IMPROVEMENTS IN THE MANUFACTURE OF SUGAR
Year: 1873

page_text: ´LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF SUGAR."-A communication
from abroad by Louis Joseph Frédéric Margueritte, of Paris,
France.
Scaled the 9th December 1873, and dated the 12th July 1873.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 12th July 1873.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THEe Manufacture of SUGAR," to
be as follows:-
:-
This Invention relates first to the purification of the second and third
products, whose market value, owing to the quantity of molasses or ash
they contain or yield has hitherto been depreciated to an extent dis-
proportionate to their actual inferiority.

page_text: The following is the method of operating :-I take beetroot syrup after
it has been defecated, filtered through charcoal and evaporated, or in other
words what is known as the first product, marking from 28 to 35 degrees
Beaumé, to which I add the second and third products it is desired to
purify. I would here observe that it must be borne in mind that this
syrup at 35° Beaumé being already saturated cannot dissolve any more
sugar.
After a sufficient lapse of time to allow the grains of sugar to become
moistened the mixture is worked up in a mixer which by the slight
friction thereby produced promotes the separation of the molasses.
adhering to the surface of the sugar, after which it is subjected to the
action of a centrifugal machine with a current of steam. In this
manner a very white and pure sugar is obtained. The syrup of course
becomes charged with the molasses by which the second and third
products were impregnated, and also collects the fine sugar which passes
through the meshes of the centrifugal machine in considerable quantity
now that the grains are deprived of their coating of molasses, by which
when previously centrifugaled they were prevented from passing out.
In any case the loss in weight of the sugar thus treated is only temporary,
the sugar being afterwards recovered.
The result of returning the molasses of the inferior products to the
primary syrup will be found to be of but little importance and without
any perceptible effect on the quantity or quality of the sugar ultimately
obtained. The process is thus a simple refining operation, consisting in
the employment of a whiter and purer liquor than the molasses it is
desired to displace, and as it possesses more fluidity it does not adhere to
the crystals which it purifies, but is entirely eliminated by the action of
the hydro-extractor and the steam.
It should be remarked that the liquor resulting from the direct evapo-
ration of beet-root syrup is obtained without the necessity of redissolving
any sugar which would require to be reconcentrated and purified, by an
extra series of operations, whereas this liquor serves in the ordinary
course of manufacture the same purpose, and possesses the same advan-
tages as a refiner's liquor without any of its objections. The clarification
or purification of inferior quality sugars may in this manner be very
quickly effected by the aid of the hydro-extractor, the time occupied in
which may by proper arrangement be rendered inconsiderable. The

page_text: purifying syrup should be used largely in excess of the sugar to be
treated, and be constantly renewed so that a maximum effect is main-
tained, this advantage being unobtainable with refiners' liquor.
It is evident that instead of employing the primary syrup the second
product may be purified by using the syrup drained from the first
product in the hydro-extractor, but with a less perfect result owing to
the smaller mass of liquid over which the impurities would be dis-
tributed.
The Invention further relates to a method of accelerating and
increasing the crystallization of sugar, and also of extracting sugar from
molasses by the employment of salts of soda, ammonia, baryta, lime,
strontian, manganese, iron, zinc, and other salts, which (being abundant
and low priced are suitable for the purpose) when added under certain
conditions to a saturated sugar solution at the ordinary temperature will
promote the more or less rapid crystallization of a portion of the sugar
contained. The quantity thus eliminated from the solution varies
according to the nature of the salt employed, and in certain cases is very
considerable. The action of the salt, whether favorable or not to the
crystallization, appears to depend rather on its base than on its acid.
Thus for example nearly all the salts of potash are unfavorable in
various degrees; salts of soda are either without effect or favorable,
while the salts of magnesia and those of manganese all produce such a
degree of crystallization as to greatly increase the product.
The salts most suitable for use on a large scale are sulphate of soda,
and among magnesian salts the sulphate and chloride of magnesium
obtained from sea water in inexhaustible quantities. Among man-
ganesian salts I use chloride of manganese, forming a residue of the
manufacture of chlorine, and the sulphate which may be readily pro-
duced from the. chloride; also sulphates of iron and zinc and their
chlorides, which are obtainable in sufficiently large quantities. .
It is unnecessary to include the salts formed from organic acids, which
are rare and expensive, not excepting the acetates. Nitrates and
ammonia salts may also be mentioned in the same category, including
nitrate of soda, they being all at a high price, although they, might be
subsequently utilized as fertilizers.
.
It is evidently unnecessary to treat the first product of the beet. or
cane, as this is at once convertible into sugar on being concentrated;

