IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HORACE
CORY, of Narrow Street, Limehouse, in the County of Middlesex, Batchelor
of Medicine, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent, under the Great Seal of Great Britain, bearing date at
Westminster, the Third day of November, in the second year of Her reign;
did, for Herself, Her heirs and successors, give and grant unto me, the
said Horace Cery, Her especial licence, full power, sole privilege and
authority, that I, the said Horace Cory, my exors, adññiors, and assigns, or
such others as I, the said Horace Cory, my exors, adññiors, or assigns,
should at any time agree with, and no others, from time to time and at all
times 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, my Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF WHITE LEAD;" in which said Letters Patent is contained a proviso that I,
the said Horace Cory, shall cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to
be inrolled in Her Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear."
NOW KNOW YE, that in compliance with the said proviso, I, the said
HoraceCory, do hereby declare the nature of my said Invention, and the manner

page_text: Figure I represents a section of the works in elevation, and Figure 2 shews
a plan of them, some of its parts being in section. X represents a section of a
lime kiln, similar to one of those known as Count Romford's, connected with
a chamber Y, into which the carbonic acid gas from the lime kiln passos by a
pipe, as shewn by the Drawing. Y is the chamber in which the solution of
lead used in the process is submitted to the action of the carbonic acid gas;
this chamber is divided into several compartments by partitions a, a, b, b, which
are so arranged as to cause the gas to take a circuitous route before it arrives
at the point c, where there is an opening or way to the external atmosphere;
d, d, are plates of copper or other suitable material perforated with small holes,
such plates being turned down at their edges in order that their edges may
enter loosely into grooves or troughs, thus allowing of the plates d, d, being
readily removed, should any of the holes be stopped up. The lower part of
the chamber is an inclined plane, shewing the trough e, e, and z, a vat, by
means of which a constant supply of the solution of lead is poured incessantly
through the chamber; n aud o are saturating vats, in which the solution of
lead is prepared; p and q are settling vats, into which the solution when pre-
pared is raised by the pumps s,s, and in which it is left to settle till it becomes
clear; f, g, and h are the precipitating vats, in which the white lead is first
deposited; and 1,1, the puddling vats, in which the white lead is prepared for
drying; 7, 1, and rare three pumps, worked by a three-throw crank, which is
to be actuated by a steam engine or other power. These pumps have a suitable
arrangement of pipes and stop-cocks for communicating with the settling vats,

page_text: and with the precipitating vats, and also with the vat z (as is clearly shewn in
the Drawing), and in such a manner that any of the pipes or stop-cocks may
be opened to or shut off from the pumps.
The formation of the white lead is thus effected:-The solution of lead
which is kept constantly supplied to the upper compartment of the chamber,
falls through the perforated plates in mutually divided showers, as shewn
by the blue arrows in Figure 1, and in that state comes in contact with
the carbonic acid gas, providing that part of the chamber below the plates d
and the solution of lead descending through the chamber will be acted
on thereby, and be progressively converted into white lead; and as the
gas has to take a very indirect course before it arrives at the vent c, as
indicated by the black arrows, it will be evident that but little will escape
into the atmosphere and be lost; the solution of lead falls through the
chamber into the inclined trough e, e, from whence it will flow into one or
other of the precipitating vats f, g, h, according as the sluice or opening i,j, or
k be open. In these precipitating vats the white lead will settle down and be
deposited, while the solution is raised from the vatabove the perforated plates,
and again and again submitted to the action of the gas in the chamber, till
process of conversion is completed. The precipitation of the white lead
will take place in the vessels or vats f, g, h, and when the process of conversion
is completed the liquor left after depositing its precipitate is run off through
the pipes m, m, into the vats n, o, to be again saturated, and the precipitated
white lead is raked into one of the puddling vats l. 1.
the
Having thus described the nature of the parts and process, I will proceed to
describe more in detail the materials and manner of working.
PREPARATION OF THE GAS.
The shaft of the kiln being filled with limestone through the hopper B, and
the shutter A being down and closing the gas pipe, the fire is to be lighted and
the process of lime making will go on, as is well understood. When the fire
is well lighted the shutter A is to be drawn up, so that the carbonic acid
gas
evolved will pass through the gas pipe into and through the compartments of
the chamber Y, as indicated by the black arrows. I would here remark, that
although I prefer the arrangement of the lime kiln shewn in the Drawing, I
do not confine myself thereto, as the same may be varied, so long as the
arrangement is made suitable for conveying off the carbonic acid gas evolved
to the purpose of making white lead in place of being evolved into the
atmosphere,

