IMPROVEMENTS IN THE TREATMENT OF SUGAR AND OF CANE JUICE
Year: 1874

page_text: LETTERS PATENT to James Duncan, of Mincing Lanc, in the City
of London, Sugar Refiner, for the Invention of " IMPROVEMENTS IN THE
TREATMENT OF SUGAR AND OF CANE JUICE."
Scaled the 28th July 1874, and dated the 8th June 1874.
PROVISIONAL SPECIFICATION left by the said James Duncan at the
Office of the Commissioners of Patents, with his Petition, on the
8th June 1874.
I, JAMES DUNCAN, of Mincing Lane, in the City of London, Sugar
Refiner, do hereby declare the nature of my said Invention for "IMPROVE-
MENTS IN THE TREATMENT OF SUGAR AND OF CANE JUICE," to be as follows:-
:―
Sugar, but more especially cane sugar, contains more or less glucose.
The glucose prevents the crystallization of the crystallizable sugar, and
its removal is a matter of considerable importance.

page_text: When a solution of cane sugar is heated with an excess of caustic
lime the whole of the glucose is destroyed, but the lime must be removed
before the solution can be refined.
My Invention consists in the employment of dilute sulphuric acid for
the purpose of converting the lime into sulphate of lime with the
following result:-
In the case of raw cane sugar the sugar is melted to a density of about
25° Beaumé. The amount of glucose is then determined, and about an
equal weight of lime to the amount of glucose is added to the solution.
The whole is then well mixed and heated. I have found a temperature
not exceeding 170° Fahrenheit to be most beneficial for this purpose.
When the glucose is destroyed the lime is nearly all converted into
sulphate by the addition of dilute sulphuric acid. I prefer however to
leave the liquid slightly alkaline, and to neutralize the rest of the alkali
with sulphate of alumina, which is added until the solution is decidedly
acid. This part of the process should be conducted rapidly, and as soon
as the liquid is found to be acid chalk or whiting is to be added so as to
completely neutralize the mineral and organic acids. The solution is
then heated and filtered, and passed through the usual stages of the
refining process.
Although raw cane sugar is herein-before mentioned this process is

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Duncan in the Great Seal Patent Office
on the 5th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
DUNCAN, of Mincing Lane, in the City of London, Sugar Refiner, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day. of June, in the year of
our Lord One thousand eight hundred and seventy-four, in the
37th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said James Duncan, Her special license
that I, the said James Duncan, my executors, administrators, and
assigns, or such others as I, the said James Duncan, my executors,
administrators, or 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 THE TREATMENT OF SUGAR AND OF CANE JUICE," upon the condition
(amongst others) that I, the said James Duncan, my executors or
administrators, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said Inven-
tion, 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 James Duncan, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement, that is to say :-
Sugar, but more especially cane sugar, contains more or less glucose.
The glucose prevents the crystallization of the crystallizable sugar, and
its removal is a matter of considerable importance.
When a solution of cane sugar is heated with an excess of caustic
lime the whole of the glucose is destroyed, but the lime must be removed.
before the resolution of sugar can be refined.

page_text: '
Now my Invention consists. in the employment of dilute sulphuric
'acid for the purpose of converting the lime contained in the solution of
sugar into sulphate of lime with the following result :—
In the case of raw cane sugar the sugar is melted to a density of about
twenty-five to thirty degrees Beaumé. The amount of glucose is then
determined, and about an equal weight of lime to the amount of glucose
is added to the solution. The whole is then well mixed and heated. I
have found a temperature not exceeding 170° Fahrenheit to be most
beneficial for this purpose.
When the glucose is destroyed the lime contained in the solution is
nearly all converted into sulphate by the addition of dilute sulphuric
acid. I prefer however to leave the liquids slightly alkaline, and to
neutralize the rest of the alkali with sulphate of alumina, which is added
until the solution is decidedly acid. This part of the process should be
conducted rapidly, and as soon as the liquid is found to be acid chalk or
whiting is to be added so as to completely neutralize the mineral and
organic acids. The solution is then heated and filtered, and passed
through the usual stages of the refining process.
Although raw cane sugar is herein-before mentioned this process is
also applicable to the treatment of raw beet sugar and the sugars of the
date palm.
In treating cane juice I proceed in the same manner, only instead of
leaving the liquid alkaline I make it acid by means of sulphuric acid,
and neutralize the excess of sulphuric acid with sulphite of lime, which
tends to improve the color of the sugar, but the juice may be treated in
the same way as the raw sugar solutions, and sulphurous acid added
before boiling.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
First. The reduction or removal of the glucose contained in sugar,
cane juice, or other saccharine solutions by means of lime, and the
neutralization or precipitation of the excess of lime by means of sulphuric a
acid or of sulphate of alumina, as herein-before described.

page_text: Second. The neutralization of the free acids or of sulphate of alumina
employed or arising in the course of the foregoing process by means of
carbonate of lime or with sulphite of lime, as herein-before described.
In witness whereof, I, the said James Duncan, have to this my
Specification, set my hand and seal, this First day of December
One thousand eight hundred and seventy-four.
JOHN HENDERSON THOMSON, Witness.
JAMES STRCHAN, Witness.
JAMES DUNCAN. (L.S.)