IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN THE PREPARATION OF CERTAIN MATERIALS TO BE USED THEREIN, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE MANUFACTURE OF ALKALIES
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
HENRY BALMAIN and EDWARD ANDREW PARNELL, both of Saint Helens, in the
County of Lancaster, Manufacturing Chemists, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fifth day of March, in the twelfth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto us, the said
William Henry Balmain and Edward Andrew Parnell, Her especial licence,
full power, sole privilege and authority, that we, the said William Henry
Balmain and Edward Andrew Parnell, our exors, adñors, and assigns, and
such others as we, the said William Henry Balmain and Edward Andrew
Parnell, our exors, admors, or assigns, should at any time agree with, and no
others, from time to time and at all times during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, our Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN THE PREPARATION OF
CERTAIN MATERIALS TO BE USED THEREIN, PARTS OF WHICH IMPROVEMENTS ARE
ALSO APPLICABLE TO THE MANUFACTURE OF ALKALIES;" in which said Letters
Patent is contained a proviso obliging us, the said William Henry Balmain
and Edward Andrew Parnell, by an instrument in writing under our hands
and seals, particularly to describe and ascertain the nature of our said Inven-
tion, and in what manner the same is to be performed, and to cause the
same to be inrolled in Her Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part

page_text: recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
William Henry Balmain and Edward Andrew Parnell, do hereby declare that
the nature of our said Invention, and the manner in which the same is to be
performed, is particularly described and ascertained in and by the following
description thereof, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say) :-
Our Invention relates, in the first place, to processes for manufacturing
silicate of soda, silicate of potash, silicate of barytes, and double silicates of
these bases, by heating their respective sulphates with sand and carbonaceous
matter. We are aware that glass is made by heating a mixture of sand,
sulphate of soda, charcoal, and lime or limestone; but we find that it is advan-
tageous to make silicate of soda in the first instance, and afterwards convert
that into glass by fusion with the proper materials.
In making silicate of soda by our process we find it advantageous to use
such proportions of materials as shall produce a silicate containing either about
twenty or about twelve per cent. of soda. To make a silicate of soda of about
twenty per cent., we mix three hundredweight of sand, two hundredweight of
dry sulphate of soda in fine powder, and from sixteen to eighteen pounds of
finely-ground charcoal, and heat the mixture to whiteness in a furnace con-
structed as herein-after described, or by any of the means in ordinary use. As
the silicate of soda falls from the furnace referred to, it is received into a
vessel of water, which renders it more easy to grind, and by dissolving the
excess of sulphate of soda, presents that substance in a convenient form for
being recovered.
To make a silicate of soda of twelve per cent. we mix three parts of sand
and one part of sulphate of soda, and heat the mixture (with occasional
stirring) in an ordinary reverberatory furnace. By a proper management of
the fire, the deoxidizing power of the flame is sufficient to effect the decom-
position of the sulphate without the addition of any other form of carbonaceous
matter, and by exposure to a low red heat for from six to ten hours, a perfect
silicate of soda is formed. In case imperfect work should give a result con-
taining a little undecomposed sulphate, we remove that by washing with water.
In making silicate of potash we proceed in exactly the same way as in
making silicate of soda, the relative weights of the materials being altered to
accommodate them to the combining equivalent of potash. Thus, we make a
silicate of potash of twenty-six per cent. by heating three and a half hundred-
weight of sand, two hundredweight and. a half of sulphate of potash, and