page_text: The solution of lead I usually employ is produced by dissolving proto xide of
lead; known as massicot or litharge, in acetic acid or in a solution of acetate of
lead, all which is well understood; but I must remark at the same time, that
the following description will apply if other solvents are employed:-In the
saturating vats n, o, a quantity of litharge or massicot and a solution of acetate
of lead are to be mixed, in order to produce a basic solution of lead, as is well
understood. This solution is from time to time to be pumped into the settling
vats by the pumps s, s, and in such manner that there shall be at all times a
sufficient quantity of settled basic solution contained in one of them to be ready
when required to be pumped through the chamber into any of the precipitating
vats..
To work the solution in any one of the settling vats, say q, the stopcocks of
the pipes must be so adjusted that on working the pumps the solution will be
raised and passed into the vat Z, whence it will flow through the opening y, so
as to keep all the perforated plates d, d, equally and uniformly covered. It
then descends through the plates into the chamber, where it will be acted on
by the carbonic acid gas, and from thence flow into any one of the precipita-
ting vats, say y, through the sluice j, and the communication with the settling
vat q being then cut off, and the cock to the vat g being opened, the solution
will be again and again pumped from the precipitating vat g, through the
chamber, and acted on by the gas, and returned into the same vat g, and so
on till the solution has been sufficiently acted on by the carbonic acid gas. It
is then allowed to settle its precipitate in the vat. After the white lead is
precipitated, the solvent is to be run off therefrom into one of the saturating
vats (where it is again mixed with massicot or litharge), and the precipitated
white lead is to be raked or drawn into one of the puddling vats. The white
lead which is contained in the puddling vat is to be operated on, in the manner
which is now practised in puddling; when the white lead has been sufficiently
freed from the solution by the operation of puddling, it may be taken out of
the puddling vats, and deposited in pans to be dried in the usual way. It
will only be desirable further to remark, that the solution in any other of the
settling and precipitating vats is to be worked in the same manner. Thus it
will be seen that there are always a settling vat and precipitating vat ready
for continuing the working, whilst other of the precipitating vats are allowing
the solution to deposit the white lead, and allowing of the white lead being
raked into the puddling vats. It will, therefore, be understood that the

page_text: pumps are continually working while the process is going on, and t is an
over-flow pipe, by which any excess of the solution pumped up will flow down
into the inclined trough e, e. I have stated the solution of lead I usually
employ is produced by dissolving protoxide of lead (known as massicot and as
litharge) in acetic acid, or in a solution of acetate of lead, all of which is well
understood, and forms no part of my Invention, similar solutions having been
before prepared in the process of making white lead; and the same have been
converted into white lead by means of streams of carbonic acid gas forced
through such solutions when contained in a proper vessel. This part of my
Invention does not, therefore, consist of converting solutions of lead by means.
of carbonic acid gas into white lead, but ouly to the mode of doing so by
submitting such solutions in showers, or in such like minutely divided state to
the action of the gas, whereby the process is more advantageously carried on.
And I would have it understood, that although I have mentioned acetic acid
and acetate of lead as means of obtaining solutions of basic acetate of lead,
yet I do not confine myself thereto, as other suitable solvents may be
employed, and the solutions of lead so obtained submitted to the action of
carbonic acid gas according to my Invention.
Having thus described my Invention, I would remark, that although I
have shewn the two parts of it as combined into one process of making lime
and of making white lead, yet it will be evident that each may be used
separate from the other, but in combination with other suitable means for
performing the respective processes; thus the carbonic acid gas of the process
of lime-making may be received by proper blowing apparatus, and caused to
pass into suitable vessels containing suitable solutions of lead, and thereby
convert the same into while lead by forcing the same through such solutions
of lead, and combine such process of making white lead with the process of
lime making, and thus beneficially use the carbonic acid gas evolved in the
latter process. In place of receiving the carbonic acid gas into suitable
blowing apparatus, the same may be received into a gasometer similar to
those used at gas works, and then used in the making of white lead.
And further it will be evident, that the second part of my Invention may
be used with other means of obtaining carbonic acid gas, all that is necessary
being to keep a constant supply of that gas (however produced) in the cham-
ber or apparatus Y, shewn in the Drawings. And it will readily be under-
stood, that this apparatus may be varied, so long as it possesses the capability
of dividing the solution of lead into minute streams or showers, and thus
extending the surface acted on by the carbonic acid gas pervading the appa-.