IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR MANUFACTURING WHITE LEAD
Year: 1879

page_text: "
LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company, Patent
Solicitors, at Frankfort on the Main, in the Empire of Germany, for the
Invention of IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR
MANUFACTURING WHITE LEAD." A communication from George Dahm,
trading under the Firm of "Georg Dahm," of Cologne and London, of Cologne,
in the Empire of Germany.
Sealed the 9th January 1880, and dated the 22nd July 1879.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office of
the Commissioners of Patents on the 22nd July 1879.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at Frank-
fort on the Main, in the Empire of Germany. IMPROVEMENTS IN THE METHOD
OF AND APPARATUS FOR MANUFACTURING WHITE LEAD." [A communication
from George Dahm, trading under the Firm of "Georg Dahm," of Cologne and
London, of Cologne, in the Empire of Germany.]
This Invention relates to improvements in the method of and apparatus for
manufacturing white lead.
In carrying the said Invention into practice I provide a wooden chamber or box
made to be closed air tight whose dimensions are about from fifteen to twenty
feet long, five or six feet wide, and one foot high. This chamber or box is fastened
to a beam about eight or nine inches thick provided with iron pivots on both
ends. The box is placed on uprights or standards provided with iron bearings,
fitting to the axes of the beam in such a way that the chamber or box can
easily be moved from side to side. The most simple means for effecting this motion
is to fix either on the bottom of the box or its top a beam or lever, and to connect
this by a connecting rod to a crank which is fixed on the end of a shaft above the
box, if the said shaft is turned with the crank one side of the box is naturally raised
by means of the lever on the box and forced down again, and in this manner the
box will have imparted to it a motion similar to that given to a cradle. This box*
or chamber is then filled with fine strips or pieces of lead or lead wire, and is closed
in a suitable manner. In both ends of the box there are holes of four or five inches
diameter, and in these holes copper pipes are inserted. One of these copper pipes is
by means of india-rubber hose connected with another pipe designed for the purpose
of leading carbonic acid into the box, while the pipe on the other end of the box is
'

page_text: also by means of india rubber hose connected with a pipe leading into a vessel
filled with a basic solution of lead.
The object of this arrangement-is-to-utilize any carbonic acid which might pass
unabsorbed through the box, and also to prevent carbonic acid from coming into
the-working rooms to endanger the health of the operators. The box is further
connected by means of india rubber hose with a vessel containing a basic solution
-of-lead for the purpose of leading thereby- this solution of lead into the box. Cocks,
faucets, or other means are provided in convenient positions on the box for the
purpose of letting off the liquid contents of-the-box, consisting-of-white lead, and.
neutral solution of lead, which are run into a receiver conveniently placed for
that purpose. In order to somewhat check the carbonic acid in its passage through
the box and force the same to pass through the lead wire contained in the box, the
box is divided into several compartments by means of deal boards extending from
the top of the box to about four inches from the bottom, thus leaving a passage way
of four inches high through which the carbonic acid has to pass to the place of exit.
When in this manner the box is prepared it is set in motion, and then filled by means
of the india rubber hose with basic solution of lead to such a height that the liquid
comes up to the rim of that side of the box which is lowest. At the same time
carbonic acid is introduced into the box through the india rubber hose, provided for
that purpose, by means of an air pump, or otherwise, while the box is kept constantly
in motion. It is advisable to use the carbonic acid warm, and for this purpose to
lead the same through a pipe heated by steam or otherwise. The introduction of
carbonic acid into the box is continued till the basic solution of lead has become
neutral, which is ascertained by blue litmus paper turning red if brought in
contact with some of the liquid contained in the box; all the time the box is con-
tinually kept in motion. The white lead formed inside the box is by the constant
motion kept in suspense in the liquid, and then together with the liquid allowed to
run off into a vessel provided for that purpose, where it settles to the bottom of the
vessel, leaving the clear liquid over it. The clear liquid is then drawn off from the
lead and made basic again to be used over and over again, while any trifling quantity
that may be lost is replaced by acetic acid. The box is forthwith filled again after
having been emptied by another portion of basic solution of lead, and so on
alternately emptying and again filling the same.
The said process of producing white lead may now be easily explained, that is to
say, through the motion of the chamber or box only that portion of the lead wire
in the part of the box which hangs low is covered by the basic solution of lead,
while the other portion of lead wire being high is only moistened by the solution,
and in consequence of the great surface of the wire a great surface is exposed to the
action of the carbonic acid. White lead is therefore immediately formed on the
surface of the lead wire which is as quickly washed off by the liquid when the box
goes down, covering the wire by the liquid and moistening at the same time again
the lead-wire-with-subacetate-of-lead. According to the strength of the solution of
lead used, and the quantity of carbonic acid introduced into the box, each box may
produce from three to five hundred pounds of dry white lead daily. The basic
solution of lead can be produced by dissolving litharge or oxide of lead in diluted
acetic acid; as however litharge or oxide of lead may contain more or less oxides of
other metals, and as these would injure the colour and the quality of the white lead,
I prefer to make the solution of lead from the metal directly in the following
manner, that is to say :-
Lead wire or strips or pieces of lead are put in casks of a size to hold from six to
eight hundred quarts, and then covered by good fitting lids or covers, these casks
are then filled up with diluted acetic acid. Immediately after the casks are full
the acid is drawn off again, whereupon forthwith a strong oxidation of the lead,
inside the casks will take place in consequence of the oxygen of the air attacking
the lead, forming oxide of lead on the surface of the lead wire, which at the same
time becomes very hot. If then after a lapse of five or six hours the diluted acetic
acid is brought into the casks again it will at once dissolve the oxide of lead formed

