IMPROVEMENTS IN THE MANUFAC- TURE OF GLASS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Frank Wirth at the Office of the
Commissioners of Patents on the 4th February 1878. A communication from
Joseph Rosenegger, Factory Manager, of Innsbruck, in the Empire of
Austria.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at Frank-
fort-on-the-Main, in the Empire of Germany. "IMPROVEMENTS IN THE MANUFAC-
TURE OF GLASS." [A communication from Joseph Rosenegger, Factory Manager, of
Innsbruck, in the Empire of Austria.]
My Invention relates to the use of slag as raw material, and to the working
thereof in a solid or liquid state for the manufacture of glass. The following
advantages are obtained in practising my said Invention, that is to say, heretofore
the slag has been valueless, and as it replaces silicate, calcium, line, and like sub-
stances, economy is obtained by its use.
Fuel is economized, as slag glass fluxes more easily by itself; also where the
situation favors it the slag as the base of glass can be brought into the pot in a red-
hot state like fluxing from the furnace. As by this new process the slag can be
used in a very granulated condition, an intimate mixture of all the materials is
produced, and consequently a more homogenous glass. As the slag colours the glass
on account of its own contents of metal oxides (manganese and iron oxides) the use
of coloring matter for the glass is dispensed with.
The slag is a ready silicate, which I use as a base, combining therewith the
necessary material according to analysis. The substances which are in common
use for making glass, such as acid and basic salts, serve to compose by smelting a
silicate; consequently, in practising my said Invention, the melting process is
effected quicker and easier than by the ordinary process.
Glass produced according to my said Invention is very strong and of great
resistance.
In carrying my said Invention into practice the slag, after being analysed, is used
either in a cold or melted state. When used cold the slag which formerly was
thrown away as worthless is, after being analysed, crushed by suitable mechanical
means, or it may have been previously granulated in a hot state by the influence of
CD 011

page_text: water.
Then certain measured quantities, according to the result of analysis, are
placed in the glass stove, tank, pot, or other vessel to be employed, and sand, lime
and other materials are added, the mixture then being worked in the usual manner.
The said analysis shews what materials, and how much of the same the slag needs;
for instance, a very silicious slag needs less sand than others.
. Old slag is worked by grinding, crushing, or by any other suitable mechanical
ineans. Hot slag is led into cold water, either sweet or salt, by which means the
crushing, granulating, or chilling is effected.
I can also lead water in a stream, or by means of a shoot or sprinkler upon the
hot slag, and heat the pieces of cold slag to crush them by means of water. Then
I dry the granulated produce by means of heat, mix it in the manner described,
and place it in the pot.
If the slag is placed in the tank or other vessel in a hot state, that is to say,
melted, I cause it when fluxing from the iron furnace to be conveyed or poured
into vessels of suitable dimensions, and bring it quickly to the stove, or it can be
led direct when fluxing out of the iron furnace to the glass-melting vessel.
The materials to be added are in this case placed in layers or strata, one layer of
slag, and another layer of other materials, so that the most intimate mixture is
effected.
The manganese or iron oxide in the slag causes a more or less green, brown,
amber, or other colored glass. I can reduce the dark colours by calcining the
crushed or granulated slag, so that the produce looks like clear glass.