IMPROVE- MENTS IN OBTAINING IODIDE OF POTASSIUM WHEN TREATING CERTAIN METALS
Year: 1853

page_text: LETTERS PATENT to Farnham Maxwell Lyte, of Florian, Torquay,
in the County of Devon, Esquire, for the Invention of "IMPROVE-
MENTS IN OBTAINING IODIDE OF POTASSIUM WHEN TREATING CERTAIN
METALS."
Sealed the 6th October 1853, and dated the 26th July 1853.
PROVISIONAL SPECIFICATION left by the said Farnham Maxwell
Lyte at the Office of the Commissioners of Patents, with his
Petition, on the 26th July 1858.
I, FARNHAM MAXWELL LYTE, of Florian, Torquay, in the County of
Devon, Esquire, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OBTAINING IODIDE OF POTASSIUM WHEN TREATING CERTAIN
METALS" to be as follows:-
My Invention is based on the discovery that chloride of silver, when
added to a mixed solution of iodides and chlorides, produces double
decomposition, and iodide of silver subsides, leaving soluble chlorides
alone in solution, and consists in the application of this discovery to
the production of iodide of potassium in the process of silver refinery,

page_text: in which it has heretofore been usual to fuse chloride of silver with
carbonate of potassa, and it also consists in applying a like process
when treating mercury.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Farnham Maxwell Lyte in the Great Seal Patent
Office, on the 12th January 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
FARNHAM MAXWELL LYTE, of Florian, Torquay, in the County of Devon,
Esquire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of July, in the year
of our Lord One thousand eight hundred and fifty-three, in the seven-
teenth year of Her reign, did, for Herself, Her heirs and successors,
give and
grant unto me, the said Farnham Maxwell Lyte, Her special
licence that I,,the said Farnham, Maxwell, Lyte, my executors, adminis-
trators, and assigns, or such others as I, the said Farnham Maxwell
Lyte, 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
"IMPROVEMENTS IN OBTAINING IODIDE OF POTASSIUM WHEN TREATING
CERTAIN METALS," upon the condition (amongst others) that I, the
said Farnham Maxwell Lyte, 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 per-
formed, 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 Farnham Maxwell Lyte, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof (that is to say):

page_text: My Invention consists in the discovery that when the chlorides or
some soluble salts of certain metals are placed in contact with solutions
containing mixed iodides and chlorides double decomposition ensues,
and insoluable metallic iodides are formed, and that by continuing the
addition of the chlorides this continues so long as any soluable iodide
remains in the solution; also, that the insoluable iodide can afterwards be
converted into a metal and a soluable iodide by any of the processes in
use at present for the decomposition of metallic chlorides, as in refining
silver. For instance, I refine silver, and at the same time produce
iodide of potassium from such solutions, as bittern or matters which
contain these mixed iodides and chlorides. Having dissolved the silver
in nitric acid, and precipitated it with a soluble chloride, as chloride of
silver, I divest it of copper by washing with water. I then project the
the chloride so produced into the solution of mixed chlorides and iodides
(which, for brevity, I will call "mixed salts "), and continue the addition,
with frequent stirring, till on adding a portion of the chloride of silver
to a test sample of the liquid it ceases to become yellow. Then, to
insure all the silver being converted into iodide, I add a very small
portion more of the mixed salts, so that there may be a small excess of
iodine in the solution, rather than a trace of chlorine in the pre-
cipitate. The addition of ammonia facilitates the decomposition; so
also does heating the liquid. The iodide of silver thus produced I
convert into iodide of potassium and metallic silver by projecting it
when completely dessicated into a crucible containing fused carbonate
of potassa, according to the method now in use for the reduction of
the chloride, only that by my process iodide of potassium is formed
instead of the chloride as formerly, a valuable instead of a product of
little value.
By adding a soluable salt of lead to the mixed salts till all the iodine
is precipitated, and decomposing the iodide thus formed by the same
method, iodide of potassium is formed, which may be dissolved and
purified by re-crystallization.
The periodide of mercury (a most splendid pigment) is produced by
adding the bichloride of mercury to the mixed salts.
By these methods all the iodine is recoverable from the mixed salts,

page_text: whereas by the old process generally used a great deal was lost as
chloride of iodine.
Having thus described the nature of my said Invention, I would
have it understood that what I claim is, the mode of treating mixed
salts with certain metals, and manufacturing iodide of potassium, as
herein described.
In witness whereof, I, the said Farnham Maxwell Lyte, have
hereunto set my hand and seal, this Seventh day of January,
in the year of our Lord One thousand eight hundred and fifty-
four
Witness,
R. HODGSON.
FARNHAM MAXWELL LYTE. (L.S.)