IMPROVEMENTS IN THE EXTRACTION AND SEPARATION OF THE SULPHUR CONTAINED IN PRODUCTS RESULTING FROM THE ALTERNATE EXPOSURE. OF CERTAIN METALLIC OXIDES TO GASES CONTAINING SULPHURETTED HYDROGEN AND TO OXYGEN
Year: 1867

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LETTERS PATENT to Arthur McDougall, of the Firm of McDougall,
Brothers, of the City of Manchester, Manufacturing Chemist, for the
Invention of "IMPROVEMENTS IN THE EXTRACTION AND SEPARATION OF THE
SULPHUR CONTAINED IN PRODUCTS RESULTING FROM THE ALTERNATE EXPOSURE.
OF CERTAIN METALLIC OXIDES TO GASES CONTAINING SULPHURETTED HYDROGEN
AND TO OXYGEN."
Sealed the 10th March 1868, in pursuance of an Order of the Lord Chancellor,
PROVISIONAL SPECIFICATION left by the said Arthur McDougall at the
Office of the Commissioners of Patents, with his Petition, on the
12th August 1867.
I, ARTHUR MCDOUGALL, of the Firm of M'Dougall, Brothers, of the City
of Manchester, Manufacturing Chemist, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE EXTRACTION AND SEPARATION OF THE
SULPHUR CONTAINED IN PRODUCTS RESULTING FROM THE ALTERNATE EXPOSURE OF
CERTAIN METALLIC OXIDES TO GASES CONTAINING SULPHURETTED HYDROGEN AND
TO OXYGEN," to be as follows:-
My said Invention consists in the use of oils, naphthas, or bi-sulphide of
carbon to dissolve out sulphur from the products resulting from the alternate
exposure of certain metallic oxides to gases containing sulphuretted hydrogen
and to oxygen. Owing to its cheapness I prefer to use the dead oil obtained
from the tar produced in the destructive distillation of carbonaceous substances.

page_text: This I heat, and then wash the products above described with it, the heated oil
dissolves the sulphur which crystallises from it upon cooling. When I use
napthas or bi-sulphide of carbon I prefer to separate them by distillation
from the dissolved sulphur; when the remaining oxide has been freed from
the mechanically adhering solvent it can be again used for the decomposition
of sulphuretted hydrogen.
SPECIFICATION filed in pursuance of the conditions of the Letters Patent,
and of an Order of the Lord Chancellor, by the said Arthur McDougall
in the Great Seal Patent Office on the 12th March 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
MCDOUGALL, of the Firm of McDougall, Brothers, of the City of Manchester,
Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of August, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Arthur McDougall,. Her special, license, that I, the said Arthur McDougall,
my executors, administrators, and assigns, or such others as I, the said
Arthur McDougall, executors, administrators, or assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE EXTRACTION AND SEPARATION OF THE SULPHUR CONTAINED IN PRODUCTS
RESULTING FROM THE ALTERNATE EXPOSURE OF CERTAIN METALLIC OXIDES TO
GASES CONTAINING SULPHURETTED HYDROGEN AND TO OXYGEN," upon the condition
(amongst others) that I, the said Arthur McDougall, my executors or
administrators, by an instrument in writing under my hand and seal, should
particularly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be
filed in the Great Seal Patent Office within seven calendar months next and
immediately after the date of the said Letters Patent.
.
NOW KNOW YE, that I, the said Arthur-McDougall, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the follow-
ing statement, that is to say:

