IMPROVE- MENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1866

page_text: LETTERS PATENT to William Robert Lake, of the "International Patent
Office, No. 8, Southampton Buildings, Chancery Lane, in the County
of Middlesex, Consulting Engineer, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF WHITE LEAD."-A communication from
abroad by William Bell, Thomas Mara Fell, and Ambrose George Fell,
all of New York City, United States of America.
Sealed the 18th December 1866, and dated the 26th June 1866.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents, with his Petition, on the
26th June 1866.
I, WILLIAM ROBERT LAKE, of the "International Patent Office," No. 8,
Southampton Buildings, Chancery Lane, in the County of Middlesex, Con-
sulting Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD," a communication,
to be as follows:-
The said improvements consist in certain processes of manufacturing white
lead either from the ores of lead or from the metal lead direct.
In the treatment of ores containing lead, the same are first calcined or
oxidized by means of a reverberatory furnace in the ordinary way of roasting
ores.

page_text: Secondly, the resulting oxide (which should be as free as possible from
iron, copper, and other foreign matters) is submitted to contact with nitric
acid, diluted with water, in suitable glass or porcelain vessels, thus forming a
soluble nitrate of leadd.
Thirdly, this nitrate of lead is drawn off into a separate set of vessels and
treated with sulphuric acid sufficient to precipitate the bulk of lead, but
leaving a portion thereof still in solution for the purpose of preventing an
excess of sulphuric acid, which would be detrimental in the after process. The
precipitated sulphate of lead soon settles or subsides to the bottom of the
precipitating vessels, and is then removed for further treatment herein-after
explained. The nitric acid thus set free can now be returned to a fresh lot
of oxide, and will again extract a quantity of lead equal to the amount thrown
or precipitated down by the sulphuric acid. In the treatment of metallic
lead direct no previous oxydation is required, but the processes described as
the second and third stages of manufacture are followed.
The fourth manipulation or conversion of this common sulphate of lead
into merchantable white lead constitutes the principal subject matter of these
improvements, and is as follows:-The precipitated sulphate, whether derived
either from the ores, or the metal, has hitherto been of inferior value on
account of its crystaline structure and want of what is termed "body" or
spreading quality, this objectionable property is entirely removed by the
treatment herein described, and a fine close grained white lead is the result.
This sulphate derived from soluble nitrates is submitted to an intimate contact
with a solution of potash or soda, slightly heated and stirred in large vessels,
the proportion used is about three per cent. of the latter, the effect of this
alkali, which may be either potash or soda, or both, is to deprive the sulphate
of a portion of its acid in combination, and thereby produce a new article or
a sub-sulphate of lead, which possesses qualities superior to the best white
lead of commerce; this sub-sulphate is then washed in vats,.collected and
dried at a low temperature, either by heating in pans or on shelves in a
building expressly constructed for air drying. It is obvious that the pro-
portions above given may be changed or varied, and more or less alkali used,
and very near results may also be obtained by the use of other alkalies, or the
salts of these materials. The constitution of the sulphate may be first changed
into a carbonate of lead by the use of the carbonates of either potash, soda,
or lime, and finally treated with the alkali solution, the sulphate may also be
derived by the use of acetic instead of nitric acid.

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 26th December 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the "International Patent Office," No. 8, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Consulting Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of June, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Robert Lake, Her special license 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 of "IMPROVEMENTS
IN THE MANUFACTURE OF WHITE LEAD," upon the condition (amongst others) that
I, the said William Robert Lake, my executors or administrators, by an instru-
ment 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 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 J, 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:
The said improvements consist in manufacturing white lead, either from
the ores of lead or from the metallic lead direct by the peculiar treatment of
the sulphate of lead derived from the said ores or metal. In .the treatment
of ores containing lead the same after being well ground are calcined or
oxydized by the ordinary process of roasting by means of a reverberatory
furnace. The resulting oxide (which should be as free as possible from
silica, iron, copper, and other foreign matter) is submitted to contact with
nitric acid diluted with water in vessels lined with hard rolled sheet lead or

