IMPROVE- MENTS IN THE MANUFACTURE OF SALTS AND OXIDES OF LEAD, AND IN APPARATUS THEREFOR.
Year: 1872

page_text: LETTERS PATENT to William Marriott, of Huddersfield, in the County
of York, Manufacturing Chemist, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF SALTS AND OXIDES OF LEAD, AND IN
APPARATUS THEREFOR.'
"
Sealed the 2nd May 1873, and dated the 8th November 1872.
PROVISIONAL SPECIFICATION left by the said William Marriott at
the Office of the Commissioners of Patents, with his Petition, on
the 8th November 1872.
I, WILLIAM MARRIOTT, of Huddersfield, in the County of York,
Manufacturing Chemist, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SALTS AND OXIDES OF
LEAD, AND IN APPARATUS THEREFOR," to be as follows:-
-
This Invention has for its object improvements in the manufacture of
salts and oxides of lead, more especially carbonate of lead or white lead.
In the process of making carbonate of lead, commonly employed metallic
lead, either sheet or cast, is exposed for several weeks to the joint
action of air, moisture, and carbonic, and acetic acid, and the lead is

page_text: gradually converted into carbonate of lead. In another process the car-
bonate of lead is made by passing carbonic acid over a moist mixture of
oxide of lead (litharge), acetate, or other soluble salt of lead. Other
processes have also been employed for converting metallic lead or oxide
of lead into carbonate of lead.
My improvements consist in reducing metallic lead to an almost.
impalpable powder, which is converted into the various salts and oxides.
of lead. They also consist in the peculiar apparatus employed in my
process.
My improved apparatus for reducing the lead to powder is constructed
somewhat on the principle of the "Gifford" injector, that is to say, the
said apparatus has a cup for containing the molten lead, from the bottom
of which cup a pipe or tube projects down, and is extended in a horizontal
direction. This tube is surrounded by another tube, into which super-
heated steam is admitted. This steam in passing through the said pipe
creates a draught or current, whereby the lead is drawn through the first-
mentioned pipe and ejected into any suitable receptacle. In some cases I
provide the said apparatus with another pipe, whereby air is introduced
and mixed with the steam and lead as the latter issues from the inner
pipe.
My apparatus for converting the lead powder into carbonate of lead
is constructed as follows:-I provide a cylinder or tube of cast-iron or
other suitable material; within this cylinder at the bottom I place an
agitator, consisting preferably of perforated cross tubes, which are fixed on
a vertical central hollow shaft that extends up through the cylinder, and is
geared with a horizontal driving shaft. The upper end of this hollow
shaft is connected with a pipe, whereby steam, air, and carbonic acid are
admitted to the said shaft and to the agitator. The cylinder is supplied
with water through another pipe or pipes. The powdered lead, in either
a metallic or oxidised condition, is placed in the cylinder, and by the
action of the agitator the lead is kept in suspension in the water while
the steam, air, and carbonic acid are admitted to the same through the
perforations in the agitator. As the lead rises to the surface. of the water
it passes away from the cylinder through suitable exit pipes in the form
of carbonate of lead, the process of manufacture being continuous.
In the manufacture of acetate of lead I expose the powdered lead
in a moist condition to the atmosphere till it has been converted into

page_text: protoxide of lead, and then dissolve the same in acetic acid. Then I follow
the ordinary process of evaporation, concentration, and crystallization.
In the manufacture of the lead powder into red lead I employ the
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Marriott in the Great Seal Patent Office
on the 8th May 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MARRIOTT, of Huddersfield, in the County of York, Manufacturing
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of November, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Marriott, Her special licence
that I, the said William Marriott, my executors, administrators, and
assigns, or such others as I, the said William Marriott, 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 SALTS AND OXIDES OF LEAD, AND IN APPARATUS THEREFOR,'
upon the condition (amongst others) that I, the said William Marriott,
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 Scal
Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
"
NOW KNOW YE, that I, the said William Marriott, 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

