IMPROVEMENTS IN THE MANUFACTURE OF TARTARIC AND CITRIC ACIDS, AND CERTAIN SALTS IN CONNECTION THEREWITH
Year: 1859

page_text: LETTERS PATENT to. George Jordan Firmin, of the Atlas ChemicalWorks,
Borough Road, Southwark, in the County of Surrey, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF TARTARIC AND CITRIC ACIDS,
AND CERTAIN SALTS IN CONNECTION THEREWITH."
Sealed the 20th January 1860, and dated the 30th November 1859.
PROVISIONAL SPECIFICATION left by the said George Jordan. Firmin at
the Office of the Commissioners of Patents, with his Petition, on the
30th November 1859.
I, GEORGE JORDAN FIRMIN. of the Atlas Chemical Works, Borough Road,
Southwark, in the County of Surrey, do hereby declare the nature of the
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF TARTARIC AND CITRIC
ACIDS, AND CERTAIN SALTS IN CONNECTION THEREWITH," to be as follows:-
In the ordinary method of treating these acids and their salts, they are in
course of manufacture freed from their impurities by subsidence or filtering
through textile fabrics. I use a vessel (with or without agitators, as may
be most convenient for the purposes hereafter mentioned,) in which vessel iş
placed a perforated false bottom,(orother arrangement to prevent the agitator,
if any, from disturbing thefilter bed;) between this and the bottom is arranged
a filter bed of sand, or crushed spa, or sulphate of baryta, or animal charcoal,
or other suitable material, which is placed upon a layer of bricks, stones,
coke, or other coarse filtering surface, the whole filter bed being previously
Price 8d1

page_text: washed in hydrochloric acid, to free it from any impurities that would interfere
with the processes; the filter is now filled to the level of the false bottom
and attached to a receiver which communicates with an air pump, and is
ready for operation, to which form of filter bed I make no claim separate from
carrying out my Invention. In the vessel described I place the tartrate or
citrate of lime, (I now speak only of the tartrate or citrate of lime in
illustration of my process, but it is equally applicable for tartrates or citratesof
baryta, or other salt forming an insoluble or nearly insoluble precipitate of the
tartrate or citrate of the base;) the tartrate or citrate of lime is now agitated
with water until it attains a proper consistency, when the precipitateis allowed
to fall, the clear top liquor is run off, and the precipitate subjected to pressure
. to remove the remaining liquor; the pressure may be obtained either by an
injection of steam into the receiving vessel or chamber, or from the air pump.
After the first washing I add water from time to time, either drawing it all
through the filter, or running off the supernatant liquor, and drawing only the
last portion through the filter; this washing I continue until the liquor is free
from color(of these washings I shall presently speak). The tartrate or citrate
being now washed is decomposed in the usual manner by sulphuric acid, and
subjected again to the filtering process described to separate the acid liquor
from the earthy sulphate. The acid solution is thenevaporatedand granulated
as described in the Specification of a Patent granted to me, and dated May 9th
1856, by preference, (but the ordinary method of crystalizing may be adopted,)
and passed over an exhausted surface to remove the liquor; the impure salt
is then melted in hot water, treated with a decolorizing agent, and filtered
through a bed similar to that before described. In the manufacture of tartaric
acid from bitartrate of potash, the resulting tartrate of potash may be treated
with sulphate of lime or other salt forming an insoluble tartrate and soluble
salt of potash, which may be separated by filtration; or the tartrate of potash
may be soparated from the insoluble tartrate, and treated by the process
patented by me June 24th 1851, for obtaining oxalate of potash; this oxalate
of potash solution after separating the bitartrate of potash formed by placing
the mixed salts over an exhausted surface is evaporated, and when it has
attained a proper density, is agitated until it cools and granulates, when I
place it over an exhausted surface to separate the mother water, which is
returned for a new operation. 2. The tartrate of potash may be treated with
sulphate of soda, and the resulting sulphate of potash and Rochelle salt
(tartrate of potash and soda) separated from each other by filtration, as
described; the Rochelle salt solution is then evaporated, granulated, and the
impure salt (separated from its mother water by filtration, as described,) is

