AN IMPROVED METHOD OF PRODUCING WHITE PIGMENTS FROM LEAD
Year: 1868

page_text: LETTERS PATENT to John Gallemore Dale and Edward Milner, of
Warrington, in the County of Lancaster, for the Invention of
"AN IMPROVED METHOD OF PRODUCING WHITE PIGMENTS FROM LEAD."
Sealed the 25th September 1868, and dated the 2nd April 1868.
PROVISIONAL SPECIFICATION left by the said John Gallemore
Dale and Edward Milner at the Office of the Commissioners of
Patents, with their Petition, ou the 2nd April 1868.
We, JOHN GALLEMORE DALE and EDWARD. MILNER, of Warrington,
in the County of Lancaster, do hereby declare the nature of the said
Invention for AN IMPROVED METHOD OF PRODUCING WHITE PIGMENTS FROM
LEAD," to be as follows:-
Our Invention relates to an improved method of producing white
pigments from lead, and consists,―
First. In taking the oxide of lead commonly known as litharge and
treating it in a finely ground state, and under constant agitation with
[Price 8d.]

page_text: a solution of a chloride of the alkalies or alkaline earths. After one
or two days' contact we obtain an exceedingly white and flocculent
compound, which after being washed from any adhering soluble saline
matter is in a state to be used as hereafter described in the third part.
We do not bind ourselves to any particular proportions of litharge
and chloride salt, but we may state that we find a mixture of sixty
parts of water with ten parts of litharge and one part chloride of
sodium, barium, or calcumini to answer well.
Secondly. Instead of the process above described we prepare hydrated
oxide of lead by any of the well-known methods, that is to say, by
the solution of lead ores, litharge, or. metallic lead in any suitable acid,
and subsequent precipitation by an alkali or alkaline earth; for instance,
the ordinary lead ore known as galena may be dissolved in hydrochloric
acid, and the hydrated oxide of lead fully precipitated from the
resulting chlorido by lime, or sulphate of lead obtained as a bye product
in several manufacturing processos may be treated with soda or any
suitable alkaline solution, whereby it is decomposed, and the hydrated
oxide of lead is produced. The hydrated oxide of lead by whatever
process prepared after being freed by washing from any soluble saline
matter is ready to be treated as next described.
Thirdly. We now take the compound made as described in our first
part, hydrated oxides of lead or mixtures of any proportion of them,
and add sufficient water to form a thin paste which is put into a
suitable vessel, either with the addition of from one to five
per cent.
of acetic acid or acetate of lead, or not, as may be found desirable.
The said vessel being closed and fitted with machinery to keep the
mixture in constant agitation; carbonic acid is now passed into this
vessel, either under pressure or otherwise, when it is rapidly absorbed,
and the whole mass or nearly so after the lapse of three or four days
will be found converted into carbonate of lead possessing great body
and opacity. When the conversion is deemed complete it is well
washed, and, if necessary, ground and levigated to free it from any
undecomposed litharge, which may be again treated as before described.
The levigated pigment is then dried, and may be used for any of the
purposes for which the so-called white lead of commerce is applicable.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Gallemore Dale and Edward Milnor in the
Great Seal Patent Office on the 1st October 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
GALLEMORE DALE and EDWARD MILNER, of Warrington, in the County
of Lancaster, send greeting.
י
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of April, in the year
of our Lord, One thousand eight hundred and sixty-eight, in the
thirty-first year of Her reign, did for Herself, Her heirs and successors,
give and grant unto us, the said Jolin Gallemore Dale and Edward
Milner, Her special license that we, the said John Gallemore Dale and
Edward Milner, our executors, administrators, and assigns, or such
others as we, the said John Gallemore Dale and Edward Miluer, our
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
"AN IMPROVED METHOD OF PRODUCING WHITE PIGMENTS FROM LEAD," upon the
condition (amongst others) that we, the said John Gallemore Dale and
Edward Milner, our executors or administrators, by an instrument in
writing under our, or their, or one of our or 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 we, the said John Gallemore Dale and
Edward Milner, do hereby declare the nature of our 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):
Our Invention relates to an improved method of producing white

page_text: First. In taking the oxides of lead commonly known as litharge and
massicot, and treating them in a finely ground state, and under constant
agitation with a solution of a chloride of the alkalies or alkaline earths.
After one or two days' contact we obtain an exceedingly white and
flocculent compound, which after being washed from any adhering
soluble saline matter is in a state to be used as hereafter described in
the third part. We do not bind ourselves to any particular proportions
of litharge and chloride salt, but we may state that we find a mixture
of sixty parts of water with ten parts of litharge and one part chloride
of sodium, barium, or calcumini to answer well.
Secondly. Instead of the process above described we prepare hydrated
oxide of lead by any of the well-known methods, that is to say, by
the solution of lead 'ores, litharge, or metallic lead in any suitable acid,
and subsequent precipitation by an alkali or alkaline earth; for instance,
the ordinary lead ore known as galena may be dissolved in hydrochloric
acid, and the hydrated oxide of lead fully precipitated from the resulting
chloride by lime; or salphate of lead obtained as a bye product in
several manufacturing processes may be treated with soda or any
suitable alkaline solution, whereby it is decomposed, and the hydrated
oxide of lead is produced. The hydrated oxide of lead by whatever
process prepared after being freed by washing from any soluble saline
matter is ready to be treated as next described.
Thirdly. We now take the compound made as described in our first
part, hydrated oxides of lead or mixtures of any proportion of them,
and add sufficient water to form a thin paste, which is put into a
suitable vessel, either with the addition of from one to five per cent.
of acetic acid or acctate of lead, nitric acid, nitrate or sub-nitrate of
lead, or not, as may be found desirable. The said vessel being closed
and fitted with machinery to keep the mixture in constant agitation,
carbonic acid is now passed into this vessel either under pressure oi
otherwise, when it is rapidly absorbed, and the whole mass or nearly
so after the lapse of three or four days will be found converted into
carbonate of lead possessing great body and opacity. When the con-
version is deemed complete it is well washed, and, if necessary, ground
and levigated to free it from any undecomposed litharge, which may
be again treated as before described. The levigated pigment is then

page_text: dried, and may be used for any of the purposes for which the so-called
white lead of commerce is applicable.
In witness whereof, I, the said Edward Milner, for and on
behalf of myself and the said John Gallemore Dale, have
hereunto set my hand and seal, this Twenty-fourth day of
September, in the year of our Lord One thousand eight hundred
and sixty-eight.
Signed, sealed, and delivered by the
within named Edward
in the presence of
Milner
G. SEPTIMUS HUGHES,
Patent Agent,
Manchester.
EDWARD MILNER. (L.S.)