page_text: following statement, reference being had to the accompanying Drawing
forming a part of this Specification :―
This Invention has for its object improvements in the manufacture of
salts and oxides of lead, more especially carbonate of lead or white lead.
Hitherto in the process of making carbonate of lead, metallic lead, either
sheet or cast, is commonley employed; this is exposed for several weeks
to the joint action of air, moisture, and carbonic and acetic acids, whereby
the lead is gradually converted into carbonate of lead. In another
process the carbonate of lead is made by passing carbonic acid over a
moist mixture of oxide of lead (litharge), acetate, or other soluble salt
of lead. Other processes have also been employed for converting metallic
lead or oxide of lead into carbonate of lead.
'
My improvements consist in reducing metallic lead to an almost
impalpable powder, which is converted into the various salts and oxides
of lead. They also consist in the peculiar apparatus employed in my
process, as herein-after described, and as illustrated in the accompanying
Drawing, in which Figure 1 is a vertical longitudinal section of my
improved apparatus for reducing the lead to powder; Figure 2 is an
elevation of my improved apparatus for making carbonate of lead;
Figure 3 is a vertical section of the said apparatus and its appur-
tenances.
In practising my said Invention the lead. is first reduced to a fine state
of division; this operation is effected in a very simple manner by the
apparatus illustrated in Figure 1, which I will now describe. The said
apparatus has a receiving chamber a, injecting apparatus b, and furnace c.
The injecting apparatus consists of the cup or funnel d, and pipes e, f.
'The pipe e has preferably an internal diameter of about three-eights of
an inch, and is nine inches long, terminating at its upper end in the said
funnel d. At e¹ the opening in the said pipe or tube is about one-
sixteenth of an inch in diameter; the tube e is enclosed within the tubef,
which has a branch for the admission of steam. The tube has
an internal diameter of three-quarters of an inch to the point 1, where it
is increased to one inch, this diameter being continued to the point where
the said tube enters the chamber a. À coke or coal fire is kept burning
in the furnace or fire pan c while the apparatus is at work, or I may use
gas burners instead of a coke or coal fire. The whole of these parts are
preferably made of wrought iron, though other suitable metal may be
used if desired.

page_text: The fire when lighted is allowed to burn until the apparatus is heated
to a dark redness, and this temperature is maintained so long as the
apparatus is at work. Steam superheated to not less than six hundred
degrees Fahrenheit, and having a pressure of not less than fifty pounds
per square inch, is admitted by the branch pipe, filling the annular
space surrounding the pipe c, and thence rushes with great velocity into
the chamber a, creating or drawing a strong draught or current through
the tube e. The funnel d is kept filled with molten lead; this lead
coming in contact with the superheated steam is separated into fine dust,
and driven into the chamber a, where it falls as an almost impalpable
powder, while the steam escapes by an opening a¹ in the roof of the said
chamber. At the bottom this chamber must be made to hold water for
a depth of a few inches, into which the finely divided lead settles. The
said chamber may be made of wood, brick, stone, or lead, and of any
required capacity. It should be of such a length that the injected lead
in entering does not strike against the opposite end; nine feet square and
twenty feet long will be a convenient size. The lead powder is jigged or
sifted under water through very fine sieves, and any lead not passing
through these sieves is returned to the melting pot.
The next process is the conversion of the finely divided or powdered lead
into protoxide of lead; this process is effected in a room heated to about
seventy degrees Fahrenheit. The powdered lead is placed on the floor
in heaps, having previously been deprived of its excess of water, and it
soon begins to heat. At this point, and until the oxidation is complete,
great care and attention are required to prevent the heating of the lead
to such a degree as to expel the moisture and form anhydrous protoxide
of lead instead of hydrated protoxide of lead. To prevent this result
water in fine spray is thrown over the mass, and the same is constantly
turned to prevent the accumulation of the heat in one place. A little
practise will enable the operator to judge as to the condition of the lead,
and if due attention is paid, so that no accident happens, the lead is
converted into hydrated protoxide of lead in from four to seven days.
The oxide of lead so produced is then ground with water in an ordinary
mill constructed for this purpose, and may then be used for making
nitrate, acetate, and carbonate of lead, or by further oxidation minium or
red lead. To make nitrate of lead, the oxide is dissolved in dilute nitric
acid S. G. 1150, then evaporated to the proper strength, and crystallized.

