IMPROVEMENTS IN SUGAR REFINING
Year: 1878

page_text: LETTERS PATENT to Edward Hunt, of Number 11, Worsley Street, Salford,
in the County of Lancaster, Analytical Chemist, for the Invention of
"IMPROVEMENTS IN SUGAR REFINING."
PROVISIONAL SPECIFICATION left by the said Edward Hunt at the Office
of the Commissioners of Patents on the 29th November 1878.
EDWARD HUNT, of No. 11, Worsley Street, Salford, in the County of Lancaster,
Analytical Chemist. "IMPROVEMENTS IN SUGAR REFINING."
My improvement consists in the employment of a strong solution in water of a
very basic subsulphate of alumina to clarify, decolorize, and purify sugar and
saccharine solutions.
A solution of subsulphate of alumina suitable for the purpose, and which I
propose to call "aluminous water," is made from the salt known as the sulphate of
alumina or neutral tersulphate of alumina, by withdrawing from a strong solution
of this salt in water a proportion of not less than one half of the sulphuric acid
combined with the alumina in the salt.
The withdrawal of the proper proportion of sulphuric acid may be effected by
means of the chemical equivalent of lime in milk of lime or in chalk, or by such
other agents well known to chemists, by which the requisite proportion of sulphuric
acid may be rendered insoluble, and so capable of being separated by filtration from
the "aluminous water" which remains in solution.
On adding the "aluminous water" to several volumes of pure water or to a
freshly prepared solution of sugar in water, most of the alumina contained in it
falls out of solution.

page_text: The insoluble alumina that separates is a powerful mordant, and as it falls out of
solution it separates and attaches to itself much of such coloring matters or
albuminoid impurities as may be contained in the water or solution of sugar to
which it is added.
"
The quantity of aluminous water," of say specific gravity 1.150, found necessary
to add to a freshly prepared solution of sugar of specific gravity 1.250 varies from
less than one per cent. to about three per cent. according to the amount of color and
other impurities contained in the sugar solution.
The precipitation of the alumina with the impurities attached is much facilitated
by heat.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said Edward Hunt in the
Great Seal Patent Office on the 16th June 1879.
EDWARD HUNT, of Number 11, Worsley Street, Salford, in the County of
Lancaster, Analytical Chemist. "IMPROVEMENTS IN SUGAR REFINING."
I make a saturated solution of sulphate of alumina in water of the temperature
of 150 degrees Fahrenheit. To this I add by small quantities at a time so much
chalk in the form of milk of chalk, or lime as milk of lime, but by preference chalk,
that the clear filtrate from the mixture shall when of a specific gravity of 1150
become turbid on being heated to a temperature not. exceeding 150 degrees
Fahrenheit; or expressed otherwise, to every 100 lbs. of pure crystalized
sulphate of alumina contained in solution in water saturated with the salt at
150 degrees Fahrenheit I add 13½ lbs. of pure burnt lime or 24 lbs. pure dry
chalk, the lime or chalk being mixed with sufficient water, so that it be added in
the form of thick milk, and not in lumps.
Lime, chalk, and the commercial sulphate of alumina vary somewhat in com-
position, and the method first given is the best practical guide to a manufacturer to
obtain a liquor of suitable and uniform character.
The aluminous water may be obtained in a state even more basic than is produced
by means of the proportions above given. To secure such a result the solution of
sulphate of alumina employed must be saturated with the salt at a temperature above
150 degrees Fahrenheit, and more chalk used. The filtrate from this will become
turbid at a lower temperature in proportion as the alumina salt in solution is more
basic, and the point to be noted is, that at the strength of solution made, sufficient of
the acid of the sulphate of alumina be left in to maintain the whole of the alumina
in a state of solution under such varying conditions of atmospheric temperature as
may prevail.
It is understood that with a smaller proportion of lime or chalk a liquor may be
made less basic than is produced by the employment of the quantities given, and
yet which will preciptate a portion of its alumina on being added to pure water or
to other liquids, but the proportion of alumina that will so fall out of solution is
less as the amount of acid left in is greater.
The lime or chalk being added, the liquor is filtered from the insoluble sulphate
of lime, and is then fit for use.
The insoluble sulphate of lime is first washed with a dilute solution of commercial
sulphate of alumina in water and then with water alone.
The washings are used to make a new saturated solution of sulphate of alumina
for a renewed operation.
Aluminous water made substantially as described when added to pure water, or
to a solution of coloring matter in water, or to such liquids as beer or wine, or to a
solution of sugar in water, will even when cold become turbid, owing to the alumina
contained in it falling out of solution. As this alumina separates it attaches to
itself and throws out of solution much of the albuminoid and coloring matters
which may be contained in such solutions, and thereby greatly clarifies, decolorises,
and purifies these.
When applied to the decolorising and purifying of sugar solutions such a quantity
is used as may be just adequate to produce a noticeable precipitate. The liquor is
then heated to about 170 degrees Fahrenheit to facilitate the separation and con-
solidation of the precipitate, and it is then filtered.
If the sugar solution is hot in the first instance such a quantity of aluminous
water only is used as may be shewn on trial of a small sample to produce the
maximum decolorising effect.

page_text: When the sugar solution is so impure or contains so much uncrystallizable sugar
as to need the employment of more than one part of aluminous water of specific
gravity 1150 to 100 parts of sugar solution of specific gravity 1250, a quantity of
lime in the form of milk of lime may be added in the proportion of from one to
two parts of dry lime to every hundred parts of aluminous water used, but the use
of lime is not needful when due care has been taken by means of such instructions
as are given to make the aluminous water sufficiently basic.
In witness whereof, I, the said Edward Hunt, have hereto set my hand and
seal, this Seventh day of June, One thousand eight hundred and seventy
nine.
EDWARD HUNT. (L.S.)