page_text: nor yet the second product, which crystallizes quickly and without
difficulty; but for treating third quality syrups and molasses especially
the process presents great advantages. The latter should always be
used for making experiments, which cannot fail to be decisive when
sugar is extracted from a product which has been put aside as useless
for the production of sugar by the ordinary mode of manufacture.
The following is the method of operation:-I take for example
sulphate of magnesia, which is very active, and is both abundant and
cheap. I add to the spent molasses (composed of 50 per
cent. of sugar,
15 per cent. of salts, and 20 per cent. of water) crystallized sulphate in
the proportion of 20 per cent. by weight, together with a little water to
make a solution of the sulphate, marking 100 degrees Beaumé. The
whole is then centrifugaled in a machine having cither unperforated
sides or very fine wire cloth. The sulphates of lime and potash precipi-
tated are retained, and the liquor is then filtered through charcoal and
evaporated in vacuo. After cooling a certain quantity of pounded sugar
is added to form nuclei, and the syrup is lastly subjected to the ordinary
temperature, alternately raising and lowering the heat, and after a few
days the crystallization becomes exceedingly abundant, and continues to
increase for some time, after which the hydro-extractor is again
employed.
The above comprises the whole operation, which is very simple.
The proportions of sulphate of magnesia or other salt employed will
vary according to the nature of the molasses and the results of
experience. The same conditions will apply to the use of chloride of
magnesium, and the sulphates and chlorides of manganese and other
salts. The chlorides possess the advantage of not forming sulphate of
lime, but their action would appear to be less prompt and efficient..
These various salts when added to the molasses react on those it originally
contained, and subsequently double decompositions and double salts are
produced, giving rise to combinations favorable to the crystallization of
the sugar, for which reason it is advantageous to employ sulphate of
magnesia, which precipitates in the form of sulphates the lime and
potash, and forms a corresponding quantity of salts with a base of
magnesia, all of which as has been before observed promote to a greater
or less extent the crystallization of the sugar.
The above method of treatment may be applied both to molasses and
thirds, and when employed for second quality products (although

page_text: with less advantage) it has for immediate effect to considerably increase
the yield of the second and third products, and at same time increase
the value of thirds, which become equal to seconds.
It has been seen that certain salts, when added to the molasses and
syrups, generally will effect the crystallization of a portion of the sugar
they contain, and that the nature of the base has a great influence on
the quantity of sugar deposited, while other salts, on the contrary, will
impede the crystallization to an extent which may be readily ascer-
tained.
.
"
Experience having shown that the action of salts generally with a
base of potash is to prevent crystallization it is important to climinate
the same as much as possible from the molasses or syrups. The
saccharine matter in which this elimination may most easily and
efficiently be effected is molasses, properly so called, as it is in the latter
product of the manufacture that are accumulated all the salts, among
which those of potash, which are the most prejudicial predominate.
Suppose molasses to yield 15 per cent. of sulphuric ash, representing
sulphate of potash, in order that the double decomposition may be
effected between the salts of potash and the sulphate of magnesia,
the latter salt must be added in the proportions of their respective
equivalents, that is to say 1089: 1395: 15 : × = 19.875, or in
round numbers 44 lbs. of hydrated sulphate of magnesia for every
220 lbs. of molasses. The sulphate of magnesia is first dissolved in a
small quantity of water and then poured into the molasses, which is
diluted to about 35 degrees Beaumé, the whole being at the ordinary
temperature. In this manner an abundant precipitate is immediately
formed consisting of sulphate of lime and sulphate of potash which are
separated by the aid of a centrifugal machine or filter press. The clear
liquor is then filtered through charcoal, and finally boiled to proof in the
ordinary apparatus. When cooled to about 90 or 100 degrees Fahrenheit
a nucleus of fine sugar is next added, and the crystallization at once
commences and becomes very abundant. This crystallization of the
sugar results from the elimination of the potash, the salts of which are
prejudicial, its place being filled by the magnesia, whose salts are favor-
able thereto. The same remarks apply in the case of lime.
Other sulphates, besides those of magnesia, will produce analogous
results, such as sulphates of soda, magnesia, zinc, or iron.

