IMPROVEMENTS IN MAKING WHITE LEAD
Year: 1870

page_text: LETTERS PATENT to Isham Baggs, of High Holborn, in the County
of Middlesex, Scientific Chemist, for the Invention of "IMPROVEMENTS
IN MAKING WHITE LEAD."
Sealed the 4th October 1870, and dated the 16th April 1870.
PROVISIONAL SPECIFICATION left by the said Isham Baggs at the
Office of the Commissioners of Patents, with his Petition, on the
16th April 1870.
I, ISHAM BAGGS, of High Holborn, in the County of Middlesex,
Scientific Chemist, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MAKING WHITE LEAD," to be as follows:-
My Invention consists in mixing, bruizing, and grinding the alkaline
carbonates and bi-carbonates with the salts and sub-salts of lead in the
ratio of their respective equivalents, and I effect this in the dry state, or
nearly so, and with or without the water of crystallization; the ground
mixture is then allowed to remain with occasional stirring, for twenty-

page_text: four hours, or as long as may be deemed necessary in order that the
chemical action thus set up may be completed. The earthy and other
carbonates may sometimes be substituted with advantage.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Isham Baggs in the Great Scal Patent Office on
the 15th October 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ISHAM
BAGGS, of High Holborn, in the County of Middlesex, Scientific Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Sixteenth day of April, in the year of
our Lord One thousand eight hundred and seventy, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Isham Baggs, Her special licence that I, the
said Isham Baggs, my executors, administrators, and assigns, or such
others as I, the said Isham Baggs, 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 MAKING WHITE
LEAD," upon the condition (amongst others) that I, the said Isham
Baggs, my executors or administrators, 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 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 Isham Baggs, 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 :-
My said Invention consists in mixing, bruizing, and grinding the
alkaline carbonates and bi-carbonates with the salts and sub-salts of
lead in the ratio of their respective equivalents or thereabouts.

page_text: The materials employed are, in the first instance, to be roughly
powdered and dried. I take two equivalents of sub-acetate of lead, one
equivalent of common carbonate of soda, and one equivalent of bi-
carbonate of soda, and intimately mix and pound them together. At
the commencement of the treatment the powders are quite dry, but
after pounding and mixing for a short time it will be found that the
mixture becomes very perceptibly damp, and afterwards, after a very
short period from the commencement of the process the compound will
assume the appearance of white mud, and will be thin enough to pour
from one vessel into another. At this stage the white lead is in fact
made; it is then allowed to stand without further treatment in the
mortar or other vessel which has been employed for twenty-four hours,
during which time carbonic acid is given off. The mass swells to twice
its original bulk, and then slowly subsides to its former dimensions.
The white lead now merely requires to be washed and dried and is ready
for the market. On a large scale the mixing and grinding is effected
between millstones, or, more simply still, by placing the mixture in a
barrel, or in a receptacle of a rectangular or other suitable shape, which
is fixed diagonally on an axis and caused to revolve.
The original sub-acetate of lead is prepared by dissolving litharge in
acetic acid, or by exposing a large surface of blue lead to the alternate
action of acetic acid and atmospheric air.
All the materials employed are recovered again and again after use
so that nothing but the lead requires to be found for each succeeding
operation. Thus the acetate of soda resulting from decomposition is to
be filtered and washed out of the carbonate of lead, and then con-
centrated by boiling. This liquor is to be decomposed by sulphuric
acid, and the acetic acid recovered in a pure state by distillation in the
ordinary way, or by the well-known process known as that of Mollerat,
with or without distillation. The sulphate of soda resulting under either
mode of working is to be reconverted into carbonate, and a portion of
the latter into bi-carbonate by carbonic acid from any cheap source, as
from burning charcoal or limestone, as well understood.
Having thus declared and ascertained the nature of my said In-
vention, and in what manner the same is to be performed, I would
observe in conclusion that what I consider novel and original and
therefore claim as constituting the Invention secured to me by the said

page_text: herein-before in part recited Letters Patent is, the method of making
white lead as hercin-before set forth and described, or any mere
modifications thereof.
In witness whereof, I, the said Isham Baggs, have hereunto set
my hand and scal, this Fourteenth day of October, in the year of i
our Lord One thousand eight hundred and seventy.
ISHAM BAGGS. (L.S.)