G L A 
853 
G L A 
the whole substance of the glass. In others, 
which were the more common, the colour 
was only on one side, scarcely penetrating 
within the substance above one-third of a 
line ; though this was more or less according 
to the nature of the colour, the yellow being 
always found to enter the deepest. '1’hese 
last, though not so strong and beautiful as 
the former, were of more advantage to the 
workmen, since on the same glass, though 
already coloured, they could shew other kind 
of colours where there was occasion to em- 
broider draperies, enrich them with foliage, 
or represent other ornaments of gold, silver, &c. 
In order to this, they made use of emery, 
grinding or wearing down the surface of the 
glass, till they were got through the colour 
* to the clear glass. Ibis done, thev applied 
the proper colours on the other side of the 
glass. By this means, the new colours were 
hindered from running and mixing with the 
former, when they exposed the glasses to the 
tire, as will appear hereafter. 
When, indeed, the ornaments were to ap- 
pear white, the glass was only bared of its 
colour with emery', without tinging the place 
with any colour at all; and this was the man- 
ner by which they wrought their lights and 
heighteuings on all kinds of colour. 
The first thing to be done in order to paint 
or stain glass in the modern way, is to de- 
sign and even colour the whole subject on 
paper. They then choose such pieces of 
glass as are clear, even, and smooth, and 
proper to receive the several parts, and pro- 
ceed to distribute the design itself, or papers 
it is drawn on, into pieces suitable to those of 
the glass ; always taking care that the glasses 
may join in the contours of the figures and 
the folds of the draperies, that the carnations 
and other finer parts may not be impaired by 
the lead with which the pieces are to be 
joined together. The distribution being 
made, they mark all the glasses as well as 
papers, that they may be known again; 
which done, applying every part of the de- 
sign upon the glass intended for it, they 
copy or transfer the design upon this glass 
with the black colour diluted in gum water, 
by tracing and following all the lines and 
strokes as they appear through the glass with j 
the point of a pencil. 
When these strokes are well dried, which 
will happen in about two days, the work be- 
ing only in black and white, they give a slight 
wash over with urine, gum arahic, and a little 
black, and repeat it several times, according 
as the shades are desired to be heightened, 
with this precaution, never to apply a new 
wash till the former is sufficiently dried. 
This done, the lights and risings are given 
by rubbing off the colour in the places with a 
wooden point, or the handle of the pencil. 
As to the other colours above-mentioned, 
they are used with gum-water, much as in 
painting in miniature, taking care to apply 
them lightly for fear of effacing the outlines 
of the design; or even, for the greater secu- 
rity, to apply them on the other side ; espe- 
cially yellow, which is very pernicious to the 
other colours, by blending with them. And 
here too, as in pieces of black and white, par- 
ticular regard must always be had not to lay 
colour on colour, or lay on a new lay till 
such time as the former are well dried. 
It may be added, that the- yellow is the 
only colour that penetrates through the glass, 
SLA 
and incorporates with it by the fire; the rest, 
and particularly the blue, which is very dif- 
ficult to use, remaining on the surface, or at 
least entering very little. When the paint- 
ing of all the pieces is finished, they are car- 
ried to the furnace or oven, tq anneal or 
bake the colours. 
The furnace here used is small, built of 
brick, from 18 to 30 inches square; at six 
inches from the bottom is an aperture to put 
in the fuel, and maintain the lire. Over this 
aperture is a grate, made of three square 
bars of iron, which traverse the furnace, and 
divide it into two parts. Two inches above 
this partition is another little aperture, 
through which they take out pieces to exa- 
mine how the coction goes forward. On the 
grate is placed a square earthen pan, six or 
seven inches deep, and live or six inches 
less every way than the perimeter of the 
furnace. On the one side is a little aper- 
ture, through which to make trials, placed 
directly opposite to that of the furnaces des- 
tined for the same end. In this pan are the 
pieces of glass to bo placed in the following 
manner : First, the bottom of the pan is co- 
vered with three strata or layers, of quick 
lime pulverized ; those strata being separated 
by two others of old broken glass, the design 
of which is to secure the painted glass from 
the too intense heat of the lire. '1 his done, 
the glasses are laid horizontally on the last or 
uppermost layer of lime. 
The first row of glass they cover over with 
a layer of the same powder, an inch deep ; 
and over this they lay another range of 
glasses, and thus alternately till the pan is 
quite full, taking care that the whole heap 
always end with a layer of the lime -powder. 
