IMPROVEMENTS IN THE MANUFACTURE AND REFINING OF SUGAR
Year: 1877

page_text: LETTERS PATENT to Hunter Henry Murdoch, of No. 7, Staple Inn, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE AND REFINING OF SUGAR." A communication from abroad
by Robert Stothert Kirkpatrick, of Brussels, in the Kingdom of Belgium, Civil
Dreineer
Sealed the 8th February 1878, and dated the 10th December 1877.
PROVISIONAL SPECIFICATION left by the said Hunter Henry Murdoch
at the Office of the Commissioners of Patents on the 10th December 1877.
HUNTER HENRY MURDOCH, of No. 7, Staple Inn, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN THE MANUFACTURE AND REFINING OF SUGAR.'
[A communication from abroad by Robert Stothert Kirkpatrick, of Brussels, in the
Kingdom of Belgium, Civil Engineer.]
This Invention consists of the improvements herein-after described in the manu-
facture and refining of sugar, and is applicable to the manufacture and refining of
sugar either from cane juice or beet juice, or other saccharine juices or syrups.
The objects of the said Invention are,-
1st. To purify the syrups of the 2nd, 3rd, 4th, and subsequent jets so that the
sugars obtained from them shall be equal in purity to the sugars of the first jet.
2nd. To obtain from the raw materials sugars which at the 2nd and subsequent
jets shall be of a better quality than would be obtained by any of the ordinary
processes.
3rdly. To diminish the quantity of animal charcoal which has to be employed
in the treatment of the raw materials in order to obtain white sugars therefrom.
4thly. To reduce the cost of the process of extracting or manufacturing sugars
from the juices or other raw materials.
5thly. To obtain a larger rendement of pure sugar than has hitherto been
obtained from the like raw materials.
This Invention resembles in certain points a process for which Letters Patent
bearing date the 20th January, A.D. 1876 (No. 240), were granted to me; and the

page_text: said Invention also bears a certain resemblance to other processes which have been
proposed for the manufacture and refining of sugar. and notably to the ordinary
process for making sugar from beet juice; but there are certain other points in
which the present Invention differs essentially from previous processes. The main
points of resemblance are that both lime and carbonic acid are used, both of which
have been previously employed in sugar making and refining, the gassing being
continued to a certain definite extent only. In the present process, however, they
are used in a different manner.
The first part of the present Invention consists in the treatment of molasses
obtained from sugar, which has already been boiled either in the vacuum pan or in
any other way. It is well known that this molasses although it contains a very
large per-centage of sugar (sometimes as much as 65 to 70 per cent.) cannot be
reboiled in such a way as to extract the whole of the sugar, but on the contrary
the glucose and other impurities present acting upon the sugar decompose it, and so
give rise to an increased formation of glucose and consequent diminution in the
amount of crystallizable sugar obtainable. A further difficulty arises in consequence
of the concentration of the impurities in the molasses, which seriously retard the
boiling in the pan and impede the crystallization.
This first part of the present process consists essentially in defecating the molasses
from each jet (after it has been removed from the sugar) in a peculiar way, which I s
will proceed to describe. The object of this part of the Invention being to so far
purify the syrup or molasses thrown off from the sugar at each stage of the crystal-
lization, that the said syrup or molasses when boiled down shall as regards purity
be practically in the same condition as a fresh solution of sugar, or to put it in
another way, that the impurities which had been left in the original juice or syrup
having been concentrated by the evaporation, or concentrated, and crystallization
(which have had the effect of collecting nearly all the impurities originally present
in the comparatively small residue of syrup or molasses) shall be removed from
the said syrup or molasses so as to leave the sugar in the same relative state of
purity as it was at the first boiling, and so that instead of the 2nd jet sugar
being inferior to the 1st Ject it will be of the same quality.