page_text: on the wire and make a neutral or basic solution of lead according to the strength of
the acetic acid used. This solution is immediately drawn off from the wire so as to
give access to the air which follows the liquid drawn off, to form a new coat of
oxide of lead on the surface of the wire, which again after five or six hours is
dissolved, when the former solution of lead is brought on again, producing then a
strong basic solution. By placing another cask of the same size and filled with
wire on the top of the lower one in such a manner that the liquid contents of the
same run through a cock or tap into the lower one, the process of making a strong
basic solution will be much accelerated.
To make lead wire I provide a box of deal boards about five feet long, two and a
half feet high, and two feet wide. A roller is also provided about two inches over
the bottom of the box in the corner of one side of the same, and another roller is
placed outside over the other end of the box. An endless band of linen or the like
passes in such a manner over these two rollers that when the upper roller outside
the box is rotated it will rotate the lower roller inside the box, and so keep the
band constantly running. The box is filled with water, and a tunnel with small
holes as large as the wire required is placed over the roller in the bottom of the
box. If molten lead is poured in this tunnel it will run through these holes into
the water where it forms wire, which, by the turning of the outside roller and the
consequent motion of the endless band, is carried up over the upper roller and drops.
down outside the box.

page_text: SPECIFICATION-in-pursuance-of-the-conditions_of_the_Letters
Patent filed
by the said Frank Wirth in the Great Seal Patent Office on the 21st
January 1880.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at Frank-
fort-on-the-Main, in the Empire of Germany. "IMPROVEMENTS IN THE METHOD OF
-AND-APPARATUS. FOR MANUFACTURING WHITE-LEAD." A communication from
George Dahm, trading under the Firm of "Georg Dahm," of Cologne and London,
of Cologne, in the Empire of Germany.
This Invention relates to improvements in the method of and apparatus for
manufacturing white lead.
In carrying the said Invention into practice I provide an apparatus as shewn in
the accompanying Drawing, in which,-
Figure 1 is a longitudinal section.
Figure 2 is a plan or top view; and
Figure 3 is an end elevation of the said apparatus.
A is a chamber or box; B, B, are compartments into which the said bar is divided
by boards g which reach from the top to within about four inches of the bottom;
a, a, are the doors to close openings provided for the purpose of filling the box with
lead wires, and so arranged as to close the said box air tight; b, b', are copper pipes
at each end of the box, from one of which extends india-rubber hose to an apparatus
furnishing carbonic acid, the pipe on the other end of the box is also connected by
an india-rubber hose to another pipe for conducting the unabsorbed carbonic acid
and other kinds of gas into a vessel filled with subacetate of lead; B' is a beam
upon which the box is fastened, and which extends under the whole length of the
said box, and is provided with iron axes on the ends fitting in suitable bearings on
the framework. To the pipe e is attached an india-rubber hose connecting the box
with a vessel containing subacetate of lead by which the liquid runs into the box;
d is a lever which is connected with the crank D by means of the connecting rod f
for giving motion to the said box; F is a sheave or pulley by which motion is
imparted to the shaft E and crank; H is a cork or spigot for the purpose of emptying
the said box.
I prefer that the wooden chamber or boxe A should be made to be closed air tight,
and should be about from fifteen to twenty feet long, five or six feet wide, and one
foot high. This chamber or box is fastened to the beam B¹, about eight or nine inches
thick, provided with iron pivots on both ends; the box is placed on uprights or
standards provided with the aforesaid iron bearings, fitting to the axes of the beam
in such a way that the chamber or box A can easily be moved from side to side.
The most simple means for effecting this motion is to fix either on the bottom of the
-box-or-its.top.the-beain_or_lever_d, and to connect this by the rod f to the crank D
which is fixed on the end of the shaft E above the said box; if the said shaft is
turned with the crank one side of the box is naturally raised by means of the lever
on the box and forced down again, and in this manner the said box will have
imparted to it a motion similar to that of a cradle. This box or chamber is then
filled with fine strips or pieces of lead or lead wire and closed in a suitable manner.
In both ends of the said box there are provided holes of four or five inches in diameter,
and in these holes the copper pipes b¹ are inserted. One of these copper pipes, as
above described, is by means of an india-rubber hose connected with another pipe
designed for the purpose of leading carbonic acid into the box, while the pipe on
the other end of the said box is also by means of the hose connected with a pipe e
leading into a vessel filled with a basic solution of lead. The objects of this arrange-
ment are to utilize any carbonic acid which might pass unabsorbed through the box,
and also to prevent the entrance of carbonic acid into the working rooms to endanger
the health of the operators. The box A is further connected by means of the india-
rubber hose with a vessel containing a basic solution of lead for the purpose of

