IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD (MEANING CARBONATES OF LEAD.
Year: 1860

page_text: LETTERS PATENT to Thomas Cobley, of Meerholz, in the Electorate of
Hesse, Germany, Mine Owner, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF WHITE LEAD (MEANING CARBONATES OF LEAD.)"
Sealed the 22nd February 1861, and dated the 26th October 1860.
PROVISIONAL SPECIFICATION left by the said Thomas Cobley at
the Office of the Commissioners of Patents, with his Petition, on
the 26th October 1860.
I, THOMAS COBLEY, of Meerholz, in the Electorate of Hesse, Germany,
Mine Owner, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD (MEANING CARBONATES
OF LEAD)," to be as follows, that is to say:
I first grind or pulverize the ore to be acted upon, and then oxidize it in an
ordinary furnace; after oxidization I treat it with the acetic acid of commerce
or with any other acetic liquid, so as to form a fully saturated acetate salt of
lead; this may also be effected with acetous gases obtained by heating alkaline
acetates with acid; this liquid salt of lead being gently heated carbonic acid
also heated is introduced into it, and the white lead deposits itself; it is then
washed out, pressed and dried, and in this state is ready for use. The carbonic
acid used may be obtained from thermal springs, or by the decomposition of
lime or coal or any other ordinary well known method.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Cobley, in the Great Seal Patent Office on the
23rd April 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
COBLEY, of Meerholz, in the Electorate of Hesse, Germany, Mine Owner,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of October, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Cobley, Her special licence that I, the said Thomas Cobley,
my executors, administrators, and assigns, or such others as I, the said Thomas
Cobley, 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 THE
MANUFACTURE OF WHITE LEAD (MEANING CARBONATES OF LEAD)," upon the condi-
tion (amongst others) that I, the said Thomas Cobley, 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 Thomas Cobley, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
Having first ground or crushed the ore to be acted upon I then put it
upon a simply constructed furnace consisting of a surface of iron plates or
otherwise, and carefully roast it, taking care that no insoluble oxides or
silicates of lead are formed.
If I am now about to form pigment white lead, meaning pure white lead,
I treat the roasted ore with the acetic acid of commerce, either in a liquid
or a gaseous form; the latter obtainable either by decomposition of alkaline
acetates or acetates formed from the earthy bases or vaporized acetic acid, in
which case the vapour or gas is introduced by means of a pipe from an appa-
ratus for that purpose into a closed tank or vessel, which is divided into two

page_text: parts by means of a finely perforated diaphragm upon which the roasted ore is
placed and which is kept wet in order to condense the vapour. The quantity
of acid which I employ in the process depends entirely upon the per centage
of lead in the ore used, but it should be in such proportions, as to form a
subacetate of lead. I propose also to brighten acetate salts of lead formed by
any process whatever from the ore by means of animal charcoal, or other
decolorizing matter, and either by the method of filtration or otherwise.
Should the ore contain silver to any extent I free the latter by means of
amalgamation with quicksilver. I now take the liquor obtained as before
described and precipitate it by means of carbonic acid. I propose to obtain
my carbonic acid by decomposing carbonaceous matters, or from by products
given off in the manufacture of silicate of soda from carbonate of soda, or of
chloride of barium from carbonate of baryta, or by the decomposition of
marble, limestone, dolomite, magnesite, or any other of the alkaline carbonates
either obtained by the direct application of the said carbonates, or by double
decomposition, or from the carbonates or proto-carbonates of iron or other
available metallic carbonate. When I use carbonic acid I always prefer to
apply it in a heated state; and furthermore I prefer to purify it before use by
passing it through a solution of copper or lead or by any other well known
The method I adopt for bringing the carbonic acid into combination
with the liquid, so as to cause precipitates is as follows, the liquor is allowed
to percolate through a large holder and meets the gas, which is introduced at
the bottom of the said holder by means of a series of pipes. The excess of
oxide in the subacetate thus thrown down as carbonate of lead is allowed to
settle, the liquor is then drawn off, it is now washed and dried, and is then
ready for market. I now treat the neutral liquor with a fresh supply of ore pre-
pared as before until a subacetate is again formed, and again I precipitate, as
before and continue charging and precipitating alternately, hence the cost of
the acetic acid becomes nominal, as I only use it as a carrier.
means.
In producing white lead which is used by potters, porcelain manufacturers,
colour makers, and others, I employ a cheaper course of obtaining acetic acid,
that is to say, I use the crude pyroligneous acid of commerce as a liquid, or
the vapour of the said acid, or pyroligneous gas produced from dry distillation
of wood. In this process I take the pyroligneous liquor and mix the ore with
it, taking the latter warm from the calcining furnace using the necessary
proportions of each. I then allow it to stand, lixiviate it with hot water,
brighten it as before described, then precipitate it in the manner before
mentioned. If the vapour from the acid itself is used, then it must be applied
to the wet calcined ore through perforations in the manner described in the

page_text: former process. When pyroligneous gases are used the calcined ore in a wet
state must be placed in an apparatus supplying the place of the condensor in
the ordinary process of distilling wood. The liquor obtained by any of the last
described methods is to bo precipitated by the process first mentioned; the
neutral liquors being used over and over again after the manner first
described.
Ilaving now described the nature of my Invention, and how the same is
carried into operation and the results obtained, I wish it understood that
what I claim and wish secured to me by the before in part recited Letters
Patent is, the manufacture of white lead (meaning carbonates of lead)
from the native carbonates of lead (ore) or or from any readily oxidized com-
bination of lead or native oxides by the process and methods and means herein
fully set forth and described, or by the use of any analogous or similar known
methods, and by the use of analogous and similar known means.
In witness whereof, I, the said Thomas Cobley, have hereunto set my
hand and seal, this Twenty-second day of April, in the year of our
Lord One thousand eight hundred and sixty-one.
Witness,
JAMES WRIGHT,
42, Bridgo St., Blackfriars,
London.
TH. COBLEY. (L.S.)