The molasses or syrup from the 2nd jet syrup is again treated in the same way,
and thus a product of one uniform quality is obtained, and by this means the
necessity for the employment of animal charcoal is in great many cases obviated,
or where not obviated altogether the quantity necessary is diminished to a small
fraction only of the quantity which would be required under the ordinary processes,
and the destruction of the sugar in the boiling processes is prevented to some extent,
and an increased rendement is obtained.
In order to carry the process into effect lime, preferably in the form of milk or
cream of lime, is added to the syrup or molasses to be treated in such proportion
that the proportion of lime shall be sufficient to act as follows, viz., to combine
with any free glucose which may be present to neutralize any free acid which may
be present to combine with any organic acid which may be present in a state of
combination, or otherwise so as to form salts with these organic acids, to render
insoluble any matters which are capable of being coagulated by lime, and so to
separate them from the syrup or molasses, and after effecting all these objects to
leave an excess of lime sufficient to combine with from 5 to 10 per cent of the sugar
present, and form sucrate of lime. This necessary proportion of milk or cream of
lime is added while the syrup or molasses is cold, and while still cold the limed
syrup or molasses is subjected to the action of a current of carbonic acid gas, which
is forced into the lined syrup or molasses until a certain peculiar and well marked
gelatinous character is produced.
The essential features of this part of the process are that the current of carbonic
acid gas is passed through the cold limed syrup or molasses for a sufficiently long
time to cause a distinct and well defined gelatinization thereof, but the current of
gas is not continued long enough to decompose this gelatinized syrup or molasses,
and to separate the lime in the form of carbonate of lime. The gelatinous compound

page_text: does not consist of carbonate of lime, but of sucrate of lime, and probably carbonic
acid in some form of combination. The limed and gassed syrup or molasses is then
boiled for a short time (say from one to five minutes) by which boiling the gela-
tinous compound present is coagulated and forms another chemical compound or
other compounds of lime and sugar and carbonic acid, which in its or their congu-
lation or formation carries or carry with it or them much of the impurities present
in the syrup or molasses.
While the boiled syrup or molasses is hot, and preferably while it is as near
the boiling point as possible, it is filtered, preferably through a filter press in which
it can be filtered under pressure. The filtered syrup or molasses is regassed with
carbonic acid gas while it is hot, preferably while it is nearly at boiling point (or in
some cases it is regassed under pressure, as herein-after described), and is again
filtered while hot to separate the carbonate of lime formed. At this stage of the
process the current of gas is continued long enough to convert all the lime which
will combine with carbonic acid into carbonate of lime.
If necessary the purified syrup or molassos may be passed through animal charcoal,
of which far less will be required than under any ordinary process of sugar making
or refining, but whether this is or is not done the purified syrup or molasses will bo
more pure, and in better condition for boiling and crystallizing, and so making
sugar therefrom, than syrup or molasses treated by any process hitherto known.
The chief point in which the herein-before described process differs from the process
described in the aforesaid Specification, No. 240, A.D. 1876, is that whereas in that
Specification the use of lime once, and the treatment of the limed juice or liquor
with carbonic acid gas twice, first hot and then cold, was described, and whereas
in that Specification the application of the process to crude juice or liquor, or to the
solution formned by dissolving raw sugar is described.
The process herein-before set forth describes the treatment of syrups or molasses,
from which part of the crystallizable sugar has been already extracted, by liming
the said syrups or molasses, and treating them with carbonic acid gas while cold,
and after boiling and filtration, again treating them with carbonic acid gas while
hot, and in repeating this process of defecation as often as may be necessary upon
cach separate jet of syrup or molasses obtained, whether this syrup or molasses is
obtained from sugar which has originally been manufactured or refined, in accordance
with the aforesaid Specification, No 240, A.D. 1876, or not.
This Invention consists further of a modification of the process of 2nd gassing
herein-before described Whereas according to that process syrup or molasses, and
according to the process described in the aforesaid Specification, No. 240, of 1876,
saccharine juice or liquor is (after liming, gassing, boiling, and filtering) treated
while hot (and preferably while boiling, and under atmospheric pressure only)
a second time with carbonic acid gas in order to separate the residual lime from it.
