AN IMPROVED MODE OF MANUFACTURING SULPHURIC ACID
Year: 1854

page_text: LETTERS PATENT to James Shanks, of Saint Helens, in the County of
Lancaster, Manufacturing Chemist, for the Invention of "AN IMPROVED
MODE OF MANUFACTURING SULPHURIC ACID."-A communication from
Robert Von Seckendorf, of Gera, in the State of Reuss, in Germany.
Sealed the 15th December 1854, and dated the 9th October 1854.
PROVISIONAL SPECIFICATION left by the said James Shanks at the
Office of the Commissioners of Patents, with his Petition, ou the
9th October 1854.
I, JAMES SHANKS, of St. Helens, in the County of Lancaster, Manufacturing
Chemist, do hereby declare the nature of the said Invention for "AN IMPROVED
MODE OF MANUFACTURING SULPHURIC ACID " to be as follows:-
This Invention for the manufacture of sulphuric acid consists in certain
means used for the separation or extraction of sulphuric acid contained in
gypsum or sulphate of lime, either in a native or artificial state.
It is necessary, in the first place, to provide a large vessel or receptacle, which
I call a decomposing vessel or vat, made of wood, stone, or lead, or of
any other
suitable material, and of sufficient size to produce a large quantity of sulphuric
acid at one operation; I then take 86 parts by weight, or one equivalent, of
native gypsum, or 68 parts by weight of anhydrous sulphate of line, in a finely
pulverized state, and place it in the decomposing vessel or vat, and add to

page_text: it 140 parts by weight of chloride of lead; I then add a large quantity of
water, at the temperature of 130° to 180° of Fahrenheit's thermometer, and
then stir the whole well together. An immediate decomposition takes place
sulphate of lead immediately subsides, and chloride of calcium is held in the
supernatant liquid.
In order to save trouble and expedite the process, it is desirable that the
solution of chloride of calcium should indicate only 4° on Twaddle's hydrometer.
The heavy white precipitate which now remains in the decomposing vessel is
sulphate of lead. This substance is to be treated with hydrochloric acid, and
in order to get a full decomposition of the sulphate of lead, I find it advisable
to use more than its equivalent of the hydrochloric acid.
By adding hydrochloric acid to the sulphate of lead, and mixing them well
together by stirring at a temperature of about 150° Farenheit, an immediate
change takes place, and chloride of lead is formed, which falls to the bottom
of the vessel, while the liquid sulphuric acid is now set free. The sulphuric
acid being thus liberated, is now to be withdrawn from the decomposing vessel
in the usual manner, and evaporated to the strength required for manufacturing
or other purposes. A further quantity of water may be added to the decom-
posing vessel for washing out more of the sulphuric acid from the chloride
of lead, and which further quantity may be evaporated or used for washing
out further quantities of chloride of lead.
In performing
In performing this cycle of
at which I began. Another
operations, I have now arrived at the point
similar quantity of gypsum in a finely divided state, as herein-before described,
is again to be added in mixture with the chloride of lead in the decomposing
vessel, with the required quantity of water at the temperature of 150° Fahren-
heit, and by these means an indefinite quantity of sulphuric acid may be
produced by the agency of a comparatively small quantity of lead.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Shanks in the Great Seal Patent Office on the
7th April 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
SHANKS, of Saint Helens, in the County of Lancaster, Manufacturing Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of October, in the year of our Lord

page_text: me,
One thousand eight hundred and fifty-four, in the eighteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
the said James Shanks, Her special license that I, the said James
Shanks, my executors, administrators, and assigns, or such others as I, the
said James Shanks, 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
"AN IMPROVED MODE OF MANUFACTURING SULPHURIC ACID," being a communi-
cation from Robert Von Seckendorff, of Gera, in the State of Reuss, in
Germany, upon the condition (amongst others) that I, the said James Shanks,
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 James Shanks, 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 (that is to say):-
This Invention for the manufacture of sulphuric acid consists in certain
means used for the separation or extraction of sulphuric acid contained in
gypsum or sulphate of lime, either in a native or artificial state.
It is necessary, in the first place, to provide a large vessel or receptacle (the
form I prefer to be of great horizontal area, but of small depth), and which I
call a decomposing vessel or vat, made of bricks, stone, lead, or any other
suitable material, and of sufficient size to produce a large quantity of sulphuric
acid at one operation; I then take eighty-six parts by weight, or one equiva-
lent, of native gypsum, or sixty-eight parts by weight of anhydrous sulphate of
lime, in a finely pulverized state, and place it in the decomposing vessel, and
add to it one hundred and forty parts by weight of chloride of lead;. I then
add a large quantity of water, at a temperature of about one hundred and
thirty degrees Fahrenheit's thermometer; or the water may be added at the
atmospheric temperature, and brought up afterwards by the application of
steam or external heat. The whole is then to be thoroughly mixed and well
stirred. An immediate change takes place; sulphate of lead speedily subsides,
and chloride of calcium is held in solution in the supernatant liquid. In
order to save trouble and expedite the process, it is desirable that the solution

