IMPROVEMENTS IN TREATING SAC-
Year: 1874

page_text: LETTERS PATENT to Charles Haughton Gill and Francis Neison
Girdlestone Gill, both of 6, Christian Street, in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN TREATING SAC-
PROVISIONAL SPECIFICATION left by the said Charles Haughton Gill
and Francis Neison Girdlestone Gill at the Office of the Commis-
sioners of Patents, with their Petition, on the 29th September 1874.
We, CHARLES HAUGHTON GILL and FRANCIS NEISON GIRDLESTONE
GILL, both of 6, Christian Street, in the County of Middlesex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
TREATING SACCHARINE SOLUTIONS TO SEPARATE POTASH THEREFROM," to be as
follows:-
The object of this Invention is the removal of potash from saccharine
solutions. This object we attain by converting the said base (potash)
into neutral or acid oxalates by the addition of a quantity of oxalic acid,
either in the solid form or in solution, sufficient to combine with the
whole or part of the potasli present in the solution to be treated. Ou

page_text: stirring the mixture so made neutral or acid, oxalates of potash will
separate in the crystalline form, and can be removed from the liquid in
any convenient manner. The solution separated from the precipitated
oxalates is then neutralized by addition of lime or whiting, whereby all
the oxalic acid remaining in solution is precipitated as insoluble oxalate i
of lime, which can be removed by subsidence or filtration.
The oxalic axid used can be recovered from the oxalates formed in this
process by any of the well-known methods, as, for example, the oxalates
of potash may be treated with milk of lime, and the oxalate of lime so
made separated from the solution of potash simultaneously formed and 1
decomposed, together with that portion made by neutralizing the sac-
charine solution by sulphuric acid in the usual manner. The solution
of potash can be evaporated in iron pans and obtained in the caustic
state, or can be converted into carbonate of potash by injection of
carbonic acid and then evaporated.
]
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Haughton Gill and Francis Neison Girdle-
stone Gill in the Great Seal Patent Office on the 27th March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CHARLES
HAUGHTON GILL and FRANCIS NEISON GIRDLESTONE GILL, both of 6, 2
Christian Street, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of September, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs, and successors, 2
give and grant unto we, the said Charles Haughton Gill and Francis
Neison Girdlestone Gill, Her special license that we, the said Charles
Haughton Gill and Francis Neison Girdlestone Gill, our executors,
administrators, and assigns, or such others as we, the said Charles
Haughton Gill and Francis Neison Girdlestone Gill, our 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
.

page_text: t
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
TREATING SACCHARINE SOLUTIONS TO SEPARATE POTASH THEREFROM," upon the
condition (amongst others) that we, the said Charles Haughton Gill and
Francis Neison Girdlestone Gill, our executors or administrators, by
an instrument in writing under our or their hands and seals, or under
the hand and seal of one of us or them, 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 Charles Haughton Gill, on behalf
of myself and the said Francis Neison Girdlestone Gill, 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 the removal of potash from saccharine
solutions. This object we attain by the addition to the saccharine
solution of oxalic acid, in the state of powder or of hot or cold solution,
in quantity sufficient to form the oxalate, binoxalate, or quadroxalate of
potash, or of a mixture of these salts, which being comparatively little
soluble crystallise out more or less completely, and we prefer to work in
the following manner:-To the cool or cold syrup of convenient density
(say 25 to 35 degrees of Beaumé's hydrometer) contained in a suitable
vessel, provided with some means of stirring its contents, we add a
quantity of oxalic acid, in hot or cold solution or in powder, equal to 63,
or preferably to 126 lbs. (or even 252 lbs.) of the crystallised acid for
each 39 lbs. of potassium present in the syrup operated on.
We keep
the mixture stirring till the reaction is judged to be complete (say,
an hour), and then either allow it to stand at rest till it is found that the
crystalline oxalates of potash have settled to the bottom of the liquid, or
filter off the liquid from the precipitate. The clear syrup is then drawn
off into another vessel, also provided with stirring gear, and is there,
together with the portion of syrup separated from the magma of crys-
talline oxalates, neutralised by addition of milk of lime or whiting
stirred up in water. The neutral or nearly neutral syrup is then boiled,
bag filtered, and treated in the usual way.
The advantages of this process are, amongst others, that the removal
of a portion of the potash renders a quantity of sugar crystallisable,

page_text: :
which would otherwise go to form molasses; that on neutralisation by
lime or chalk, a very large proportion of the iron present is precipitated
and removed; that when soda salts are present in large quantities, a
portion of the soda will be precipitated as oxalate together with the
oxalates of potash, and will be removed from the solution with them;
that we can operate on saccharine solutions containing a very large pro-
portion of potash, since the precipitate formed on neutralising the acid
liquid separated from the oxalates of potash opposes no difficulties in the
way of filtration.
The expense of carrying out the process is reduced to a comparatively
small amount, either by selling the oxalate of potash obtained as such,
or by recovering the oxalic acid for re-employment, and selling the potash
separated at the same time. For the latter purpose it may be advisable
to work in the following manner:-The oxalate of potash (whether
mono, bin, or quodroxalate) is dissolved in hot water and decomposed by
a sufficiency of lime, carbonate of lime, or chloride of calcium, and the
insoluble oxalate of lime so prepared separated from the solution of
caustic potash, carbonate of potash, or chloride of potassium simul-
taneously produced. This oxalate of lime, together with that obtained
on neutralising the acid saccharine liquor separated from the original
precipitate of oxalates of potash, can then be decomposed by sulphuric
acid, and the oxalic acid thereby brought into solution. Afterwards the
oxalic acid is crystallised. The liquids containing the potash in solution
can likewise be evaporated and brought into a marketable form.
:
We do not claim this method of recovering oxalic acid from the
oxalates, but we claim the use of oxalic acid to separate potash from
saccharine solutions, substantially as described.
In witness whereof, I, the said Charles Haughton Gill, have herc-
unto set my hand and seal, this Twenty-fifth day of March,
in the year of our Lord One thousand eight hundred and seventy-
five.