page_text: conducting thereby this solution of lead into the box. Cocks or faucets H, or other
means, are provided in convenient positions on the box for the purpose of discharging
its liquid contents, consisting of white lead and neutral solution of lead, which are
run into a conveniently arranged receiver. In order to somewhat check the carbonic
acid in its passage through the box and force the same to pass through the lead
wire contained in the box A, the said box is divided into the aforesaid compart-
ments B by means of the boards g, which are arranged as above described, so that
they leave a passage about four inches high through which the carbonic acid has to
pass to the place of exit.
When in this manner the said apparatus is prepared it is set in motion, and then
supplied by means of the india-rubber hose with basic solution of lead to such a
height that the liquid rises to the rim of that side of the box which is lowest. At
the same time carbonic acid is introduced into the box through the india-rubber
hose, provided for that purpose, by means of an air-pump, or otherwise, while the
said box is kept constantly in motion. It is advisable to use the carbonic acid
warm, and for this purpose to conduct the same through a pipe heated by steam or
otherwise. The introduction of carbonic acid into the box A is continued until the
basic solution of lead has become neutral, its condition being ascertained or indicated
by blue litmus paper turning red if brought in contact with some of the liquid
contained in the said box. During this time the box A is continually kept in
motion. The white lead formed inside the said box is by the constant motion or
agitation kept in suspense in the liquid and then together with the liquid is allowed
to run off into a vessel provided for its reception wherein it settles to the bottom
leaving the clear liquid over it. The clear liquid is then drawn from the lead and
made basic again for repeated use, while any trifling quantity that may be lost is
replaced by acetic acid. The box A is forthwith refilled after having been emptied
by another portion of basic solution of lead, and so on alternately emptying and
refilling the same.
The said process of producing white-lead may now be easily explained, that is to.
say, through the motion of the chamber or box A only that portion of the lead wire
in the part of the box which hangs low is covered by the basic solution of lead,
while the other portion of lead wire being high is only moistened by the solution,
and in consequence of the great quantity of the wire a large surface is exposed to
the action of the carbonic acid, white lead is therefore immediately formed on the
surface of the lead wire which is as quickly washed off by the liquid when the box
descends, covering the wire in the liquid and at the same time again moistening the
lead wire with subacetate of lead. According to the strength of the solution of
lead used and the quantity of carbonic acid introduced into the box each box may
produce from three hundred to five hundred pounds of dry white lead daily. The
basic solution of lead can be produced by dissolving litharge or oxide of lead in
diluted acetic acid, as however litharge or oxide of lead may contain more or less of
oxide of other metals, and as these would injure the color and the quality of the
white lead, I prefer to make the solution of lead from the metal directly in the
following manner, that is to say :-
Lead wires or strips or pieces of lead are put in casks of a size to hold from six to
eight hundred quarts and then covered by well fitted lids or covers, these casks are
then filled up with diluted acetic acid. Immediately after the casks are full the
acid is drawn off again, whereupon a strong oxidation of the lead inside the casks
will take place in consequence of the oxygen of the air attacking the lead, forming
oxide of lead on the surface of the lead wire, which at the same time becomes very
hot. If after a lapse of five or six hours the diluted acetic acid is returned to the
casks it will at once dissolve the oxide of lead formed on the wire and make a
neutral or basic solution of lead according to the strength of the acetic acid used.
This solution is immediately drawn off from the wire so as to permit access to the
air which follows the liquid drawn off, to form a new coat of oxide of lead on the
surface of the wire, which again after five or six hours is dissolved, when the former
solution of lead is brought on again, thus producing a strong basic solution. By

page_text: placing another cask of the same size, and filled with wire, on the top of the lower
one in such a manner that the liquid contents of the same run through a cock or
tap into the lower one-the-process-of-making-a-strong-basic-solution will be much
accelerated.
To make lead wire I-provide a box-of-deal-boards preferably about five feet long,
two and a half feet high-and two feet wide. I also provide a roller about two inches
above the bottom of the box-in-the-corner of one side of the same 'and another
roller is placed outside and over the other end of the said box. An endless band of
linen-or-other-suitable material passes in such a manner over these two rollers that
when the upper roller outside of the box is rotated it will rotate the lower roller
inside the said box and so keep the band constantly running. The said box is
filled with water, and a tunnel with holes corresponding in size with the required
size of the wire is placed over the roller in the bottom of the box, if then molten
lead is poured in this tunnel it will run through these holes into the water where
it forms wire, which by the turning of the outside roller. and the consequent
motion of the endless band is carried up over the upper roller and drops down
outside the box.
Having thus fully described the said Invention, and the manner of performing
the same, I wish it understood that I claim,—
First. The use of a movable box or chamber divided into compartments as 'above
described and for the purposes specified.
Second. The manner or process of making white lead by means of the aforesaid
apparatus and preferably from lead wire or strips as above described.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand
and seal, this Fifteenth day of January, in the year of our Lord. One thou-
sand eight hundred and eighty.
FRANK WIRTH. (L.S.)