page_text: "
vessels of glass, porcelain, or other suitable material, a soluble nitrate of lead
is formed by this process, the solvent consists by preference of three parts
water, and one part of nitric acid 36° Baumé, but these proportions may be
varied without materially affecting the result; this nitrate of lead is then
drawn off into a separate set of vessels and treated with sulphuric acid in
sufficient quantity to precipitate the bulk of lead, leaving only a portion
thereof still in solution for the purpose of preventing the presence of sulphuric
acid which would be detrimental while the nitric acid is being again used as a
solvent, the precipitated sulphate of lead soon settles or subsides to the
bottom of the precipitating vessels, and is then removed for further treatment.
The nitric acid thus set free can now be returned to a fresh quantity of oxide,
and will again extract a quantity of lead equal to the amount precipitated or
thrown down by the sulphuric acid. In the treatment of metallic lead direct
the metal is by preference first melted and then converted into a sponge
by being poured into a rosso! containing water, the said sponge is then
treated with the solvent and precipitant as above described. The metallic
lead may be also converted into an oxide by the ordinary plan of making
litharge, the said litharge being afterwards treated in a similar manner to that
described with respect to the calcined ore or "sponge." The sulphate may
also be derived by the use of acetic acid as a solvent in place of nitric acid,
the former acid has a similar action in operating on the oxide, but acts more
slowly, must be used in larger quantities, and consequently is more expensive.
The nitric acid is recovered by allowing the sulphate to settle down on the
bottom of the vessel when the said acid can be drawn off for further use as a
solvent, it may also be recovered after the formation of the sulphato by gentle
evaporation in suitable pans, or other vessels, and then condensed. The
precipitated sulphate whether derived from ores, metallic lead, or its oxides,
is of inferior value on account of its crystaline structure, and want of what is
termed "body" or "spreading quality." These defective and objectionable
properties are entirely removed from the said sulphate by the improved
treatment herein described, and a fine close grained white lead is the result;
this sulphate derived from soluble nitrates is submitted to an intimate contact
with an alkali solution contained in boilers or other suitable vessels, and is
boiled from two to three hours, the quantity of the alkali used may be about
three per cent. of the quantity of sulphate. The effect of the alkali is to
deprive the said sulphate of a portion of the acid and water in combination
therewith, and thereby produce a new article which may be termed a sub-
sulphate of lead, and which possesses qualities superior to the best white lead
of commerce hitherto known; this product being washed in vats, is afterwards

page_text: collected and dried in pans or on shelves in a building expressly constructed
for air drying, or it may be dried in suitable chambers by the application of
heat. The proportions of the alkali and sulphate, as above given, may be
varied without greatly affecting the result of the process, but the above stated
quantities are found to answer well. The constitution of the sulphate may
be first changed into a carbonate of lead by the use of a carbonate of an
alkaline base, and finally treated with the alkali solution, an alkaline effect is
produced on the sulphate by the direct use of any one of the alkaline com-
pounds without the after treatment by an alkali solution, nearly the same
results being obtained; the said alkali solution may be made from either
potash or soda.
Having thus fully described the said Invention, as communicated to me by
my foreign correspondents, and shown how the same may be conveniently and
advantageously carried into practise, I claim,-
First, the treatment of sulphate of lead with an alkali solution in the
manner and for the purpose substantially as described.
Second, the treatment of sulphate of lead with a carbonate of an alkaline
base, followed by an alkali solution, in the manner and for the purpose
substantially as described.
Third, the treatment of sulphate of lead with any one of the alkaline
compounds in the manner and for the purpose substantially as described.
Fourth, the manufacture of white lead from the ores of lead, from the
metallic lead, or from the oxide of that metal, by the employment of nitric
and sulphuric acids, in combination with a treatment by an alkali solution
either with or without the prior treatment by a carbonate of an alkaline base,
substantially as described.
In witness whereof, I, the said William Robert Lake, have hereunto
set my hand and seal, this Twenty-fourth day of December, in the
year of our Lord One thousand eight hundred and sixty-six.
WILLIAM ROBERT LAKE. (L.S.)
Witness,
GEORGE HASELTINE,
8, Southampton Buildings,
London.