IMPROVE- MENGO IN THE MANUFACTURE OF SODA AND POTASH " MENTS IN THE MANUFACTURE OF SODA AND POTASH
Year: 1874

page_text: LETTERS PATENT to James Mactear, of Glasgow, in the County of
Lanark, North Britain, Chemist, for the Invention of "IMPROVE-
MENGO IN THE MANUFACTURE OF SODA AND POTASH "
MENTS IN THE MANUFACTURE OF SODA AND POTASH,
"
PROVISIONAL SPECIFICATION left by the said James Mactear at the
Office of the Commissioners of Patents, with his Petition, on the
22nd September 1874.
I, JAMES MACTEAR, of Glasgow, in the County of Lanark, North
Britain, Chemist, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF SODA AND POTASH," to be as
follows, that is to say :-
This Invention has for its object to economise materials, plant, labor,
and time-in the manufacture of-soda and potash, and comprises improve-
ments in carrying out what is known as Leblanc's process."

page_text: 2. The time occupied in finishing each charge being reduced an
increased number of charges can be worked in a given time.
3. There is a great saving of coal and carbonate of lime.
4. A diminished proportion of waste is left on lixiviating, and conse-
quently less soda is lost with the waste.
5. A diminished proportion of caustic soda and sulphides is found in
the liquors, the total caustic lime being alterable at pleasure.
In the case of potash the treatment will be the same as for soda,
excepting that ordinary furnaces will generally be employed on account
of the comparatively small quantities operated on. In working with
potash there will be the great advantage that the temperature does not
require to be so high as in the ordinary process, and that there will
consequently be less loss by volatilisation.
.
filed by the said James Mactear in the Great Seal Patent Office
on the 13th March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
MACTEAR, of Glasgow, in the County of Lanark, North Britain, Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of September, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said James Mactear; Her special licence that I,
the said James Mactear, my executors, administrators, and assigns, or
such others as I, the said James Mactear, 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

page_text: • OF SODA AND POTASH," upon the condition (amongst others) that I, the said
James Mactear, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly 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 James Mactear, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement in writing, that is to say:--
My said Invention has for its object to economise materials, plant,..
labor, and time in the manufacture of soda and potash, and comprises
improvements in carrying out what is known as Leblanc's process.
In furnacing sulphate of soda, coal, and carbonate of lime together it ]
has hitherto been customary, and has been considered necessary to the
production of good results, to use a quantity of carbonate of lime
considerably in excess of that corresponding to chemically equivalent
proportions.
When using a revolving furnace, which kind I also prefer in carrying 2
out the present Invention, the charges have been worked in either of
two ways. In one mode of working all the materials for a charge are
put into the furnace at once and finished off, but the resulting ball soda
is apt to be hard and difficult to dissolve. In the second mode the
carbonate of lime and part of the coal are first charged and heated for 2
some time with the view of producing a quantity of caustic lime, the
sulphate of soda and the remainder of the coal being subsequently
charged. This second method has hitherto given the best results.
The plan has been tried of charging a mixture of caustic lime and
carbonate of lime with the sulphate of soda and coal, but it has not a
succeeded, the balls turning out bad in quality and difficult to
dissolve.
By my present Invention a mixture of sulphate of soda with coal and
with a quantity of carbonate of lime barely in excess of the chemical
equivalent is charged at one time into the furnace, and the heating a

page_text: operation is allowed to proceed until the reaction is nearly complete,
which is recognisable by the fluxing of the materials and other signs.
At this point a small quantity, say ten per centum, of crushed caustic
lime is added, and then as soon as this added caustic lime is thoroughly
mixed with the other materials the entire charge is withdrawn. In this
way the disadvantage of having caustic lime present during the reaction
is avoided, whilst the intermixture of a suitable small proportion of
caustic lime at or near the end has the effect of rendering the resulting
balls easily soluble and well conditioned for the subsequent operations.
The quantity of caustic lime to be thus added near the end of the process
will vary accordingly as the manufacturer wishes to have more or less of
the soda in a caustic state, 3 to 4 per centum having in practice given
good results in cases in which a minimum proportion of caustic soda
was desired.
Several important advantages attend the practical application of my
said Invention, amongst which the following may be stated, namely:-
1. The proportion of carbonate of lime being diminished a much
increased quantity of sulphate of soda may be decomposed in a furnace
of a given' size.
2. The time occupied in finishing cach charge being reduced, an
increased number of charges, can in most cases be worked in a given
time.
3. There is a great saving of coal and carbonate of lime.
4. A diminished proportion of waste is left on lixiviating, and conse-
quently less soda is lost with the waste.
5. A diminished proportion of caustic soda and sulphides are found in
the liquors, the total caustic lime being alterable at pleasure.
In the case of potash the treatment will be the same as for soda,
excepting that ordinary furnaces will generally be employed on account
of the comparatively small quantities operated on. In working with
potash there will be the great advantage that the temperature does not
require to be so high as in the ordinary process, and that there will
consequently be less loss by volatilisation.
Having thus particularly described my said Invention, and the manner
of performing the same, I have to state that I do not restrict myself to

page_text: the precise details herein-before referred to, but that what I believe to
be novel and original, and claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, the improved mode of
furnacing sulphate of soda or of potash, in which a small quantity of
caustic lime is added to the mixture of sulphate, coal, and carbonate of
lime at or near the end of the reaction, substantially as and for the
purposes herein-before described.
In witness whereof, I, the said James Mactear, have hereunto set
my hand and seal, this Eleventh day of March, in the year of our
Lord One thousand eight hundred and seventy-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES MACTEAR.
(L.S.)