According to this part of the Invention the juice, or liquor, or syrup, or molasses,
to be treated (this part of the Invention being applicable to syrup or molasses as
well as to the original cane juice or other sugar liquors) is put in a closed vessel,
such as, or similar to a steam boiler, and superheated so as to raise its temperature
above its ordinary boiling point, and is therein regassed a second time by forcing
the carbonic acid gas in under a pressure in excess of that due to the steam pressure
generated by the superbeated juice, or liquor, or syrup, or molasses, allowing the
excess of carbonic acid gas i.e., the part (if any) which does not combine with the
lime present to escape through a safety valve or other suitable appliance, so as by
this gassing under excess of pressure, as distinguished from gassing under atmospheric
pressure only, to cause a more perfect combination between the lime and the carbonic
acid gas, and consequently to separate the limo more completely from sucrate and
glucate of lime, and convert the sucrate of lime into sugar and carbonate of lime
and decompose the glucate of lime, thus setting free the sugar which has been
combined with the lime, in the form of sucrate of lime, and also setting free the
decomposition products resulting from the decomposition of the glucate of lime.
This regassed juice, or liquor, or syrup, or molasses, is filtered (preferably while

page_text: still under pressure), so as to separate from it the precipitated carbonate of lime
and the greater part of the decomposition products resulting from the glucate of
lime, and so to leave the juice, or liquor, or syrup, or molasses, in a state better
adapted for reboiling, because the excess of lime has been more completely removed.
If necessary the liquor may at this stage be passed through animal charcoal, and if
this be done a very small quantity of charcoal will be sufficient.
Another part of this Invention consists of an improved process of refining sugar.
A large proportion of the sugar made, such as those kinds known as Taal Zulu, and
Ilo Ilo, and other similar qualities, are of such an extremely low character that
a refiner is not able by the ordinary processes to extract from them more than 30 to
40 per cent. of good sugar suitable for consumption. In order to diminish the cost
of refining such sugar the processes herein-before described are or may be used, and
in addition the aforesaid or other raw sugars are treated as follows:-
Instead of bringing the low sugar to this country and dissolving it in water
according to the ordinary method of blowing up, as practised by refiners, it is
dissolved in cane juice (preferably warm), which has by preference been treated
with from one to three per cent of lime, so as to prevent it from being decomposed or
in any way acted upon by the heat, and then if necessary a further proportion of
lime is added to the solution so that the total proportion of lime shall be sufficient
to combine with and decompose all the glucose present, and combine with a sufficient
proportion of sugar to form sucrate of lime. The solution is then gassed with
carbonic acid gas, and the process is completed exactly in the same way as herein-
before described with reference to syrups and molasses. The essence of this part
of the Invention consists in dissolving low sugars in cane juice instead of water and
so avoiding the addition of the water ordinarily used in refining, which has to be
subsequently evaporated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Hunter Henry Murdoch in the Great Seal Patent Office on the
10th June 1878.
HUNTER HENRY MURDOCH, of No. 7, Staple Inn, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN THE MANUFACTURE AND REFINING OF SUGAR."
A communication from abroad by Robert Stothert Kirkpatrick, of Brussels, in the
Kingdom of Belgium, Civil Engineer.
This Invention consists of the improvements herein-after described in the manu-
facture and refining of sugar, and is applicable to the manufacture and refining of
sugar either from cane juice, or beet juice, or other saccharine juices or syrups, or
from the syrups, molasses, or treacle, obtained from sugars.
The objects of this Invention are,-
Firstly. To purify the syrups of the second, third, fourth, and subsequent jets so
that the sugars obtained from them shall be about equal in purity to the sugars of
the first jet.
Secondly. To obtain from the raw materials sugars which at tho second and
subsequent jets shall be of a better quality than would be obtained by any of the
ordinary processes.
