ployed; one by precipitation, and the other 
coe the she ig A of pure gold 
‘containing about ei oe ce 
regia, (nitro- ic acid). The gold 
more readily Seve, if it is either out Ro 
plates, or divided into small grains, by pouring it 
water when melted. A e heat being applied, 
‘facilitate the ss, and by occasionally stirring 
it with a ; rod, the gold will be wholly taken 
up. _A solution of sulphate of iron or green vitriol, in 
able ‘eight times its weight of water, is made at the 
same time, and if it leaves any sediment, it must be se- 
parated and tendered clear. i‘ 
To precipitate the gold in a state of powder, a small 
ti the solution of sulphate of iron is poured in- 
the containing the solution of gold, and a red 
immediately falls to the bottom from the nitro- 
uriatic acid, leaving the gold to unite with the iron of 
the vitriol, for which it has a4 greater affinity. The 
fluid must be now poured off, and leaves the bright 
gold powder at the Bottom of the glass, which is then 
to be filled with clean water, and the powder stirred up 
to wash it from any remains of acid. Te will soon settle 
again, and the water must be poured off to leave the 
powder as dry as possible. e remaining water is 
sat teiga by exposing the powder in the air upon a 
ece 
a Another method of producing gold powder, is to form 
an nadie of gold with mercury, by the same process 
as desi for wash-gilding, namely, heating the gold 
‘to redness, and throwing it into mercury, heated near- 
ly to its point of evaporation. The gold forms an amal- 
with the mercury, and after being separated from 
e superfluous mercury, by passing through a piece of 
leather, the amalgam is put in a crucible or a glass, 
and ex to a sufficient heat to evaporate the mercu- 
, and this leaves the gold in a fine yellow powder. 
or this method, the mereury must be quite pure, and 
free from any admixture of lead, otherwise the powder 
) ‘will be found in lumps, and discoloured. 
ering. Gold may be m ge reduced to a powder by 
grinding leaves of gold with a muller upon a marble 
Stone, and working it up with fine clear honey. The 
fragments brushed off by the leaf-gilders will answer 
this purpose, and the grinding must be continued un- 
til the gold forms a yellow paste with the honey. 
This paste being thrown into water, the honey is taken 
, up by it, and the gold settles in a fine”powder. It 
‘must be repeatedly washed till the honey is quite se- 
, and then the powder is dried. This does not 
: uce so brilliant a der as the former means, be- 
12 cause the particles of gold are bruised, and rendered 
dull by the action of the muller and stone. 
__. ° The cement or size used for japanners’ gilding is 
composed of linseed oil and gum. The oil S boiled, 
and whilst upon the fire, pieces of gun anime being put 
in, will be dissolved. The proportion of gum should 
be about one-fourth (by weight) of the oil ; the mix. 
ture is boiled till it is reduced to the consistence of tar, 
and then strained through a cloth, When wanted for 
use, it must be ground: with vermilion, adding as much 
oil of turpentine as will ‘make it work with a brush, 
Some gilders add to the above composition asphaltum, 
red lead, and umber. These fea Sage are pounded 
~ and mixed with the gum, before it is put into the oil. 
Such additions give the size a colour, which is 
More necessary in gilding with der than for leaf 
ilding, because the size appears in innumerable small 
‘VOL, X, PART I 
GILDING. 
281 
specks, which will diminish the lustre of the gold un- Gilding. 
less the size is of a brilliant colour. Sa 
The operation of gilding with powder, is nothing 
more than to paint the work over with the size, mixed 
Up with oil of ine ; and when the size is so far 
dried that it feels adhesive without coming off when 
touched with the finger, the gold powder is applied, 
by dipping a piece of soft Wash leather into it, and 
daubing it upon the work, When the work is small, it 
is best to strew the powder upon it, and shake off the 
superfluous gold. re 
' Gilding upon Porcelain or Glass—The gold is tedu- Gilding up- 
éed to a fie powder by any of the means described un- °° Porcelain 
der japanters’ gilding, and mixed with borax, adding as 
much gum water as will make it work with the pen- 
cil, with which it is to be laid upon the porcelain or 
glass ; it must then be subjected. to a sufficient heat to by-gold 
make tlie enamel soft, to which the borax contributes Powder. 
very much. This fixes the gold, and it can afterwards 
be burnished ; or leaf-gold’ may be laid on with gum 
water, and fixed by burning. Borax is sometimes mix- 
ed with the gum. 
To gild upon glass without burning, a cement or size 
may be made of amber, melted in drying oil, and boil- 
ed to a strong consistence. It must be tempered for 
working with the pencil by oil of turpentine, and laid 
on the glass or porcelain, and the gold leaf spread over 
it. When perfectly dry, it will bear a careful burnish- 
ing, and is durable, 
~ False or Imitative Gilding.—Wash gilding cannot be False or 
imitated ; it must, as we have before metitioned, be of imitative 
pure gold. Leaf gilding may be done in Dutch leaf, 84"s- 
which is made of copper covered with’ gold upon its Dutch leaf 
surface, by the wash gilding process, and afterwards 
beat out in the same manner as the gold ; but the leaves 
are much thicker, because there is little inducement to 
reduce them so far, and they are more easily laid on. 
When first done, this work has all the appearance of 
true gold, but soon tarnishes by the air, and any damp- 
ness will produce spots in it ; if secured by a transpa- 
rent varnish, it preserves its beauty as long as the var- 
nish lasts, and in this case becomes a very good substi« 
tute. The proper varnishes are made of mastic sanda- 
fac, white resin, or copal, these alone being sufficiently 
white and transparent. 
Silver leaf and tin-foil are made to represent gold, by Silver or tin 
covering them with a varnish or lacker of white resin, f#l- 
gum-sandarac, aloes, and red lead, mixed up and boiled 
with linseed oil. See Gilding on Leather. 
False Gilding upon Leather. This is an art which Palse gitd- 
was formerly practised very extensively for the hang- ing upon 
ings of apartments. At’ present it is scarcely known, leather. 
but some very fine specimens which remain perfect, For hang- 
after being in use for a century, shew that it is a most ings. 
durable kind of furniture for rich apartments. In the 
French Collections des Arts et des Metiers, the followi 
account of this art is given. * The leather of calf skin is 
preferable to any other ; the skins are softeried in water, 
then beaten on a stone, and curried out to their greatest 
extent whilst wet ; when dry they are cut square, and 
all reduced to the same size; after which, if any skins 
are defective, they are pieced with the fragments, which 
are joined by glue; the edges of the joints being pared 
away so as to make no increase of thickness. The grain sizing the 
side of the leather is now rubbed over with a piece of leather. 
size, whilst in a state of jelly ; and before this size dries, 
leaves of silver are laid on in the manner before de- } 
scribed of the gold leaves for butnished gilding. When Silvering. 
2N- 
Operation, 
or keaf-gold. 
varnished. 