page_text: dissolved in hot water with a decolorizing agent, again filtered and evaporated.
3. The tartrate of potash may be decomposed by other acids which precipitate
the bitartrate of potash, leaving a soluble salt of potash, which I separate as
described. The bitartrate of potash obtained by either of these processes, or
in its crude state, I dissolve and treat with a decolorizing agent, and filter
as described.
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 30th May 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
JORDAN FIRMIN, of the Atlas Chemical Works, Borough Road, Southwark,
in the County of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the 'Thirteenth day of November, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-third 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 thereafter
during the terin 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 TARTARIC AND CITRIC ACIDS, AND CERTAIN SALTS IN CON-
NECTION THEREWITH," upon the condition (amongst others) that I, the said
George Jordan Firmin, 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 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
following statement thereof, that is to say:-
This Invention has for its object improvements in the manufacture of tartaric

page_text: and citric acids, and certain salts in connection therewith, and consists in the
use, in various processes of such manufactures herein-after set forth of a-filter
consisting of a bed or layer of some finely divided and insoluble material
through which the liquids to be filtered are forced by forming a vacuum under
the filter bed, and allowing, the pressure of the air to exert itself on the
surface of the liquid above, or the pressure may be obtained by closing the
filter vessel at the top and forcing the liquid into this vessel by a pump, or
air may be forced into the vessel, or pressure may be obtained by means
of a head of liquid.
b
Figure 1 is a longitudinal section of a filter such as I prefer to employ; it
consists of a wooden vessel a, from the bottom of which a pipe 6 passes to a
vessel c, and a vacuum is maintained in this vessel by an air pump in connec-
tion with the pipe d, which enters this vessel. The vessel c should be made of
such a capacity as to contain all the liquid which it is required to filter at one
time; it is fitted with a glass tube guage c', to indicate the quantity of liquidit
contains. At a short distance above the bottom of the vessel a, a layer of
bricks e is laid, supported on other bricks f; the joints between the bricks e
are left open, no mortar or cement being used in laying them; on the bricks a
layer of pebbles g is placed, and over this a layer of fine sand; on the sand a
grating of wood h is placed, and the intervals between the bars of the grating
is also filled with sand which just covers the bars. The liquid to be filtered is
run into the vessel a, and a vacuum being formed in the vessel c, it speedily
passes through the layer of sand. The solid matter separated may be removed
by shovels from the filter, which is prepared to be again used by spreading a
thin layer of fresh sand on the wooden grating, or the precipitate may, if
desired, be stirred up with a small quantity of water by means of an agitator
with which the vessel a may be furnished.
Figure 2 shews a vertical section of a similar filter, constructed to work by
artificial pressure at the top, as already mentioned, in place of by vacuum
below; this filter is, as will be seen, fitted with an agitator. The filters are
prepared for use by washing them first with water, then with dilute hydro-
chloric acid, and again with water. I would remark that although I have
spoken of the use of sand to form the filter bed, other finely divided and in-
soluble matters'may be employed, as, for example, the sulphate of baryta, which
indeed, when it can be readily obtained in a suitable form, is to be preferred to
sand, as it is difficult to obtain sand free from alumina, which acts injuriously
on solutions of the acids to which this Invention relates. Raw cotton fibre
may also be conveniently employed when filtering concentrated solutions
which might be acted on injuriously by sand. I would remark that I make no