page_text: The chlorides, and among others chloride of magnesium, although
favoring the crystallization of the sugar in a solution of pure sugar, will
not eliminate the lime and potash, but will increase the amount of salts.
and consequently the density of the liquor at proof, and for this reason
they do not possess nearly the same advantages as the sulphates.
It is to be noted that the acid acts in each class of salts according to
its nature, and for this reason, generally speaking, the chlorides and
nitrates are less favorable than the sulphates.
It has been seen that the selection of the salt is an important point,
and that of all the salts which promote the crystallization of sugar
sulphate of magnesia is the one which furnishes the best. results by
reason of its base, which favors the crystallization, and of its acid which
eliminates the lime and potash (whose action is injurious) in the form of
insoluble sulphates.
It is evident that it is preferable to operate on molasses rather than on 1
the anterior products, because, as has been before mentioned, the salts in
molasses are at a maximum degree of concentration, and the effect of the
sulphate when added is immediate and final.
The sulphates of lime and potash are instantly precipitated, leaving
but small quantities to be afterwards deposited, which are soluble between 2
35 and 46 degrees Béaumé (proof point). On the other hand, should first
and second products be so treated at each boiling, and indeed throughout
the whole process of concentration the sulphates of lime and potash
would deposit in the worms and on the sugar crystals.
In all cases the sugar thus obtained should be freed from the sulphates 2
of lime and potash it contains, which deposit between 35 or 40 degrees
Beaumé and the proof point. This may be effected in two ways.
1st. The sugar may be re-dissolved, filtered through charcoal, and
evaporated; upwards of 80 per cent. of pure sugar being thus obtained.
The syrups from the centrifugal machine having been evaporated, are 3
then suddenly cooled to prevent the sugar from crystallizing and cause
the deposition of the sulphate of potash, which is afterwards separated
from the liquor by centrifugal action.
Or, 2ndly. The impure sugar is added to ordinary molasses brought to
the point of saturation, that is to say, in a condition in which it will not 3
dissolve the sugar. In this manner the sulphates alone are dissolved,

page_text: and after being centrifugaled the sugar will be found to be pure. The
molasses act as a kind of clarifying liquor, which not being saturated
with sulphates dissolves them, leaving the sugar intact, and having
effected this purification it may be treated in the usual course with
sulphate of magnesia.
It is evident that the syrups draining from the centrifugal machine
after the re-dissolution of the sugar purified by the first method, and
which contain sulphates, may also, like the clarifying liquor above
mentioned be returned to the general mass. of molasses to be treated.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 10th January 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of July, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, admi-
nistrators, and assigns, or such others as I, the said Alexander
Melville Clark, 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 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 MANUfacture of Sugar,” a communication to me
from abroad by Louis Joseph Frédéric Margueritte, of Paris, France,
upon the condition (amongst others) that I, the said Alexander Melville
Clark, 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

