IMPROVEMENTS IN THE TREAT- MENT OF CERTAIN SALTS OF POTASH AND LIME
Year: 1862

page_text: LETTERS PATENT to George Jordan Firmin, of Millwall, Poplar, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN THE TREAT-
MENT OF CERTAIN SALTS OF POTASH AND LIME."
Sealed the 23rd December 1862, and dated the 2nd October 1862.
PROVISIONAL SPECIFICATION left by the said George Jordan Firmin
at the Office of the Commissioners of Patents, with his Petition, on
the 2nd October 1862.
I, GEORGE JORDAN FIRMIN, of Millwall, Poplar, in the County of Middle-
sex, do hereby declare the nature of the Invention for "IMPROVEMENTS IN
THE TREATMENT OF CERTAIN SALTS OF POTASH AND LIME," to be as follows:-
My improvements in the treatment of certain salts of potash and lime
consist in utilizing the wasto liquors arising in the manufacture of tartaric
and citric acids to obtain therefrom valuable products, as follows:-The
usual method of manufacturing tartaric or citric acids is to saturate bi-tartrate
of potash or lemon juice with carbonate of lime, and to treat the resulting
tartrate or citrate of lime with sulphuric acid to obtain the tartaric or citric
acids.
In the manufacture of tartaric acid after the saturation of the bitartrate
of potash by carbonate of lime a neutral tartrate of potash is formed, which
in the usual method of manufacture is treated with muriate, sulphate, or
nitrate of lime to precipitate the tartaric acid in the form of tartrate of lime;
the supernatant liquor, consisting of a solution of muriate, sulphate, or nitrate
of potash, is separated from the precipitated tartrate of lime, and evaporated.

page_text: To obtain the potash salt, the tartrate of lime is repeatedly washed with water
to free it from impurities, and these washings are for the most part run away
as of no value.
My improvements consist in treating the first liquor (after the ordinary
decomposing of the neutral tartrate of potash) with sufficient sulphuric acid
to convert the undecomposed neutral tartrate of potash into bi-tartrate of
potash (which I then treat as in the original process). The liquor when cool
is separated from the tartrate of lime formed by this process, and evaporated
to obtain the potash salt; the tartrate of lime is added to that formed in the
original process.
The subsequent washings of the tartrate of lime, which all contain more or
less potash salt (but for the most part in quantities too small to be worth
evaporation in the ordinary manner) I collect in receivers, and use for dis-
solving fresh quantities of bi-tartrate of potash and for washing tartrate of
lime in place of using water. The citrate of lime formed in the ordinary
process of making citric acid is repeatedly washed with water to remove the
coloring and extractive matter and other impurities contained in the lemon
juice; these washings are run away as valueless.
My improvements consist in evaporating the highly colored washings by a
gentle heat to recover the citrate of lime held in solution (which citrate of
lime I treat in the usual manner for obtaining citric acid); the after washings
I collect in a receiver, and use in place of water in treating other lemon
juice.
I have hitherto only named carbonate of lime as the alkali for saturating
bi-tartrate of potash or lemon juice; but my improvements apply equally
where baryta or other alkali is used to combine with the tartaric or citric acid
to form a precipitate of the acid and the base. In these processes the
liquors may be separated from the precipitates by decantation or ordinary
filtration, but I prefer to use the vacuum filter patented by me on the 80th
November 1859, No. 2718.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Jordan Firmin in the Great Seal Patent Office on
the 2nd April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
JORDAN FIRMIN, of Millwall, Poplar, in the County of Middlesex, send 8
greeting

