Norwich bulletin., 1922-03-23


:. Crowel at the MONDAY luncheon of |
tae Norwich Rotary club on Wednesday |
at the Wauregan hotel. Mr.. CroWell re- |
viewed the history OF the manufacture |
of glass and told the various ways in !
which it is manufactured in this coun- |
try. He said in part;
The Egyptians practiced glass blow. |
ing more than 1000 years ago, although |
The invention of glass is sometimes as
crihed to the Phoenicans. Glass found |
IN the ruins of some of the ancient Greek !
cities show that the Greeks were familiar |
with the art of making glass at least 500 !
years before Christ, Gaul in France was
one Of the western countries practicing the
art at this time, Venice also early be-
came a famous glass producing center.
There is documentary evidence that glass
making in that city in 1890, and for 500
years held a foremost place in it's man
ufactpre. In comparatively modern
times. glass making has extended to 9TH
er countries. It became established as
an industry in the United States early
i'm the 18th century
Pennsylvania has been a producer of
glass from the early history of the coll
ony for Widdiam Penn wrote a let
ter in 1888, in which he alluded to glass
works in his domain. A flint glass fac
tory was established near Lancaster in
1859 and in III a plant for making
green bottles was established in Phila-
delphia. In 1897 a window glass fac
tory was built in Pittsburgh being prob
ably the first factory in which coal was
used for fuel, for as late as 1910 wood
was used in all glass plants except those
in or near Pittsburgh. In 1903 the first
flint glass house was built in Pittsburgh
and this plant was the first to success
frrT1 oil in Tinted
States.
few words about the History of
Plate Glass. Plate Glass was first made
In France in 1858 and the terms French
Plate Glass or French Mirrors has
| It's origin from the development of the
| plate glass industry in France.
The first cast plate made in the United
! States was produced in 1850 and perfect
! ed few years later so that it nay be
| noted that this Is a modern product
| compared to window glass which was
made during the early settlement Of this
| country, at jamestown, Va, about
1893.
| The raw materials may be said to BE-
! virtually the same in plate glass as in
| window glass, the main difference in the
| finished products being due to the great
| care exercised in selecting and in puri-
flying the ingredients, and the elaborate
| method of casting, grinding and polish
/ ing plate glass. as compared to the sim
pie and rapid process of producing win
! dow glass from blown cylinders. While
| both require skill and painstaking care
on the part Of the operator, the one Will
never equal the other in appearance or
| efficiency while the methods of produc-
ton are SC. widely different.
Glass Making.
The principal ingredients are silica
(whits-sand) soda (soda-ash) and lime
! Cime-stone). Also arsenic, charcoal
and culltet (broken glass;.
AS stated before, the method Of pro-
ducing plate glass widely differs from
window glass and it is little known that
the melting, casting, rolling, annealing
grinding, and polishing Of plate involves
the mining of silica and coal, the quar-
rying of limestone, the chemical man
ufacture of soda-ash on large scale
the reducing ard treatment of fire-clay
and an elaborate system of pot-making
for crucibles. all Of which requires al
enormous financial investment, multi
tude Of men. and extensive factory prop
critics.
1t should be stated that the produc
| of the American factories is. by com
parison, equal in every way to the Europ
can plate glass in c,earness. freedom
from flaws and defects, homogeneous
ness and finish.
The making of irregular thickuos1es
s or superhne quality for mirrors or othe
J uses where special glass is needed, re
quires special processes and entails ad
ditional expense in producing. and tn
making Of beveled plates and morror
% necessitates two more elaborate lines 0
work and machinery and a corps Of ex
perts and skilled workmen.
= Pot Making.
4 Pots of FIRE clay are such heav
10 expense in plate glass manufacture an
] take 50 important a part in the sue
S cessful making of plate glass that tn
g subject deserves special notice. TIL
d different clays after being mined are ez
| posed to the weather for some time t
= bring about disintegration.
At the proper stage finely sifted RAJ
:. clay is mixed with coarse, burned ella
u and water. This reduces liability {
shrinkage and cracking. It is then plug
Il / ged" or kneaded in mill; kept
n long time (sometimes a YEAR, in storag
bins to ripen; and afterwards goe
d through the laborious process of tread
i ing No machinery has thus far bee
invented by which the Dlasti2ity can h
developed as does this primitive treat
ing by the bare feet of men. The ella
/ must he treaded many times. TIL
I building of the pots is a slowf tediou
d and time-killng affair; but this is e!
e sential
Without extreme care, some element
s in the making Of the pots might be fuse
p into glass while undergoing the inten:
To- heat Of the furnace; or they might brea
I in the handling, and much depends upc
- the strength of the pots. The averaG
pot must hold about ton of molrc
r glass, and the average furnace he,
- necessary is about 5000 degrees Fahre1
- heit
y After completion comes The rropt
e / drying out Of the pots; and this is III
% ! other feature in which the greatest scie
]. tifc care is required No pot may l
@ used until it has been left to season &
h AT least three months, and even Z ye'
10 is desirable. And after all tnis t
pot has bue twenty-five days of usefu
d ! ness.
- Melting and Casting.
re- The not. having been first broug
'e to the necessary high temperature,
D. filed heaping full with its mixed ''batcl
W of ground silica, soda, lime, cullet, Ell
al Melting reduces the bulk so much tn
is the pot IS filed three times before
h contains a sufficient charge Of metal.
it When the proper molten stage
N reached the pot is lifted out of the fu