A NEW OR IMPROVED MODE AND MEANS FOR THE Manufacture of Bichromate of PotasH
Year: 1875

page_text: LETTERS PATENT to Jules Antoine César Frédéric Clouet, of 2, Rue
S. Appoline, Paris, France, Knight of the Legion of Honour, for
the Invention of "A NEW OR IMPROVED MODE AND MEANS FOR THE
Manufacture of Bichromate of PotasH.”
Sealed the 4th January 1876, and dated the 6th July 1875.
PROVISIONAL SPECIFICATION left by the said Jules Antoine César
Frédéric Clouet at the Office of the Commissioners of Patents,
with his Petition, on the 6th July 1875.
I, JULES ANTOINE CÉSAR FRÉDÉRIC CLOUET, of 2, Rue St. Appoline,
Paris, France, Knight of the Legion of Honour, do hereby declare the
nature of the said Invention for "A NEW OR IMPROVED MODE AND Means
FOR THE MANUFACTURE OF BICHROMATE OF POTASH," to be as follows:-
°
According to my Invention, instead of reverberatory furnaces hereto-
fore employed, and heated at a very high temperature, consequently
consuming very large quantities of coal, I employ retorts used in the
manufacture of burning gas by the distillation of coal, in which I

page_text: make the following modifications:-The necessary temperature for the
operation being comparatively not very high, this furnace can be
composed of from one to eight retorts, or even of a greater number, and
heated with coke, coal, or other fuel. The retorts are closed at each of
their ends by a movable plate placed at the side of the fire-place.
This movable plate has apertures formed in it, which may be stopped
when required, whilst at the other extremity the head of the retort
carries at its upper part a tube about three yards or more in height
provided with a register. The fire being lighted and the retorts charged,
by opening one or more of the apertures in the plate aforesaid and
regulating the register, a large or small quantity of air can be made to
pass into the retort. It is preferable to introduce this air previously
heated by means of the waste heat from the furnace.

page_text: point is poured in a boiling state into the crystallizing vessels of any
suitable size and form, and lined with lead, on the bottom and sides of
which the bichromate of potash crystallizes. After a given time the
crystals are detached by an iron spatula, washed, dried, and they are
ready for commerce.
The mother waters proceeding from the crystallizing vessels are after-
wards evaporated in sheet-iron basins; the greatest part of the sulphate
of potash which it contains becomes precipitated to the bottom of the
basin. This deposit effected, the liquors which remain are taken to the
saturating boilers, where, mixed with those proceeding from the filters,
they are as before treated by sulphuric acid and put to crystallize.
The material remaining in the filter is dried, a part of the mineral of
chrome is then added to it, and a part of the carbonate of potash to form
a new mixture to be calcined. It is not necessary for this second
calcination to add to the mineral and to the carbonate of potash a new
part of carbonate of magnesia, that introduced into the first mixture
remaining almost entirely in the filter, and can be used not only for a
second calcination, but for several successive calcinations. This number
is only limited by a too large accumulation of inert mineral matters
("gange" and the peroxide of iron) and of the carbonate of the
magnesia employed. These three materials after having been well
mixed with one another are introduced into the retorts, and treated as
before as a mixture of new materials. The carbonate of magnesia
introduced into the first mixture may also be used a great number of
times.
When it is considered that the volume of the residue of the last
calcination is too great for there to be any advantage gained by with-
drawing the small quantity of chrome material which it still contains,
by calculating the work and the fuel required to do it, this last residue
may be used. For this purpose it is treated cold by weak sulphuric
acid, all the magnesia dissolves, and there remains as a residue an
excellent mineral of iron, free from arsenic, phosphorus, and sulphur,
containing a per-centage of chromate of iron, and consequently pro-
ducing an iron or steel of a superior quality. In the sulphate of
magnesia thus produced by treating the solution with carbonate of lime
almost all the magnesia employed can be withdrawn, which can then be
used for new calcinations.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Jules Antoine César Frédéric Clouct in the Great
Seal Patent Office on the 6th January 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULES
ANTOINE CESAR FREDERIC CLOUET, of 2, Rue St. Appoline, Paris,
France, Knight of the Legion of Honour, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Sixth day of July, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Jules Antoine Cesar Frederic
Clouet, Her special licence that I, the said Jules Antoine Cesar Frederic
Clouet, my executors, administrators, and assigns, or such others as
I, the said Jules Antoino Cesar Frederic Clouct, my executors, ad-
ministrators, and 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 "A NEW OR IMPROVED
MODE AND MEANS FOR THE MANUFACTURE OF BICHROMATE OF POTASH," upon
the condition (amongst others) that I, the said Jules Antoine Cesar
Frederic Clouet, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and scals,
should particularly describe and ascertain the nature of the said In-
vention, 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 Jules Antoine Cesar Frederic
Clouet, 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 thereof, that is to say:-
According to my Invention, instead of reverberatory furnaces hereto.
fore employed and heated at a very high temperature, consequently
consuming very large quantities of coal, I employ retorts used in tho

