On the Manufacture of Glass. 119 
thrust down to the bottom of the pot, through the melted 
glass, when the sudden conversion of the contained water 
into vapour, creates a motion throughout the whole mass, 
resembling ebullition, raising the glass to the tops of the 
pots. is soon subsiding, they are next filled with frag- 
ments of glass, and the cookies again placed in the rings. 
s the fire is continued, large quantities of air in the form 
of bubbles rise and burst on the surface, until eventually the 
fluid mass becomes perfectly clear. 
When this fact has been ascertained, the furnace is suffer- 
ed to cool down, for one hour or until the glass stiffens on 
the tops of the pots. During this time the doors of the fur- 
nace are opened, to clear out of the tone the slag ashes and 
coal which may have accumulated during the melt. 
fire is now gradually increased, until the metal becomes of 
a proper consistence for blowing. lowers are then 
called, and the master stoaker delivers the care of the fur- 
in operation nine months, from September to June, and then 
to employ the three summer months, in repairing the works. 
A furnace of ten pots, of the ordinary capacity, will make 
from seven hundred to one thousand boxes of glass 
month, according to the good or bad success attending its 
operatio oe 
Blowing.—There is one blower and a boy or apprentice, 
allotted to each pot. The blower commences by first put- 
ting the end of his pipe into the ring, leaving it until it is near-_ 
ly red, then putting it into the water, when the oxide flies off, 
and leaves a metallic surface—it is then dipped into the metal, 
and by turning it around a quantity adheres to it—this is ta- 
ken out, and if necessary, fashioned by an iron, termed a 
strike iron, it is again taken to the pot, and by repeated dip- 
pings a sufficient quantity is accumulated to form a cylinder 
—this usually requires three gathermgs as it is technically 
termed. The workman now puts the ball of glass a short 
distance within the ring, where he holds it a few moments, 
(constantly turning it,) that it may acquire the precise tem- 
perature necessary. Itis then withdrawn, and by means of 
the strike iron the semi fluid mass is crowded near the end of 
the pipe, when it is conveyed toa concavity, formed in a 