page_text: eighteen pounds of charcoal. A silicate of potash of fourteen per cent. may
be made by using, as above described, a mixture of nine and a half hundred-
weight of sand and three hundredweight of sulphate of potash.
In making the double silicates of the bases above mentioned.wo proceed in
the same way, adapting the proportionate quantity of sand and charcoal to the
combining equivalents of the two bases, using, when the materials are to be
fluxed in the furnace of our Invention, a single equivalent of charcoal to each
equivalent of sulphate, and three equivalents of sand to one of base, though
we do not confine ourselves to such proportions. In some cases we find it
advantageous to use one base in the state of sulphate, and the other in the
state of carbonate, or in the uncombined state. In such cases we use a mix-
ture of sulphate, sand, and charcoal in the proportions above mentioned, and
add to it the base, or the carbonate of the base, with its equivalent, quantity
of sand, but without any additional charcoal, the latter substance being. only
required when a sulphate is to be decomposed. For instance, to make a
double silicate of soda and barytes we may use either of the following
mixtures:-No. 1, two hundred and seventy-three parts of sand, seventy-
two parts of sulphate of soda, one hundred and seventeen parts of sul-
phate of barytes, and twelve parts of charcoal; No. 2, two hundred and
seventy-three parts of sand, seventy-two parts of sulphate of soda, ninety-
nine parts of carbonate of barytes, and six parts of charcoal. In all these
cases when it is desirable that the result should be fluxed or vitrified, wo
prefer heating the mixture in the kind of furnace described in the present
Specification; but when the material is not to be fluxed, it may be heated in
an ordinary reverberatory furnace. It is important to observe that' slight
circumstances, as rapidity of work, strength of blast, &c. given to the furnace
may render it desirable to increase or diminish slightly the quantity of char-
coal. This alteration may be accurately made by an observant workman. A
flow of sulphate indicates want of charcoal, and a brown colour in the result
shews that too much charcoal is present; but it is also necessary to note that
both these effects may be produced. by too low a heat in the furnace, which
must be guarded against. The best working temperature is a fair white heat.
It is also useful to observe, that the addition of about five per cent. of com-
mon salt to the raw mixture greatly facilitates the fluxing of the materials
used, and is not injurious to the result, and further, that it is important that
the alkaline sulphate should be in a finely-divided state. We use it' so'fine
as to pass through a sieve of twelve holes to the linear inch. .
....
Our improvements relate, in the second place, to the use of a sulphuret ör
byposulphite in the place of carbonaceous matter, and also in the place of

page_text: charcoal in making glass. The substitution of a sulphuret or a hyposulphite
instead of charcoal, as a deoxidizing agent to decompose the sulphate in
making glass, is sometimes more economical, and is further desirable on
account of the evolution of less gas than when charcoal is used, and because
the combination of the materials takes place more rapidly. Our mode of pro-
ceeding is simply to substitute the sulphuret or byposulphite for the charcoal
in the above-mentioned mixtures, the amount of sulphate used being reduced
in quantity (or that of sand increased) equivalent to that of the sulphuret or
hyposulphite used. Half an equivalent proportion of sulphuret, or a single
equivalent of hyposulphite, should be used in the place of each equivalent of
charcoal, although we do not confine ourselves to the exact proportions. Thus
twenty parts of sulphuret of sodium would be employed instead of six parts of
charcoal, or a silicate of soda of about twenty per cent. may be made with
forty parts of protosulphuret of sodium, one hundred and forty-four parts of
sulphate of soda, and four hundred and eighteen parts of sand. In making
glass or a double silicate either one of the bases may be used in the form of sul-
phuret. Hence, the applications which may be made of this principle, that is,
the conjoined use of a sulphuret and a sulphate in glass making, are very varied.
To produce soda-lime glass, for example, by the use of a sulphuret on the
above principle, either one of the three following mixtures may be used:-
1, Sand with sulphate of soda, sulphuret of sodium, and lime; 2, sand with
sulphuret of sodium, sulphate of lime, and sulphate of soda; 3; sand with
sulphuret of calcium (or hyposulphite of lime) and sulphate of soda. When
the sulphuret is readily soluble in water, we prefer mixing it with the other
materials in concentrated solution, by which course we are enabled to distribute
it perfectly and readily throughout the other materials; but if it is not readily
soluble, we reduce it to a state of moderately fine division by any of the ordi-
nary means of crushing or grinding. The sulphurets may be procured by any
of the well-known processes. In making sulphuret of sodium we prefer heat-
ing the ordinary materials, namely, sulphate of soda and small coal, in our
fluxing furnace in the manner herein-after described. If the materials used in
this operation were sufficiently free from iron, the sulphuret thus obtained may
be used for the production of a silicate or glass without any further preparation
than grinding; but on account of the presence of iron, and also for the sake
of extracting the carbonate of soda (which is present) in the manner after-
wards described, we prefer lixiviating the sulphuret in the ordinary way, and
"boiling down" the solution until all the carbonate, sulphate, and muriate
which may be present "fall" or "salt out," leaving a nearly pure solution of
sulphuret (with some bisulphuret) of sodium. Sulphuret of barium, which

