IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN FURNACES OR APPARATUS THERE- FOR
Year: 1879

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF GLASS, AND IN FURNACES OR APPARATUS THERE-
FOR." A communication from abroad by Richard Mead Atwater, of Millville,
New Jersey, and James Whitall, of Philadelphia, Pennsylvania, both in the
United States of America.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 6th February 1879.
JOHN HENRY JOHNSON, of No. 47, Lincoln's Inn Fields, in the County of Middle-
sex, Gentleman. "IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN FUR-
NACES OR APPARATUS THEREFOR.' A communication from abroad by Richard Mead
Atwater, of Millville, New Jersey, and James Whitall, of Philadelphia, Pennsyl-
vania, both in the United States of America.
The main object of this Invention is the saving of time, fuel, and fluxes in glass-
houses by melting a batch of glass ingredients in one furnace at a high temperature
demanded for the first melting, and then discharging the molten glass into a separate
working furnace, where the more moderate heat required in working the glass may
be employed.
Another object of the Invention is to utilize the waste heat of the working fur-
naces by combining a tempering oven or ovens with the same, in the manner
hereinafter described.
It has heretofore been usual to melt the batches of glass ingredients in crucibles
in the same furnace from which it is gathered by the workmen. This plan is
objectionable for several reasons, the most prominent of which is the large extent
of space required for the crucibles, and the consequent demand for the consumption
of a large amount of fuel and fluxes.
In carrying this Invention into effect it is preferred to employ apparatus con-
structed in the following manner, vist
The melting furnace may be fixed, but it is preferred to make it movable for
reasons hereinafter explained. This furnace may be made cylindrical in the middle,
and with opposite tapering ends, and consists of substantial iron plates properly

page_text: lined with refractory material, the furnace being supported by rollers, so that it can
be turned at pleasure.
The furnace has at one end a central opening communicating with two passages
_in_brickwork, and at the opposite-end-a-like opening communicating with another
passage in brickwork:==
The furnace is charged with a batch of glass ingredients through an opening,
which-is-furnished with a suitable-detachable cover lined with refractory material.
Inflammablo gases from a generator are directed through one of the passages
before referred-to-into_the_furnace, and heated air through the adjoining passage,
these elements combining at the entrance of the furnace-and-producing an intense
heat, which acts directly on the batch of glass ingredients. The products of com-
bustion which finally escape through a central opening may be employed to heat
the volumes of air or gas, or both, prior to their introduction into the furnace-in a
manner which is too well known in connection with other furnaces to need descrip-
tion here.
The upper portion of the batch of glass and the lining of the furnace above the
same necessarily become more intensely heated than the lower portion of the batch
and the lining below.
To compensate for this, and in order to subject the entire batch to the same
temperature, or nearly so, and facilitate, the melting and clearing operation, the
furnace is turned on its rollers to an extent of one half of a revolution at suitable
intervals; this brings the highly heated portion of the lining in direct contact with
that portion of the batch which had previously received the least heat, and at the
same time the pasty semi-fluid glass adhering to the lining as the furnace is turned
is exposed to the direct action of the flame in a condition most favorable to quick
and thorough melting and clearing, and this action may be further promoted by
making the inner surface of the lining rough or corrugated.
From opposite sides of the structure which supports the melting furnace extend
two working furnaces or troughs, each of which is made with sides converging
from the top, which has an arched roof having working holes, through which the
workmen gather the glass.
When one of these troughs has to receive a supply of molten glass from the
furnace the latter is turned until a spout with which it is provided is in a suitable
position, and a fire-clay plug which closes an opening in the lining communicating
with the spout is removed, after which the contents of the furnace flows down an
inclined plane and through suitable passages or channels into the trough, after
which the opening last mentioned may be replugged, the furnace recharged, and
the melting of the second batch may be proceeded with as before, while the work-
men stationed near the working holes proceed with their duties.
It is here where economy of time becomes most apparent, for there is no waiting
on the part of workmen for batches of glass to melt, as is the case with ordinary
furnaces, and there is always a new batch of melted glass ready when that in the
trough has been exhausted. It is preferred-to-furnish the tapping hole with a plug,
so fitted to the lining that it can be readily driven inwards when the glass has to
be withdrawn from the furnace.
A flame derived from combined air and gas enter each trough through an
opening at the end nearest the melting furnace, and if desired at other suitable
points, and this flame is conducted through the trough, where it acts on the surface
of the glass, and finally escapes at a reduced temperature into a tempering chamber,
and thence through a chimney or other suitable outlet.
I
On the floor of this chamber are one or more tracks adapted to the wheels of
metal cars, which can be introduced into and withdrawn from the chamber through
openings on opposite sides of the same, each opening being provided with suitable
sliding or otherwise movable doors.
When the working trough is in operation one of the cars is always in the
'tempering chamber, the doors of the latter being closed, and the articles of glass-as