page_text: My said Invention consists in the use of bi-sulphide of carbon employed as
herein-after described to dissolve out sulphur from the products resulting from
the alternate exposure of certain metallic oxides herein-after mentioned to
gases containing sulphuretted. hydrogen and to oxygen. The bi-sulphide of
carbon is separated and recovered by distillation from the dissolved sulphur.
When the remaining oxide has been freed from the adhering solvent it can
be again used for the decomposition of sulphuretted hydrogen.
The products upon which I operate by the agency of bi-sulphide of carbon
are the oxide of iron or other metallic oxide mixed with more or less free
sulphur, the mixture being produced by the alternate exposure of the oxide to
sulphuretted hydrogen and to oxygen as is now usual in the manufacture and
purification of ordinary gas in gas works, and I would specially remark that a
very important result is obtained from the application of my process by the
production of a renovated oxide of a new and superior character free from
impurities and suited for being again used in the purification of gas with great
advantage.
The sulphuretted hydrogen may be derived from any of the following
sources:(A) that contained in coal gas, (B) that obtained by the decom-
position of alkali.makers' waste, (C) that obtained by passing steam over a
heated mixture of sulphate of lime and carbonaceous matter.
And in order that the mode of carrying out my said Invention may be fully
understood, I shall now proceed to describe an apparatus which I find suitable
for that purpose and the process I employ. The apparatus I prefer consists
of, first, a vessel or vessels which I call "digesters;" second, a vessel or vessels
which I call "stills;" third, condensers and store tanks. with pipes, pump, and
other requisite fittings.
The "digesters" consist of air-tight vessels made by preference of wrought
iron and about six feet square by, say, four feet deep containing a grating or,
perforated false-bottom-or-filter situate a few inches from the real bottom.
Into this "digester" I introduce a quantity of the oxide of iron materials
containing sulphur, and lixiviate it with bi-sulphide of carbon which dissolves
out the sulphur; I draw off this solution and leave behind only the iron.
residue and the adhering bi-sulphide of carbon. I connect several of these
digesters together by means of taps and pipes in a system similar to-the
lixiviators well known to manufacturing chemists, and thus obtain a saturated
solution of sulphur; the sulphur moreover is completely washed out of the oxides
contained in each "digester" in its turn. To remove that portion of bi-sulphide
of carbon which cannot be run off in the solution of sulphur from the oxide of
iron residue, I have a large pipe or still head leading from the upper part of the

page_text: 'digesters" to a condenser; near the bottom of the "digester" I use a coil of
pipe heated by steam, and also surround the digester" with a double casing, or
use other means of applying heat. To remove the last portions of the bi-sulphide,
I find it advantageous to run in sufficient hot water. to render the contents liquid
and of sufficient temperature to distill off the bi-sulphide. The saturated solution
of sulphur before mentioned is conveyed into stills which are in all respects
like the digesters, with this exception, that they have no false bottoms or.
filters. When the still is heated, the bi-sulphide distills off and passes into the
condenser and leaves the sulpher in the still. Should the oxide material;
contain tarry matters they are liable to soil the sulphur. left on distillation;
this may be avoided by running off the liquid portions when the greater part
of the bi-sulphide has been removed into another still, and this takes with it
the greater part of the impurities. Or I wash the sulphur. left.in the still with
fresh bi-sulphide of carbon or bi-sulphide of carbon: saturated with sulphur.
The condenser I use may consist of an ordinary condensing worm (connected.
with the still) kept cool by water, and connected at its lower extremity with.
the bi-sulphide of carbon store or reservoir so that the condensed bi-sulphide
may be pumped up into the digesters, and again used. for the extraction .of.
sulphur as before described. Each of the digesters. and..stills is provided
with a man hole on the top, and also with one at. the side near the bottom for s
the purpose of introducing or withdrawing the charges thereof.
Having now described and particularly ascertained the nature of my said
Invention and the method in which, I carry the same into effect, I would
observe in conclusion that what I claim as my Invention is, the application
and use of, bi-sulphide of carbon to and in the dissolving out of sulphur froin
the products herein-mentioned substantially in the manner herein-described so
as to enable the bi-sulphide of carbon to be recovered and 'to produce sulphur
and renovated oxides in a condition fit for use.
In witness whereof, I, the said Arthur McDougall, have to this my
Specification set my hand and seal, the Eleventh day of March, One
thousand eight hundred and sixty-eight.
ARTHUR M'DOUGALL. (L.S.)