AN IMPROVEMENT OR IMPROVEMENTS IN THE PROCESS OF MAKING OR MANUFACTURING CERUSE OR WHITE LEAD
Year: 1835

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
GoSSAGE, of Stoke Prior, in the County of Worcester, Chemist, and EDWARD
WHITE BENSON, of Wickbold, in the same County, Chemist, send greeting.
WHEREAS His present Majesty King William the Fourth, by His Letters
Patent under the Great Seal of the United Kingdom of Great Britain and
Ireland, bearing date at Westminster, the Twenty-ninth day of March now
last past, did give and grant unto us, the said William Gossage and Edward
White Benson, His especial licence, full power, sole privilege and authority,
that we, tho said William Gossage and Edward White Benson, our exccutors,
administrators, and assigns, or such others as we, the said William Gossage
and Edward White Benson, our executors, administrators, or assigns, should
at any time agree with, and no others, from time to time and atall times there-
after during the term of years therein expressed, should and lawfully might
make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, and also in all His said Majesty's Colonies and Planta-
tions abroad, our Invention of "AN IMPROVEMENT OR IMPROVEMENTS IN THE
PROCESS OF MAKING OR MANUFACTURING CERUSE OR WHITE LEAD;" in which said
Letters Patent there is contained a proviso obliging us, the said William
Gossage and Edward White Benson, by an instrument in writing under our
hands aud seals, or under the hand and seal of one of us, particularly to
describe and ascertain the nature of the said Invention, and in what manner
Price dl

page_text: the same is to be performed, and to cause the same to be inrolled in His
said Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said recited Letters Patent, as in and
by the same, reference being thereunto had, will more fully appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
William Gossage and Edward White Benson, do hereby declare that the
nature of our said Invention, and the manner in which the same is to be per-
formed, is described and ascertained in manner following, that is to say:-
In manufacturing ceruse or white lead by our improved process we make
use of oxides of lead, acetic acid, or acetate of lead and carbonic acid gas.
Oxides of lead are materials well known in commerce. Any oxide of lead,
however prepared, which is capable of uniting with carbonic acid, and thereby
producing white lead, may be employed in our process; and of these oxides
which are usually met with in commerce we find those called litharge and
massicot to be particularly suitable; but that called red lead does not answer
the purpose. The acetic acid we employ is that which is sufficiently free from
coloring matter, as the presence of this would be liable to give color to our
white lead, and thereby injure its quality. We make use of acetic acid
either in a free acid state or in a state of combination with oxide of lead.
The former, as it is well known to chemists, may be obtained very nearly
colorless by distilling vinegar of commerce, or it may be procured by the
decomposition of acetate of lime or other combinations of acetic acid with
alkaline bases or metallic oxides. The processes by which this decomposition
is effected are well known to chemists, and the acetic acid thus prepared is an
article of commerce. When acetate of lead is made use of it may be pro-
cured in the state of sugar of lead, or of solution of acetate of lead, com-
monly called Goulard's Extract of Lead, both which are articles of commerce.
Carbonic acid gas may be obtained by various processes which have been
heretofore in use; but the one we prefer, because of its economy, is that of
burning charcoal, coke, or coal with atmospherical air. In order to obtain
carbonic acid gas by this process suitable for the purpose of our Invention it
is desirable to make use of the material as free as it is possible to obtain it
from all bituminous or volatile matter, and consisting almost wholly of pure
carbon. This should be submitted to combustion in a common stove or fur-
nace, and the gases produced, consisting of carbonic acid gas mixed with the
residual atmospheric air, may be conducted through a series of metallic tubes,
which should be so arranged, either by being placed in water or exposed to
currents of cold air, that the gases shall be cooled down to a moderate
temperaturo during their passage through these tubes. And for the purpose

page_text: of arresting any portions of unconsumed carbon, or other matter which might
give a color to the white lead, we cause these gases to pass through a filter or
series of filters, which are charged either with a coarse sand, or other metallic
lead granulated, by pouring this, when melted, into water.
These filtering
materials are placed in a vessel through which the gases are caused to per-
colate, and we cause a very small stream of water to pass gradually through
these vesseis, so as to keep the filtering materials continually moist, which we
find assists greatly in ensuring a more perfect purification of the gases; and
if we apprehend the presence of sulphur with the carbon we are consuming
we add a little alkali to the water used for moistening the filtering materials.
Notwithstanding these precautions, we consider it necessary to be careful in
selecting the material for producing carbonic acid gas. The carbonic acid
gas which is present in the atmosphere can be employed for carbonating the
oxide of lead by our process; but as the proportion of carbonic acid usually
contained in the atmosphere is small, this causes the conversion of the oxide
of lead into carbonate to proceed slowly; we therefore prefer making use of
carbonic acid gas prepared artificially.
Having thus described the materials required for our process, we will now
give a description of the manner in which we consider it best to make use of
them. If the oxide of lead is in considerable masses it should be reduced to
the state of a coarse powder; but litharge seldom requires this operation, as
it will answer the purpose in the state it is usually met with. We mix the
oxide of lead with the requisite quantity of acetic acid, or of acetate of lead,
und with as much water as will bring the mixture to such a state of dampness
as will make it slightly coherent, and then spread it on trays or shelves covered
with sheet lead, causing the mixture to form a thin loose bed or stratum on the
tray or shelf. We place a number of these trays or shelves one over another in
a case or apartment, and we cause a current of carbonic acid gas, either pure or
mixed with such other gases as are not injurious to our process, to come in
contact with the inixture. The carbonic acid gas becomes absorbed and com-
bines with the oxide of lead, so as to form carbonate of lead, which is ceruse
or white lead; and as this process of absorption advances we find it is accele-
rated by raking or stirring the mixture so as to expose new surfaces to the
action of the carbonic acid gas; and if this gas does not contain sufficient
watery vapour combined with it, we add as much water to the mixture as
will keep it in a certain state of dampness. The most favorable degree of
this is soon ascertained by a few trials of the operation. We find as the
process advances the oxide of lead becomes changed from a colored to a
white substance, and when the mixture appears to be completely free from all