page_text: of chloride of calcium should indicate only four degrees specific gravity on
Twaddle's hydrometer.
It is also desirable that no loss of lead should take place in this process;
therefore the solution of chloride of calcium now in the decomposing vessel
should be examined as to whether it contains any traces of lead in solution.
This may be done either while it remains in the decomposing vessel, or by
transferring it by means of a syphon to another vessel large enough to contain
the whole. A few drops of this solution should then be taken in a glass tube,
and any of the usual re-agents for ascertaining the presence of salts of lead,
such as a solution of sulphuretted hydrogen, or any of the soluble sulphurets,
may be dropped into the tube containing the solution of chloride of calcium.
A black or dark brown precipitate will appear if any lead be present, in
which case a small quantity of hydrate of lime or any other neutralizing agent
may be added to the solution of chloride of calcium till no blackness is to be
observed. When this point is attained, and the oxide of lead thus separated
from the solution is precipitated, the solution of chloride of calcium may be
run away, or disposed of in any other way which may be thought proper, while
the precipitated compound of lead may be added from time to time to the salts
of lead in the first-named decomposing vessel.
The heavy white precipitate which now remains in the decomposing vessel
is sulphate of lead. This substance is now to be treated with hydrochloric
acid. And in order to get a full decomposition of the sulphate of lead, I find
it desirable to use rather more than its equivalent of hydrochloric acid, and
at a specific gravity not less than twenty degrees to thirty degrees on Twaddle's
hydrometer.
By adding the hydrochloric acid to the sulphate of lead, and mixing well
together, while the whole ingredients are raised to a temperature of one
hundred and forty degrees Fahrenheit's thermometer, or thereabouts, by the
application of steam or external heat, an immediate change takes place, and
chloride of lead is formed, which falls to the bottom of the vessel, while
sulphuric acid is set free as a liquid.
The sulphuric acid being thus liberated, is now to be withdrawn from the
decomposing vessel, and evaporated to the strength required for manufacturing
or other purposes. A further quantity of water may be added to the decom-
posing vessel for washing out more of the sulphuric acid from the chloride of
lead, and which further quantity may be evaporated or used for elutriating
further quantities of chloride of lead. In performing this cycle of operations,
I have now arrived at the point at which I began. Another similar quantity
of gypsum in a finely pulverized state, as herein-before described, is again to

page_text: be added in mixture with the chloride of lead in the decomposing vessel, with
the required quantity of water, at the temperature and under the conditions
already mentioned. By these means an indefinite quantity of sulphuric acid
may be produced by the agency of a comparatively small quantity of lead.
Having thus described the nature of the Invention of "An Improved Mode
of Manufacturing Sulphuric Acid," as communicated by my foreign corre-
spondent, and explained the manner of carrying the same into effect, I would
have it understood that I do not confine myself to the exact details either of
proportions of materials used, or description of apparatus employed, in these
processes; but what I do claim is,―
First, the decomposition of sulphate of lime, whether native or artificial, by
means of chloride of lead, in the manner herein-before described, for the
purpose of obtaining sulphate of lead.
And, secondly, I claim the decomposition of sulphate of lead, so obtained by
the use of hydrochloric acid, for the purpose of obtaining free sulphuric acid,
also herein-before described.
In witness whereof, I, the said James Shanks, have hereunto set my
hand and seal, the Sixth day of April, in the year of our Lord One
thousand eight hundred and fifty-five.
CLAUDIUS BUCHANAN, Witness,
of Liverpool,
Ironfounder.
JAMES SHANKS. (L.S.)