page_text: may be economically prepared and easily obtained in crystals, has the advantage
over the native carbonate and sulphate of being free from iron. The impure
sulphuret of calcium or hyposulphite of lime, produced when lime is used for
purifying ordinary coal gas (in the "dry lime process"), is a convenient source
of that substance. We are aware that the refuse lime of gas works has been
used in making common bottle glass; but hitherto it has only been used as a
cheap source of lime without regard to its deoxidizing power, which has been
allowed to be more or less injured by exposure to air. We only claim the use
of this article when it is employed in the place of charcoal, or as sulphuret of
calcium or hyposulphite of lime, to perform the function of a deoxodizing agent
in the manner just related. Mixtures of this kind may be used for producing
glass at one operation in the manner now commonly practised, as is the case
supposed in the illustration given above of the modes of producing soda-lime
glass on this principle; but in some cases, particularly in the manufacture of
flint glass, it is preferable to divide the making of glass from the above mate-
rials into two operations; that is, first, to make a silicate or rough glass, which
best be done in a furnace, and afterwards to melt and "fine" the silicate
or glass in a pot, as usual, either mixed or not with any additional materials,
as the case may require. This mode of procedure also admits of a great
variety of modifications which it would be superfluous to specify; but that
the peculiarity of the operation may be properly understood we shall describe
a case of this kind relating to flint glass, consisting in the preparation of a
double silicate of barytes and soda. For this purpose let eighty-four parts of
sulphuret of barium, one hundred and forty-four parts of sulphate of soda, and
four hundred and ten parts of sand, be well mixed together and heated to
whiteness in the furnace described below. The product is a double silicate of
barytes and soda, which should contain, if the process has been properly con-
ducted, about fourteen per cent. of soda and eleven per cent. of barytes in a
fit state for use in the manufacture of inferior flint glass, being mixed for that
purpose with such proportions of sand, red lead, &c. as the glass maker prefers.
may
Our improvements relate in the third place to a furnace of peculiar construc-
tion applicable to the manufacture of glass and certain silicates, sulphurets, &c..
An advantageous form of the furnace is represented in the Drawing accom-
panying this our Specification.
Fig. 1 is a longitudinal vertical section of the furnace; Fig. 2 is a sectional
plan of the furnace taken in the line a, b, Fig. 1; and Fig. 3 is a vertical sec-
tion of the same taken in the line c, d, Fig. 1. These Figures are on the scale
of four tenths of an inch to the foot. The furnace consists of a fireplace n
built after the manner of ordinary reverberatory furnaces, and two inclined

page_text: beds or flues 0, 0, over or through which the fire plays. Both fireplace
and bed or flue are made of the most refractory materials. We have found-it
convenient to construct the bottom and covering of the, inclined beds or flues
of blocks made of fire clay. The beds or flues are supported on wrought-iron
bearers P..P. the space underneath the beds being open at the sides; the ends
of the bearers are supported in brickwork. One fireplace may be made to
heat. a number of these working beds or flues. We have adopted the plan
of covering with blocks to avoid the expence and inconvenience of "bracing,"
but in other respects we prefer an arched roof. The necessary degree of
incline and length of bed will vary with the nature of the materials to be
worked, being dependent on the fusibility of the result, and the time required.
for the chemical action. With a very fusible material the bed may be hori-
zontal, sufficient inclination being given by the material in its flow. It is not
essential that the flow of material should be towards the fire, but we find it
most advantageous that it should be so in all cases where it is important that
the result should be in a highly finished state. It is not essential that the
working bed or flue be straight, but we do not find such advantages in using a
curved bed as to induce. us to recommend that in preference to the straight
one described. The materials are introduced at the top of the inclined beds
or Blues through an opening r in the roof by a moveable hopper, shewn
detached at Fig. 4... The supply of material may be continuous or interrupted
according to the convenience of the workman. In making rough glass or a
silicate, it is preferable to introduce from twenty to twenty-five pounds of
raw mixture at a time, which may be repeated about every ten minutes.
When the charge has been introduced the hopper is removed, the charge
levelled by a bent rod introduced through a hole in the side s, Figures 1 and 2,
and, the small opening in the roof is, covered with a brick. As the materials
become melted they flow down the inclined bed, and are allowed to fall out
in a fluxed state at or near the bottom, that is, near the fire bridge t, an
opening being left for that purpose, either in the side, or, as we prefer, in the
bottom of the flues o, as shewn at v, Figures 1, 2, and 3. The fluxed silicate
or glass is received in a vessel of water, w, placed immediately underneath,
by which it is disintegrated and better fitted for subsequent melting in the
glass-house pot. This furnace may be worked with an ordinary chimney
draft, but we prefer: producing a blast of air by a circular fan, the pipe or
flue for conveying the blast terminating in the ashpit, about a foot below the
fire bars, as shewn at a, Fig. 1. When the blast is used the front of the
ashpit is closed by a door. The arrangement of fire bars and bearers
(whether the blast is used or not) may be exactly similar to that of the

