IMPROVEMENTS IN THE REPINING OF RAW SUGAR
Year: 1871

page_text: LETTERS PATENT to Saint John Vincent Day, of No. 166, Buchanan
Street, Glasgow, in the County of Lanark, North Britain, Con-
sulting Engineer, for the Invention of "IMPROVEMENTS IN THE REPINING
OF RAW SUGAR." A communication from abroad by Richard
William Bender, of Boston, in the State of Massachusetts, United
States of America.
-
Sealed the 17th November 1871, and dated the 23rd May 1871.
PROVISIONAL SPECIFICATION left by the said Saint John Vincent
Day at the Office of the Commissioners of Patents, with his Petition,
on the 23rd May 1871.
I, SAINT JOHN VINCENT DAY, of No. 166, Buchanan Street, Glasgow,
in the County of Lanark, North Britain, Consulting Engineer, do
hereby declare the nature of the said Invention of "IMPROVEMENTS IN THE
REFINING OF RAW SUGAR," to be as follows, that is to say :-
This Invention relates to improvements in the refining of raw sugar,
and by means of the said improvements a superior product to what

page_text: has resulted from the processes now or heretofore in use is obtained,
and that at a diminished cost.
In carrying the said Invention into practice the raw sugar is first dis-
solved in water, the solution being preferably made as heavy as possible,
and after the addition, when necessary, of lime water or milk of lime or
phosphate of soda or other chemical equivalent (but preferably the phos-
phate of soda), in the proportion of one to three parts by weight to each
thousand parts by weight of raw sugar, the solution, without filtration
or settling, is boiled down in a vacuum pan until sufficiently concen-
trated for crystallization. The crystallization may be effected in the
vacuum pan, or the concentrated syrup may be taken off to crystallizing
vats and there left until the granulation has sufficiently progressed. At
this stage there is obtained an admixture of comparatively pure, sugar
crystals contained in the more impure syrup, and by putting the said
admixture into a centrifugal machine the crystals are by the centrifugal
action freed from a considerable amount of the syrup. To the crystals
contained in the basket of the centrifugal machine a wash either of pure
water or of water having sugar dissolved in it is applied, which has the
effect of forming the crystals more perfectly, producing a sugar product
which may be designated No. 1, and a syrup product No. 1. This syrup
product is again crystallized and treated in the manner herein-before
set forth, the result being sugar product No. 2 and syrup product No. 2.
The process herein-before set forth is successively applied to the syrup
product obtained after each treatment, until the syrup is brought to so
weak a state that it fails to crystallize, and in which condition it is
considered as molasses.
The several sugar products obtained in the manner herein-before
described are next dissolved in water, for the purpose of separating from
them the insoluble impurities by filtration through cloth or its equi-
valent. Blood may be added to the solution to facilitate filtration as
the viscous substances have been freed from the crystals, and from the
precipitates by the action of the centrifugal machine, and the precipitates
having obtained a greater degree of consistency by the prolonged
exposure to heat in the vacuum pan, the filtration proceeds with greater
facility even without the use of blood. The filtrate thus obtained is a
cane sugar solution of considerable purity, both fitted to preserve itself
during subsequent treatment and with less liability to loss, and which
by crystallization in vacuum pans, and purging in centrifugal machines

page_text: or in moulds yields a fair commercial product. It is preferred however
to give the filtrate an additional filtration through animal charcoal or
bone black.
SPECIFICATION in pursuance of the conditions of the Letters. Patent,
filed by the said Saint John Vincent Day in the Great Seal Patent
Office on the 18th November 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, SAINT JOHN
VINCENT DAY, of No. 166, Buchanan Street, Glasgow, in the County
of Lanark, North Britain, Consulting Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of May, in the year
of our Lord One thousand eight hundred and seventy-one, in the 35th
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Saint John Vincent Day, Her special license
that I, the said Saint John Vincent Day, my executors, administrators,
and assigns, or such others as I, the said Saint John Vincent Day,
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 "IM-
PROVEMENTS IN THE REFINING OF RAW SUGAR," a communication to him from
abroad by Richard William Bender, of Boston, in the State of Massa-
chusetts, United States of America, upon the condition (amongst others)
that I, the said Saint John Vincent Day, 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
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 Saint John Vincent Day, 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 :-
The said Invention relates to an improvement in refining raw sugar,
by which improvement I am enabled not only to produce a superior