page_text: fast as they are blown, pressed, or moulded are placed in the car through a suitable
opening in the brickwork above the door, or in the door itself.
When the car is full a suitable cover is placed over it, or sand is deposited on the
articles so as to exclude the air, after which the car is moved out of the way in
order that its contents may be gradually cooled, an empty car being introduced
into the chamber for receiving another lot of glass objects.
Returning to the working trough it should be understood that the supplies of
air and gas are so graduated that the heat will not be as intense as in the melting
furnace, for in order to properly work glass it must be maintained at a much lower
temperature than is required to melt it in the first instance, the temperature
required for melting the batch of glass ingredients being about 2,400° Far., and
that for maintaining the glass in a proper condition for being worked about 1,400°
Far.
The heat being applied to the upper surface only of the glass in the trough no
impurities can rise, and there will be an absence of blisters.
The shape of the trough herein before referred to is desirable as it insures the
presentation of an extended surface area of glass to the flame; the shape morcover
tends to preserve the integrity of the interior of the trough, and renders the
detaching of particles of the lining difficult.
Another advantage of the peculiar shape of the working trough is that when the
glass is reduced in quantity it occupies a contracted space, and hence there is less
waste than if the furnace had vertical sides.
It may be remarked here that the working furnaces or troughs should be heated
before glass is introduced into them.
There should be in the melting furnace, and preferably in the cover of the feed
opening, a spy-hole, which is always above the surface of the glass, the furnace
being turned to the extent of one half only of its circumference, and then back
again at such intervals as the condition of the charge may suggest.
The molten glass may be removed from the melting furnace through the charging
opening if desired.

page_text: -SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal-Patent_Office_on the 1st
August 1879.
E:
JOHN HENRY-JOHNSON,-of-47, Lincoln's Inn Fields, in the County of. Middlesex,
Gentleman. IMPROVEMENTS-IN-THE-MANUFACTURE OF GLASS, AND IN FURNACES
A communication from abroad by Richard Mead
Atwater, of Millville, New Jersey,-and-James-Whitall, of Philadelphia, Pennsyl-
vania, both in the United States America.
_ OR APPARATUS THEREFOR."
The main object of the said Invention is the saving of time, fuel, and fluxes in
glass houses by melting a batch of glass ingredients in one furnace at a high tempe-
rature demanded for the first melting, and then discharging the molten glass into a
separate working furnace where the more moderate heat required in working the
glass may be employed.
Another object of the Invention is to utilize the waste heat of the working fur-
naces by combining a tempering oven or ovens with the same in the manner
hereinafter described.
It has heretofore been usual to melt the batches of glass ingredients in crucibles
in the same furnaces from which it is gathered by the workmen. This plan is
objectionable for several reasons, the most prominent of which is the large extent of
space required for the crucibles, and the consequent demand for the consumption of
a large amount of fuel and fluxes.
In carrying out the present Invention it is preferred to employ apparatus such
as are illustrated in the accompanying Drawings and hereinafter described by the
aid of letters of reference marked thereon, the same letters indicating corresponding
parts in all the Figures.
Figure 1 of the accompanying Drawings is a plan showing the melting furnace,
one working furnace, a tempering oven, and part of a second working furnace;
Figure 2 is a sectional elevation drawn to an enlarged scale, the section being
taken along the line 1-2 (Figure 1); the view is assumed to be taken in the
direction of the arrow, the melting furnace being shewn partly in section; Figure 3
is a transverse section taken along the line 3-4, Figure 2; and Figure 4 is a
vertical section of the tempering oven.
The melting furnace may be fixed, but it is preferred to make it movable, for
reasons hereinafter explained. This furnace, marked A in the Drawings, is made
in the present instance cylindrical in the middle, and with opposite tapering ends,
and consists of substantial iron plates properly lined with refractory material, the
furnace being supported by rollers a, so that it can be turned at pleasure. The
furnace is provided at one end with a central opening b communicating with the
two passages B, B1, (Figure 1) in the brickwork H, and at the opposite end with a
like opening 6 communicating with-the-passage D in the brickwork H.
The furnace is charged with a batch of glass ingredients through an opening h,
which is furnished with a suitable detachable cover h¹ lined with refractory
material.
Inflammable gases from a generator are directed through one of the passages B
into the furnace, and heated air is introduced through the adjoining passage, these
elements combining at the entrance of the furnace, and producing an intense heat
which acts directly on the batch of glass ingredients. The products of combustion,
which finally escape through the central opening b' may be employed to heat the
volumes of air or gas, or both, prior to their introduction into the furnace in a
manner which is too well known in connection with other furnaces to need descrip-
tion here.
The upper portion of the batch of glass and the lining of the furnace above the
same necessarily become more intensely beated than the lower portion of the batch
and the lining below.

