IMPROVEMENTS IN THE MANUFACTURE OF ALRAT.T
Year: 1852

page_text: LETTERS PATENT to Thomas Greenshields, of Stoke Works, in the
County of Worcester, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ALRAT.T"
Sealed the 9th February 1853, and dated the 22nd December 1852.
PROVISIONAL SPECIFICATION left by the said Thomas Green-
shields at the Office of the Commissioners of Patents, with his
Petition, on the 22nd December 1852.
I, THOMAS GREENSHIELDS, of Stoke Works, in the County of
Worcester, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF ALKALI " to be as follows: -
The method generally in use for the manufacture of alkali, is,―
First, to make sulphuric acid.
Second, to decompose common salt by means of the sulphuric
acid so made.

page_text: Third, to decompose the salts of soda formed in the second ope-
ration. To obtain carbonated alkali from this operation a considerable
refuse is left.
Many attempts have been made to supersede the necessity of
making sulphuric acid, for which purpose both the metallic and
earthy sulphates have been used. Sulphate of lime (an earthy
sulphate) has been used by mixing sulphate of lime, carbonate of
magnesia, common salt and water, and boiling the mixture..
The improvements consist in the decomposition of common salt,
for making alkali by using sulphate of lime, fine slack (or coke), and
coinmon salt.
The decomposition is effected by mixing the sulphate of lime and
fine slack (or coke) together, and subjecting the mixture to a heat
at or below a dull red, and afterwards adding the salt, and con-
tinuing the heat until the decomposition is effected. Before the
salt is added, the mixture of sulphate of lime and finer slack may
be drawn from the furnace, and added to a solution of salt or
saturated brine, and decomposed by heating.
In obtaining from the residue or waste left from the decomposition
of the soda salts, obtained from the decomposition last described, the
sulphurous, sulphuric, or similar products in combination with lime,
and using the same for decomposing salt as described, or collecting
the sulphuretted hydrogen in a convenient receptacle, and decom-
posing the saune with sulphurous acid vapour, water or steam.
SPECIFICATION in pursuance of the conditions of the Letters 25
Patent, filed by the said Thomas Greenshields in the Great
Seal Patent Office on the 22nd June 1853.
ย
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
THOMAS GREENSHIELDS, of Stoke Works, in the County of Worcester,
send greeting.
30
WHEREAS Her most Excellent Majesty Queen Victoria, by Her

page_text: Letters Patent, bearing date the Twenty-second day of December,
One thousand eight hundred and fifty-two, in the sixteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Thomas Greenshields, Her special license that I,
the said Thomas Greenshields, my executors, administrators, and
assigns, or such others as I, the said Thomas Greenshields, my ex-
ecutors, 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 ALKALI," upon the con-
dition (amongst others) that I, the said Thomas Greenshields, by an
instrument in writing under my hand and seal, 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 Thomas Greenshields, do hereby
declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof (that is to say):
To sixty-eight pounds of sulphate of lime (burned and pulverised)
in a fine powder add eight pounds of fine slack (finely pulverised coal)
and cause them to be well mixed, and put into a reverbatory or
other suitable furnace, and kept stirred until the whole has become
of one uniform dull red heat throughout, care being taken that the
temperature be rather lower than higher than a cherry or dull red
heat. Sixty pounds of fine grained salt is now to be added, and the
whole well and thoroughly mixed, and the temperature of the furnace
is to be raised to a good red, but below a white heat. The mixture
will gradually flux, and become quite fluid, when it is to be well
mixed by raking or stirring until the mass has become thoroughly

page_text: heated of one uniform temperature; pulverised coke is to be added,
and well raked in, and in sufficient quantity to well separate the
fluid mass, and to cause it to work freely without adhering to the
rake or instrument used in working. The temperatures to be main-
tained until the whole of the chlorine is driven off; and this may
be
readily ascertained by drawing portions of the charge to the furnace
door, as a very small portion of gas escaping may then be seen.
When the whole of the chlorine is driven off, the charge is to be
drawn from the furnace, and suffered to cool. The sulphate of lime,
slack, and coke may be all mixed before putting them into the
furnace, but I prefer the method before described.
When the mass has become cold, it is placed in lexiviating vats,
and the soda salts dissolved by water, and the solution allowed to
run off through a filter from the unconsumed carbonaceous and
other unsoluble matter into a receiver. It is then to be reduced by
evaporation to a salt. The soda salts so obtained is to be mixed
with fine slack and carbonate of lime, and placed in a reverbatory
known as a black ash furnace for decomposing the soda salts, and
obtaining carbonate of soda as is well understood.
When the decomposition has been completed in the black ash
furnace, the charge is drawn from the furnace and allowed to cool,
and then placed in lexiviating vats, and the carbonate of soda dis-
solved by water. The solution is allowed to run off the unconsumed
carbonaceous matter, and the insoluble sulphate and other combina-
tions of sulphur with lime, and the liquid converted into carbonate of
oda, as is well understood. The insoluble residue left in the vats
is again used in decomposing salt, as before described.
do not confine myself to the proportions stated, as other pro-
portions may be used, but I prefer to use those described. I do not
confine myself to the apparatus herein-before mentioned, as other
apparatus may be employed for the purpose. What I claim as my
Invention is, the mode above described for effecting the decomposi-
tion of salt by means of the sulphate of lime, fine slack, or coke, for
obtaining soda salts as before described.

page_text: I also claim, as my invention, the residue left in the black ash vats
or effecting the decomposition of salt for obtaining soda salts.
In witness whereof, I, the said Thomas Greenshields, have here-
⚫unto set my hand and seal, this Twenty-second day of June,
in the year of our Lord One thousand eight hundred and fifty-
three.
Witness,
JNO. ALCOCK.
THOMAS GREENSHIELDS. (L.S.)