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of October, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-sixth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
George Jordan Firmin, Her special licence that I, the said George Jordan
Firmin, my executors, administrators, and assigns, or such others as I, the said
George Jordan Firmin, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after 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 "IMPROVE-
MENTS IN THE TREATMENT OF CERTAIN SALTS OF POTASH AND LIME," upon the con-
dition (amongst others) that I, the said George Jordan Firmin, my exe-
cutors 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 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 George Jordan Firmin, 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 fol-
lowing statement thereof, that is to say :-
My improvements in the treatment of certain salts of potash and lime
consist in utilizing the waste liquors arising in the manufacture of tartaric and
citric acids to obtain therefrom valuable products as follows:-The usual
method of manufacturing tartaric or citric acid is to saturate bi-tartrate of
potash or lemon juice with carbonate of lime, and to treat the resulting
tartrate or citrate of lime with sulphuric acid to obtain the tartaric or citric
acid.
In the manufacture of tartaric acid, it is usual to take bi-tartrate of potash,
dissolve it in water, and add carbonate of lime; this produces a precipitate of
tartrate of lime, and leaves tartrate of potash in solution. The precipitate
having been separated and washed repeatedly with water is, as above mentioned,
decomposed with sulphuric acid to set free the tartaric acid. The tartrate of
potash left in solution is then treated with the muriate, sulphate, or nitrate of
lime. The sulphate is commonly used; this produces tartrate of lime, which
is precipitated and separated (and also treated with sulphuric acid as before),
and sulphate of potash which remains in solution; as, however, the reaction.

page_text: of the sulphate of lime is not complete, the liquor contains also some un-
decomposed tartrate of potash; it also contains some tartrate of lime, which is
to an appreciable extent soluble in the solution of sulphate of potash. These
salts of tartaric acid have heretofore been lost, for it is usual at once to
evaporate the solution, and send into the market the potash salt obtained.
According to my Invention, however, I recover the tartaric acid contained in
the liquid, and this 1 do by adding to it sulphuric acid. I prefer to proceed
as follows; I evaporate the liquor to a thin syrupy consistency, and then
allow it to cool; some of the potash salt crystallizes out, and this I separate
and treat, as herein-after mentioned. To the remaining liquor I add sulphuric
acid until tartrate of potash is no longer detected in the solution by the
ordinary tests; in this manner bi-tartrate of potash is produced, which being
nearly insoluble in cold water, falls. As a precipitate, it is separated and
reworked in the same manner as the bi-tartrate originally taken. The con-
centrated solution of sulphate of potash is then evaporated to dryness, and the
salt obtained, together with that previously crystallized out, is also treated
with sulphuric acid, but in this case sufficient acid is added not only to chango
any tartrate of potash which may be present into the bi tartrate, but also to
carry the process further, and set free the tartaric acid both from it and from
the tartrate of lime. I then filter the acid liquor from the salts, and wash
the same with a small quantity of water; the acid liquor and washing water
I take back to the commencement of the process where the tartaric acid
becomes neutralized by the carbonate of lime, forming tartrate of lime, which
mingles with that which is at the same time formed from the bi-tartrate of
potash which is being worked.
In place of conducting the operation in this manner, the bulk of the
sulphate of potash solution (resulting from the action of the sulphate of lime
on the tartrate of potash) may, without concentration and crystallization of
salts, be treated at once with sulphuric acid to convert the tartrate of potash
which the solution contains into bi-tartrate, but I find it more convenient
to proceed by the process of concentration and crystallization, as first
described.
In place of sulphuric acid other acid may be employed, but sulphuric is
the more convenient. In washing in the usual manner the tartrate of lime
produced in the process, the washings which are not sufficiently concentrated
to be worth evaporation I collect in reservoirs, and use for dissolving fresh
quantities of bi-tartrate of potash and for washing tartrate of lime in place of
using water.
The citrate of lime formed in the ordinary process of making citric acid is

page_text: repeatedly washed with water to remove the coloring and extractive matter
and other impurities contained in the lemon juice; these washings are run
away as valueless.
My improvements consist in evaporating the highly colored washings by a
gentle heat to recover the citrate of lime held in solution (which citrate of
lime I treat in the usual manner for obtaining citric acid); the after washings
I collect in a receiver, and use in place of water in treating other lemon
juice.
I have hitherto only named carbonate of lime as the alkaline earth for
saturating bi-tartrate of potash or lemon juice, but my improvements apply
equally where baryta or other alkaline earth is used to combine with the tartaric
or citric acid to form a precipitate of the acid and the base. In these pro-
cesses the liquors may be separated from the precipitates by decantation or
ordinary filtration, but I prefer to use the vacuum filter patented by me on
the 30th November 1859 (No. 2718.)
In witness whereof, I, the said George Jordan Firmin, have hereunto
set my hand and seal, this Twenty-seventh day of March, in the year
of our Lord One thousand eight hundred and sixty-three.
AT
GEORGE JORDAN FIRMIN. (..)
GEORGE JORDAN FIRMIN. (v.O.)