Thirdly. To diminish the quantity of animal charcoal which has to be employed
in the treatment of raw materials in order to obtain white sugars therefrom.
Fourthly. To reduce the cost of the process of extracting or manufacturing sugars
from the juices or other raw materials.
Fifthly To obtain a larger "rendement" of pure sugar than has hitherto been
obtained from the like raw materials.
This Invention resembles in certain points a process for which Letters Patent
bearing date the 20th January, A.D 1876, No 240, were granted to me, in the
Specification of which Letters Patent a certain process or processes for the manu-
facture and refining of sugar from beet juice and other saccharine juices, and from
raw sugar, was or were described. In the present process lime and carbonic acid
gas (both of which have been used before in sugar making and refining, see the
Specification of the aforesaid Patent, No. 240, A. Ď. 1876), are employed in a novel
manner and upon different materials.
The first part of the present Invention consists in the treatment, as herein-after
described, of syrups or molasses obtained by draining or centrifugalling from sugar
which has already been boiled either in the vacuum pan or in any other way, and
specially of syrups or molasses obtained by draining or centrifugalling from sugar
which has been manufactured or refined according to the processes described in the
Specification of the Patent No. 240, A D. 1876.
It is well known that syrups or molasses although they contain a large per-
centage of sugar (sometimes as much as 65 to 70 per cent.) cannot be reboiled in
such a way as to extract the whole of this sugar by crystallization, but that on the
contrary the glucose and other impurities present acting upon the sugar decomposes
it and so give rise to an increased formation of glucose, and consequent diminution
in the amount of crystallizable sugar obtainable. This increased formation of
glucose, and the consequent diminution in the amount of crystallizable sugar
obtainable, do not take place so readily when the sugar from which the syrups or
inolasses is obtained has been originally manufactured or refined according to the
process described in the Specification No. 240, A.D. 1876, as when the sugar has
been manufactured or refined in the ordinary way, and this is the reason that the
process described in the present Specification is inore applicable to the syrups or
molasses obtained from the sugar which has been manufactured or treated according
to one of the processes described in the Specification No. 240, A.D. 1876, than to
other syrups or molasses.
This part of the present Invention consiste essentially in defecating in a peculiar
way, as herein-after described, the syrups or molasses obtained from each jet after

page_text: the said syrups or molasses have been removed from the sugar The objects of
this part of the Invention are to so far purify the syrups or molasses thrown
off after each successive jet of sugar has been obtained that the said syrups or
molasses when again boiled down shall, as regards purity, be practically in the same
condition as a solution of sugar defecated for the first jet, or in other words, that the
impurities which remained in the original juice syrup or solution of sugar, and
which have been concentrated by the evaporntion of the water and the crystalliza-
tion of the sugar, shall be removed from the syrups or molasses thrown off from the
crystallized sugar so as to leave the remaining dissolved sugar in the same relative
degree of purity as it was at the first boiling, and so that instead of the second jet
sugar being inferior to the first jet sugar it will be of nearly or quite as good
quality.
The molasses or syrup from the second jet sugar is also defecated, as heroin
described, and thus a product of uniform purity is obtained, and by this means the
necessity for the employment of animal charcoal is obviated unless a white sugar is
required, or where the use of animal charcoal is not altogether obviated the quantity
is diminished to a small fraction only of the quantity which would be required
under the ordinary processes, or under the process described in No 240, A.D. 1870,
and the destruction or decomposition by boiling of the sugar contained in the
molasses is to some extent prevented, and an increased "rendement" is thereby
obtained.
The material to which this part of the Invention is applied is not cane juice, or
beet juice, or a solution of raw sugar, but it is the molasses or syrup which has been
obtained from the manufacturing or refining of sugar by ordinary processes, and
preferably by the process described in my aforesaid Specification, No. 240, A.D. 1876,
but the proportion of lime to be used, and the mode of treatment to be adopted,
differ materially from those described in the said Specification.
