Iм- PROVED PROCESSES FOR THE EXTRACTION OF IODINE
Year: 1873

page_text: LETTERS PATENT to Bristow Hunt, of Serle Street, Lincoln's Inn, in
the County of Middlesex, Gentleman, for the Invention of "Iм-
PROVED PROCESSES FOR THE EXTRACTION OF IODINE."-A communication
from abroad by Alvaro Francisco Carlos Reynoso, of Paris, France,
Chemist.
Sealed the 21st April 1874, and dated the 15th November 1873.
PROVISIONAL SPECIFICATION left by the said Bristow Hunt at the
Office of the Commissioners of Patents, with his Petition, on the
15th November 1873.
I, BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Inven-
tion for "IMPROVED PROCESSES FOR THE EXTRACTION OF IODINE" (a communi-
cation to me from abroad by Alvaro Francisco Carlos Reynoso, of Paris,
France, Chemist), to be as follows:-
This Invention consists of the following improvements which may be
divided into two groups. The first group comprehends the methods
suitable for treating the ashes of varec (sea wrack), and other products

page_text: in order to separate the soluble substances from others which are
insoluble. The second group comprises wet processes which permit of
the rapid precipitation of the iodide in a free state, and also the means
of purifying the same and causing its crystallization.
Treatment of the Ashes of Varec and other Products.--These processes
apply to the treatment of the ashes or the charcoal of varec, and of the
same plants in their natural state, suitably prepared, but without having
been submitted to the action of heat; they consist in treating these three
orders of bodies with water in closed vessels at a suitable pressure and
temperature in order to obtain at a single operation a saturated solution.
When this saturated solution is obtained and the soluble products are
thus separated from the insoluble these two bodies are then separated
and the solution treated in a suitable manner in order to remove the
salts of potash and soda, and to leave the residue of iodides and bromides
from which the iodine and bromine are then to be extracted. This
treatment also applies to the ashes of all plants and to the rock (caliche)
from whence nitrate of soda is extracted in Peru.
Extraction of the Iodine.-
Firstly. The chlorates of potash and soda in presence of sulphuric,
azotic, hydrochloric, phosphoric, and other acids exert two different
actions on iodides of potash and soda, giving birth to iodates or
especially to iodic acid, or to free iodine, according to the proportions of
the bodies under operation.
A. Taking as a starting point the proportions indicated by the equa-
tion:-KO, Cl 05 +IK+2 (SO³, HO) = 2 (KO, SO³)+10%, HO+C1 H,
a transparent colorless liquid is obtained from which it is possible to
precipitate the iodide contained in the state of iodic acid by means of
numerous reducing agents such as the salts of protoxide of iron, or of
tin, chrome copper, and so on, also by sulphurous, azotous, phosphorous,
and hypophosphorous acids, as well as by the solutions of sulphites,
azotites, phosphites, hypophosphites, and iodide of potassium by the
nascent hydrogen obtained by adding zinc, and lastly by an electric
current having previously driven off the hydrochloric acid by ebullition
with an excess of azotic acid. For this latter experiment it is preferable
to employ azotic acid from the commencement.
B. Taking the proportions indicated by the equation :--
KO, CI O' + 6IK + 7 (SO³ HO)= 61 +7 (KO, SO³) + 6HO + Cl H,

page_text: necessary to employ a small excess of acid, or to assist the reaction in
certain cases by a slight elevation of temperature.
Secondly. To extract the iodine by engaging it at once in combination
with copper, forming in fact a proto-iodide of copper, this body can be
prepared completely in a pure state in order to decompose it later or
immediately on its formation in presence of the free iodine disengaged.
A Preparation of Cupreous Iodide.-The solutions containing iodides
are to be mixed with a suitable quantity of salts of copper, such as
sulphate, chloride, azotate, and so forth; and into this mixture are to be
introduced strips of copper perfectly clean, and the latter after a certain
time will precipitate all the iodine set free by the reaction, and also
decompose the cupric iodide formed. There is obtained as a final result
of this operation proto-iodide of copper without the least mixture of free
iodine. The supernatant liquor is then decanted and the precipitato
washed by decantation and then collected on a filter if it is desired in a
dry state. In the contrary case it is better to leave it in the flask with
a little water. Whichever method is adopted the cupreous iodide will
be decomposed by azotic acid; the iodine immediately becomes free,
vapors are disengaged, and the azotate of copper is formed; the iodine
obtained is amorphous, it agglomerates readily into a single mass which
should be divided in order to wash it well, it is then allowed to drain, and
dried.
When these operations are accomplished the product is pulverized and
placed in contact with sulphide of carbon, and the mixture is frequently
and violently agitated; if the iodine still contains water it will float on
the solution, and it should then be separated by means of a funnel pro-
vided with a tap. The solution of iodine in sulphide of carbon should
then be submitted to a very low temperature, and the iodine will pre-
cipitate itself in part in the form of beautiful crystals; a part of the
iodine will remain in solution in the sulphide of carbon.
B. To obtain the iodine in a rapid manner there is no need to prepare
the cupreous iodide completely at once, it is sufficient to mix the soluble
iodide with the salt of copper, and then add azotic acid in a slight excess
at the ordinary temperature or at a slight increase of the same, according
to the proportion between the quantity of cupreous iodide formed and
the mass of liquid, in either case all the iodine is precipitated imme-
1

