CERTAIN IM- PROVEMENTS IN THE MANUFACTURE OF SUGAR
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
COWPER, of Southampton Buildings, Chancery Lane, in the County of Mid-
dlesex, Patent Agent, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twentieth day of
November, One thousand eight hundred and forty-nine, in the thirteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Cowper, my exors, admiors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Charles
Cowper, my exors, admors, and assigns, or such others as I, the said Charles
Cowper, my exors, admors, or assigns, should at any time agree with, and no
others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England; Wales, and the Town of Berwick-upon-Tweed, and in the Islands
of Jersey, Guernsey, Alderney, Sark, and Man, and also in all Her said
Majesty's Colonies and Plantations abroad, an Invention of "CERTAIN IM-
PROVEMENTS IN THE MANUFACTURE OF SUGAR," communicated to me by a certain
Foreigner residing abroad; in which said Letters Patent is contained a
proviso that I, the said Charles Cowper, shall cause a particular description
of the nature of the said Invention, and in what manner the same is to
be performed, by an instrument in writing under my hand and seal, to be
enrolled in. Her said Majesty's High Court of Chancery within six calendar

page_text: months next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Charles Cowper, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof (that is to say):-
The Invention relates to a system of manufacturing sugar by the employ-
ment of baryta, and to certain methods of recovering the baryta from the salts
of baryta formed in the operation. And in order that the Invention may be
fully understood I will first proceed to describe the method of employing the
baryta, and I will afterwards describe the methods of recovering the same.
The method of employing the baryta consists of two distinct processes:
Firstly, the precipitation of the sugar in combination with baryta; and
secondly, the decomposition of the precipitate by means of an acid. Various
acids may be employed, but I prefer to employ carbonic acid. The cane juice,
beetroot juice, or other saccharine liquid, is heated to a temperature of about
one hundred and sixty-seven degrees of Fahrenheit's thermometer, and a
quantity of caustic baryta, previously slaked and mixed with water into a sort
of cream, is added. The whole is then well mixed together, and rapidly heated
until it boils, when the combination of sugar and baryta, or saccharate of
baryta precipitates. The quantity of caustic baryta employed is about sixty
pounds to one hundred gallons of juice, but the quantity required will of
.course vary with the quality and nature of the juice, the richest juice requires
most baryta. The boiling is now discontinued, and the saccharate of baryta
speedily settles to the bottom of the vessel. The supernatant liquor is then
drawn off, and the sugar is thus at once separated from the greater portion
of its impurities, and from the large quantity of water contained in the juice.
The precipitate of saccharate of baryta is then washed with, a small quantity
of water, or squeezed in a press to remove the remaining liquid. If the pre-
cipitate is merely washed with water, it is obtained in the state of a magma
or thin paste; but if it is pressed, it is in the form of cakes, which are broker
up into small pieces to facilitate the second process which is performed in the
following manner:-The small pieces of saccharate of baryta are diffused in
and well mixed with one and a quarter times their weight of water, or when
the magma of saccharate of baryta is employed, a sufficient quantity of water
is added to it to obtain a mixture in the same relative proportions. A current
of carbonic acid gas, which has been washed by passing through water, is now
passed into the mixture until it is in slight excess. The baryta now pre-

page_text: cipitates in the state. of carbonate of baryta, while the sugar is, set free and is
held in solution by the water. The mixture is now filtered to remove tho
carbonate of baryta, which is washed or pressed. The solution of sugar, which
passes through the filter, is evaporated until it acquires a specific gravity
of about 1.27 at the boiling point (distilled water being 1.00).. It is then
filtered to separate a small quantity of carbonate of baryta, which will have
precipitated during the evaporation. The syrup is then again evaporated to
the crystallizing point, and poured into the moulds, and the sugar is obtained
almost or quite white, and free from uncrystallizable sugar. The liquor. from
which the saccharate of baryta was precipitated in the first process contains
a little sugar, which may be turned to account by converting it into alcohol
by fermentation, for which purpose the liquor is first evaporated to a specific
gravity of about 1.27 at the boiling point, and is filtered to remove the car-
bonate of baryta, which precipitates. The filtered syrup is further. con-
centrated by evaporation, and may then be employed for conversion into
alcohol, or for the extraction of the alkaline salts contained in it. In some
localities it may be advantageous to employ some other base than baryta, such
as strontia or oxide of lead, capable of forming an insoluble combination with
sugar; and in some cases a soluble saccharate may be first formed and converted
into an insoluble saccharate by double decomposition, the soluble saccharate
being mixed with a solution of a soluble salt capable of producing by double
decomposition an insoluble saccharate and another soluble salt. Other acids
than carbonic acid may be employed, provided they are capable of forming
insoluble salts with baryta; as, for instance, sulphuric acid, phosphoric acid,
and boracic acid. I have spoken above of the application of the process
to cane juice and other saccharine liquids, the process is equally applicable to
the refining of raw sugars, which merely require to be dissolved in water.
About sixty pounds of caustic baryta, or its equivalent of hydrate of baryta,
should be employed for one hundred pounds of sugar. The syrup from which
the baryta has been separated may be submitted to any of the ordinary
refining processes. The liquor from which the saccharate of baryta precipitates
will contain the uncrystallizable sugar, which may be converted into alcohol,
as above mentioned. In the same way may be separated the portion of crys-
tallizable sugar contained in molasses. It will be readily understood that the
proportion of baryta to be employed will vary with the richness of the
sugar or saccharine liquid operated upon a weak solution of sugar, not
requiring so much baryta.
I will now proceed to describe the methods of recovering the caustic or
hydrated baryta from the salt of baryta, formed as above described.

