IMPROVEMENTS IN THE MANUFACTURE OF DRY WHITE LEAD AND WHITE LEAD PIGMENT FROM METALLIC LEAD.
Year: 1869

page_text: LETTERS PATENT to William Robert Lake, of the "International™
Patent Office," Southampton Buildings, London, Consulting.
Engineer, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF DRY WHITE LEAD AND WHITE LEAD PIGMENT FROM METALLIC LEAD.".
A communication from abroad by George Thompson Lewis, of
Philadelphia. Pennsylvania, United States of America.
Sealed the 22nd December 1869, and dated the 25th October 1869.
PROVISIONAL SPECIFICATION left by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition, on
the 25th October 1869.
I, WILLIAM ROBERT LAKE, of the "International Patent Office,"
Southampton Buildings, London, Consulting Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF DRY WHITE LEAD AND WHITE LEAD PIGMENT FROM METALLIC
LEAD," a communication, to be as follows:-
Heretofore dry white or the basis of white lead pigment has been
most generally made from metallic lead by the use of acetic acid
in earthen vessels immersed in decomposing matter, such as dung or

page_text: tan. This treatment requires from five to twelve weeks, the lead being
afterwards ground, washed, and dried before it is fit to be used as the
basis of a pigment.
This Invention relates to subliming metallic lead and then oxydizing
the vapors and collecting them in separate chambers or bags. Metallic
lead is finely divided or granulated by being slowly poured while in a
molten state from a height of from four to six feet into water in a state
of agitation. The finely granulated lead in small quantities is then
mixed with carbon, preferably fine washed pea or dust anthracite coal,
in the proportion of half and half, and the mixture is then heated in a
compound reducing and oxydizing furnace. Dense white fumes or
vapors pass off; these are conveyed into a separate chamber or receptacle,
where the vapors are strained by passing through bags or screens of
muslin or other fabric, or are allowed to deposit by being passed slowly
through an extended chamber in the way in which lamp black, oxide of
zinc and the like have been heretofore collected. To prevent the
fluxing of the mass together and otherwise to facilitate the subsequent
operations caustic lime or the carbonate of lime (in the form of pulverized
limestone or otherwise) or metallic iron or its oxides, whether native or
artificial, preferably however in the form known as brown hematite, may
be added to the mixture of carbon and granulated lead in the proportion
of about 200 pounds of lime to every 400 pounds of the lead. This
addition is not essential, although under some circumstances it is
desirable and beneficial. Lead in this condition will form when mixed
with oil a superior white pigment. It differs from and is superior in
quality as a pigment to the white oxide of zinc or anything heretofore
produced from mixed metallic ores, or to the oxide of lead produced
in the ordinary way for such purposes as litharge, red lead, or orange
mineral are generally applied. The product obtained by said process
may be used not only as the basis of pigment but as a drier and in all
manufactures where oxide of lead is desired.
The form of the furnace employed is not material provided it be
so arranged as to evolve metallic vapor and then oxydize the vapor. The
furnace which has been found to work well for the purposes above
mentioned is commonly known as the Wetherill zinc furnace.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Robert Lake in the Great Seal Patent
Office on the 23rd April 1870..
TO ALL TO. WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the "International Patent Office," Southampton
Buildings, London, Consulting Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of October, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Robert Lake, Her special licence
that I, the said William Robert Lake; my executors, administrators,
and assigns; or such others as. I, the said William Robert Lake, 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 MANUFACTURE OF DRY WHITE LEAD AND WHITE LEAD PIGMENT FROM
METALLIC LEAD," a communication to me from abroad by George
Thompson Lewis, of Philadelphia, Pennsylvania, United States. of
America, upon the condition (amongst others) that I, the said William
Robert Lake, my executors or administrators, by an instrument in
writing under my; or their, or one of their hands and seals, should par-
ticularly 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 William Robert Lake, 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, reference being had to the accompanying
Drawing forming a part of this Specification.
Heretofore dry white or the basis of white lead pigment has been
most generally made from metallic lead by the use of acetic acid in
carthen vessels immersed in decomposing matter, such as dung or tan.

