IMPROVEMENTS IN CONCENTRATING AND DISTILLING SULPHURIC ACID
Year: 1854

page_text: LETTERS PATENT to Robert Von Seckendorff, of Saint Helens, in the
County of Lancaster, Manufacturing Chemist, for the Invention of
65
IMPROVEMENTS IN CONCENTRATING AND DISTILLING SULPHURIC ACID."
Sealed the 23rd February 1855, and dated the 18th December 1854.
PROVISIONAL SPECIFICATION left by the said Robert Von Seckendorff
at the Office of the Commissioners of Patents, with his Petition, on the
18th December 1854.
I, ROBERT VON SECKENDORFF, of St. Helens, in the County of Lancaster,
Manufacturing Chemist, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN CONCENTRATING AND DISTILLING SULPHURIC ACID" to be
as follows:-
My improvements consist, firstly, in substituting an iron vessel or apparatus,
or furnace constructed of iron and brickwork, or of brickwork alone, in place
of the lead, glass, or platinum vessels usually employed in the concentration
and distillation of sulphuric acid, and various forms of such apparatus may be
employed.
Secondly, my improvements consist in adding certain substances to, or mixing
them with, the sulphuric acid which is to undergo the process of concentration

page_text: and subsequent distillation. The substances I employ are sulphate of lead,
sulphate of lime, sand, or any other substance which will not reduce or
decompose sulphuric acid at a high temperature. My object in adding the
above-mentioned substances is to prevent the sudden bursts of ebullition or
explosions in concentrating or distilling sulphuric acid.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Von Seckendorff in the Great Seal Patent Office
on the 14th June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
VON SECKENDORFF, 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 Eighteenth day of December, in the year of our Lord
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 me, the
said Robert Von Seckendorff, Her special license that I, the said Robert
Von Seckendorff, my executors, administrators, and assigns, or such others
as I, the said Robert Von Seckendorff, 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 CONCENTRATING AND DISTILLING SULPHURIC ACID," upon the
condition (amongst others) that I, the said Robert Von Seckendorff, 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 Robert Von Seckendorff, 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 (that is to say):-
My improvements consist, first, in substituting iron vessels or apparatus in
place of lead, glass, and platinum vessels, usually employed in concentrating
and distilling sulphuric acid.

page_text: Secondly, my improvements consist also in adding certain substances to, or
mixing them with, the sulphuric acid during the process of concentration and
subsequent distillation.
In concentrating and distilling sulphuric acid by glass retorts, in the ordinary
way, considerable expense is incurred by the large number of glass vessels
required, on account of the slowness with which this process is conducted,
besides the great risk and inconvenience necessarily connected with this mode
of working, render it both precarious and expensive. When platinum retorts
are used in this process, a very large expenditure is required in the first outlay.
In the use of lead for concentrating sulphuric acid, there is a difficulty in
reducing the liquid to the proper specific gravity, as the melting point of lead
and the quick evaporating point of concentrated sulphuric acid are nearly the
same. Under these circumstances also the acid contains an objectionable
quantity of lead in solution. I therefore propose to employ iron vessels
or apparatus, whether cast or malleable, instead of the lead, glass, and
platinum vessels hitherto used in the processes of concentrating and dis-
tilling sulphuric acid, and in doing so I prefer to use cast-iron retorts or
stills similar in form to those which are in daily use for the distillation
of nitric and hydrochloric acids. In proceeding to work, I add to the
sulphuric acids certain substances of such a nature or kind as will not
decompose the acid at high temperatures, and for this purpose I prefer to
employ sulphate of lead, sulphate of lime, or common sand, either separately
or together, in a granular or pulverized state. The quantity or these
substances to be added is not definite either as to relative proportion or
absolute weight, but I prefer to add them to the liquid sulphuric acid till the
whole becomes a thin pasty mass. It is then placed in the retort or still, and
a fire applied externally in the most economical manner, as is well understood.
This operation divides itself into two stages, the concentrating or evaporating
and the distilling or rectifying. In the first stage, a quantity of weak acid
comes over, which may be returned to the chambers or boilers; a quantity of
sulphurous acid and nitrous acid fumes also escapes from the retort during the
concentrating and distilling processes. These gases are to be conveyed from
the retort into a chamber by a lead pipe or flue to form sulphuric acid, or to
be applied to any other useful purpose.
When the second stage supervenes,
the sulphuric acid (S, O3 + II, O,) is converted into vapour by the heat of the
retort, and is to be conveyed into a proper cooler and receiver by suitable pipes,
either of glass, earthenware, or platinum. By these means the concentration
and rectification of crude sulphuric acid may be as quickly performed as in
platinum vessels, and at a much less original cost.
When the sulphuric acid

page_text: is thus evaporated and distilled, another charge of crude sulphuric acid is to be
put into the retort, which vessel'still contains the sulphate of lead or other
substances which were mixed with the first charge of acid, and the same
processes to be repeated successively, as before described.
Having thus described the nature of my Invention for "concentrating and
distilling sulphuric acid," and the manner of carrying the same into effect, I
would have it understood that I do not confine myself to the exact details,
either as respects the materials used, or their respective proportions, or the
description of apparatus employed in these processes, for they may be varied to
suit circumstances; but what I do claim is,-
First, the substitution of iron vessels or apparatus instead of lead, glass,
and platinum, hitherto employed in the concentration and distillation of
sulphuric acid.
And, secondly, I claim the adding to the crude sulphuric acid sulphate of
lead, sulphate of lime, and common sand, or other suitable material which
will not decompose sulphuric acid at a high temperature, all which is herein-
before described.
In witness whereof, I, the said Robert Von Seckendorff, have hereunto
set*
my hand and seal, the Eleventh day of June, in the year of our
Lord One thousand eight hundred and fifty-five.
ROBERT VON SECKENDORFF. (L.S.)
The undersigned, Her Britannick Majesty's Minister
in Saxony, certifies the above signature,
Dresden, 11th June 1855,
FRANCIS R. FORBES.