page_text: First process: Carbonate of baryta and sulphuric acid.-Carbonate of baryta
is decomposed in close vessels by means of sulphuric acid, and the carbonic
acid which is liberated is employed in the decomposition of the saccharate of
baryta. The sulphate of baryta which is formed is collected and converted
into sulphuret of barium by means of charcoal, or other carbonaceous matter,
in a furnace or in close vessels or retorts, if it is wished to collect the carbonic
acid gas which is liberated; the residue being treated with water the sulphuret
of barium is dissolved and separated from the carbon by drawing off the liquor
and washing the carbon. The solution of sulphuret of barium is then boiled:
with oxide of copper, which produces an insoluble sulphuret of copper and
a solution of hydrate of baryta. The sulphuret of copper is reconverted into
oxide of copper by roasting, so that it may be used over again for an indefinite
number of times. It is hardly necessary to observe, that I employ the latter
part of this process when sulphuric acid has been employed in place of
carbonic acid to separate the baryta from the saccharate of baryta, for in that
case sulphate of baryta will be produced.
Second process: Carbonate of baryta decomposed by double decomposition.
―The double decomposition may be effected by all, or nearly all, the sulphates,
in the wet way with some and in the dry way with others, and with many of them
in either way. The most advantageous mode of proceeding in any particular
case will depend on the relative cost of the different materials, and the
facilities offered by the particular locality. In some places there is an advan-
tage in employing the sulphates of soda or of potash, for those sulphates may
thus be converted into carbonates or into caustic soda, or potash, which sub-
stances are in most places of more value than their respective sulphates. As
there is a little difficulty in employing the sulphates of soda and potash, I shall
now describe the mode of proceeding, which being the same with both it will
be sufficient to describe the mode of proceeding with one of them; for
instance, the sulphate of soda. But I should observe, that when sulphate of
potash is employed two hundred and eighteen parts should be used in place of
every one hundred and seventy-eight parts of sulphate of soda; if it were not
required to obtain a complete decomposition it would be sufficient to mix
together in hot or cold water one chemical equivalent of sulphate of soda and
one equivalent of carbonate of baryta, but in this case the decomposition is
incomplete; a fact which has been recognized by various authors who have
written on the subject. The result is, on the one hand, an insoluble mixture
of sulphate of baryta formed by the decomposition with undecomposed car-
bonate of baryta, and on the other hand a solution of carbonate of soda
formed by the decomposition mixed with undecomposed sulphate of soda. It

page_text: will be found that the decomposition can only be rendered complete by
employing an excess of the decomposing salt in comparison with the quantity
of the salt which is to be decomposed; and that even then, if it be required to
separate the last portions of sulphuric acid from the soda, it is necessary that
soda should be present in a free state; I therefore add to the solution an
oxide which combines with the carbonic acid as it is separated from the baryta
by the sulphuric acid, and forms an insoluble precipitate. For this purpose
lime may be employed and will generally be more advantageous than any
other oxide, as it can be obtained almost every where at a low price; this,
however, is not the only difficulty, as it is advisable to arrange the successive
excess of the two substances to be decomposed, so that the quantity resulting
from one operation shall be that required for the succeeding operation; by this
means the inconvenience of too great a multiplication of the processes is
avoided, and they work harmoniously together. This desirable result. is
obtained by successively employing two equivalents of each substance to.
decompose one equivalent of the other substance, and the use of lime in.
the decomposition. The operations succeed each other in the following order,
which I call the rotation of the decomposition:-
Operation A. Sulphate of soda as decomposing agent with carbonate of
baryta to be decomposed. One-hundred and seventy-eight parts by weight of
dry sulphate of soda are dissolved in about three times their weight of water,
and mixed with one hundred and twenty-three parts of carbonate of baryta,
and the mixture is boiled for about two hours. A precipitate of sulphate of
baryta and a solution of sulphate and carbonate of soda are thus obtained.
The solution is drawn off and the precipitate washed and laid on one side
to be converted into sulphuret of barium, as will be presently described. The
water used in washing the precipitate is also preserved for replacing the
water evaporated in the following operation B, and for dissolving the sulphate
of soda in operation C.
Operation B.-Carbonate of baryta as decomposing agent, with sulphate of
soda to be decomposed.. The solution of carbonate and sulphate of soda
obtained in operation A is mixed with two hundred and forty-six parts of
carbonate of baryta, and seventy-one parts of lime. If the lime is impure
it will be necessary to employ a larger proportion according to the degree of
its impurity; an excess of lime is not injurious. The mixture is now boiled
for about two hours, and the result is a precipitate of sulphate and carbonate
of baryta and carbonate of lime, and a solution of caustic soda, which is.
drawn off after the precipitate has subsided. The solution may be evaporated
to dryness to obtain the caustic soda, or carbonic acid gas may be passed into
the solution to obtain carbonate of soda.