page_text: claim to the construction of filters in the manner above described, but only to
the employinent of such filters as herein-after mentioned in various processes of
the manufacture of tartaric and citric acids, and of certain salts in connection
therewith. When a precipitate of tartrate or citrate of lime or other insoluble
tartrate or citrate has been obtained by any process ordinarily practised, and
which requires to be washed to free it from impurities, I run the precipitate
mixed with water into the vessel a of the filter, I allow the precipitate.to sub-
side and run off the supernatant water; I then, either by vacuum or pressure,
cause the remaining water to pass through the filter; afterwards, by means of
an agitator, it is again mixed with water and the operation is repeated, and so
on till the precipitate is sufficiently purified; it is then again mixed up with a
small quantity of water, and run into another vessel to be decomposed with
sulphuric acid to set the tartaric or citric acid free in the usual manner. This
process of decomposition produces a precipitate of sulphate of lime (if lime be
the base with which the citric or tartaric acid was previously combined), and
this also I separate by filtration through a filter such as already described.
This filtered liquid is, by preference, evaporated and granulated by keeping it
agitated while it cools, as is described in the Specification of a Patent granted
to me and dated May 9th 1856. As the mother liquor will not run freely
away from the granulated mass, I employ to separate it the filter described and
shewn at Figure 1, but it is better, as the liquid is concentrated, to substitute
sulphate of baryta or cotton fibre for sand, and I lay on the surface of the
filter a linen cloth on which the granulated mass is evenly spread, and a
vacuum produced as already described. In this manner au impure acid is
obtained, this is dissolved in hot water so as to obtain a nearly saturated
solution, which is then decolorized with animal charcoal, and for this purpose
also I employ the filter above described, preferring to use a layer of cotton
fibre with another layer of animal charcoal upon it.
In the manufacture of tartaric acid from bitartrate of potash, a tartrate
of potash is produced by treating the bitartrate of potash with carbonate of
lime, which precipitates tartrate of lime, leaving the tartrate of potash in
solution; the resulting tartrate of potash may be treated with sulphate of
lime or other salt, forming an insoluble tartrate and soluble salt of potash, and
in this process, according to my Invention, I separate the insoluble tartrate
from the soluble potash by means of the filter already described; or the
tartrate of potash may,as is described in the Specification of my Patent, dated
June 24th 1851, be treated with oxalic acid, so as to obtain oxalate of potash
and bitartrate of potash, the latter of which, not being very soluble, falls as
a precipitate, and this also, according to my present Invention, I separate by

page_text: filtration, with the filter already described. The oxalate of potash is evapa-
rated, granulated, and separated from its mother liquor by filtration, as has
been described in respect of tartaric and citric acids, or a concentrated solution
of the tartrate of potash may be treated with sulphate of soda in such pro
portions as to produce sulphate of potash and tai trate of potash and soda. As
the sulphate of potash is not very soluble it falls as a precipitate, and this pre-
cipitate is separated by filtration with the filter described. The Rochelle salt
is evaporated, granulated, separated from mother liquor, redissolved, and
decolorized in all respects as described in respect of tartaric and citric acids,
the filter being employed, as described, to separate the mother liquor from
the granulated mass, and in the decolorizing process; or the solution of
tartrate of potash may be treated with other acids in place of oxalic acid, and
the process carried on as before.
Bitartrate of potash produced by either of the methods above described
requires to be decolorized before it is fit for the market; for this purpose the
bitartrate of potash is dissolved by boiling in water (sufficient water being
used for the purpose), and the solution is filtered through animal charcoal, and
according to this Invention a filter, such as I have described, is made use of,
the animal charcoal being employed in the manner already described as
respects the decolorization of tartaric and citric acids. In order to prevent
the salt crystallizing in the filter I keep the same heated by steam pipes;
it is a convenient arrangement to substitute a grating made up of steam
pipes for the wooden grating shewn in the Drawing.
The process above described is also applicable to the treatment of crude
bitartrate of potash.
In witness whereof, I, the said George Jordan Firmin, have hereunto
set my hand and seal, this Twenty-eighth day of May, in the year
of our Lord One thousand eight hundred and sixty.
GEORGE J. FIRMAN.
(L.S.)