page_text: 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 Alexander Melville Clark, 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 (that is to say):-
It is probable that products of inferior quality (which are a con-
sequence of existing modes of manufacture) will gradually disappear as
progress is made in sugar making; and as it is to the interest of the
manufacturer to supply the market with pure white sugars only, they
will doubtless be induced to purify the second and third products (2emo
and 3m "jets"), whose market value, owing to the quantity of molasses
or of ash they contain has hitherto been depreciated to an extent dis-
proportionate to their actual inferiority and the cost of purification.
Many attempts to refine or improve them have been made but without
much success, and most sugar houses still bring low products into the
market, although it would seem that the principles of the ordinary
method of manufacture may be applied without much difficulty or
expense to effect the complete purification of the second and third
products (2nd and 3rd "jets"), which is a great desideratum in sugar
making. To attain this important result is the object of the present
Invention.
The following is the method of operation:-I take beetroot syrup,
after it has been defecated, filtered through bone black and evaporated,
or in other words, the first product or quality (1º jet) marking from 28
to 35 degrees Baumé, to which I add the second and third products it is
desired to purify. I would here observe that the syrup at 35 degrees
Baumé being already saturated cannot dissolve any more sugar, but
experience will indicate what degree between 28° and 35° is best.
After a sufficient lapse of time to allow the grains of sugar to become
moistened, the mixture is worked up in a mixer in order by the friction
produced to fluidize the molasses adhering to the surface of the sugar,
after which it is subjected to the action of a turbine or centrifugal
machine and a jet of steam. In this manner a very white and pure
sugar is obtained.
The fine liquor or syrup (clairce) of course becomes
charged with the molasses by which the second and third products are
impregnated, and also collects the fine sugar, which passes through the

page_text: meshes of the turbine in considerable quantity now that the grains are
deprived of their coating of molasses, by which when previously
turbined they were prevented from passing out. In any case the loss in
weight of the sugar thus treated is only temporary, the sugar being
afterwards recovered.
"
The return of the molasses of the low products into the primary
syrups will have no appreciable effect on the quantity or quality of the
sugar ultimately obtained. For example, assuming a masse cuete"
(or
mass, consisting of grain, sugar, and syrup) first quality (1* "jet"),
› yielding the following products :—
Thus in 100 parts of first (1st " jet") the proportion of second (2nd
"jet") is 18.1 containing 1.5% or 0.27 of ash, and of third (3rd "jet ")
6.2 containing 3.11% or 0·18 of ash, making together 0.45 of ash, which,
multiplied by the co-effecient 5 gives 2.25 of molasses. Thus if in the
course of manufacture syrup yielding 100 of the first quality is employed
only to treat the proportions of second and third qualities it contains
already (which are respectively, 181 or 6.2, or together 24-3 of low.
products), the additional amount of ash introduced would not exceed a
half per cent., and have scarcely any influence on the purity of the first
product to be obtained and but little on the second and third products,
which are themselves to be purified in like manner.
This small quantity
of ash (0.45) introduced by the second and third products will no doubt
permit a much larger proportion of the latter to be mixed with the first
syrup, especially at the beginning of the campaign, when they are
easier to work and of greater purity as well as of more rapidly purifying
and disposing of the low products. The process is thus a simple refining
operation, consisting in the employment of a whiter and purer liquor
(clairce) than the molasses it is desired to displace, and as it possesses
more fluidity it does not adhere to the crystals which it purifies, but is

