IMPROVEMENTS IN THE MANUFACTURE
Year: 1867

page_text: LETTERS PATENT to William Huskisson, the younger, of 76, Swinton
Street, Gray's Inn Road, in the County of Middlesex, Manufacturing
Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
Sealed the 9th June 1868, and dated the 16th December 1867.
PROVISIONAL SPECIFICATION left by the said William Huskisson at the
Office of the Commissioners of Patents, with his Petition, on the
16th December 1867.
I, WILLIAM HUSKISSON, the younger, of 76, Swinton Street, Gray's Inn
5 Road, in the County of Middlesex, Manufacturing Chemist, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE MANU-
FACTURE OF BICARBONATE OF POTASH AND SODA," to be as follows:-
This Invention has for its object improvements in the manufacture of
bicarbonate of soda and potash. At the present time bicarbonates are
produced either by passing free carbonic acid gas over the crystals of the
monocarbonate or by passing the gas over the surface of a solution of the
monocarbonate or by allowing it to bubble up through the solution. All

page_text: these processes are tedious, and the first of them which is most usually resorted
to in the manufacture of bicarbonate of potash requires the salt to be re-
crystalized, and even then yields a bicarbonate which is not fully saturated
with carbonic acid.
Now according to my Invention 1 employ a solution of the monocarbonate,
which I saturate with carbonic acid gas in a close vessel under pressure, the
said close vessel being so constructed and worked as constantly to raise the
solution and pour it down in streams through the gas, or otherwise constantly
to expose fresh surfaces of the liquid to the action of the gas. The vessel I
employ by preference is a cylinder mounted on horizontal axes and rotated
by suitable driving gear. In the cylinder are four or other number of radial
shelves or partitions attached to the cylinder; the width of these shelves or
partitions is less than the radius of the cylinder, so that there is a space left
free around the centre. The cylinder is about half filled with the solution and
the carbonic acid gas is admitted through the axis at one end, which is hollow.
A vent is left open until all the air is swept out of the veseel; this is then
closed and a moderate pressure applied, whilst the cylinder in revolving takes
up the solution and pours it through the gas under pressure as already
explained. The salt becomes rapidly bicarbonized and falls in a granular
condition. If a puro solution of the monocarbonate has been treated the
bicarbonate will not require recrystallization, a process which it is desirable to
avoid as it involves the loss of carbonic acid. I dry the crystals in a current
of air at the ordinary temperature of the atmosphere, as I find that if heated
air be employed there is a loss of carbonic acid gas and the salt becomes more
or less caustic. The carbonic acid in this manufacture may advantageously
be generated from dolomite or magnesite, consisting of carbonate of magnesia
as free as may be from carbonate or other salt of lime. A suitable material
is found in the island of Eubea in the Grecian Archipelago, and is imported into
this country. I decompose the dolomite or magnesite with sulphuric acid, and
to assist the decomposition I heat the mixture. The gas which passes off
I cool by passing it through a coiled pipe having a stream of cold water
passed in contact with it. The residue from the decomposition of the dolomite
or magnesite is liquid and is readily run out of the decomposing vessel. It is
valuable for the manufacture of Epsom salts.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Huskisson in, the Great Seal Patent Office on the
16th June 1868..
TO ALL TO. WHOM THESE PRESENTS SHALL COME, I; WILLIAM.
HUSKISSON, the younger, of 76, Swinton Street, Gray's Inn Road, in tho
County of Middlesex, Manufacturing Chemist, send greeting.
.
WHEREAS Her most Excellent: Majesty Queen Victoria, by. Her Letters
Patent, bearing date the Sixteenth day of December in the year of our Lord.
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs, and successors, give and grant unto me, the.
said William Huskisson, Her special licence, that I, the said William.
Huskisson, my executors, administrators, and assigns, or such others as I, tho
said William Huskisson, 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 "IMPROVE-
MENTS IN THE MANUFACTURE OF. BICARBONATE OF POTASH AND SODA," upon the
condition (amongst others) that I, the said William Huskisson, 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 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 William Huskisson, 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 thereof, that is to say :-
At the present time bicarbonates are produced either by passing free:
carbonic acid gas over the crystals of the monocarbonate or by passing the
gas. over the surface of a solution of the monocarbonate or by allowing it to
bubble up through the solution. All these processes are tedious, and the
first of them which is most usually resorted to in the manufacture of bi-
carbonate of potash requires the salt to be recrystallized, and even then yields
a bicarbonate which is not fully saturated with carbonic acid.
Now according to my Invention I employ a solution of the monocarbonate,
which I saturate with carbonic acid gas in a close vessel under pressure, the-

page_text: said close vessel being so constructed and worked as constantly to raise the
solution and pour it down in streams through the gas, or otherwise constantly
to expose fresh surfaces of the liquid to the action of the gas.. The vessel 1
employ by preference is a cylinder, say, about six feet long and three feet in
diameter; it is made conveniently of cast iron, and it is closed at the ends
with covers in the centres of which are stud axes, and on these the cylinder
is supported horizontally in suitable bearings. By a driving band. or in
other convenient way the cylinder is rotated at a speed of about 4 or 5
revolutions per minute. In the cylinder are four radial shelves equally
spaced and about nine inches wide, so that there is a space left free around
the centre. The cylinder is about half filled with the solution of the mono-
carbonate, which I make as strong as the quality of the monocarbonate will
admit; if it be pure or nearly pure a specific gravity of 1.500 may be attained.
The carbonic acid gas, which may be obtained as heretofore or in any con-.
venient manner, is admitted through the axis at one end which is hollow. A
vent is left open until all the air is swept out of the vessel; this is then closed.
and a moderate pressure (I prefer from 10 to 15 pounds to the square inch),
is applied by means of a force pump or weighted gas holder. The cylinder:
in revolving takes up the solution and pours it through the gas under pressure,.
as already explained. The salt becomes rapidly bicarbonized and falls in a
granular condition, and in about 24 hours. the process is complete. If the
specific gravity of the solution be less than that above indicated the time.
occupied in the process will also be less. At the end of the operation the
salt is raked out of the cylinder through a door which opens in its periphery,.
and there are also doors in the ends of the cylinder by which the rakes are
introduced. If a pure solution of the monocarbonate has been treated the
bicarbonate will not require recrystallization, a process which it is desirable to.
avoid as it involves a loss of carbonic acid. I dry the crystals in a current of
air at the ordinary temperature of the atmosphere, as. I find that if heated
air be employed there is a loss of carbonic acid. gas and the salt becomes.
more or less caustic. The construction of the close cylinder or vessel may
be varied, for example, it may contain a paddle wheel agitator or be otherwise
constructed so long as the liquid is effectually agitated and fresh surfaces of
it constantly exposed.
What I claim is, the manufacture of bicarbonates of potash and soda by
saturating a solution of the monocarbonate with carbonic acid gas in a close
vessel under pressure, the said vessel being so constructed and worked as
constantly to raise the solution and pour it down in streams through the gas,

page_text: or otherwise to agitate the solution and expose fresh surfaces. of the liquid to
the action of the gas.
In witness whereof; I, the said William Huskisson, have hereunto set
my hand and seal, this Fifteenth day of June,, in the year of our Lord
One thousand eight hundred and sixty-eight.
WILLIAM HUSKISSON, Jun. (L.S.):