page_text: common reverberatory furnace. The details of this furnance may be varied
considerably without affecting the principle of this our Invention, which
consists in effecting such a construction as shall cause each portion of the
material to be removed from the sphere of action as soon as the heat has caused
the necessary decomposition and combination, the product being caused to flow
by its own weight when in a fluxed state, either altogether out of the furnace
or.into a heated reservoir or pot. When the product is used for glassmaking
it is either allowed to drop into water, that it may present a convenient form
of cullet, or it is conveyed into a pot heated by the waste heat of the furnace,
and, when "fine," used by the workman without having been allowed to cool.
In this case two pots should be adapted to the furnace, communicating with
two openings which may be stopped at pleasure, so that one pot of glass may
be "fining" while the other is being filled. When the product is a sulphuret
or alkali, it is simply allowed to run into any convenient box or mould of
iron. We may remark, that the advantage of this furnace in glass making,
consists chiefly, in its affording the means of producing a melted silicate or glass
from the raw materials at a small expence for fuel and labor, and without
introducing alkaline carbonates or sulphates into the glass-house pot, which
is considerable importance, as it is well known that the wear of the pots is
chiefly caused by the corrosive action of the alkaline carbonate or sulphate;
and, further, glass makers who are at present obliged to use carbonates as
their source of alkaline base are hereby enabled to use sulphates, which are
considerably cheaper.
•
Our Invention relates in the fourth place to a process for preparing silicate
of soda by acting on a mixture of sand and salt with sulphurous acid and air,
assisted by heat and carbonaceous matter, and to the preparing of sulphate of
soda in a fit state for making glass or alkali by acting upon salt, with or
without sand, with air and sulphurous acid gas aided by heat. One of the
principal advantages which this process possesses is, the facility which it presents
for the application of sulphurous acid when so mixed with air, carbonic acid,
and other gases, as to be unfit for conversion into sulphuric acid in the leaden
chamber by the usual process. Thus the sulphurous acid disengaged in the
production of a glass or silicate from a sulphate in an open furnace, and that
disengaged in the roasting of metallic sulphurets previous to the ore being
smelted, may be advantageously rendered available. When the sulphurous
acid from these otherwise waste sources is thus applied, additional heat may
not be necessary, as the gaseous products of combustion may contain sufficient ;
but when the sulphurous acid is obtained by burning sulphur or pyrites,
additional heat must be supplied. In conducting this operation, we mix three

page_text: parts of sand with one part of salt, and damp the mixture so that it will cohere
on being dried. The damp mixture is then spread on a drying table, in a
layer about one inch thick, and when dry is broken into moderate-sized pieces.
These lumps are placed in an upright flue or kiln of any convenient dimen-
sions, having an aperture at or near the top to introduce the material, and
another at the bottom to remove it. The top of the flue is connected with a
chimney or other source of draft, and at or near the bottom the sulphurous
acid and hot air are allowed to enter. The conversion of salt into sulphate of
soda takes place at a low red heat; but the temperature may be advan-
tageously raised above this point. When the lowest lumps in the kiln or flue
are free from salt, or nearly so (we having observed that it is desirable to leave
about five per cent.), they are removed, and fresh lumps are introduced at the
upper aperture, thus the process is rendered continuous. When the result
required is a silicate of soda, the firing and the admission of air must be so
regulated that the gaseous products shall be alternately oxidizing from the
presence of excess of air, and deoxidizing from the presence of unburnt
carbon. In this case sulphate is produced during the first period, and
decomposed and converted into silicate during the second period. When it is
not desirable to produce a silicate at once, but a mixture of sand and sulphate
to be afterwards converted into silicate or glass, or else lixiviated with the
object of using the sulphate of soda in alkali, making the "firing" and admis-
sion of air should be so managed as to insure the constant presence of air in
excess. The presence of sand is not essential to the conversion of salt into
sulphate of soda by the action of sulphurous acid and air. It may be replaced
by a silicate or by a sulphate of barytes, or the salt may be converted into
vapour by heat, and brought in that state into contact with sulphurous acid
and air; or the salt may be introduced in porous lumps formed by the con-
glomeration of small crystals; but we prefer mixing it with some inert sub-
stance, because that enables us to raise the salt to the temperature at which it
melts, without danger of the lumps loosing their porosity. Steam may be
introduced along with the air and sulphurous acid, but the addition of steam
is not essential.
We are aware that a Patent has been granted for effecting the conversion
of salt into sulphate of soda for the purposes of alkali making, by exposing a
mixture of salt and an oxide of iron to the action of sulphurous acid and air,
and we do not claim the use of oxide of iron, having ascertained that the pre-
sence of the additional chemical agent is not necessary to enable sulphurous
acid and air to decompose common salt.
Our improvements relate, lastly, to the recovery or economy of the alkali