page_text: entirely eliminated by the action of the hydro-extractor and the steam,
as in the case of the first product.
It should be remarked that the liquor resulting from the direct
evaporation of the beetroot syrup costs nothing to produce, and is obtained
without the necessity of re-dissolving any sugar, which remaining
involved in the operation would itself require to be reconcentrated and
purified by an extra series of operations, whereas this liquor serves in
the ordinary course of manufacture the same purpose, and possesses the
same advantages as a refiner's liquor, without any of its objections.
On examination it will be found that the modifications required in the
ordinary method of manufacture are but trifling. It has been stated
that the beetroot juice is evaporated to from 28° to 35° Baumé in the
"triple effect," and then mixed with 24 per cent. of low products,
turbined and washed by steam. After this operation the syrup may be
conducted directly into the concentrating vessel, but if the fine liquor
marks 35 degrees it is preferable to dilute it with water to bring it to a
suitable condition for being filtered through charcoal and for boiling to
grain. If however the fine liquor marks 28 degrees it is unnecessary to
dilute it, and it may be at once passed on to the bone black and after-
wards boiled.
"
This 'liquoring' or purification of low sugars it will be seen
necessitates only the centrifugaling operation, the time occupied in
which may by proper arrangement be rendered inconsiderable. Even
admitting that it would be necessary to increase the number of
turbines the advantages resulting from the adoption of this improved
process in a sugar manufactury are more than sufficient to compensate
for the additional expense.
The purifying process may be carried on either at the beginning
or the end of the campaign, throughout the whole time of manu-
facture. It is however preferable to do it at the commencement, as a
the juices, owing to their greater purity at this time, are better suited
to take up the molasses, and the purified sugars are sooner ready for
the market. When from the quality of the saccharine juices, the care
taken in the manufacture, and the plant admit of the prompt
crystallizion and turbining of the second products the puricfication a
of the latter may be effected in the ordinary course of manufacture
by "liquoring" them with syrup of the first quality. On the other

page_text: hand when, with a view of obtaining a more perfect crystallization
and consequently a larger yield, or for other reasons, the second product
is not treated until towards the end or even after the close of the
manufacture its purification is necessarily deferred to the next campaign
for want of the fine beet syrup. In this case a loss of interest is
incurred on the sugar so stored, which loss, although slight as compared
with the greatly increased value of the purified sugars, should be
curtailed as much as possible by treating the second and third products
at the commencement of the next campaign.
The process herein-before described differs from those hitherto
proposed for the purification of low products, inasmuch as the
"liquor" which serves as the refining agent costs nothing, being the
natural result of the ordinary manufacture, and also because it does
not necessitate any remelting of sugar, or special boilings and repeated.
crystallizations to recover the sugar involved originally. The purifying
syrup should be used largely in excess of the sugar to be heated and
be constantly renewed, so that a maximum effect is maintained, this
advantage being unobtainable with refiners' fine liquor.
It is evident that instead of employing the primary syrup the
second product may be purified by using the syrup drained from the
first product in the hydro-extractor, but with a less perfect result,.
owing to the smaller mass of liquid over which the impurities would
be distributed.
The Invention further relates to a method of accelerating and
increasing the crystallization of sugar, and also of extracting sugar
from molasses by the employment of the salts of soda, ammonia,
baryta, lime, strontia, manganese, iron, zinc, and other salts, which by
their abundance and low price are suitable for the purpose.
.
The improvement is based on the supposition that if certain products
possess the property of rendering sugar soluble others will render it
less so, that is to say, will make it crystallize, which improvement has
led to practical results of great value in sugar making.
A great number of salts when added under certain conditions to a
satuarated solution of sugar. at the ordinary temperature will promote
the more or less rapid crystallization of a portion of the sugar contained. .
The quantity thus eliminated from the solution varies according to the

page_text: nature of the salt employed, and in certain cases is very
considerable.
The action of the salt, whether favorable or not to the crystallization
of the sugar appears to depend rather on the base of the salt than on
its acid. Thus for example nearly all the salts of potash are unfavorable
in varous degrees; salts of soda are either without effect or favorable,
while the salts of magnesia and those of manganese all produce such
a degree of crystallization as to greatly increase the product. Tho
salts I propose to use are those which, their bases being favorable, are
found in abundance in nature, or which are the residue of another
manufacture, and of such small value as to permit of their being
entirely devoted to the purpose.
The salts most suitable for use on a large scale are sulphate of soda,
and among magnesian salts the sulphate and chloride of magnesium
obtainable from sea water in inexhaustible quantities. Among magnesian
salts I use chloride of manganese, forming a residue of the manufacture
of chlorine, and the sulphate which may be readily produced from the
chloride) also sulphates of iron and zinc, and their chlorides, which
are obtainable in sufficiently large quantities.
It is necessary to include the salts formed with organic acids,
which are rare and expensive, not excepting the acetates. Nitrates
and ammonia salts may also be mentioned in the same category,
including nitrate of soda, they being all high priced, although they
might be subsequently utilized as fertilizers. The recrystallization or
regenertion of the salts employed, the salts of ammonia for example,
would give rise to complications, which should be avoided in the
manufacture of sugar.
In laying stress on the exceptions I have made in the enumeration of
the salts which are capable of inducing the crystallization of sugar, it is
in order to indicate clearly those only which are of practical utility.
This point being established the following is the method of operation :—
It is evidently unnecessary to treat the first product of the beet or cane,
as this is at once convertible into sugar on being boiled to grain, nor yet
the second products which crystallises quickly and without difficulty,
but for treating third quality syrups and molasses expecially the process
presents great advantages. Experiments made upon molasses cannot
fail to be decisive when sugar is extracted from a product which has
been put aside as useless for the purpose with the ordinary process of