The pan being thus prepared, they cover- 
up the furnace with tiles, on a square table 
of earthenware, closely luted all round, 
only leaving five little apertures, one at each 
corner, and another in the middle, to serve 
as chimneys. Things thus disposed, there 
remains nothing but to give the tire to the 
work. 'The fire for the first two hours must 
be very moderate, and must be increased in 
proportion as the coction advances, for the 
space of ten or twelve hours, in which time 
1 it is usually completed. At last the lire, 
which at first was Charcoal, is to be of dry 
wood, so that the flame covers the whole 
pan, and even issues out at the chimneys. 
During the last hours, they make essavs, 
from time to time, by taking out pieces laid 
for the purpose through the little aperture of 
the furnace and pan, to see whether the yel- 
low is perfect, and the other colours in good 
order. When the annealing is thought suf- 
ficient, they proceed with great haste to ex- 
tinguish the lire, which otherwise would soon 
burn the colours, and break the glasses. 
By several statutes, regulations are made 
for making, importing, and exporting glass, 
which is to be under the management of the 
officers of the customs and excise. See Com- 
plete Abridgement of the Exc.se Laws. 
GLAUBER’S salt, a cathartic or purging 
salt. See Soda, suiph.it >f. 
GLAUCOPIS, in ornithology, a genus of 
birds of the order picac. Bill incurvate, arch- 
ed, the lower mandible shorter, and caruucu- 
late beneath at the base, nostrils depressed, 
1 half-covered with a membrane ; tongue slit, 
and fringed at the tip ; feet walkers. It in- 
j habits ISew Zealand* 
GLAUX, milkwort, a genus of the mono- 
gyuia order, in the pentandria class of plants, 
and in the natural method ranking under the 
17th order, calycanthems. The calyx is 
monophvllous; there is no corolla ; the cap- 
sule is unilocular, -quinquevalved, and pen- 
taspermous. There is one species. 
GLAZIER, an artificer who works in 
glass. The principal part of a glazier’s busi- 
ness consists in fitting panes of glass to the 
sashes and window-frames of houses, pictures, 
&c. and in cleaning the same when required. 
Glazier’s vice, is an instrument for 
drawing lead: see Plate Miscel. fig. 102. 
PG, Qil, are two axles running in the frame 
K.L, ML; C, D, two wheels of iron case- 
hardened, 1 \ inch broad, and of the thickness 
of a pane of glass ; these wheels are fixed to 
the axles, and run very near one another, 
their distance not exceeding one-tenth of an 
inch: across their edges several nicks are 
cut, the better to draw the lead through. 
E, F, are two pinions, each of twelve leaves, 
turning one another and going upon the ends 
of the axles, which are square, being kept 
fast there by the nuts P, Q, which arc screw- 
ed fast with a key. A, B, are two cheeks of 
iron, case- hard ivied, and fixed o:i each side 
to the case with screws; these are cut with 
an opening near the two wheels, and set so 
near to the wheels as to leave a space equal 
to the thickness of the lead ; so that between 
the wheels and the cheeks there is left a hole 
of the form represented at N, which is the 
shape of the lead when cut through. The 
frame KLML is held together by cross bars 
passing through the sides, and screwed on ; 
and a cover is put over the machine to ex- 
clude the dust. The whole is screwed down 
fast to a bench by screw-nails LL. When 
the vice is used, the lead to be drawn is first, 
east in moulds, into pieces a foot long, with a 
gutter on each side. One of these pieces is. 
taken, and an end of it sharpened with a 
knife ; then being put into the hole between, 
the wheels, by turning the handle I the lead, 
is drawn through the vice, and receives the 
form designed. 
GLAZING, the crusting over earthen- 
ware by a vitreous substance, the basis of 
which is commonly lead. 'The usual compo- 
sition for glazing ware is formed of white 
sapd 40 pounds, of red-lead 20 poClnds, of 
pearl-ashes 20 pounds, and of common salt 
12 pounds. Powder the sand by grinding 
it, and then add it to the other ingredients, 
and grind them together; after which calcine 
them for some time with a moderate heat, 
and when the mixture is cold, reduce it to 
powder, and when wanted tor use temper it 
with water. The proportion of these ingre- 
dients may be occasionally varied. 'The 
ware, after being turned on the wheel and 
dried in the open air, is covered over with 
the above composition by means of a brush ; 
and when set in the furnace, the violent heat 
soon reduces, it to a perfect glass, covering 
the whole internal and external surface of 
the vessel. We may observe, however, that 
lead, being poisonous, ought to be excluded 
from tne composition of glazings,, and other 
fluxes substituted in its stead. A transparent 
glazing may be prepared without lead by 
calcining 40 pounds of white sand, 25 pounds 
of pearl-ashes, and 15 pounds of common 
salt, and proceeding as before: and a more- 
perfect transparent glazing may be made of 
