The morning news. [volume] (Savannah, Ga.) 1887-1900, 1892-07-17
HOW MIRRORS ARE MADE.
Different Methods Pursued in the
Countries OF Europe.

Countries OF Europe.
From the Philadelphia Press.
WASHINGTON, June 20.-Politics having
occupied nearly tho exclusive attention of
newspapers Of late, which has been SUBJ
ject IN which the ladies are not so intensely
interested, It may be worth while to turn
for a moment to q subject which Is sup
posed by some to be more interesting to
them, mirrors. The state department re-
Gently called upon its representatives abroad
for some information about the manufact-
ure of mirrors in foreign countries, and a
numbar Of them have responded with state
ments which will be Of interest. The re-
ports extend over a trife Of $50 years in
the history of the mirror and mirror glass.
The report from Consul General Gold
schmidt OF Vienna, arting out by the
manufacture of glass in Austria, goes back
as far as 1442. Consul Rublee of Prague,
says the mirror glass industry has been es-
tablished in Bohemia about 200 years. 1t
seems that only within the last $50 years,
however, has the subject received an con-
siderable attention. The developments of
Bohemian and German mirror glass took
place under very similar conditions, and
small mirror glasses were blown and sis
NCIou IN NuEoinDuTk IN Nu6 66N6Qb6buLn
century. In Bohemia about 600 people
are now employed In the manufacture of
glassware, OF which a large proportion Is
mirror glass and mirrors.
The glass from which mirrors are made
according TO the best information that can
be obtained, is the following: Quartz, 200
parts; potash, 1873 parts; marble, &c parts;
saltpetere, 13parts, and arsenic, parts.
Another formula uses 240 parts of fine
white sand, which, Of course, is quartz; $50
parts of sulphate of soda; % parts of Stacked
lime, and parts of nitrate of soda.
TIE GLASS FOR MIRRORS.
The glass which is used for the mirrors ia
made by two processes in one process it
Is blown, in the other it is rolled and cast.
In either case, after the glass Is made sheets,
after blowing, or casting and rolling, It
must be published. Consul Rublse gives
the following description of the way the
Bohemian mirrors, which probably rank
highest in point Of perfection, are made. In
both processes, tho glass mixture is melted in
about the same manner, and the purest and
best materials are used. The process In the
factory from the moment the glass is run
out OF the glass pots is something after the
following description: The glass pots have
to be refilled, and this Is the work of the
Smelter. The various component mater
ials-crystal sand. soda. calcite, charcoal,
and powered arsenic-mixed In the proper
proportions and placed In the empty
glass pot, this filling being
repeated after an interval of four or five
hours. After the smeter has put in the
second quantity. he heats the furnace to
such q point that melting begins In twelve
or fourteen hours. When the mixture is
melted. the smelter must see to it that 1t is
clear and free from air bubbles, for which
purpose he purihes the glass by subjeotiug
IL to a more intense heat. This purifying is
accomplished generally in about eight hours.
The glass being Ia a molten condition the
finishing process begins. When the glass Is
to be blown wait of ten or twelve hours
become thick enough for tho glass blower to
take it upon his blow pipe. On the other
hand, when glass is to be rolled the con-
tents are poured on the casting table imme-
diately after the melting and rolled at once,
the fiuidity OF the glass being an essential in
this process.
The glass blowers method Is about the
following: By means Of an iron pipe about
IL meters in length he takes up q small
quaatity OF glass. accomplishing it by turn
ing the end Of the pipe around in the glass
mixture. he next smooths or rounds the
quantity thus taken up, by turning the pipe
about followed wooden block, until the
mixture hardens into d dark red glow,
whereupon he dips into the glass pot for the
second time and takes up another and
larger quantity Of glass. The quantity of
the glass taken up depends on the size of
the plate or mirror so be made, and varies
from fifteen to forty-dve pounds. The
glass is thersupon smoothed and rounded,
and at the same time blowing into
the now rounded mass Of glass is
begun, the glass expanding gradually. AL
| ternstely the glass is then heated and ex-
pended, both in length and breadth, until
the desired dimensions have been attained
when the bulb at the lower end is opened :.
This opening Is extended until it reaches
that 1t assumes the shape OF cylinder, re-
sembling glass bell, which. however, is
still closed at one end, when it is attached
to the blowers pipe. The cylinder is then
detached from the pipe and placed in the
cooling oven. When taken from the COOL
ing oven it ia cut lengthwise. again heated
in the fiattening oven and then spread out
on the hattening stone until the sheet Of
glass is level After it has slowly cooled
and cut on its four sides it can be turned
over in the polisher.
ROLLED GLASS.
The process in the manufacture Of rolled
mirror glass is quite different one. The
specially constructed glass furnace admits
Of being opened and the glass pot, filed
with the melted glass, is seized by pair of
large tonRs and is placed on a small car
running on a track. The car, with it's load,
is then moved under an iron crane, from
which is suspended a chain with a pair Of
tongs attached fitting the glass pot. The
glass pot is firmly seized and lifted some
three feet in the air, when the crane re-
wolves, describing an angle OF about 90e,
and the glass pot Is thereby sus pended
over the molding table, which also runs on
a track leading to the cooling oven. The
molding table has a solid iron surface on
its iron frame. On each side of it are
iron posts. an iron roller resting on them at
such hight that the table can just pass
under it. An iron rim, varying In hight,
according to the thickness OF the glass TO be
made, is fastened to the edge Of the table.
The glass pot is slightly tilted and its con-
tents poured upon the molding table in
front of the roller, the table is then set in
motion and passes under the roller, which
distributes the mass Of glass evenly accord
ing 70 the hight of the surrounding rim.
To prevent the accumulation of too much
glass IN front Of the roller. a workman is on
hand with an iron rake, which he regulates
the amount OF glass. After passing under