page_text: Operation C. The precipitate obtained in the previous operation B, and
which does not require to be washed, is mixed with a quantity of sulphate of
soda equal to that employed in operation A, dissolved in the water used for
washing the precipitate in operation A. The mixture is boiled for about two
hours, and the result is a precipitate of sulphate of baryta and carbonate of
lime, and a solution of carbonate and sulphate of soda, similar to that obtained
in operation A, and required for operation B. The operation B is now
repeated with this solution and a fresh portion of carbonate of baryta, and
the precipitate resulting from this operation B is employed with a fresh portion
of sulphate of soda for repeating the operation C. Thus, the operations B
and C are perpetually following one another, and the three substances
employed, videlicet, carbonate of baryta, sulphate of soda, and lime,' are
converted into caustic soda and a mixture of sulphate of baryta and carbonate
of lime. I have described these decompositions as taking place in the hot
state, but they also take place in the cold state, thereby economizing fuel;
but the action is so much slower that it will generally or always be preferable
to employ heat. The proportions given above do not require to be rigorously
adhered to, but are selected as simplifying and facilitating the rotation of the
decomposition. It is also for the sake of abridging and simplifying the process
that I dispense with the operation of washing the precipitate obtained in
operation B. The sulphate of baryta, although mixed with carbonate of
lime, is converted into sulphuret of barium by heating it with carbonaceous
matter in the ordinary way without altering the process on account of the
presence of the carbonate of lime, which is rather beneficial than injurious to
the reaction. This process is performed in close vessels or retorts heated
to redness, for the purpose of collecting the carbonic acid liberated from the
carbonate of lime, and that formed by the reaction of the carbon on the
sulphate of baryta. This carbonic acid, after being washed by passing
through water, may be employed in carbonating the soda, and in decomposing
the saccharates. The result of this decomposition, consisting of lime, sul-
phuret of barium, and carbon, is mixed with water and allowed to settle.
The solution of sulphuret of barium is drawn off and the residue washed.
This residue consisting of lime mixed with carbon may be again employed
in the rotation of the decomposition, and the carbon will remain inert until
it arrives at the part of the process for converting the sulphate of baryta into
sulphuret of barium, when it will be brought into use. There now only
remains one. operation to be performed, that of converting the sulphuret of
barium into baryta, which is performed in the manner which has already
been described. The processes above described present the great advantage
of recovering the baryta from the salts of baryta obtained in the decom

page_text: position of the saccharate of baryta, and thereby reducing the total cost
of the manufacture of the sugar. This observation particularly applies to the
last process, in which sulphates of soda or potash are converted into the
more valuable carbonates of those bases. I should observe, that the Invention
does not require any particular form of apparatus, but may be employed with
various forms of well-known apparatus.
Having now described the nature of the Invention, and the manner in which
the same is to be performed, I wish it to be understood that I claim,-
Firstly, the recovery of baryta from carbonate of baryta formed in the
manufacture of sugar, by decomposing the same with sulphuric acid, as above
described under the head of the first process for the recovery of baryta.
Secondly, I claim the recovery of baryta from carbonate of baryta formed
in the manufacture of sugar, by means of the operations described under the
head of the second process for the recovery of baryta.
In witness whereof, I, the said Charles Cowper, have hereunto set my
hand and seal, this Eighteenth day of May, in the year of our Lord
One thousand eight hundred and fifty.
Enrolled the Eighteenth day of May, in the year of our Lord One
thousand eight hundred and fifty.