page_text: diately in a free state with a disengagement of vapors and formation of
azotate of copper, and washed, dried, and treated, as before described.
Besides the treatment at a low temperature recourse may be had to
other means for separating the iodine from the sulphide of carbon; in
fact the sulphide of carbon may be evaporated in a variety of ways—
Firstly by carrying it off by a current of air which may be created by
In all these operations the apparatus will be arranged in such a 1
manner that the sulphide of carbon can be conveniently collected.
Instead of dissolving the amorphous iodide in sulphide of carbon it is
also possible to cause it to crystallize by sublimation.
The salt of copper floating on the iodine set free will be collected in
order to be used again in such a manner that actually the only expense 1
consists in the quantity of azotic acid employed for the decomposition of
the cupreous iodide.
In certain cases it may be convenient to employ ether, chloroform,
benzine, oil of naptha, wood spirit, petroleum, spirit of turpentine, and
other similar agents as solvents of the iodine.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Bristow Hunt in the Great Seal Patent Office on
the 14th May 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BRISTOW
HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex, 2
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of November, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and 8
successors, give and grant unto me, the said Bristow Hunt, Her special

page_text: licence that I, the said Bristow Hunt, my executors, administrators, and
assigns, or such others as I, the said Bristow Hunt, my executors,
administrators, 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 "IMPROVED PROCESSES
FOR THE EXTRACTION OF IODINE" (a communication to me from abroad by
Alvaro Francisco Carlos Reynoso, of Paris, France, Chemist), upon the
condition (amongst others) that I, the said Bristow Hunt, my executors
or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, 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 Bristow Hunt, do hereby declare
the nature of the 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:—
This Invention consists of the following improvements which may be
divided into two groups. The first group comprehends the methods
suitable for treating the ashes of varec (sea wrack), and other products
in order to separate the soluble substances from others which are
insoluble. The second group comprises wet processes which permit of
the rapid precipitation of the iodide in a free state, and also the means
of purifying the same and causing its crystallization.
Treatment of the Ashes of Varec and other Products.-These processes
apply to the treatment of the ashes or the charcoal of varec, and of the
same plants in their natural state suitably prepared, but without having
been submitted to the action of heat; they consist in treating these
three orders of bodies with water in closed vessels at a suitable pressure
and temperature.
The apparatus in the form of boilers arranged vertically, horizontally,
or in any other manner may be provided in the interior with agitators
for well stirring up the mass and increasing the points of contact with
the solvent liquid, and may be heated either by fire direct or by steam

page_text: KO, CI O³+ 6IK +7 (SO³ HO) = 61 +7 (KO, SO³) + 6HO + Cl H,

page_text: a free iodine pure and more or less crystallized is obtained. It is
necessary to employ a small excess or to assist the reaction in certain
cases by a slight elevation of temperature.
Secondly. To extract the iodine by engaging it at once in combination
with copper, forming in fact a proto-iodide of copper, this body can be
prepared completely in a pure state in order to decompose it later or
immediately on its formation in presence of the free iodine disengaged.
A Preparation of Cupreous Iodide.-The solutions containing iodides
are to be mixed with a suitable quantity of salts of copper, such as
sulphate, chloride, azotate, and so forth, and into this mixture are to be
introduced strips of copper perfectly clean, and the latter after a certain
time will precipitate all the iodine set free by the reaction, and also
decompose the cupric iodide formed. There is obtained as a final result
of this operation proto-iodide of copper without the least mixture of free
iodine. The supernatant liquor is then decanted and the precipitate
washed by decantation and then collected on a filter if it is desired in a
dry state, in the contrary case it is better to leave it in the flask with
a little water, whichever method is adopted the cupreous iodide will be
decomposed by azotic acid, the fodine immediately becomes free, vapors
are disengaged, and the azotate of copper is formed; the iodine obtained
is amorphous, it agglomerates readily into a single mass which should
be divided in order to wash it well, it is then allowed to drain, and
dried.
When these operations are accomplished the product is pulverized and
placed in contact with sulphide of carbon, and the mixture is frequently
and violently agitated. If the iodine still contains water it will float on
the solution, and it should then be separated by means of a funnel pro-
vided with a tap. The solution of iodine in sulphide of carbon should
then be submitted to a very low temperature, and the iodine will pre-
cipitate itself in part in the form of beautiful crystals; a part of the
iodine will remain in solution in the sulphide of carbon.
When a continuous manufacture is carried on this solution will serve
afresh to dissolve the amorphous iodine obtained in the following
operations. Other means of separation are herein-after indicated:-
To obtain the iodine in a rapid manner there is no need to prepare the
cupreous iodide completely at once, it is sufficient to mix the soluble
iodide with the salt of copper and then add azotic acid in a slight excess

page_text: In all these operations the apparatus will be arranged in such a 2
manner that the sulphide of carbon can be conveniently collected.
Instead of dissolving the amorphous iodide in sulphide of carbon it is
also possible to cause it to crystallize by sublimation.
The salt of copper floating on the iodine set free will be collected in
order to be used again in such a manner that actually the only expense
consists in the quantity of azotic acid employed for the decomposition of
the cupreous iodide.
With a little practice it is possible to commence with a very small
quantity of salt of copper, to add a suitable proportion of iodides, to
decompose the cupreous iodide by azotic acid, to add immediately a 8
fresh portion of iodide, to decompose the cupreous iodide, and to
continue in the same manner until the desired operation has been com-
pleted. It it not always however advantageous to operate in this
manner because of the quantity of water which finally weakens the