page_text: manufacture. I take for example sulphate of magnesia which is very
active, and is both abundant and cheap. I add to the spent molasses
(containing say 50 per cent. of sugar, 15 per cent. of salts, and 20 per
cent. of water) crystallized sulphate in the proportion of 20 per cent. by
weight together with a little water to make a solution of the sulphate
marking 100° Baumé. The whole is then centrifugaled in a machine
having either imperforated sides or very fine wire cloth, the sulphates of
lime and potash precipitaed are retained and the liquor is then filtered
through charcoal, and boiled in vacuo. After cooling a certain quantity
of pounded sugar is added to form nuclei, and the syrup is lastly
subjected to the ordinary temperature of "fillings" the heat being
alternately raised and lowered, and after a few days crystallization
becomes exceeding abundant and continues to increase for some time
after which the hydro-extractor is employed.
The above comprises the whole operation, which is very simple.
The proportion of sulphate of magnesia or other salt employed will
vary according to the nature of the molasses and the results of
experience. The same conditions will apply to the use of chloride of
magnesium, and the sulphates and chlorides of manganese, and other
salts. The chlorides possess the advantage of not forming sulphate of
lime, but their action would appear to be less prompt and efficient.
These various salts when added to the molasses react on those it
originally contained, and the subsequent double decomposition and the
double salts which may be produced must be borne in mind in order to
give rise as much as possible to those combinations which are most
favorable to the crystallization of the sugar, for which reason it is
advantageous to employ sulphate of magnesia which precipitates the
lime and potash in the form of sulphates, and forms a corresponding
quantity of salts with a base of magnesia all of which as has been before
observed promote to a greater or less extent the crystallization of the
sugar.
The above method of treatment may be applied both to molasses and
to thirds, and when employed for second products (although with less
advantage), it has the immediate effect of considerably increasing the
yield of the second and third products, and at same time increases the
value of the thirds which become equal to seconds..
It has haan non that contain colts when added to the molassand

page_text: syrups generally will effect the crystallization of a portion of the sugar
they contain, and that the nature of the base has a great influence on
the quantity of sugar deposited, while other salts on the contrary
will impede the crystallization to an extent which may be readily
ascertained.
It should be observed that the acid acts according to its nature in
each class of salts, for which reason in a general way the chlorides and
nitrates are less favorable than the sulphates.
Experience having shown that the action of salts generally with a base
of potash is to prevent crystallization, it is important to eliminate the same
as much as possible from the molasses or syrups. The saccharine matter
in which this elimination may most easily and efficiently be effected is
molasses properly so called, as it is in the latter product of the ordinary
manufacture that are accumulated all the salts among which those of
potash which are the most prejudical predominate. Suppose molasses
to yield 15 per cent. of sulphuric ash representing sulphate of potash in
order that double decomposition may take place between the salts of
potash and the sulphate of magnesia, the latter salt must be added
in the proportions of their respective equivalents, that is to say,
1089: 1395: : 15: x=19.875 kilogrammes, or in round numbers
20 kilogrammes (44 lbs.) of hydrated sulphate of magnesia for every
100 kilogrammes (220 lbs.) of molasses. The sulphate of magnesia is
first dissolved in a small quantity of water and then poured into the
molasses which is diluted to about 35 degrees Baumé, the whole being
at the ordinary temperature. In this manner an abundant precipitate
is immediately formed consisting of sulphate of lime and sulphate of
potash, which are separated in a centrifugal machine or filter press.
The clear liquor is then filtered through charcoal and finally boiled to
proof in the ordinary apparatus. When cooled to about 90
or 100
degrees Fahrenheit a nucleus of fine sugar is next added and the
crystallization at once commences and becomes very abundant. This
crystallization of the sugar results from the elimination of the potash,
the salts of which are prejudical, its place being taken by the magnesia
whose salts are favorable thereto. The same remarks apply in the case
of lime.

