IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID AND ALUM
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, JAMES
THOMSON WILSON, of Glasgow, but now of Middlesex, Chemist, seud greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-eighth day of
March, One thousand eight hundred and forty-nine, in the twelfth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto the
me,
said James Thomson Wilson, my exors, adñiors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said James Thomson
Wilson, my exors, adiñors, and assigns, and such others as I, the said James
Thomson Wilson, my 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 expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID AND ALUM;" in
which said Letters Patent is contained a proviso that I, the said James
Thomson Wilson, should cause a particular description of the nature of my
said Invention, and in what manner the same is to be performed; by an
instrument in writing under my hand and seal, to be inrolled in Her said
Majesty's High Court of Chancery within six calendar months next and-
immediately after the date of the said in part recited Letters Patent, as in
and by the same, reference being thereunto had, will more fully and at large
annoar

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
James Thomson Wilson, do hereby declare that the nature of my said In-
vention, and the manner in which the same is to be performed, are fully
described and ascertained in and by the following statement thereof, reference
being had to the Drawings hereunto annexed, and to the figures and letters
marked thereon, that is to say:-
My improvement in the manufacture of sulphuric acid relates to the con-
struction of the "chambers" in which that acid is formed when manufactured
in the manner in use in this country. These "chambers" it is well known
have long been constructed of lead, which, although less acted on by the
acid vapors than the other cheap metals, is yet soon corroded, and in a few
years requires to be replaced at very considerable expence. My improvement
consists of using glass instead of lead in the construction of such chambers.
And in order that my said Invention may be fully understood, and readily
carried into effect, I will proceed to describe how such "chambers"
may be
constructed when using numerous pieces, panes, or sheets of glass, and also
the manner in which I prefer that the various parts should be formed and
united, so that chambers so constructed may be tight and, durable. The
sole of the chamber, may be made of lead as usual, my Invention applying
only to the upper part or body of the chamber. This I construct of glass
framed in wood. I prefer for the purpose sheet glass carefully flattened and
annealed, and which is not heavier than sixteen ounces to the square foot,
unless, for the top when to be exposed to the weather, in which case it should
be sufficiently strong to resist hail storms. The glass may be divided into
panes fifteen inches in width, and forty inches in length. This I prefer as
the largest convenient size for sixteen ounce glass. The framework or window
bars I prefer to make of thoroughly seasoned yellow pine selected free from
knots. The vertical bars I make one inch on the face by one and a quarter
inch deep. The top bars are of the same breadth by one end and a half or
two inches deep: On one face of these bars I form a rebate on each side,
three sixteenths of an inch broad, by one quarter of an inch deep, as shewn
in cross section, Figure 1", in front, Figure 5", and in side section, Figure 4",
all of full size. The corner vertical bars are formed as shewn in cross section,
Figure 2. The vertical bars are nine or ten inches shorter than the height
of the chamber, and the top bars rather longer than the breadth of the
chamber. I prefer that they should be of the thickness hero stated for panes
of the size mentioned when made of glass not exceeding sixteen ounces to
the foot, but in no case should the timber be of such strength that its tendency
to warp would run any risk of fracturing the glass. On the face of the bars

