Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1911-01-19
Things Worth Knowing
Valuable Industrial Data Cleaned
from Authorities for the Ken
nebec Journal.
GLASS.

Glass is non crystalline mixture
| of silicates, usually of calcium or
lead, with those of potassium or sodi-
| un, that has been fused in prepara-
ton
Ordinary glasses have silica. general
| ly in the form of clean-waShed sand.
as a basis, which is fused with al
kalis and alkaline earths or oxide OF
lead. The simplest system of prepar-
ing glass is the old Venetian method,
in which the materials are fused in
open pots or crucbles set in a circu-
lar furnace with dome. In this vari-
ETY. OF furnace the air usually enters
by ar underground tunnel, which also
serves as an ashpit. Round the fur
mace there may be eight openings. one
or two of these being for feeding in
the fuel. and six or seven for working
the glass. The dome or arch of fire
bricks, built so as 10 cover the pots
and reverberate the heat downward,
is an important and essential element.
Those kinds of glass which contain
a large proportion Of lead oxide Clint
glass; cannot be made or melted in
open pots, as the furnace glass would
reduce some of the lead to the metal
lie state and discolor the glass. SINH
larly il is necessary to protect GER
tain iine colored glasses. and glasses
intended for optical purposes. from the
furnace dust and gases. The method
adopted is to use Il melting pot hay
ing a contracted mouth turned toward
one Of the openings in theScireular
furnace The most pcrfecxE modern
furnaces are fed with "prodeacer gas"
heated by 'regcncrators'-a system
Which gives the utmost cleanliness anu
the most complete control of the heat,
Tank furnaces are employed for
making the cheaper kinds of window
ard bottle glass. and consist OF large
fire-clay tanks. heated by producer
gas. in which the glass is melted, and
containing partitions under Which the
glass has to flow to separate il from
surface impurities or glass gall
Flint glass-Sand. 100; red lead. so;
potassium carbonate 49, nitre ).
Hard Bohemian glass,-Clean sand.
100: potassium carbonate. 50; limestone
or chalk, l..
Sheet Glass Plate Glass. and Crown
Glass.-A cheap glass is made of such
a mixture IS the following: Sand, l00
limestone or tIIdlh, %. SDtiuilI SUI
phatt. Sc: broken glass or culiet. 30
tn 100
Bottle GlasSes.-A fine greenish glass
may be made from sand. 100, limestone
or chalk. 17-25. dry sodium carbonate,
50. The cCarser bottle glasses are
made up by adding more or less of
mari. clay, barium sulphate or basal
tic rock to the mixture. Indeed, III
some cases black glass has been
made by simply melting basaltic
rock. or mixture of basaltic rock and
wood ashes.
Special Optical GlasSes.-Untl about
1880 scarcely any glasses other than
carefully prepared flint and crown
We're used in making optical lenses,
but since then a neW industry has
arisen at Jena. Germany, in which
special glasses for optical, thermomet-
RE, and other uses are prepared
Colored lasses.-Narious metallic
oxides and compounds will color glass
if fused with the materials which, 10
produce the best results have to be
under delicately balanced conditions
of oxidation or reduction. Red by cop
per in The suboxidized state. or gold,
yellow. by silver. iron in the ferric
state or anthony; blue. by cobalt;
amethyst. by manganese; green, by
copper as cupric oxide. or by sesquo
ixide of chromium: neutral or smoke
tibts. by platinum or iridium; also
the deeper blacks by the use of mix
lures of colors which practically cut
out all tints of the spectrum-e. Z.
manganese. copper and iron, or even
manganese and iron alone.