IMPROVEMENTS IN THE MANUFACTURE OF CHLORINE
Year: 1855

page_text: LETTERS PATENT to Charles Tennant Dunlop, of Glasgow, in the County
of Lanark, North Britain, Chemist, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF CHLORINE."
Sealed the 9th November 1855, and dated the 31st May 1855.
PROVISIONAL SPECIFICATION left by the said Charles Tennant Dunlop
at the Office of the Commissioners of Patents, with his Petition, on the
31st May 1855.
I, CHARLES TENNANT DUNLOP, of Glasgow, in the County of Lanark, North
Britain, Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF CHLORINE" to be as follows, that is
to say:
This Invention relates to the employment and use of the residuum obtained
in the manufacture of chlorine, which residuum ordinarily consists of chlorido
of manganese in the preparation of an artificial oxide of manganese, which is
well suited for the manufacture or production of chlorine. The special process
which I prefer to adopt in carrying out my said Invention is the transformation
of the chloride of manganese into a carbonate of manganese by the agency of
any of the means well known to chemists, and then subjecting the carbonate
thus prepared to the action of heat in contact with atmospheric air. Whatever
impurity the chloride of manganese may contain, as chloride of iron, for instance,
is first separated either by calcination or by the agency of a suitable precipitate.
Practical working has decided that the carbonate of manganese thus treated
yields oxide of a thickness equivalent to 80 per cent. of pure peroxide.
The carbonate of manganese may be obtained by precipitation from tho

page_text: chloride of manganese by the agency of carbonate of ammonia. The muriate
of ammonia resulting from this treatment may either be sold or employed as
such, or it may be re-transformed into a carbonate in the usual way, and then
again employed for the precipitation of fresh chloride of manganese. In
situations where the ammoniacal liquor may be cheaply obtained from gas
works this process may be convenient. Hydrate of lime is also employed in
the production of carbonate of manganese from these residual matters, the
hydrated oxide of manganese thus obtained being subsequently transformed into
carbonate of manganese by the transmission through it of carbonic acid.
By another process, carbonate of manganese is obtained by passing carbonic
acid through the solution of chloride of manganese which has been previously
mixed with a quantity of carbonate of lime. The carbonate of lime under the
influence of the carbonic acid decomposes the chloride of manganese into car-
bonate of manganese, from which latter the oxide can be obtained, as well as
chloride of calcium, which remains in solution. The production of oxide of
manganese suitable for the obtainment of chlorine has been often attempted
by following the process of precipitating the manganese as an oxide, and then
bringing it to a higher state of oxidation by heating it in contact with atmno-
spheric air, as well as by other means. But the essential feature of the present
Invention is, the production of oxide of manganese from the residuum of the
chlorine manufacturer, by first producing the carbonate of manganese, and
then heating this carbonate in contact with atmospheric air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Tennant Dunlop in the Great Seal Patent Office on
the 27th November 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
TENNANT DUNLOP, of Glasgow, in the County of Lanark, North Britain,
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of May. in the year of our Lord
One thousand eight hundred and fifty-five, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Charles Tennant Dunlop, Her special license that I, the said Charles
Tennant Dunlop, my executors, administrators, and assigns, or such others
as I, the said Charles Tennant Dunlop, my executors, administrators, or
assigns, should at any time agree with, and no others, from time to time and

page_text: 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 MANUFACTURE OF CHLORINE," upon the condition
(amongst others) that I, the said Charles Tennant Dunlop, 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 six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Charles Tennant Dunlop, 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
following statement in writing, that is to say :-
My said Invention relates to the employment and use of the residuum
obtained in the manufacture of chlorine, which residuum ordinarily consists of
chloride of manganese in the preparation of an artificial oxide of manganese,
which is well suited for the manufacture or production of chlorine. The special
process which I prefer to adopt in carrying out my said Invention is the
transformation of the chloride of manganese into a carbonate of manganese by
the agency of any of the means already well known to chemists, and then sub-
jecting the carbonate thus prepared to the action of heat in contact with
atmospheric air. Whatever impurity the chloride of manganese may contain,
as chloride of iron, for instance, is first separated either by calcination or by the
agency of a suitable precipitant. Practical working has decided that the car-
bonate of manganese thus treated yields an oxide of manganese of a richness
equivalent to about eighty per cent. of pure peroxide.
The carbonate of manganese may be obtained by precipitation from the
chloride of manganese by the agency of carbonate of ammonia. The muriate
of ammonia resulting from this treatment may either be sold or employed as
such, or it may be re-transformed into a carbonate in the usual way, and then
again employed for the precipitation of fresh chloride of manganese. Hydrate
of lime is also employed in the production of carbonate of manganese from these
residual matters, the hydrated oxide of manganese thus obtained being sub-
sequently transformed into carbonate of manganese by the transmission through
it of carbonic acid.
By another process, carbonate of manganese is obtained by passing carbonic
acid through the solution of chloride of manganese which has been previously
mixed with a quantity of carbonate of lime. The carbonate of lime under the

page_text: influence of the carbonic acid decomposes the chloride of manganese into car-
bonate of manganese, from which latter substance the oxide of manganese can
be obtained, as well as chloride of calcium, which remains in solution. The
production of oxide of manganese suitable for the obtainment of chlorine has
been often attempted by following the process of precipitating the manganese
as an oxide, and then bringing it to a higher state of oxidation by heating it in
contact with atmospheric air, as well as by other means. But the essential
feature of my present Invention is, the production of oxide of manganese from
the residuum of the chlorine manufacture, by first manufacturing or producing
the carbonate of manganese, and then heating this carbonate in contact with
atmospheric air.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,―
First, the system or mode of manufacturing or producing chlorine from the
oxide of manganeso derived from the chlorine manufacturer's residual matter,
by first producing an artificial carbonate of manganese, and then transforming
such carbonato into oxide by the agency of heat and air.
Second, the manufacture or production of oxide of manganese from the
residuum of the chlorine manufacture, by first producing the carbonate of
manganese, and then heating the same in contact with atmospheric air.
Third, the preparation of carbonate of manganese for the
purpose of pro-
ducing oxide of manganese, by precipitating as hydrated protoxide by the
hydrate of lime the manganese contained in the residual matter of chlorine
manufacturers (commonly consisting of chloride of manganese), and passing a
current of carbonic acid through or over this hydrate.
In witness whereof, I, the said Charles Tennant Dunlop, have hereunto
set my hand and seal, this Twenty-sixth day of November, One thousand
CHARLES TENNANT DUNLOP. (L.S.)