page_text: or carbonate of soda, which is produced during the decomposition of sulphate,
of soda with small coal, as in the process for making sulphuret of sodium
before described. When the process of making sulphuret of sodium is well
conducted, the result is free from sulphate, but contains carbonate of soda in
considerable quantity, and an application being found for the sulphuret of
sodium, there is considerable economy in conducting this process to produce
carbonate of soda, the time and much of the labor in the "black ash". opera-
tion of the ordinary process being dispensed with. In order to obtain car-
bonate of soda sufficiently pure for ordinary purposes, we receive the mixed
sulphuret and carbonate of soda as it falls from the furnace in a convenient
iron vessel, and when nearly cold, dissolve it in water with or without the aid
of heat; it is then allowed to stand, and the clear strong solution is drawn off.
The residue of the insoluble matter is very small, being little more than the
ash from the coal, and a small excess of carbon. This is washed, and the
weak liquor coming therefrom is used to dissolve fresh portions of sulphuret
and produce more strong liquor; the strong liquor is conveyed into an ordinary
cast-iron "salting-down pan," placed over the fire, and "boiled down" as long
as any deposit takes place, the alkali which falls being "fished out" in the
usual way and set to drain. This operation is rendered easy of execution by
the presence of the sulphuret, which prevents the carbonate from adhering to
the pan, and may be continued until little or no carbonate remains in the
liquor. After being drained, the carbonate is washed once with some of the
clear sulphuret liquor which has not been concentrated, and is then dried in
an ordinary "finishing furnace," When the sulphuret of sodium exceeds the
quantity in demand, it may be partially oxidized by exposire to air, and used
without additional sulphate of soda in glass and silicate making.
Having now described the nature of the several parts of our Invention, and
the means employed by us for carrying the same into effect, we would observe
in conclusion that we claim as of our Invention,-
First, the preparation of silicate of soda, silicate of potash, and silicate of
barytes, and the double silicates of these bases, by heating their respective
sulphates with sand and carbonaceous matter.
Secondly, the use of a sulphuret or hyposulphite in the place of carbonaceous
matter in making silicates, and in the place of charcoal as heretofore used in
making glass by means of a sulphate.
Thirdly, the use in glass and alkali making of a furnace of the peculiar
construction above described, whereby the removal without labor of each
portion of the material from the sphere of action is effected as soon as the heat
has caused the requisite decomposition and combination, the product being

page_text: caused to flow by its own weight either altogether out of the furnace or into an
attached reservoir or pot.
Fourthly, the preparation of a silicate of soda by exposing a heated mixture
of sand and common salt first to the action of air and sulphurous acid, and
afterwards to carbonaceous matter or other deoxidizing agent. And also the
preparation of sulphate of soda in a fit state for glass or alkali making by
exposing salt or a mixture of salt with sand, or other inert substance, to the
united action of heat, air, and sulphurous acid. And,
Fifthly, the separation of carbonate of soda from the mixture of carbonato
of soda and sulphuret of sodium produced during the decomposition of sulphate
of soda by carbonaceous matter.
In witness whereof, we, the said William Henry Balmain and Edward
Andrew Parnell, have hereunto set our hands and seals, this First
day of September, in the year of our Lord One thousand eight hundred
and forty-nine.