IMPROVEMENTS IN THE MANUFACTURE OF ACETIC ACID
Year: 1875

page_text: LETTERS PATENT to John Scoffern, M.B., of 272, Lancaster Road,
and Roland John Atcherley, Ph.D., of 20, Pennroad Villas,
Holloway, both in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF ACETIC ACID."
PROVISIONAL SPECIFICATION left by the said John Scoffern and
Roland John Atcherley at the Office of the Commissioners of
Patents, with their Petition, on the 22nd June 1875.
We, JOHN SCOFFERN, M.B., of 272, Lancaster Road, and ROLAND
JOHN ATCHERLEY, Ph.D., of 20, Pennroad Villas, Holloway, both in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ACETIC ACID," to be
as follows:-
-
We dissolve acetate of lead in water and pass through the solution a
stream or streams of sulphurous acid gas. Under this treatment direct
decomposition ensues, white sulphite of lead being thrown down and
acetic acid left in solution.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Scoffern and Roland John Atcherley in the
Great Seal Patent Office on the 22nd December 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
SCOFFERN, M.B., of 272, Lancaster Road, and ROLAND JOHN ATCHERLEY,
Ph.D., of 20, Pennroad Villas, Holloway, both in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 1
Letters Patent, bearing date the Twenty-second day of June, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto us, the said John Scoffern and Roland
John Atcherley, Her special license, that we, the said John Scoffern 1
and Roland John Atcherley, our executors, administrators, and assigns,
or such others as we, the said John Scoffern and Roland John Atcherley,
our 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 OF ACETIC ACID," upon the con-
dition (amongst others) that we, the said John Scoffern and Roland
John Atcherley, our executors or administrators, by an instrument
in writing under our or their hands and seals, or under the hand and
seal of one of us or them, 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 we, the said John Scoffern and Roland John
Atcherley, do hereby declare the nature of the said Invention, and in
what manner the same is to be performed. to be particularly described

page_text: '
and ascertained in and by the following statement thereof, that is
to say:-
This Invention has for its object improvements in the manufacture of
acetic acid.
We generate sulphurous acid by any of the ordinary means known to
chemists, and transmit it through a solution of acetate of lead, this
latter term comprehending the sub-acetates. By this means complete
decomposition ensues, the results being sulphite of lead, which we use
as a white pigment, and acetic acid, which is applicable to every purpose
of the acetic acid of commerce prepared by existing means.
Although we do not restrict ourselves to any special means of
generating sulphurous acid yet the source we recommend is either
sulphur or pyrites, either of which, on being burnt in atmospheric air,
yields sulphurous acid, as is well known. Pyrites is ordinarily prefer-
able, that is to say, because it is more convenient, and when employed
we burn it in any ordinary pyrites' burner connected with a flue.
Having generated sulphurous acid we next bring it into intimate
contact with a solution of acetate of lead in water, and we do this by
one of the following means:-Either we connect the flue draught way.
with a pump (a three-throw cylinder pump by preference) and thus
force it through our acetate of lead solution, or else we connect thefl ue
way with either a steam blast or an ordinary blowing machine, and thus
force the gas into contact with acetate of lead solution. But inasmuch
as the pressure of neither a steam blast nor a blowing machine is
considerable we in case of the use of these do not attempt to force the
gas through a body of dissolved acetate but through a continuous
shower of the same comparable to what would happen on the small
scale if a current of gas were to be forced through an ordinary shower
bath in action.
Of the two means of propulsion we consider pumping the best, but
none of the ordinary metal used in pump making must be employed,
inasmuch as sulphurous acid exercises a chemical action upon them.
German silver answers perfectly, and this is the material we have
employed. We do not restrict ourselves, however, thereto, but use any
material of which pumps can be made so long as it be not affected by
sulphurous acid.

page_text: The acetate solution may be of any strength, inasmuch as our process
of decomposition answers equally well on all strengths. The manu-
facturer must regulate his strength according to the quality of acetate
of lead used and the strength of acetic acid and product required.
In conducting our operation the chief point to be attended to is the 5
complete separation of every trace of lead from the solution. To
ascertain this a little must be tested from time to time, but the operation
of testing requires some special precautions. We assume that sul-
phuretted hydrogen solution or gas is to be used as the test, and here it
is to be specially remarked that this test will not indicate the presence 1
of lead in the presence of free sulphurous acid. Hence the following
plan of testing must be rigidly adhered to:-The fluid to be tested must
be boiled with excess of chalk and filtered. The filtrate or filtered
liquid will have no free sulphurous acid, hence if lead be present the
test will now act, revealing a tint of blackness if the slightest trace of 1
lead be present. The appearance of such a tint will demonstrate that
the intended decomposition is not complete, and that the transmission
of sulphurous acid must be longer continued.
When the operation of decomposition is complete the resulting fluid
will consist of aqueous acetic acid, with sulphite of lead partly deposited 2
and partly in suspension. The two may be separated either by
deposition and decantation or by filtration. Both means are equally
effectual, and the two may be combined.
Usually the acetic acid produced will be slightly charged with
sulphurous acid. No special means are needed for discharging the 2
latter; it escapes of itself after a few hours under open exposure of the
fluid charge at a temperature of not less than 60° F.
The acetic acid solution may be distilled if so desired, but we do not
consider distillation of any use, all lead being absolutely separated if
our operation, as described, be adhered to.
The white sulphite of lead thrown down must be well washed and
dried before using as a pigment. It has two special advantages, the
following-
It never crows dark colored or experiences other chance of tint
8

page_text: (2). It is not poisonous, and therefore cannot affect with lead colic or
paralysis those persons who use it.
Having thus described the nature of our said Invention, and the
manner of performing the same, we would have it understood that we
claim the manufacture of acetic acid with the production of sulphite of
lead as a bye product, substantially as described.
In witness whereof, we, the said John Scoffern and Roland
John Atcherley, have hereunto set our hands and seals,-this
Twenty-second day of December, in the year of our Lord One
thousand eight hundred and seventy-five.