In order to carry this part of the Invention into effect lime which has been
slacked with water and diluted so as to form milk or creain of limo is added to the
syrup or molasses to be treated in such proportion, that the proportion of lime shall
be sufficient to act as follows, viz, to combine with any freo glucose which may be
present, to neutralize any free acid which may be present, to combine with any
organic acid which may bo present in a state of combination, or otherwise, so as to
form salts with these organic acids, to render insoluble any matters which are
capable of being coagulated by lime, and so to separate them from the syrup or
molasses, and atter effecting all these objects to leave an excess of lime sufficient to
form enough suciate of lime to render filtration casy; thus, for instance, in order to
carry the process into effect in the case of first jet syiup or molasses obtained from
sugar which has been treated according to the process described in the aforesaid
Specification, No. 240, A.D. 1876, the said syrup or molasses having a specific
gravity of about 1330 or 38° Baumé, and containing about 50 per cent. of sugar,
not more than 1 per cent. of glucose and about 2 per cent. of matters capable of being
coagulated or precipitated by lime, the syrup or molasses should first be diluted by
mixing it with water until its specific gravity is reduced to about 1110 to 1130, or
15° to 18° Baumé, and lime in the form of milk or cream of limo is then added in
such quantity as to be equivalent to from 8 to 10 per cent. on the sugar present, or,
say, from 2 to 21 per cent. on the total quantity of diluted molasses. The diluted and
limed syrup or molasses should then have a specific gravity of about 1080 to 1110,
say, 12° to 15° Baumé.
When the organic impurities are less in quantity the syrup or molasses need not
be diluted to the same extent, but only sufficiently to admit of the liquor being
readily filtered after gassing and boiling, as herein-after described.
-
In the case of third or fourth jet syrups or molasses containing a larger proportion
of impurities it is necessary to add a larger proportion of lime relatively to the
crystallizable sugar present, in order to ensure defecation; thus, for instance, in the
case of a third jet syrup or molasses, which has been obtained from sugar treated
according to the process described in the aforesaid Specification, No. 240, A.D. 1876,

page_text: having a specific gravity of about 1330, equal to about 38° Baumé, and containing
about 45 per cent of sugar, from 1/, per cent. to 1 per cent. of glucose, and 3 or 4
per cent. of organic matters capable of being coagulated or precipitated by lime, and
in addition an increased proportion of those organic colouring matters which impede
the crystallization of the syrup or inolasses, the proportion of the lime relatively to
the crystallizable sugar should be increased to from 12 to 15 per cent. on the sugar
present. This increase in the proportion of lime renders it desirable to dilute the
syrup or molasses more than in the case of first jet syrup or molasses already referred
to, say, to a specific gravity of from 1070 to 1080 or 10 to 12 Baumé. If the
dilution is less than this the liquid syrup or molasses gassed and boiled, as herein-
after described, will not filter freely, and consequently, although the filtrate will be
good, the filtration will be effected slowly and with difficulty.
If syrup or molasses of still worse quality is to be treated the proportion of lime
must be still further increased. The general rules are that every increase of glucose
or organic impurity necessitates an increased proportion of lime, and that the limed
syrup or molasses must be so diluted that after gassing and boiling it will filter
freely, and give a filtrate of a good colour. If this effect cannot be obtained at one
operation without excessive dilution the process must be repeated again on the same
sample of syrup or molasses In any case the milk or cream of lime is added while
the syrup or molasses is cold, and preferably after it has been diluted. While this
limed diluted syrup or molasses is cold it is subjected to the action of a current of
carbonic acid gas, which is forced into it until a well-marked gelatinized condition
is produced.
The essential features of this part of the process are that the current of carbonic
acid gas is passed through the cold limed and by preference diluted syrup or
molasses for a sufficiently long time to cause a distinct and well-defined gelatiniza-
tion, but the current of gas is not continued long enough to decompose the
gelatinous compound so formed, and thereby separate the lime in the form of
carbonate of lime.
