceffary. This, and the fame 
cautious management of the fire, are to be repeated for 
every 'additional coat of enamel the nature of the work 
may demand. 
As foon as the number of coatings are fufficient, it be¬ 
comes neceffary to give an even fur-face to the enamel, 
which, though polifiied by the fire, is neverthelefs irre¬ 
gular. This is done with an Englilh fine-grained file and 
water. As the file wears fmootli, dmd is ufed. Much 
precaution and addrefs are required in this part of the 
work, not only becaufe it is eafy to malqe the enamel 
feparate in fplinters from the metal, but likewife becaufe 
the colour would not be uniform if it were to be ground 
thinner at one part than at another. The-deep fcratches 
of the file are in the next place taken out, by rubbing the 
furface with a piece of deal wood and fine fand and water. 
A polidi is then given by a fecond ignition. This polifh, 
however, is frequently infiifficient, and not fo perfectly 
uniform as the delicacy of the work may require. 
The fubdance ufed by the enamellers, as a-polidiing 
material, is known by the name of rotten-done ; which is 
prepared by pounding, wafiiing, decanting off the turbid 
water, fuffering the fine fufpended particles to fubfide 
from this water, and ladly levigating it upon a glafs plate. 
The work'is then cemented to a fquare piece of wood 
with a mixture of rofin and brick-dud, and by this means 
fixed in a vice. The fird operation of polilhing is made 
by rubbing the work with rotten-done upon a fmall drait 
bar qf pewter. Some delicacy is here required, to avoid 
fcratching or producing flaws in the enamel, by prefling 
it too hard. In this way the piece is rendered perfectly 
even : but the lad brilliant polidi is given'by a piece of 
deal wood and the fame rotten-done. 
This is the general method of applying enamels; but 
fome colours require more precaution in the management 
of 