page_text: To make acetate of lead I substitute acetic acid for nitric acid, observing
the ordinary precautions used in making acetate of lead.
To make carbonate of lead I employ the improved apparatus shewn in
Figures 2 and 3, which I will now explain. The cistern g is filled with
a solution of nitrate or acetate of lead, S. G. 1030, or of any suitable
strength. By means of a coil of pipes laid in the bottom of the cistern,
the solution is heated to one hundred degrees Fahrenheit. I find the
best white lead is made at about this heat, but the same may be increased
or diminished as required. The solution beated as above described is
now allowed to run into the mill h; this mill has a vertical shaft i
provided at the bottom with an agitator j, and connected by the gear
wheels k, l, with the driving pulley m, whereby the said shaft is rotated.
The mill is supplied with the protoxide of lead, as herein-before described.
The solution of nitrate or acetate of lead dissolves the protoxide of lead,
and the clear solution flows off by the pipe n into the carbonator o; the
latter has a shaftp, with an agitator q, which are driven by the wheels 1, 8,
from the pulley t. Carbonic acid is introduced through the pipes u, v,
and combines with the oxide of lead held in solution by the nitrate or
acetate, and forms carbonate of lead. When the carbonator is filled up
to the spout or nozzle o' the solution holding the white lead in suspension
flows therefrom, and as the solution rises higher it escapes through one
or other of the spouts o³, o³, o', and is conducted into a cistern, wherein
it quickly settles. As the liquid rises in the vessel o to the height of
cither of the said spouts, those below are closed by suitable plugs. At
the bottom the said vessel is provided with a cock o' for drawing off its
contents. The white lead is kept in suspension in the liquid in the
carbonator by the agitator acting as above described.
The liquid from which the white lead is deposited is again pumped up
into the cistern g, and a continuous formation of the white lead is main-
tained in the carbonator so long as the mill / is supplied with oxide of
lead and the carbonator o with carbonic acid. After the white lead has
settled it is well washed and dried in the usual manner. The carbonic
acid may be obtained from any economical source, but it must be quite
free from sulphurous acid or sulphuretted hydrogen.
I do not confine myself to the precise form or dimensions herein
described of any part of my improved apparatus, as the same may be
varied according to the quantity of material required to be produced in

page_text: a given time. I find the apparatus is best made of wood, but it may be
made of iron coated with lead where it comes in contact with the lead
solution.
If desired the finely divided or powdered lead may be used instead of
sheet or cast lead in the manufacture of white lead, by the process known
as the old Dutch process.
To make red lead, I take either the protoxide of lead or the carbonate
of lead made as above, and subject the same to heat in a suitable
furnace, until the required colour is obtained.
Having thus fully described my said Invention, and the manner of
performing the same, I wish it understood that I claim,-
First. The reduction of metallic lead into fine powder by the action of
superheated steam, as herein set forth.
Second. The injecting apparatus, for reducing metallic lead to powder,
constructed and operating as herein set forth.
Third. The conversion of the lead powder obtained by my process into
protoxide of lead, red lead, or any of the salts of lead, as herein
specified.
Fourth. The apparatus for the continuous production of white lead,
constructed and operating as herein set forth, and for the purpose
specified.
In witness whereof, I, the said William Marriott, have hereunto
set my hand and seal, this Fifth day of May, in the year of our
Lord One thousand eight hundred and seventy-three.
WM. MARRIOTT. ·(L.S.)