IMPROVEMENTS IN THE PURIFICATION OF LEAD
Year: 1862

page_text: LETTERS PATENT to Edward Scripps Tudor, of Upper Thames Street, in
the City of London, White Lead Manufacturer, for the Invention of
"IMPROVEMENTS IN THE PURIFICATION OF LEAD"
PROVISIONAL SPECIFICATION left by the said Edward Scripps Tudor
at the Office of the Commissioners of Patents, with his Petition, on
the 28th October 1862:
I, EDWARD SCRIPPS TUDOR, of Upper Thames Street, in the City of London,
White Lead Manufacturer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE PURIFICATION OF LEAD," to be as follows:-
My Invention of improvements in the purification of lead has for its object
to eliminate from lead the other metals and substances with which nearly all
metallic lead is usually found to be in combination, so that when all these
foreign matters are removed the metallic lead will be obtained in an absolute
state of purity.
The principal substances which I seek to remove or separate from the lead
are arsenic, antimony, and tin, which are more valuable than the lead itself.
In carrying out my Invention I melt the lead in a crucible, melting pot, or
other suitable vessel, and bring it in the molten state into the presence of
litharge or other oxide of lead, which, when reduced to a pasty state by heat,
will part with some of its oxygen to the arsenium, antimony, and tin found in
the lead, and will form therewith a scum on the top of the metallic lead. In
order to bring every part of the molten lead into contact with the oxide, the
lead should be stirred from time to time, and after exposure for about three

page_text: hours to the action of the oxide, the lead will be found quite pure, and may
then be drawn or poured off. The scum will be very rich in the more valuable
metals, which may be subsequently extracted therefrom by any of the well
known processes. A quantity of litharge or oxide sufficient to cover the
surface of the molten lead will effect the object of the Invention, but it is
advisable that the oxide should always be in excess. Instead of simply floating
the molten litharge or oxide on the surface of the lead in the melting pot, the
lead may be melted in a separate vessel, and then rained down in drops into
the vessel containing the molten oxide. By this means the contact of every
particle of lead as it sinks through the oxide will be ensured, and the process
of purification will be accelerated. It will, of course, be understood that
when the litharge becomes highly charged with the impurities of the lead, and
no longer acts energetically thereon, the scum should be removed, and fresh
oxide added in its place.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Scripps Tudor in the Great Seal Patent Office on
the 28th April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
SCRIPPS TUDOR, of Upper Thames Street, in the City of London, White Lead
Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of October, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Edward Scripps Tudor, Her special licence that I, the said Edward
Scripps Tudor, my executors, administrators, and assigns, or such others as I,
the said Edward Scripps Tudor, 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 THE PURIFICATION OF LEAD," upon the condition (amongst
others) that I, the said Edward Scripps Tudor, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and cause

page_text: 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 Edward Scripps Tudor, 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 :—
This Invention relates to improvements in the process of purifying lead.
This process consists in subjecting the lead melted in a furnace, pot, crucible,
or any other suitable vessel or apparatus, to the action of litharge or other
oxide of lead in a state of fusion or semi-fusion.
The litharge or oxide is brought into contact with the impurities in the
lead, and thus parts with its ogygen to them, reducing the litharge to metallic
lead, and leaving the impurities with the excess of litharge floating on the top
of the molten metal. In practice I have found this process most effective
when the litharge is sufficiently heated to reduce it to a pasty or semi-fluid
condition. The lead may be melted first, and when in a molten state, the
litharge or oxides added thereto in the same vessel. In this case it is necessary
to increase the heat of the melted metal after the litharge is added to reduce
it to the required condition. The process, however, is more perfect in its
operation when the litharge and lead are melted in separate vessels, so that the
litharge and lead are melted in separate vessels, so that the litharge can be
first reduced to the required state, and then melted lead added by pouring it
upon the litharge through a colander. The object of this is, by dividing the
molten metal as it passes through the colander, to expose as much surface to
the action of the litharge as practicable.
Having thus described and ascertained the nature and object of my said
improvements, and the means whereby the same may be carried into effect in
practice, I hereby further declare that I claim this process, whether applied in
single or separate vessels, as herein described, or in any apparatus suitable for
the purpose.
In witness whereof, I, the said Edward Scripps Tudor, have hereunto
set my hand and seal, this Twenty-eighth day of April, One thousand
eight hundred and sixty-three.
EDWARD SCRIPPS TUDOR. (L.s.)