On the Manufacture of Glass. 117 
thrusting this down by means of an iron rod... In this way, 
with the black oxid of manganese, I have usually succeeded, 
perfectly. The effect of the lime, (which enters into ali the 
mixtures,) is thought to. be, to aid in the-fusion of the mate- 
rial; and it certainly produces one other effect, that is, it 
renders the glass a better aacahen of calorie, . so that in 
tempering, and in the other operations which it undergoes, 
there is less liability of Joes me ne particularly, when 
— the action of the diam 
wood used in the eat far melting and blowing, is 
from res to three and a half feet in length, split so fine that 
no stick will measure more than two inches in diameter, and 
all of itrequires to be kiln dried: Six ovens built in the center 
of the manufactory, each containing a half a cord of wood, 
are used for this purpose. The ie when in gare 
es six’ cords of this wood in tw. 
he Furnace itself is constructed ether of. artificial stone; 
sade of the same clay as the pots, or of some natural 
sandstone, that is: nearly or completely infusible; when ex 
me d e elevated temperature requisite in the fusion 
of glas 
Phe kind generally preferred is that obtained from Hav- 
erstraw on the North Riv 
e pots of which ane ate ten, are habe nian on bails 
side of the furnace, upon benches extending the length of 
it, raised about twenty inches from the bottom of: the tone, 
which term is applied to the space in he middle of the: i 
nace between the pots—opposite each pot, is a ring «stone 
which a Ax ne ial denominated the ring, of about 
seven and a half na in diameter, Through this the ma- 
terials are put into the pots, and the glass taken from them 
for blowing. They also constitute the only draught to'the 
furnace, which is regulated by smail clay. stones called: cook- 
ies, At each end of the furnace, is a fire p lace of sufficient 
size to admit. the passage of the pots into the tone, with 
eee it directly communicates, The fire Serie: after the 
ie 
the wood—a space is also left at the bottom of ni door ies 
the admission of air, and the lock stone which forms the 
bottem. of the fire place is also pages aes for the same fe: 
pose, 
* 
2. 