page_text: thus prepared I cement slips or fillets of flat glass, not less than one eighth'
of an inch in thickness,' as in Figure 1, g, and on the corner bars as in
Figure 2, 9, 9. These fillets extend on the vertical bars from near the top,
as shewn, Figure 5, 9, to 8 or 9 inches below their lower end, as shown in
back view of bar and fillet, Figure 6%, and on the top bars they are shorter
by one quarter of an inch at each end than the bar itself. The ends and
one surface of the fillets should be ground so as to make tight joints, and
effect a better adhesion. Previous to being cemented on, the fillets are
perforated with holes of about of an inch diameter, at distances of two fect
or thereabouts apart, and the wood being bored opposite these holes, glass
pegs are firmly fixed in the wood; either by being imbedded in a cement
unaffected by any temperature to which it can be subjected, or by means of
a screw, as shewn at Figure 3: These bars are sustained by means of a
strong rectangular frame, the size of the chamber shewn in' plan Figure A,
a, a, a, a. This frame is strengthened by cross bars' g, g, placed at distances
of six feet or thereabouts, and when the breadth of the chamber is over
twelve feet, by longitudinal bar C along the centre. This bar is so checked
into the cross bars that its lower side is on the same plane as the lower side'
of the cross bars, and these should be so elevated above the frame that the
top window bars may pass below them. The timbers' for the whole of these
may be considerably lighter than is used for lead chambers of similar breadths,
four and a half inches deep by three inches broad will suffice for chambers not
more than twenty feet broad. When the chamber is erected in a position
sheltered from the weather, this frame may be supported in a horizontal position
on uprights, in the manner usually practised for leaden chambers, only they
may be fewer in number. But if unsheltered, then the frame should be
hung from beams placed opposite the cross bars, as shewn in cross section in
Figure Bb, so as to swing freely, that no vibration of the supports may be
communicated to the chamber. The beams can be supported by uprights
as usual, and these may at same time serve to support a roof and weather
boarding. Into the inner side of this frame the vertical bars are dovetailed,
as shewn in Figures 4 and 5, 6, 6 (at the distances required for the width of
the panes), so that the back of the rebates is in line with the inner side of the
frame, as shewn in Figure 4, r. These bars are fixed parallel by a light rail
placed near the bottom, as shewn in Figure D, r. The top bars having been
made a little longer than the breadth of the chamber, and their ends slightly
bevilled off to fit a bevil made in the portion of the vertical bar inserted in the
frame, Figure 4, b, b, F, they abut
roof slightly concave to the inside.
thereon, and are fixed so as to present a
These bars are supported in the centre by

page_text: being attached to the longitudinal bar C already mentioned. The glass slips
of the top bars rest on those of the sides and ends, the joints being carefully
made and luted. The whole is now glazed from the outside in the following
manner: The parts of the fillits which extend on each side of the bars, as
shewn in view of outside unglazed Figure D, g, g, so as to form surfaces
for the panes to bear against, are brushed lightly over with cement or lute,
and the sides of the panes are everywhere brought into close contact with
them, by inserting small chips or wedges of wood between the pane and the
back of the rebate. The panes of each face of the chamber thus lie all in one
plane, the ends being brought edge to edge close and not overlapped. The
side glazing is extended to the bottom of the slips on the vertical bars, as
shown in Figure D, P, P. The top glazing may either project over the upper
row of side panes a small distance, or these may rise above the top panes a
little way, the end of the one pane being in either case brought close up to the
face of the other, but on one side at least the top panes should project for the
purpose of carrying off the water. Slips or fillets of glass, one inch broad.
are now cemented on outside at the cross or horizontal joinings of the panes,
so as to close them completely up, and the rebates are then filled in with
a very adhesive putty, which completes the glazing. Parts of the chamber in
its various stages are seen in Figures A, B, C, and D, of which A, B, and D are
already described. C is an inside view of the upper portion of the side of the
chamber. The chamber thus made is perfectly tight, and presents everywhere
to the interior a surface of glass. As its durability is dependent on the
adhesion of the glass fillets to the bars, and the tightness of the joints, great
care is to be taken both in the workmanship and in the materials nsed for
cements and lutes. Those should be of a nature to resist the action of the
acids and heat in the highest degree. For cementing the glass fillets to the
bars, marine glue of the harder qualities may be used, and for bedding in
the glass pegs, if in a position where the heat is at all likely to soften the
resinous cements, stucco, or other substance not injuriously affected by the
temperature, may be employed. Canada balsam, or the cements formed by
dissolving lac and other resinous substances in pyroxilic spirit, are convenient
for fixing on the horizontal slips, and also for luting the other joints, being
practically unaffected by the acid vapours. These joints should invariably,
however, have the glass surfaces pressed together as closely as possible, so that
the film of cement or lute enclosed may be excessively thin. If the glass
is very flat, and the sides ground, it might even be dispensed with, and in the
vicinity of the entrance pipe from the ovens, where the temperature is bigbest
either this may be done or the lute may be formed of narrow slips of