page_text: In order to compensate for this and to subject the entire batch to the same tem-
perature, or nearly so, and facilitate the melting and clearing operation, the furnace
is turned on its rollers to an extent of one half of a revolvtion at suitable intervals;
this brings the highly heated portion of the lining in direct contact with that por-
tion of the batch which had previously received the least heat, and at the same
time the pasty semi-fluid glass adhering to the lining as the furnace is turned is
exposed to the direct action of the flame in a condition most favorable to quick
and thorough melting and clearing, and this action may be further promoted by
making the inner surface of the lining rough or corrugated..
From opposite sides of the structure which supports the melting furnace extend
the two working furnaces or troughs I, 1, each of which, as seen in the transverse
section, Figure 2, is made with sides converging from the top, which has an arched
roof J, having working holes i, through which the workmen gather the glass.
When one of these troughs, say, for example, the trough I, has to receive a
supply of molten glass from the furnace A the latter is turned until the spout m is
in the position shewn in Figure 3, and the fire clay plug which closes the opening n
in the lining communicating with the spout is removed, the contents of the furnace
will then flow down the inclined plane p and through the passages q, or through
other convenient channels into the trough I, after which the opening n may be
replugged, the furnace recharged, and the melting of the second batch may be pro-
ceeded with as before, while the workmen stationed near the working holes proceed
with their duties.
It is here where economy of time becomes most apparent, for there is no waiting
on the part of workmen for batches of glass to melt, as is the case with ordinary
furnaces, and there is always a new batch of melted glass ready when that in the
trough has been exhausted. It is preferred to furnish the tapping hole m with a
plug, so fitted to the lining as to admit of its being readily driven inwards when
the glass has to be withdrawn from the furnace.
A flame derived from combined air and gas enters each trough through an
opening at the end nearest the melting furnace, and if desired at other suitable
points, and this flame is conducted through the trough where it acts on the surface
of the glass, and finally escapes at a reduced temperature into the tempering cham-
ber K and thence through a chimney or other suitable outlet.
On the floor of this chamber are one or more tracks x (two in the present
example adapted to the wheels of metal carriages M, which can be introduced into.
and withdrawn from the chamber through openings on opposite sides of the same,
each opening being provided with suitable sliding or otherwise movable doors.
When the working trough is in operation one of the carriages is always in the
tempering chamber, the doors of the latter being closed, and the articles of glass as
fast as they are blown, pressed, or moulded are placed in the carriage through a
suitable opening in the brickwork above the door, or in the door itself.
When the carriage is full a suitable cover is placed over it, or sand is deposited
on the articles so as to exclude the air, after which the carriage is moved to any
convenient place in order that its contents may be gradually cooled, an empty
carriage being introduced into the chamber for receiving another charge of glass
objects.
Reverting to the working trough it should be understood that the supplies of air
and gas are so graduated that the heat will not be as intense as in the melting
furnace, for in order to properly work glass it must be maintained at a much lower
temperature than is required to melt it in the first instance, the temperature
required for melting the batch of glass ingredients being 2,400° Fahrenheit, and
that for maintaining the glass in a proper condition for being worked about 1,400°
Fabrenheit.
The heat being applied to the upper surface only of the glass in the trough no
impurities can rise, and there will be an absence of blisters.
The shape of the trough as illustrated is desirable, as it ensures the presentation
of an extended surface area of glass to the flame; the shape moreover tends to pre-

page_text: serve the integrity of the interior of the trough, and renders the detaching of par-
ticles of the lining difficult.
The shape and size of the trough will demand more or less alteration when large
masses-of-glass-have-been-gathered, as in the manufacture of carboys and window
glass.
Another advantage-of the-peculiar shape of working trough is that when the
glass is reduced-in-quantity-it-occupies-a-contracted space, and hence there is less
waste than if the furnace-had-vertical-sides..
_It_may_be_remarked that the working furnaces or troughs should be heated
before glass is introduced into them.
In the melting furnace, and preferably in the cover of the feed opening, there
should be provided a spy hole y, which is always above the surface of the glass, the
furnace being turned from the position Figure 3 in the direction of the arrow to
the extent of one half only of its circumference, and then back again at such
intervals as the condition of the charge may suggest.
The molten glass may be removed from the melting furnace through the charging
opening if desired.
Having now described and particularly ascertained the nature of the said Inven-
tion, and the manner in which the same is or may be used or carried into effect, I
would obser in conclusion that what I consider to be novel and original, and
therefore clai.. às the Invention secured to me by the hereinbefore in part recited
Letters Patent is,―
☐ First. As an improvement in preparing glass for being manufactured into
different articles, first melting the glass in one furnace at a high temperature, and
then tapping the contents into a separate and independent working furnace or
trough maintained at a lower temperature, substantially as herein before described.
Second. The mode described of melting glass, that is to say, causing the heated
lining of the furnace above the body of glass to take at intervals a position below
the same, while the surface is acted upon by a flame, substantially as hereinbefore
described.
Third. The combination of a movable melting furnace with a working trough or
troughs, into which the contents of the furnace can be discharged.
Fourth. The working trough or furnace, consisting of a longitudinal chamber,
having an arched roof, in which are working holes, substantially as herein before
described.
Fifth. The combination of a working trough with a tempering oven, with which
the products of combustion from the trough communicate, substantially as herein-
before described.
In witness whereof, I, the said John Henry Johnson, have to this my Specifi
cation set my hand and seal, the First day of August, One thousand eight
hundred and seventy nine.
J. HENRY JOHNSON. (L.S.)