page_text: This treatment requires from five to twelve weeks, the lead being
afterwards ground, washed, and dried before it is fit to be used as the
basis of a pigment.
This Invention relates to subliming metallic lead and then oxydizing
the vapours and collecting them in separate chambers or bags. Metallic
lead is finely divided or granulated by being slowly poured while in a
molten state from a height of from four to six feet into water in a state
of agitation. The finely granulated lead in small quantitics is then
mixed with carbon, preferably fine washed pea or dust anthracite coal, in
the proportion of half and half, and the mixture is then heated in a
Dense white fumes or
compound reducing and oxydizing furnace.
vapours pass off; these are conveyed into a separate chamber or
receptacle, where the vapours are strained by passing through bags or
screens of muslin or other fabric, or are allowed to deposit by being
passed slowly through an extended chamber in the way in which lamp
black, oxide of zinc, and the like have been heretofore collected. To
prevent the fluxing of the mass togethor and otherwise to facilitate
the subsequent operations caustic lime or the carbonate of lime (in the
form of pulverised limestone or otherwise) or metallic iron or its oxides,
whether native or artificial, preferably however in the form known as
brown hematite, may be added to the mixture of carbon and granulated
lead in the proportion of about two hundred pounds of lime to every four
hundred pounds of the lead. This addition is not essential, although
under some circumstances it is desirable and beneficial. Lead in this
condition will form when mixed with oil a superior white pigment. It
differs from and is superior in quality as a pigment to the white oxide of
zinc or anything heretofore produced from mixed metallic ores or to the
oxide of lead produced in the ordinary way for those purposes to which
litharge, red lead, or orange mineral are generally applied. The product
obtained by said process may be used not only as the basis of pigment
but as a drier, and in all manufactures where oxide of lead is desired.
The form of the furnace employed is not material provided it be so
arranged as to evolve metallic vapour and then oxydize the vapour.
The furnace which has been found to work well for the purposes above
mentioned is commonly known as the "Wetherill" zinc furnace.
This furnace is represented in the accompanying Drawing, in which
Figure 1 is a plan of the said furnace; Figure 2 is a front clevation,

page_text: Figure 3 is a back clevation thereof; and Figure 4 is. a vertical section
on the line x, x, Figure 1.
The said furnace has a main chamber a, the bottom 6 of which is
composed of iron bars perforated with small holes of about onc quarter
of an inch in diameter and about one inch apart and preferably made
slightly conical with the larger diameter downward. The size of the
holes should be such as to prevent the crushed ore and coal from falling
through. These perforated bars are suitably sustained at the ends on
the front and back walls. The ash-pit below the perforated bottom is of
equal area therewith, and is provided with a door e in front with a hole f
at the back for the reception of a pipe from a suitable blowing apparatus.
The walls g, g, and the arch or top 7 should be built of some refractory
substance, such as fire-brick; the front is entirely open and provided
with sliding doors i, by which it can be closed when working or opened
to remove the residuum. At the back there are two sliding jambs j, j,
to give access to the main chamber for stirring the charge and for
inspection. At the back near the arch there is a hole governed by a
sliding damper leading to a chimney for carrying off smoke and impure
gases in the beginning of the operation on a new charge. In the centre
of the roof there is an aperture governed by a damper or sliding
door m leading to a suitable apparatus for the collection of the oxydized
vapours of lead.
The exterior walls n, o, p, q, may be built above the
top to form two feeding troughs r, r, one on each side of the arch or
roof, and provided each with an aperture or passages leading to the
inside or main chamber, and each aperture or passage is provided with a
cover to be put on after the furnace has been charged.
Having thus fully described the said Invention as communicated to
me by my foreign correspondent, and shewn how the same may be
conveniently and advantageously carried into practice, I claim,-
First. The manufacture of the basis of a pigment by mixing finely
divided lead with carbon and subjecting the mixture to the action of heat
in a compound and reducing and oxydizing furnace and collecting the
fumes, as herein described.
Second. The employment of lime in the form of caustic lime or the
carbonate of lime or metallic iron or its oxides whether native or
artificial in combination with carbon and finely divided metallic lead in
a compound reducing and oxydizing furnace, substantially as described.

page_text: Third. Subliming metallic lead and oxydizing the vapours and
collecting them as formed in a separate chamber for the purpose of
forming a basis of pigment and for other purposes, substantially as set
forth.
Fourth. A white oxide of lead produced by subliming metallic
lead and oxydizing the vapours and collecting them in a separate
chamber.
In witness whereof, I, the said William Robert Lake, have here-
unto set my hand and seal, this Twenty-second day of April,
in the year of our Lord One thousand eight hundred and
seventy.
WILLIAM ROBERT LAKE. (L.S.)
Witness,
J. TEARE,
Clerk to Messrs. Haseltine, Lake, & Co.
Southampton Buildings,
London.