The stage at which it is necessary to stop this gassing with carbonic acid gas
may be ascertained as follows:-A small portion of the limed and diluted syrup or
molasses which is being gassed must be taken from the bulk and boiled for a short
time, say, 1 minute, and immediately after boiling and while still hot the boiled
syrup or molasses must be filtered. If the gassing with carbonic acid gas has been
carried on to the proper stage the precipitate left upon the filter, if the filtration has
been effected without artificial pressure, will be a compact slimy mass, and if it has
been filtered under pressure, say, of 60 lbs. to the inch, it will assume the form of a
hard or pulverulent cake. In both cases the precipitate will contain some sugar,
both mechanically mixed and chemically combined.
The filtrate which passes through the filter will, if the process has been satisfac-
torily conducted, be of as good a colour as liquor of the first jet containing the
same amount of sugar in solution, and if it be tested by titrating it with dilute
sulphuric acid its alkalinity will be found to be equal to about 1 to 3 centimètre
cubes of 10 per cent sulphuric acid on 100 centimètre cubes of the filtrate, that is
to say, the residuum of lime in the filtrate is equal to from 03 to 30 per cent.
If the diluted syrup or molasses is very impure, i.e., if it contains more than the
usual proportion of glucose and other organic matters, the proportion of lime left in
the filtrate will be higher. The limed and diluted syrup or molasses having been
thus gassed to the proper extent (ascertained as above) is then boiled for a short
time, say, from 1 to 5 minutes, by which boiling the gelatinous compound present
is coagulated or decomposed, other chemical compounds of lime, sugar, glucose, and
carbonic acid gas being formed. These coagulated compounds must be separated
by filtration from the boiled syrup or molasses while it is still hot, and preferably
while it is as near the boiling point as possible. By preference the filtration should
be effected under pressure through a filter press. The residue left behind in the
filters will contain a small portion of the sugar chemically combined, a small portion
of the sugar in mechanical admixture, and nearly the whole of the impurities.

page_text: Some portion however of the glucose and of the organic acids and of the lime present
will pass through with the filtrate in a state of solution, but they can be partly
extracted therefrom in the following manner-The filtrate obtained from the
gelatinous compound by boiling and filtration in the manner above provided is re-
gassed with carbonic acid gas, and after gassing it is boiled so as to drive off the
excess of carbonic acid gas, and while still hot the carbonate of lime formed by this
regassing is separated either by allowing the regassed syrup or molasses to settle, or
by filtering it or both. At this stage the current of carbonic acid gas must be
continued long enough to convert into carbonate of lime all the lime which will
combine with the carbonic acid gas at the boiling temperature of the syrup, and the
object of the decantation or filtration is to separate this carbonate of lime from the
purified syrup or molasses, and so to free the filtrate from suspended matter.
If it is required to produce white sugar the purified syrup or molasses may at
this stage be passed through animal charcoal, in which case far less charcoal will be
required than under ordinary processes of sugar making or refining.
Another part of this Invention consists of an improved process for refining low
sugars In order to diminish the cost of refining such sugar, the processes herein-
before described are or may be used, and by this means the production of sugar
would be increased.
This part of the Invention, though applicable to the treatment of low sugars, can
be also applied in many cases with great advantage to the treatment of sugars of a
better quality, such for instance, as have been manufactured by the process described
in the Specification No 240, A D. 1876, or in this Specification, and to the syrups
or molasses obtained from sugar so manufactured.
Instead of dissolving the sugar or syrup in water according to the ordinary
method of blowing up as practised by refiners, it is dissolved or diluted with cane
juico or beet juice, preferably warm, which has by preference been treated with
from 1 to 3 per cent of lime.