page_text: colored particles we judge that the operation is completed, and the whole of
the oxide is converted into white lead. We find tlie duration of this process
depends on the proportion of acetic acid or acetate of lead-employed, and on
the supply of carbonic acid gas; also on the care which is tuken to stir or
rake up the mixture and supply it with the necessary quantity of water with
the proportions of oxide of lead and acetic acid or acetate of lead we
generally make use of, and which proportions are herein-after specified; and
with a good supply of carbonic acid gas,and proper attention to the operation,
we can finish this part of the process. in from three to six days. We find it
to be an economical method of conducting this process to commence by mixing
the oxide of lead with a fall proportion of acetic acid or acetate of lead, as
herein-after indicated, and, when the oxide is wholly or very nearly converted
into carbonate, to add a further quantity of oxide to the same inixture
without a furtheraddition of acetic acid or of acetate of lead; and the mixture
being again exposed to the action of the carbonic acid gas, the oxide it
contains speedily becomes converted into carbonate, and we then add a further
portion of oxide and proceed in the same manner as before, taking care
-always to keep the mixture in the requisite state of dampness by the addition
of water. We repeat these successive additions of oxide without further
additions of acetic acid or of acetate of lead, till the proportion of acid cr
of.acetate mixed with the oxide of lead is reduced to one fourth or oven
less of the proportion nixed in the first instance. After the carbonating
process is completed, as before described, we remove the mixture to a drying
stove, where it is exposed in the usual manner, to become dry, and we then
grind-the dry substance with water, in the same manner as is practised
by those who manufacture white lead by the well-known process generally
adopted; and we dry the ground white lead in a stove, and we thus obtain
it in a state suitable to be made into paint, or to be used for the other purposes
to which white lead is applied. The mixture, when removed from the trays
or shelves, might be reduced to a fine powder by washing, or by levigating with
water without previously drying it; but we consider the quality of the white
-lead is improved by drying the mixture before it is levigated or ground with
When we use acetic acid for mixing with the oxide of lead we gene-
rally take for one hundred pounds of oxide as much liquid acetic acid as is
contained in twenty pints of such vinegar as is called "proof vinegar." by
the Excise, and is known in commerce by the appellation of Number 24;
and when we employ acetate of lead, either in the solid state or in solution
we; take as much of either of these as will contain the above proportion of
acetic acid.
.water.

page_text: We have given the proportions herein indicated as those which we consider
the most economical, and the best adapted for carrying into effect our Inven-
tion, but we do not confine ourselves to these particular proportions of acetic
acid, or of acetate of lead and oxide of lead, but we consider ourselves at
liberty to make use of those materials in any proportions within the limits
herein-after specified. We do not claim as our Invention any particular form
of apparatus for carrying our process into effect, or any peculiar mode of
generating carbonic acid gas; but we consider the forms of apparatus and the
method of generating carbonic acid gas we have described as the best adapted
for our purpose of any we are acquainted with. And whereas acetic acid,
acctate of lead, oxide of lead, water, and carbonic acid gas, have been before
employed in the manufacture of white lead, these materials being used in
such proportions that the acetic acid was capable of dissolving the whole or
the greater part of the oxide of lead if mixed with sufficient water for such
purpose of solution; and whereas these materials have been used in mixture
containing such proportion of water as would render the mixture of acetic
acid or acetate of lead with oxide of lead fluid, or would reduce it to such a
state of fluidity that the mixture would flow as a liquid from one vessel to
another, therefore we do not claim any right or privilege as to the use of
these materials in either of the proportions just stated, but we confine our
claim to the employment of these materials in the proportions herein-after
specified, that is to say:-
We claim as our Invention the formation of white lead by exposing to the
action of carbonic acid gas (either pure, or mixed with such other gases as
may not be injurious, and obtained by the means described or by other ineans,
or from the atmosphere,)a mixture of oxide of lead with acetic acid, or acetate
of lead and water, in such proportion that the acetic acid would not be capable
of dissolving more than one fourth part of the oxide of lead when assisted by
sufficient water for such purpose of solution. And we further claim as our
Invention the formation of white lead by the use of a mixture to be exposed
to the action of carbonic acid gas, which mixture shall consist of oxide of
lead and acetic acid or acetate of lead, within the proportions we have just
described, with such a proportion of water added to it as will not be sufficient
toreduce the mixture to a state of fluidity which would allow of its flowing as
a liquid from one vessel to another.
.
In witness whereof, I, the said William Gossage, have hereunto set my
hand and seal, the Twenty-eighth day of September, in the year of our
Lord One thousand eight hundred and thirty-six.
WILLIAM (L.S.) GOSSAGE.

page_text: AND BE IT REMEMBERED, that on the same Twenty-eighth day of
September, in the year above mentioned, the aforesaid William Gossage
came before our Lord the King in His Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute in that case made and provided.
Inrolled the same Twente sighth day of Santamber in th