GLASS. 
red by a mixture of the oxides of copper 
and iron ; purple by the oxide ot gold ; 
white by the oxide of arsenic and zinc ; and 
yellow by the oxide of silver, and by com- 
bustible bodies. 
We shall give now a detail of the manual 
operations in the manufacture of glass. 
Glass-blowing, the art of forming ves- 
sels of glass ; the term, however, is exclu- 
sively applied to those vessels which are 
blown by the mouth. The operation is ex- 
ceedingly simple, the workman has a tube 
of iron, the end of which he dips into a pot 
of melted glass, and thus gathers a small 
quantity of glass on the end of it, he then 
applies the other end of the tube to his 
mouth and blows air through it, this air 
enters into the body of the fluid glass, and 
expands it out into a hollow globe, similar 
to the soap bladders blown from a tobacco 
pipe. Various methods are used to bring 
these hollow globes into forms of the diffe- 
rent utensils in common domestic use, and 
several tools; the chief part of these are 
represented in Plate-glass making. 
The first and greatest of the glass-blowers’ 
implements is the furnace; it consists of 
two large domes set one over the other, 
the lower one stands over a long grating, 
(on a level with the ground,) on which the 
fuel is placed ; beneath the grate is the ash 
pit, and a large arch leading to it, conveys 
air to the furnace. In the sides of the 
lower dome, as many holes or mouths are 
made as there are workmen to make use of 
the furnace, and before each mouth a pot 
of melted glass is placed ; the pots are very 
large like crucibles, and will hold from three 
to four hundred weight of liquid glass, they 
are supported upon three small piers of 
brickwork, resting on the floor of the fur- 
nace. The form reverberates the flame 
from the roof down upon the pots, and they 
are placed at some distance within the fur- 
nace, that the flame may get between the 
wall and the pots. The upper dome is 
built upon the other, and its floor made flat 
by filling up round the roof of the lower 
dome with brickwork, there is a small 
chimney opens from the top of the lower 
dome into the middle of the floor of the 
upper one, which conveys the smoke away 
from it, and a flue from the upper dome 
leads it completely from the furnace. 
The upper dome is used for annealing the 
glass, and is exactly similar to a large oven, 
it has three mouths, and in different parts 
a small flight of steps leads up to each. We 
now come to describe the smaller imple- 
ments. 
Fig. 1 and 2, is a bench or stool with two 
arms a b at its ends, which are a little in- 
clined to the horizon ; the operator when at 
work sits upon the stool, and lays his blow- 
ing tube d across the arms, as shewn in the 
figure. 
Fig. 3, are a pair of shears, or rather 
plyers, formed of one piece of steel, they 
have no sharp edges, and spring open when 
permitted ; the workmen has several of 
these of different sizes, which are hung 
upon hooks at c in the stool fig. 4. 
Fig. 4, is a pair of compasses to mea- 
sure the work, and ascertain when it is 
brought to tlie proper size, the workmen 
should have three or four of these. 
Fig. 5, a common pair of shears for cut- 
ting the soft glass. 
Fig. 6, a very coarse flat file. 
Fig. 7, is the blowing pipe ; it is simply 
a wrought iron tube about three feet long, 
at x, it is covered with twine to prevent 
it burning the workman’s hand. 
Fig. 8, a small iron rod, of which there 
should be several. 
Fig. 9, is a stool with a flat plate of cast 
iron laid upon it, and f is another flat plate 
upon the ground behind the stool. 
To explain the use of these tools, we shall 
describe the manner of forming a lamp or 
urn of glass. Fig. 10, with a wide mouth at 
top and a small neck g at bottom, through 
which the candle is inserted, and which is 
fitted into a brass cap to support the lamp 
*>y. 
The operation is conducted by three 
workmen. The first takes the blowing 
pipe 7, and after heating it to a red heat 
at the mouth of the furnace, dips it into 1 
the pot of melted glass, at the same time 
turning it round that it may take up the 
glass, which has then much the consistence 
of turpentine ; in the quantity of metal he 
is guided by experience, and must propor- 
tion it to the size of the vessel to be blown, 
he then brings it from the furnace to the 
stool, fig. 9, and rolls the lump of glass 
upon it to bring it to a round form, after 
which he blows through the pipe, resting 
the glass upon the iron plate f behind the 
stool, as in the figure, and rolling it back- 
wards and forwards. The blowing makes 
the glass hollow, and he has several methods 
of bringing it to a proper shape to be 
worked; by simply blowing, it would as- 
sume a figure nearly globular, if he wants 