page_text: The chlorides, and among others chloride of magnesium, although
favoring the crystallization of the sugar in a solution of pure sugar,
will not eliminate lime and potash, but will increase the amount of salts,
and consequently the density of the liquor at proof, and for this reason
they do not possess nearly the same advantages as the sulphates.
In has been seen that the selection of the salt is an important point,
and that of all the salts which promote the crystallization of sugar sul-
phate of magnesia is the one which furnishes the best results, both
because its base favors crystallization and its acid eliminates the lime
and potash (which are prejudicial) in the form of soluble sulphates.
It is evident that it is preferable to operate on molasses rather than on
the anterior products, because, as has been before mentioned, the salts in
molasses are at a maximum degree of concentration, and the effect of
the sulphate when added is immediate and final.
The sulphates of lime and potash are instantly precipitated, leaving
but small quantities to be afterwards deposited, which are soluble between
35 degrees Baumé and the proof point, (46 degrees Baumé,) whereas
should the first and second products be so treated the sulphates of lime
and potash would at each boiling be deposited in the worms and on the
sugar crystals.
In all cases the sugar thus obtained should be freed from the sulphates
of lime and potash it contains, which deposit between 35 or 40 degrees
Baumé and the proof point. This may be effected in three ways:-
1st. The sugar may be redissolved, filtered through bone black, and
boiled, about 80 per cent. of pure sugar being thus obtained. The syrups
from the centrifugal machine having been evaporated are then suddenly
cooled to prevent the sugar from crystallizing and to cause the deposition
of the sulphate of potash, which is afterwards separated from. the liquor
by centrifugal action.
Or, 2ndly. The impure sugar is added to ordinary molasses brought to
the point of saturation, that is to say, in a condition in which it will not
dissolve the sugar, which it therefore holds in suspension. In this
manner the sulphates alone are dissolved, and after turbining the sugar
will be found to be pure, the molasses thus acting as a kind of purifying
liquor, which not being saturated with sulphates, dissolves them, leaving

page_text: the sugar intact; and this purification having been effected, it may be
treated with sulphate of magnesia.
3rdly. The new sugar obtained is dissolved in water until saturated.
The sulphate in excess remaining undissolved is then separated by fil-
tration, after which a solution of chloride of calcium is added to the
liquor, causing sulphate of lime to be precipitated, and forms by a double
exchange chloride of potassium with the sulphate of potash in solution.
The liquor is evaporated after filtration, and when boiled to grain fur-
nishes nine-tenths of pure sugar, while the syrupy residue is used in the
next operation. This last mode of purifying the sugar will be found the
simplest and most efficacious.
It is evident that the syrups from the turbine after the redissolution of
the sugar purified by the first method, and which contain sulphates, may
also, like the purifying liquor above mentioned, be returned to the
general mass of molasses to be treated.
Having described the nature of the Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is,-
1st. The purification of low quality sugars by "liquoring" ("clair-
cage") during manufacture, as herein described.
2nd. Crystallizing the sugar by adding to the saccharine liquors
certain salts, more especially sulphate of magnesia, as herein specified.
I also claim purifying the raw sugar obtained by the means herein
described.
]
2
In witness whereof, I, the said Alexander Melville Clark, have 2
hereunto set my hand and seal, this Tenth day of January,
in the year of our Lord One thousand eight hundred and seventy-
foun