IMPROVEMENTS IN TREATING OR PREPARING BLACK LEAD
Year: 1853

page_text: LETTERS PATENT to Benjamin Collins Brodic, junior, of 13, Albert
Road, Regent's Park, in the County of Middlesex, for the Invon-
tion of IMPROVEMENTS IN TREATING OR PREPARING BLACK LEAD."
PROVISIONAL SPECIFICATION left by the said Benjamin Collins
Brodie at the Oflice of the Commissioners of Patents, with his
Petition, on the 28th July 1853.
I, BENJAMIN COLLINS BRODIE, junior, of 13, Albert Road, Regent's
Park, in the County of Middlesex, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN TREATING OP PREPARING BLACK
LEAD" to be as follows:-
The object of this Invention is to obtain black lead in a very fine
state of division; for this purpose the powder is to be broken down to
coarse particles, and then subjected to heat with acid, preferring a
mixture of sulphuric and chromic acid; the acid is drained and pressed
out, and the remaining acid washed out with water; the black lead
is then dried and subjected to a red licat.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Benjamin Collins Brodie in the Great Seal Patent
Office, on the 26th January 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
BENJAMIN COLLINS BRODIE, junior, of 13, Albert Road, Regent's Park,
in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of July, in the year of
our Lord One thousand eight hundred and fifty-three, in the seventeenth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Benjamin Collins Brodie, Her special licence
that I, the said Benjamin. Collins.Brodie,. my.executors, administrators,
and assigns, or such others as I, the said Benjamin Collins Brodie, 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 TREATING OR PREPARING BLACK LEAD," upon the
condition (amongst others) that I, the said Benjamin Collins Brodie,
by an instrument in writing under my hand and seal, shoukl parti-
cularly 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 Benjamin Collins Brodie, 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 thereof (that is, to say):
The object of this Invention is to obtain black lead in a very fine
state of division; for this purpose the black lead is to be broken down
to coarse particles, and then subjected to heat with acid, preferring a
mixture of sulphuric and chromic acid. The acid is drained and pressed

page_text: out, and the remaining. acid 'washed out with water. The black. lead is
then dried and subjected to a red heat.
Having thus stated the nature of my said: Invention, I will proceed
to describe the manner of performing the same, and in.doing so. I would
state that black load is very different in quality, some being compa-
ratively pure, and others more or less. impure; and the process, when
the black lead requires more purification, differs from the process when
little purification is considered necessary. When acting on black lead,
whether less or more impure, according to my Invention, I proceed as
follows: The black lead is.first reduced to a powder by stamping or
grinding. This powder is then mixed with concentrated sulphuric acid,
using about one part by weight of tlic powdered black lead.:to six or
ciglit parts by weight of sulphuric acil, a small quantity (say about one:
twentieth by weight of the black lead) of chlorate of potash is to be.
thrown into the mixture gradually, and the mixture is to be stirred.
The temperature of the mixture is then to be raised to about that of.
boiling water, and kept at that temperature till the cessation of chlorous
fumes; when cold, the black lead. is to be. well mixed or stirred in a
large quantity of water, and then to be allowed to stand; after a time the
black lead will settle to the bottom, and the fluid is to be drawn or run
off, the remaining acidulated water is to be washed out of the black
lead by further quantities of water, and these matters are to be sepa-
rated by decanting or by filtration, or by both. The black lead-is-then
to be slowly dried at a moderate heat, and when dry is to be raised to
a red heat in a crucible or otherwise. The black lead will, when cold,
be in a high state of sub-division, and may be used for the purposes for
which black lead in the state of powder has before been employed; but
the black lead may be separated from impurities by stirring it in a
quantity of water; the black lead, when allowed, will float at the top of
the water, and impurities will deposit by such means; the black lead
may be separated from nearly all of its impurities. I would here
remark, that in place of chlorate of potash above mentioned, chromate
and bichromate of potash, and many other chemical substances known
as oxydizing agents, may be used; but according to my present

page_text: experience I believe chlorate of potash to be the most suitable for the
purpose.
It is well known that there are varieties of black lead which are
impure by the presence of silica or silicates. In such cases, when
treating with reference to the silex or silicates present, I add such a
chemical matter as will produce hydrofluoric acid when mixed with
sulphuric acid, and I prefer to apply fluoride of sodium, and I add it
after the black lead has been mixed with sulphuric acid, and in propor-
tion to the silex or silicates present in the black lead. The process
in other respects is conducted as above explained.
Having thus described the nature of my Invention, and the manner
of performing the same, I would have it understood that I do not
confine myself to the details herein described, so long as the peculiar
character of the Invention be retained. But what I claim is, the
treating and preparing black lead with sulphuric acid, as herein 1
described.
In witness whereof, 1, the said Benjamin Collins Brodie, have
hereunto set my hand and seal, this Twenty-fifth day of January,
in the year of our Tord One thousand eight hundred and fifty-
four.
Witness,
S. CARPMAEL.
B. C. BRODIE, JUN". (LS.)