CERTAIN IMPROVELIENTS IN THE MANUFACTURE OF SULPHURIC ACID AND CARBONATE OF SODA
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, FRANK
HILLS and GEORGE HILLS, both of Deptford, in the County of Kent, Manu-
facturing Chemists, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Fifteenth day of April, in the fourth year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto us, the said Frank
Hills and George Hills, Her especial licence, full power, sole privilege and autho-
rity, that we, the said Frank Hills and George Hills, our exors, adñiors, and
assigns, or such others as we, the said Frank Hills and George Hills, our exors,
adñiors, 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, our Invention of "CERTAIN IMPROVELIENTS
IN THE MANUFACTURE OF SULPHURIC ACID AND CARBONATE OF SODA;" in which said
Letters Patent is contained a proviso that we, the said Frank Hills and George
Hills, or one of us, shall cause a particular description of the nature of our
said Invention, and in what manner the same is to be performed, 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 appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, we, the said
Frank Hills and George Hills, do hereby declare that the nature of our
Invention, and the method of carrying the same into effect, is fully ascertained
and set forth in and by the following description thereof, reference being had
to the Drawings hereunto annexed.
Our improvements in the manufacture of sulphuric acid consist of,-
First, an improved furnace or oven for roasting or calcining pyrites, mundic
or sulphuret of iron, in order to drive off or extract the sulphur contained
therein.
Second, a process for making sulphuric acid from the residuum of pyrites
which has already been burnt in the common way of manufacturing sulphuric
acid.
And, lastly, in a method or process for making sulphuric acid from the
liquid hydro-sulphuret of lime.
Our first improvement, videlicet, the improved furnace or oven, is repre-
sented in the Drawings, Figure 1 being a horizontal section, Figure 2 a
vertical section in the direction of the flues, Figure 3 a vertical section at
right angles to the former, and Figure 4 a vertical section through the
sulphurous acid gas flue. In all the Figures the same parts are indicated by
the same letters.
The following is a description of the Drawings:-a, a, is a transverse flue com-
municating with the ignited fuel of a coke oven or other large fire, and b, b, are
a range of flues (shewn by dotted lines in Figure 1), which all branch at the
same level from the flue a, and, after making one or more turns in the direc
tion shewn in the Drawing, terminate in a fluo c leading to the chimney. These
flues (b, b,) are formed of fire brick, and the spaces between each turn of
the flue are divided by the walls d, d, into ranges of compartments or
chambers e, c, in which the pyrites are burned. These chambers are furnished
at one end with sliding doors f, f, to regulato the admission of the atmosphere
to the burning pyrites in the proportion required, so as, by combination with
the sulphur driven off from the pyrites, to form sulphurous acid gas. The
other ends of the chambers communicate with a flue or compartment g, from
the upper part of which branches a flue / leading to the condensing chamber.
This fluc is furnished with a door k, at which is introduced an iron box or
pot containing the requisite supply of nitre to convert the sulphurous acid gas
into sulphuric acid. The brickwork should be very well put together to
prevent the smoke from the flues entering the chambers in which the pyrites
are burning. Each of the flues b, b, has a damper m at its junction with the
flue c to regulate the draft.

page_text: We claim, under this branch of our Invention, the general arrangement and
construction of the furnace above described for the burning of pyrites in the
manufacture of sulphuric acid.
Our process for making sulphuric acid from the residuum of pyrites
which has already been burnt in the ordinary way of making the acid
from that material is conducted as follows: We grind the residuum
(which is in lumps of about the size of an egg, and which still contains
a considerable portion of sulphur) to a powder by a pair of edge runners,
and afterwards burn it in thin strata in any suitable furnace or oven, pre-
ferring for that purpose our improved furnace before described. The
ground pyrites is strewed on the shelves or bottom of the chambers of this
furnace to a depth of about two inches, where it remains for about six hours,
during which time it is repeatedly stirred. By the thorough exposure thus
affected of all the particles of the material to the joint action of the atmosphere
and of the heat, the whole, or nearly the whole, of the sulphur contained in
the pyrites will be driven off and converted into sulphurous acid gas, which,
being combined with nitrous acid gas in the usual way in its passage to the
condenser, will be converted into sulphuric acid.
We claim, under this head of our Invention, the grinding and subsequent
burning of the residuum of pyrites (which pyrites has been previously used for
making sulphuric acid on the common plan) with the view to expose the
whole of the materials more equally to the action of the air and of the fire, by
which means the whole, or nearly the whole, of the sulphur is driven off from
the pyrites and converted into sulphurous acid gas.
Our process for making sulphuric acid from hydro-sulphuret of lime, instead
of employing sulphur or the metallic sulphurets for that purpose, is conducted
as follows:-The hydro-sulphuret of lime (which is a residuum from the gas
purifiers at gasworks) we put into close iron vessels or boilers of any
convenient form, and by evaporation drive off the sulphuretted hydrogen,
which, after passing through a worm or other refrigerating apparatus, to
condense the steam which rises with it, is conveyed by a platina pipe to a
small furnace kept red hot, and is there inflamed and burnt; the products of
the combustion (sulphurous acid gas and vapour of water, are then conducted
into the leaden condensing chamber in the usual way, with sufficient nitrous
acid gas to convert it into sulphuric acid. The object of the red hot chamber
is to keep the sulphuretted hydrogen ignited, or to re-ignite it in case of its
becoming extinguished by inequalities in its generation, and also for con-
ducting the vapour and assisting the draft into the leaden condensing chamber.
The furnace is provided with a sliding door or valve for regulating the admis-
sion of air.

page_text: We claim, under this head of our Invention, the making or obtaining sul-
phuretted bydrogen (for the manufacture of sulphuric acid) from hydro-
sulphuret of lime by the process of evaporation.
Our improvement in making carbonate of soda consists in decomposing
sulphate of soda by barytes, which process is conducted as follows:-We
take precipitated carbonate of barytes mixed with about one third of its weight
of tar or other carbonaceous matters, and make it up into lumps of about the
size of a common brick. These lumps we put into a kiln like a lime kiln,
and burn either with flame, or by putting coal with them in the same manner
that lime is burnt. The greater portion will thus be converted into caustic
barytes, which must be dissolved in water, and the residuum must be reburnt
by being mixed with the next quantity of carbonate of barytes when it is being
made into bricks. The dissolved caustic barytes is to be added to sulphate of
soda in solution in the proportion of seventy-eight parts of dry barytes to
seventy-two of dry sulphate of soda, when a decomposition will ensuc, forming
caustic soda and sulphate of barytes. The soda may then be converted into
carbonate in the usual way by putting it into a reverberatory furnace.
We claim, under this head of our Invention, the making of carbonate of soda
by means of caustic barytes obtained from the carbonate of barytes in the way
described.
In witness whereof, I, the said Frank Hills, have hereunto set my hand
and seal, the Fourteenth day of October, in the year of our Lord Ono
thousand eight hundred and fouti