From 10 to 20 per cent of sugar is added to the limed cane juice, in some cases
as much as 25 per cent, the exact proportion depending upon the purity of the
sugar and the good condition of the juice The proportion of syrup or molasses
added must be regulated by the specific gravity of the mixture so as to insure
efficient filtration; thus for instance, with Ilo Ilo or Taal sugar of very low
quality, and cane juice or beet juice of inferior quality, 10 per cent. will be the
largest quantity which could be advantageously added, while with sugar of a better
quality and cane juice or beet juice in good condition from 15 to 20 per cent.
may be added, and when the better classes of sugais are used and the cane or beet
juice is thoroughly fresh and good, as much as 25 per cent may be used. The process
of defecation is then sufficient to refine not only the cane or beet juice itself, but
the sugar which has been added to it as well.
This refining is effected as follows:-If enough lime has already been added to
the cane or beet juice to act as herein-before described, that is to say, to combine
with any free glucose which may be present, to neutralize any free acid which may
be present, to combine with any organic acid which may be present in a state of
combination or otherwise so as to form salts with these organic acids, to render
insoluble any matters capable of being coagulated by lime, and so to separate them
from the syrup or molasses; and after effecting all these objects to leave an excess
of lime sufficient to form enough sucrate of lime to render filtration easy, no further
addition of lime will be necessary, but if the proportion of lime is not sufficient for
all these purposes, or if part of the lime so added has become converted into
carbonate of lime by the action of the carbonic acid in the atmosphere so that there
is not enough lime to effect all the purposes herein-before mentioned, more lime in
the form of milk or cream of lime must be added, so that the total proportion of
lime present shall be sufficient for the aforesaid purposes. The solution of sugar in
limed cane juice or beet juice is then gassed with carbonic acid gas, and the process
is completed exactly in the same way as that herein-before described with reference
to syrups and molasses, that is to say, the solution of sugar in limed cane juice or

page_text: beet juice is gassed until the filtrate from a portion of the solution which has been
boiled and filtered while hot contains not more than 30 per cent., or less than .03 per
cent. of lime in an alkaline condition as determined by the ordinary process of
titration with dilute sulphuric acid.
If the sugar and cane juice or beet juice have been of good quality, the
minimum proportion of lime is all that should be present in the filtrate. If they
have been of very inferior quality the maximum proportion will sometimes be left.
The solution of raw sugar in limed cane juice or beet juice having been gassed
to this stage is boiled, filtered, regassed, allowed to settle or filtered, and then either
passed through animal charcoal, or concentrated in its then state exactly in the way
herein-before described.
A modification of the last-mentioned process may be carried out by dissolving
second, third, or fourth jet sugars manufactured from syrups or molasses which
have been treated as herein-before described in syrup or molasses diluted and
defecated as herein-before described, instead of in cane juice or beet juice.
According to this process a partially purified sugar is dissolved in a defecated
solution of sugar, and by this means the gravity of the said defecated solution of
sugar is increased, and a more concentrated solution formed, having preferably a
density of about 30° Baumè. The quantity of water to be evaporated is diminished
and consequently the expense of plant and working If the solution of sugar thus
obtained is filtered through animal charcoal, a very small quantity of charcoal will
be sufficient, and the filtered solution of sugar when evaporated will yield a sugar
of white colour and a high degree of purity.
Having thus described the nature of the Invention as communicated to me by my
foreign correspondent, and the manner in which the same is to be performed, I wish
it to be understood that I do not claim the use of lime and carbonic acid alone or in
combination in sugar refining when the same are used either in the mode ordinarily
adopted, or in the mode described in the herein-before referred to Specification,
No. 240, A.D. 1876, but what I claim as the said Invention are,―
Firstly. The defecation or clarification essentially in the manner herein-before
described of the successive jets of syrups or molasses obtained from sugar.
Secondly Dissolving sugars in cane juice, beet juice, or saccharine solutions for
the purposes and in the manner herein-before described.
In witness whereof, I, the said Hunter Henry Murdoch, have hereunto set
my hand and seal, this Seventh day of June, in the year of our Lord One
thousand eight hundred and seventy-eight.
Witness,
C. I. WALLS,
his Clerk.
H. H. MURDOCH. (L.S.)