page_text: the thinner fabrics of vulcanized india rubber. The openings for pipes
are left by fitting in squares of salt glaze stone-ware with the necessary
apertures. These are supported by wooden cross bars, as in Figure D, s, and
are made so as to overlap the panes immediately around them. A collar is
made around the openings sufficient to allow of a proper luting for the pipes;
the space between this square and the panes are also made tight by luting.
Such is the general plan on which I prefer to construct these glass chambers.
The details may be varied according to the size and other circumstances, but.
the mode I have described will be found to combine economy of construction.
with perfect tightness and durability. I do not, however, confine myself to
the details here described, nor to any particular mode of carrying out my
Invention; what I claim is the use of glass in pieces, panes, or sheets for.
constructing the chambers used by sulphuric acid makers (or other vessels.
used for the same purpose of whatever form or size); and the forming or
framing such pieces, panes, or sheets into such chambers, so as to present to
the interior a surface of glass; but I do not claim the use of glass to form.
vessels blown in one piece, such vessels having been formerly used in forming
sulphuric acid.
My improvements in the manufacture of alum relate to the process for
manufacturing that article by digesting shale in diluted sulphuric acid, patented
by Mr. Spence in the year One thousand eight hundred and forty-five.
My first improvement is in the process of digestion. Hitherto it has been
the practice to introduce the liquors (videlicet), sulphuric acid diluted with
water or mother liquors) into the digesting vessel containing the shale in a
cold state, and to heat then in the said vessel by steam pipes or otherwise,
which mode of working renders it difficult or rather impossible to obtain a
proper and efficient temperature throughout the mass of shale and liquor.
My improvement consists of heating the said liquors in a separate vessel to
the required temperature for acting efficiently on the shale, which varies from
one hundred and fifty degrees to two hundred degrees Fahrenheit, or there-
abouts, and when thus heated I run them in among the shale, preferring to
use the waste heat from the furnace of the heating vessel merely to keep
the digesting vessels from cooling, by passing it under and around them.
By this means I effect a considerable saving of fuel, and at the same time
obtain a more uniform and perfect digestion of the shale.
My second improvement consists in preventing the loss of a large quantity
of sulphuric acid, which takes place in the process of this manufacture. This
loss, I believe, arises from the formation of certain compounds of sulphuric
acid with alumina, or with alumina and iron, and which acid then ceases to
be available for acting on the shale so as to form sulphate of alumina.

page_text: Hitherto the practice has been that the strong mother liquors, which contain
these compounds most abundantly, are repeatedly used as dilutents of the
acid, in which case they are thrown out of solution, and the acid they contain
is lost. In order to prevent this loss I vary the mode of working in the
following manner :-The strong mother liquors left over after depositing the alum
formed from the combination of the sulphate of alumina with the sulphate of
ammonia I do not again use to dilute the acid, but I use such liquor to
combine with ammoniacal liquor from the gasworks or elsewhere, thereby
decomposing such compounds, while their acid by this combination forms a
solution of sulphate of ammonia. As these liquors, however, contain alum
in solution, which it is desirable not to decompose, this is guarded against, in
any sensible quantity, by not adding so much ammoniacal liquor as completely
to neutralize the acid. A little experience will enable any competent person
to judge, by means of test paper, the proper point of saturation. When the
solution of this mixture of sulphate of ammonia and alum (after being filtered
or allowed to settle) is sufficiently concentrated by evaporation, it is run
in among the solution of sulphate of alumina from the digesters, when
the alum therein is deposited in the coolers along with the newly-forined
alum.
I claim, first, the heating the liquors for digesting shale in a separate
vessel.
Secondly, I claim the using of the mother liquors to combine with am-
moniacal liquors, and thus to form sulphate of ammonia.
In witness whereof, I, the said James Thomson Wilson, have hicreunto
set my hand and seal, this Twenty-seventh day of September, in the
year of our Lord One thousand eight hundred and forty-nine.
JAMES THOMSON (L.S.) WILSON.
AND BE IT REMEMBERED, that on the Twenty-seventh day of September,
in the year of our Lord 1849, the aforesaid James Thomson Wilson came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Enrolled the Twenty-eighth day of September, in the year of our Lord One
thousand eight hundred and forty-nine.