page_text: up to from 34 to 36 degrees Beaume. The liquid which arrives at this point
is poured in a boiling state into the crystallizing vessels of any suitable
size and form lined with lead, on the bottom and sides of which the
bichromate of potash crystallizes. After a given time the crystals
are detached by an iron spatula, washed, dried, and they are ready for
commerce.
The mother waters proceeding from the crystallizing vessels are after-
wards evaporated in sheet-iron basins; the greatest part of the sulphate
of potash which it contains becomes precipitated to the bottom of the
basin. This deposit effected, the liquors which remain are taken to the
saturating boilers, where, mixed with those proceeding from the filters,
they are as before treated by sulphuric acid and put to crystallize.
The material remaining in the filter is dried; a part of the mineral of
chrome is then added to it, and a part of the carbonate of potash to form
a new mixture to be calcined. It is not necessary for this second
calcination to add to the mineral and to the carbonate of potash a new
part of carbonate of magnesia, that introduced into the first mixture
remaining almost entirely in the filter, and can be used not only for a
second calcination, but for several successive calcinations. This number
is only limited by a too large accumulation of incrt mineral matters
("gange" and the peroxide of iron) and of the carbonate of the
magnesia employed. These three materials, after having been well
mixed with one another, are introduced into the retorts and treated as
before as a mixture of new materials. The carbonate of magnesia
introduced into the first mixture may thus be used a great number of
times.
When it is considered that the volume of the residue of the last
calcination is too great for there to be any advantage gained by with-
drawing the small quantity of chrome material which it still contains,
by calculating the work and the fuel required to do it, this last residue
may be used. For this purpose it is treated cold by weak sulphuric
acid, all the magnesia dissolves, and there remains as a residue an
excellent mineral of iron, free from arsenic, phosphorous, and sulphur,
containing a per-centage of chromate of iron, and consequently pro-
ducing an iron or steel of a superior quality. In the sulphate of a
magnesia thus produced by treating the solution with carbonate of soda,
almost all the magnesia employed can be withdrawn, which can then be
used for new calcinations.

page_text: Having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that although I claim the
use of gas retorts for manufacturing bichromates as being an economical
means, yet I wish it to be understood that their use is not indispensable
to the success of my new Invention, for by substituting carbonates of
magnesia in place of lime it is then possible to operate in ordinary rever-
beratory furnaces of any shape or size, particularly in those in use for
producing bichromates, but I claim as my new or improved mode and
means for the manufacture of bichromate of potash―
First. The employment of gas retorts instead of, as hitherto, rever-
beratory furnaces, or both in combination, for the manufacture of bi-
chromate of potash, substantially as described.
Second. The employment of carbonate of magnesia, or of magnesia in
whatever way it may be obtained, instead of lime as heretofore used,
substantially as described.
Third. The application of carbonate of magnesia or of magnesia,
which being employed once can be used for a great number of calcina-
tions by introducing into the residue of each calcination successive
quantities of mineral of chrome and carbonate of potash, the said
materials, carbonate of magnesia and magnesia, never having been
employed for this manufacture, all substantially as herein-before
described, together with any mere modifications thereof.
In witness whereof, I, the said Jules Antoine Cesar Frederic
Clouet, have hereunto set my hand and seal, this First day of
January, in the year of our Lord One thousand eight hundred
and seventy-six.