The Tucson citizen., 1902-09-08
GLASS FOR WINDOWS.
THE METHOD AND THE MATERIALS
OF ITS MANUFACTURE.

Enough Arsenic In the windows OF
an Ordinary House to Kill IA Regt-
ment of MeD-PrOcess of the Tank
house and the POthOuse.
People who have glass windows in
their homes do not know that the glass
contains enough arsenic to make it a
deadly poison. Glassmakers say that
the windows Of an ordinary home con
tain enough of this poison to kill reg
iment of men. The popular supposition
that glass is made of sand is correct
one, but quantity of other articles en-
ters into Its composition.
Window glass factories are divided
into ty o departments, tankhouse and
Il pothouse. The IsaOcess of glassmak-
ing in one of these departments is prac-
tically the same as in the other. In the
tankhouse the glass is all melted in inn
mense tanks which will hold thou
sands of tons. In the pothOuse the
glass is made in pots.
After the fires are lighted and tank
is heated the glass mixture is shOveled
in. 1t includes glass left over from the
former season, glass refuse, sand and
salt cake. Arsenic is not used in the
tankhouse for the reason that the heat
is so intense that the drug is volatiliZed
and escapes into the air without enter
ing the mixture. AS one mixture melts
and flows to one end Of a tank fresh
supplies are shoyeled in at the other
end.
The molten mass seethes and
works in a manner similar to that Of
a mash in distillery. From the salt
cake comes a salt water that has to be
separated from the mass, and the easi-
est way to remove it is to burn it out.
This is done by throwing stove wood
into the tank on top Of the molten
glass. The water is converted into
steam, which is destroyed by the in
tense heat from the glass. The melted
glass is then skinned by an automatic
skinner, and it is ready for the gath
erer.
A gatherer thrusts a long steel blow
pipe into one of the rings at the lower
end of the tank. He twists and turns
it until small ball of glass gathers on
the end. This ball is partially cooled
polished by being turned in a box of
sawdust and then passed on to the
blower, who heats it again until it be-
comes like taffy. The blower swings
the ball over pit that is twelve feet
deep and rapidly blows it into an elon-,
gated pear shape. When a blower is
through, the melted glass becomes a
perfect cylinder about feet long and
2 feet across. 1t then passes to snap
per-" who takes it to rack and breaks
the roller loose from the blowpipe.
The snapper gathers a small lump
Of melted glass ON the end of a rod
and dexterously runs a harrow ribbon
Of the stuff around the ends Of the
roller, both at the blowpipe end and
the closed end. The little ribbons Of
melted glass cool in few seconds,
when they are removed, leaving mar
row zone Of almost redhOt glass
around the rollers at each end. Then,
taking tool that resembles a soldering
iron, the snapper rubs it for moment
on his forehead, and when the point Of
it is moistened with perspiration he
runs the iron around the rollers at the
heated spot. The glass cracks and
separates as cleanly as If cut with 8
diamond, the blowpipe is removed, and
the closed cylinder has become a roller
and is then ready to go to the fat,
tener.
The fiattener works in another part
Of the building, where are located the
6attening ovens. These ovens are heat
ed to a temperature sufficient to soften
the glass SO that it may be rolled out
into sheets. A series Of fireelay tables
placed in d circle like the spokes Of g
wheel revOlve i'll the ovens, and on
these tables the rollers are fiattened.
They are placed inside, allowed to be-
come hot, and then a cold iron is run
along the inside from end to end. The
contact Of the iron cuts the glass,
which is t2en Strengthened out upon
the table.
The fattener has number of billets
Of green wood attached to long iron
handles, and with these billetG. which
are shaped in such manner as to do
the work expected of them. he irons"
perfectly fiat and smooth. The tables
inside the oven revolve, the fattened
sheet is carried away, and another roll
er is brought into position before the
fattener. AS the fattened sheets cool
they are lifted to place on long
/ travelling rack, on which they are by
stages removed froD@ the ovens. being
allowed to cool as they go. This is done
In order that the glass may not be
shattered by too quick an exposure to
the air.
When the sheets are taken from the
hattening ovens. they are covered with
a greasy. dirty looking coat of chem
icals-soda, potash, silicates of the diff
ferent salts etc.-which must be re-
moved. and for this purpose the rough
sheets are placed in an acid bath COM
posed Of hydrochloric and sulphuric
acids more or less diluted. After their
immersion in this bath the sheets are