San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1888-09-11
THE PROCESS VARIES WITH THE
DIFFERENT KINDS.

Material OF Which tho Melting Pot Il
Made-Coloring Done By Metallic Oxides.
Bottles and Window Glass-Ths Blow
Pipe-Plate Glass.
The process Of making glass is exceedingly
interesting, but it Is also elaborate and not
free from complication. It can. therefore,
only be set forth in brief and cursory man
ner. So intricate is the work in some Of its
departments that ooe Is puzzled at the pro-
6ciency IN the art in ancient times Tho
CONCLUSION is forced upon US that in this, az
in many other branches Of industry, the
worknlen and artifcers Of remote times were
in full command Of many means and appli-
auces Of which we are ignorant Tho compo-
sition Of which glass Is made, not to mention
the fusing and finishing, implies q largo
amount Of chemical knowledge.
What Is this compositioni Generally, Il
may be described as consisting Of certain
number Of siicates, such as soda, potash,
lime, baryta, Hagnesia, alumina aud lead,
the coIoring matter being obtained from iron,
magnesia, cobalt, uranium, copper or gold
The composition, OF course, is conditioned o.
qualified by the kind Of glass which ia
wanted. The best glass is that WHICH con-
tainS the minimun 1t unconbin.-! silica.
Bohemian glass OF the harder kiXA contains
the siicates Of potash and liz, ia predoni-
nant proporoions; Of the softer sirIs it con-
tains, in addition, DotabI, quantity Of tho
siljcate OF sluuine- Soda and lime predomi-
nate in French plate Potash and lead are
the principal sLicates in the ordinary flint or
white glass. The lead gives density, soft
ness, feasibility and brlliaacy. The exact
proportions, in different cases, OF the differ
ent ingredients belong to the secrets Of the
glassmakers art.
The process Of manufacturing varies with
the different kinds Of glass. Tbs first step in
the process, however, is the same with all
glsss The first requisite is the melting pot,
the making of which is an art by itself. 1t
is made Of the purest kind of clay aud con-
sises pretty nearly of equal proportions of
silicon and aiumina. 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
pot5-the work being Of the most particular
and laborious Undiscovered at top and bot
tom, with an opening at the side When
thoroughly dried and hardened in the fur
mace, the pots are filed with the prepared
iuaSsERiA, Ceiltcu LIlI, hlSeu VIII Small
quantity Of cullee or broken glass. After
some or ten or twelve hours, the heat Of the
furnace having been brought to the highest
point; the pots are SKINNED and the melted
material is ready for what is called the. jour
ney.. During the melting process the color
ing is done by means Of various metallic OK
ides. What is called flashed glass is pro-
duced by another and different process. 1t
is only specifically colored Pot metal,
when co!ored, 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-cDown or sheet
are made by the blow pipe What is known
as plate glass and optical glass is cast; and
the glass used for heavy domestic utensils is
the result OF a combined process Of blowing
and casting. The blow pipe to glassmaking
plays precisely the same part which is per-
formed by the potter's wheel in the manrfac-
ture Of eartbenware. It is an iron pipe
smaller at the mouth end than at the other
In the manufacture Of flint glass 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
the glass by blowing throughthe pipe, and
the glass being put into mold 6e continues
to blow r'A4@' 'A 7Une6