page_text: product to what has been obtained by the processes now or heretofore
in practice, but to produce such product at a less cost than has been
heretofore possible.
In practising my Invention I first dissolve the raw sugar in water,
making the solution as heavy as expedient, and after the addition of a
sufficient quantity of lime water, milk of lime, saccharite of lime,
phosphate of soda, or other chemical equivalent, the solution, without any
filtration or settling, is boiled down in the vacuum pan till sufficiently
concentrated for crystallization. The crystallization may be effected in
the pan itself, or the concentrated syrup may be run into crystallizing
vats and left until granulation has sufficiently progressed. I have now
a mixture of comparatively pure sugar crystals contained in the more
impure syrup. Putting this mixture into a suitable centrifugal machine
(revolving, say, at the rate of fifteen hundred revolutions per minute),
these crystals, by the centrifugal force, are freed from most of the syrup,
or from a very large amount of it. I then apply to the crystals in the
centrifugal a wash, either of pure water or water having sugar dissolved
in it, which (by the revolutions of the centrifugal) will free the crystals
more perfectly, producing a sugar product which I call No. 1, and a
syrup product which I call No. 1. This syrup product is crystallized
again and treated as before, the results obtained being called sugar
product No 2, and syrup product No. 2. Repeating the operation with
successive results, I obtain (dependent, of course, upon the greater or
lesser strength of the original raw sugar,) sugar products Nos. 3, 4, and
even 5, the successive syrup products 3, 4, and even 5, growing weaker
and weaker in power to crystallize until failing to crystallize with
sufficient force it is considered as molasses.
By this process or succession of processes of crystallization I produce
a much purer sugar than the original raw sugar, and collect in the
molasses, by mechanical extraction, nearly the entire amount of soluble
impurities (such as various kinds of uncrystallizable sugar, saline
matters, and gelatinous substances) generally contained in the raw
sugar, and not precipitated by the chemicals employed in the first stage
of the process. These foreign matters or impurities being thus separated
from the sugar are prevented from injuring the product in the
subsequent treatment.
Although the sugar products 1, 2, 3, 4, 5, differ much in relative
appearance and quality, yet they retain but a very slight per-centage

page_text: of the above-mentioned soluble impurities, and even this per-centage
may be more or less decreased by care in the boiling operations and
by skilful treatment in the centrifugal machines. They do contain,
however, all the insoluble impurities of an organic and inorganic nature
in the raw sugar as well as the precipitates caused by the action of the
above enumerated chemicals, as far as they do act on certain organic
or inorganic substances which were imparting to the sprups a slimy or
glutinous character, and which before crystallization were retarders
of crystallization, but are now partially or entirely harmless in that
respect.
I next dissolve the sugar products in water with a view of separating
from them the insoluble impurities contained therein by filtration
through cloth and other menstrua. Blood may be added to the solution
to facilitate filtration through cloth, but generally there will be but
little if any blood needed as the viscid substances have been freed from
the crystals and from the precipitates by the centrifugal machines, and
the precipitates having obtained more consistency, by the prolonged
exposure to heat in the vacuum pan, the filtration through cloth
proceeds with more facility, even with the use of but little or no blood.
The filtrate now represents a cane sugar solution of considerable
purity, both fitted to preserve itself during subsequent treatment, and
with less liability to loss; and the filtrate, by mere crystallization in
vacuum pans and purging in centrifugal machines, will yield a fair
commercial product. I prefer, however, to give to the filtrate an addi-
tional filtration through animal charcoal or bone black, by which
treatment I can produce a colourless liquor of great brilliancy and which,
in time, by recrystallization will produce a sugar of great beauty and
purity; and this result is obtained at the expense or by the use of but
a very small amount of "black," in comparison to what has to be used
by the refining processes now in vogue.
The purging of the crystallized refined product can be effected in
centrifugals or in moulds, and in either case with far greater facility
than in the old processes of refining. The resulting syrups, being only
slightly inferior in strength to the preceding liquor, can be worked up
at the option of the refiner, either by returning them to the preceding
liquor or crystallizing them by themselves.
In place, however, of subjecting the raw sugar to a preliminary
and partial purification by crystallization and purging in centrifugal

page_text: machines as herein-before described, I sometimes purge the raw sugar
in the centrifugal machines without previous crystallization, and thus
obtain the several sugar products and syrup products which are then
treated for final purification by solution and filtration as already
specified.
Having now described the nature of the said Invention and the system,
mode, or manner in or under which the same is or may be used or
practically carried into effect, I would observe in conclusion that what
I consider novel and original and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,
the refining of raw sugar by the improved processes or operations
herein-before described.
In witness whereof, I, the said Saint John Vincent Day, have
hereunto set my hand and seal, this Fourteenth day of November
One thousand eight hundred and seventy-one.