The weekly messenger. [volume] (St. Martinsville [i.e. St. Martinville] La.) 1886-1948, 1890-03-29
GLASS MANUFACTURE
Processes for Producing This
Fragile Substance.
The Well-PreServed Secrets of
the ClaSSmaker'S Art.

The process of manufacturing glass is
exceedingly interesting; but it is also
elaborate and not free from complica-
tions.
So intricate is the work in some of its
departments that one is puzzled at the
proficiency in the art in ancient times.
The composition of which glass is made,
not to mention the fusing and finish ng,
implies a large amount of chemical
knowledge. Generally 1t may be de.
scribed as consisting of certain num-
Der Of silicates such as soda, potash,
lime, baryta, magnesia, alumina and
lead, the coloring matter being obtained
from iron, magnesia, cobalt, uranium,
copper or gold. The composition, of
course, is conditioned or qualified by
the kind of glass which is wanted. The
test glass is that which contains the
minimum of uncombined silica Bohe-
milan glass of the harder kind contains
the siicates of potash and lime in pre-
dominant proportions; of the softer
kind it contains, in addition, q notable
quantity of the silicate of alumina.
Soda and lime pred in French
plate. Potash and lead are the princi.
pal silicates in the ordinary flint, or
white glass. The lead gives density,
softness, fusibility and brilliancy. The
exact proportions, in different cases of
the different Ingredients, belong to the
secrets OF the glassmaker's art.
Tho process of manufacturing varies
with the different kinds of glass. The
first step in the process, however, is the
same with all glass. The first requisite
is the melting pot, the making of which
is an art by itself. 1t is made of the
present kind of clay and consists pretty
nearly of equal proportions of silicon
and alumina. The mass, consisting also
often of pieces of old pots, is worked
up with water and then laid aside for
three or four months. 1t is after that
time made into pots-the work being
OF the most particular and laborious
Undiscovered at top and bottom, with
an opening at the side. When thor.
oughly dried and hardened in the fur
mace. the pots axe filled with prepared
material, called frit, mixed with a small
quantity of cullet, or broken glass.
After some ten or twelve hours, the
heat OF the furnace having been brought
to tho highest point, the pots
are SKINNED and tho melted material
is ready for what Is called the journey.
During the melting process the color
ing is done by means OF various metallic
oxides. What is called flashed glass is
produced by another and different pro-
cess. 1t is only specifically colored.
Pot metal, when colorcd, is colored
throughout. When the material is
thoroughly melted and SKINNED and
made ready for the journey the work of
the blower or molder begins. Bottles
and window glass-crown or sheet--are
made by the blow pipe. What is
known as plate glass and optical glass is
cast; and the glas, used for heavy do
nestle utensils is the result OF a COM
bined process of blowing and casting.
The blow-pipe in glass making plays
precisely the same part which is per-
formed by the potters wheel il the
manufacture of earthea ware. 1t
is an iron pipe smaller at
the mouth end than at the other.
In the manufacture OF flint glas, the
pipe is heated almost to redness, then
inserted into the pot of fused glass,
which adheres to it. BY turning it
round the workman gets as much metal
as he requires. He then distends tho
glass by blowing through the pipe and
the glass being put into a mold he con-
tinues to blow until the desired shape |
is produced. In this way kettles arc
made, and also almost all articles for
domestic use. Window glass is blown
into the form of cylinder. The ends
OF the cylinder are, after a cooling
process. cut off. The cylinder is then
slit by diamond from end to end, and
being again heated, it il with much
Care and labor gradually flattencd out.
Plate glass is made in different man
ner. 1t is cast or pressed. When the