IMPROVE- MENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1853

page_text: LETTERS PATENT to George Carter, of Mottingham, in the County
of Kent, Gentleman, and George Marriott, of Hull, in the County
of York, Colour Manufacturer, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF WHITE LEAD."
Scaled the 5th December 1853, and dated the 6th June 1853.
PROVISIONAL SPECIFICATION left by the said George Carter and
George Marriott at the Office of the Commissioners of Patents,
with their Petition, on the 6th June 1853.
We, GEORGE CARTER, of Mottingham, in the County of Kent,
Gentleman, and GEORGE MARRIOTT, of Hull, in the County of York,
Colour Manufacturer, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD" to be as
follows:-
Our Invention relates to the preparation of a substitute for carbonate
of lead, obtained by a peculiar mode of treating a certain oxide of lead,
by which means we procure a salt of lead which may be employed as a
pigment.
But that our Invention may be fully understood and readily carried into
effect, we will now proceed to detail the particulars of our process.
We take 400, say four hundred pounds, of fine ground litharge and
ten pounds of muriate of soda, which must be mixed and triturated

page_text: until a chloride of lead is formed; then, after thoroughly washing the
materials, twenty pounds of the sulphuric acid of commerce are to be
added, which, being duly mixed therewith, gaseous matter is disengaged
consequent on the decomposition of the chloride of lead, and a white
sulphate of lead is the result, which, being washed and dried, becomes
then fit for usc.
Although we have thus described only one method of proceeding in
preparing the sulphate of lead, the same may be obtained by modifica-
tions of the chemical process; we would, therefore, observe, that we do
not confine ourselves to the precise mode described, so long as the
principle here developed is maintained and the resulting effect is
similar. And we do declare that what we claim as our Invention is,―
The manufacture of sulphate of lead, prepared as herein described, to
be used as a pigment.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Carter and George Marriott in the Great
Seal Patent Office, on the 6th December 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we,
GEORGE CARTER, of Mottingham, in the County of Kent, Gentleman,
and GEORGE MARRIOTT, of Hull, in the County of York, Colour Manu-
facturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of June, in the year of our
Lord One thousand eight hundred and fifty-three, in the sixteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto us, the said George Carter and George Marriott, Her special
licence that we, the said George Carter and George Marriott, our
executors, administrators, and assigns, or such others as we, the said
George Carter and George Marriott, 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,

page_text: and Isle of Man, an Invention for "IMPROVEMENTS IN THE MANUFAC-
TURE OF WHITE LEAD," upon the condition (amongst others) that we,
the said George Carter and George Marriott, by an instrument in
writing under our 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said George Carter and George
Marriott, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly de-
scribed and ascertained in and by the following statement:-
Our Invention relates to the preparation of a substitute for carbonate
of lead; and it is obtained by a peculiar mode of treating certain oxides
of lead, by means of which we procure a salt of lead, suitable for being
employed as a pigment.
But in order that our said Invention may be fully understood and
readily carried into effect, we will now proceed to detail the particulars
of our processes.
We take a quantity of fine ground oxide of lead called litharge, and
to every one hundred pounds thereof add about twenty-five pounds of
muriate of soda, which must be mixed and triturated until a muriate
of lead is formed; then, after thoroughly washing the materials, five
pounds of the sulphuric acid of commerce are to be added, and a white
sulphate of lead will be the result, which, being well washed, dried, and
ground, becomes then fit for use.
Or, we sometimes take about equal parts of the oxide and the per-
oxide of lead, say, together, one ton,-and grind the whole under edge
stones; afterwards adding a solution of five hundred weights, or there-
abouts, of muriate of soda in fifty gallons of boiling water, pouring it in
by degrees as the composition thickens, and continue grinding until the
colour is of a sufficiently clear white; it is then to be removed to another
set of stones and ground as fine as possible, after which it is to be con-
veyed to a tub or other suitable vessel and well agitated with fifty
gallons of water, allowing it afterwards to settle. The water may then
be withdrawn and six and a half hundred weights, or thereabouts, of

page_text: common sulphuric acid poured over the washed materials settled at the
bottom of the tub; which being again stirred and allowed to settle, the
supernatant acid liquor must be drawn off, fresh water added, and so
on until by continued washings a neutral or nearly neutral sulphate of
lead remains. We then remove the preparation to filters, whereon it
dries and stiffens, in which state it is ready to be placed in a suitable
perforated box, to be compressed therein by an ordinary screw press;
it then only requires to be removed to proper drying rooms, wherein it
may be distributed in cakes, laid on racks, dried, and afterwards ground,
as customary in treating white lead.
Or, in lieu of the direct use of sulphuric acid, as specified in the
foregoing processes, we. sometimes substitute alum, or such of the
sulphates of the different alkalies, earths, or metals as are easily
obtainable, using them in the proportions equivalent for decomposing
the muriate of lead, and thereby obtain sulphate of lead, which is to be
washed, dried, and ground, as before directed.
Although we have thus described different methods of proceeding in
preparing the sulphate of lead, the same may be modified; we would,
therefore, observe, that we do not confine ourselves to the precise modes
described, so long as the principle herein developed is maintained, and
the resulting effect is similar. And we do declare that what we claim
as our Invention is, namely,-
The manufacture of white lead, or sulphate of lead, prepared as
herein described.
In witness whercof, we, the said George Carter and George
Marriott, have hereunto set our hands and seals, this Third day
of December, in the year of our Lord 1858.
Witness, WILLIAM SMITH.
GEO. CARTER.
(L.S.)
GEORGE MARRIOTT. (L.S.)