Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1874-11-14
NUMBER r 5.

MANUFACTURES OF Plate CAUSE.-THE,
manu- lacture of plate glass, as now conduct
ed by the Thames Pate Glass Company, ut
Blackwell, London, is rs follows:
The principal successive operations nccc7-,
sary to convert mixture in the pot into q
finished sheet of plate glass are six in num-
Der, and mny be described under the heads
Of melting, rolling. anncaling, grinding.
smoothing. and polishing. The pots arc of
S;ourbridgc clay, made on the promises. and.
are filled with the mixture, the chief ingrcd-
tents of which are silica, sand carefully
dried, lime, sulphatc of sofia, broken white
glass, and little arsenic. The sand is OBJ
tancd from Germany. After remaining in
the furnace FOR about sixteen hours, the con-
tents Of the pot are tit for removal The
molten mass is then run over the surface OF
the rolling table, and the roller passed
quickly over it, The glass commences to,
soidify almost Immediately; and while in
thick tenacious condition, and Of rich
golden tint, is rapidly transferred into the
annealing furnace. The rough sheet, as it
may now be termed, is taken from the an
neaIing furnace to the grindNg-room, Of
these there are Scycral, containing about a
dozen grinding stones, or, more properly,
beds or tables, upon which the plate is laid
fiat. These grinding frames consist of
wooden boards joined together and armor-.
plated, so to speak, at intervals over the
rolling or grinding surfaces with strips Of
wrought iron- These strips. when first
screwed on to the hnncS, are half an inch
in thickness, and when removed measure
less than onc-eigMh inch. The frames arc
mounted upon % spindle, and sec-saw,
sem-rotary movement is impaired to them
by shatting running underneath the beds.
They are also capable on being shifted by a
simple slot connection, 80 as to work over
amy part OF the surface of the sheet as re-
CURED Fhc grinding beds are Of stone, and
measure about 10 feet by II feet The ma
terlals used as the grinding agents are course
sand, fine sand, and emery \ Jet Of water
plays on the sal face of the sheet during tho
whole OF the operation. Between the grind
ing and polishing processes there is an in
tcrmediate process called smoothing, in
which two sheets of glass are employed.
One is laid over the other and caused to
move over it in u manner similar to that in
grinding. Emery is placed between the two
surfaces On entering the polishing rOo1rr
the attention of visitor is at once arrested
by the reddish tinge OF everything, extend-
ing to the dresses of the men and women
engaged therein This is due to the use Of
tie red oxide Of iron which is the polishing
agent. The sheet to he polished il laid fat
on q table, 50 as to be perfectly flush with
the edges. The rubbcrs are Of flannel and
mounted on frame, which carries them
backwards and forwards over the sheet.
The table, at the same time, has lateral
reciprocatinG motion, 50 that the whole sur
face of the sheet comes successfully under
the action of the rubbcr> The largest
plates measure about Is feet by 10 feet, and
the maximum thickness is about l.2 in
ches. One-cighth Of an inch is allowed for
loss in the operations we havedescribed. A
nest Of six boilers, and three vertical steam
engines, two Of ~ horse power and one Of
GO horse power, supply the necessary motive
power.