IMPROVEMENTS IN OBTAINING ACETIC ACID.
Year: 1872

page_text: LETTERS PATENT to John Steedman, of the Firm of Steedman and
McAlister, of Glasgow, in the County of Lanark, North Britain,
Manufacturing Chemists, for the Invention of "IMPROVEMENTS IN
OBTAINING ACETIC ACID.
Sealed the 7th February 1873, and dated the 11th October 1872.
PROVISIONAL SPECIFICATION left by the said John Steedman at the
Office of the Commissioners of Patents, with his Petition, on the
11th October 1872.
I, JOHN STEEDMAN, of the Firm of Steedman and M'Alister, of
Glasgow, in the County of Lanark, North Britain, Manufacturing
Chemists, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OBTAINING ACETIC ACID," to be as follows, that is to
Бау :-
This Invention has for its object to shorten and cheapen the process
for obtaining acetic acid, and consists in passing the vapor of the impure
acid, as obtained by processes beretofore in use, through a hydrocarbon
or through an oil or fat, such hydrocarbon, oil, or fat being maintained
at a temperature at least equal to that of the acetic acid vapor and
sufficient to liquefy it if it is not liquid, at ordinary temperatures.

page_text: Paraffin is the substance which is used by preference, and being
contained in any suitable vessel, the vapor of the impuro acetic acid is
made to pass through it by connecting the still in which the acid is
vaporised with the lower part of such vessel. The impurities are
retained by the paraffin, and the acid vapor passes on in a pure state |
to ordinary condensers, whilst the paraffin is renewed periodically as it
becomes charged with the impuritics.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Steedman in the Great Seal Patent Office
on the 9th April 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
STEEDMAN, of the Firm of Steedman and McAlister, of Glasgow, in
the County of Lanark, North Britain, Manufacturing Chemists, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of October, in the year
of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Steedman, Her special licence
that I, the said John Steedman, my executors, administrators, and
assigns, or such others as I, the said John Steedman, 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 OBTAINING
ACETIC ACID," upon the condition (amongst others) that I, the said
John Steedman, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and scals, 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 John Steedman, do hereby declare
the nature of my said Invention, and in what manner same is

page_text: 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 shorten and cheapen the
process for obtaining acetic acid, and relates more particularly to that
part of the usual series of processes for obtaining acetic acid in which
the crude or impure acid is purified or refined. My Invention consists
in passing the crude or impure acid in a state of vapor through a hydro-`
carbon, or through an oil, or fat, such hydrocarbon, or oil, or fat, being
maintained at a temperature at least equal to and by preference
somewhat higher than that of the acetic acid vapor. The temperature
must also be high enough to liquefy the substance employed, if it is not
liquid, at ordinary temperatures or at the temperature of the acetic acid
vapor.
"
I believe the substances best suited for carrying out my Invention are
paraffin, or as it is sometimes termed paraffin wax, and the oil known as
'heavy oil" and obtained in the redistillation or refining of crude
mineral oils. I do not however restrict myself to these substances, as I
have found by actual trial that numerous hydrocarbons, oils, and fats,
can be used with more or less benefit for the purposes of my Invention.
It will at the same time be obvious that volatile substances or such as
do not remain liquid at a somewhat higher temperature than that of the
acetic acid vapor will not answer.
My Invention may be practically carried out in any convenient vessel
or apparatus, in which the crude acetic acid vapors can be brought into
intimate and continued contact with the purifying substance. I employ
a copper vessel of a rectangular form, about five feet long, one foot wide,
and two feet nine inches deep. This vessel has fixed inside of it three
partitions of copper or wood, and which are horizontal in cross section
but slightly inclined longitudinally. The partitions are open at alternate
ends, and the vessel being filled with the paraffin or other purifying
substance, the acetic acid vapor which is introduced from the usual
distillatory apparatus by a pipe leading in beneath the closed end of the
lowest partition travels along through the paraffin from end to end
beneath the partitions, and is finally led from the top of the vessel
to ordinary condensing apparatus. The paraffin or other purifying
substance in the vessel is kept sufficiently heated by a coiled steam pipe,
or steam jacket, or in any other convenient way, and is withdrawn from
the vessel whenever it is considered to be as fully charged as is desirable

page_text: with impurities from the acetic acid. If wished, the acetic acid may be
passed successively through two or more vessels containing the purifying
substances, and it may be mentioned that it is convenient to use the
"heavy oil" for the separation of the grosser impurites, and to pass the
acid afterwards through the paraffin for further purification.
A purifying vessel of the dimensions herein-before named is suitable
for use in connection with a still of a size usually receiving about one
hundred gallons at a charge.
A large portion of the impurities taken up by the paraffin may be
separated therefrom by agitation with hot water; and the paraffin may
be further purified by the processos ordinarily employed for that purpose.
The heavy oil or other substances used may also in general be purified
by ordinary processes.
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 the precise details herein-before described; 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 passing
of crude or impure acetic acid vapor through a suitable hydrocarbon,
or oil, or fat, for the purpose of purifying or refining the same,
substantially as herein-before described.
In witness whereof, I, the said John Steedman, have hereunto set
my hand and seal, this Eighth day of April, in the year of our
Lord One thousand eight hundred and seventy-three.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JOHN STEEDMAN. (L.S.)