Improvements relating to the Manufacture of White Lead.
Year: 1889

page_text: Date of Application, 12th Nov., 1889
Complete Specification Left, 30th Nov., 1889-Accepted, 11th Jan., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by JOHN BLEECKER TIBBITS, of Hoosac, New York,
United States of America, Clergyman.]
Improvements relating to the Manufacture of White Lead.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of this invention to be as follows:-
The object of the present invention is the commercial manufacture by the agency
of an electric current, of white lead in the form of the hydrated carbonate which can
thus be effected quickly and uniformly instead of the tedious oxidation process herein-
before generally used.
The invention comprises the preparation of the electrolyte, the electrodes and the
various steps of the process substantially as hereinafter fully described and claimed.
The invention consists in electrically dissolving a lead electrode in an electrolyte
containing nascent or free carbon dioxide whereby the lead compound formed by
electrolytic action is precipitated to form hydrated carbonate of lead or pure white
lead which is then removed washed and dried.
One method of carrying my invention into practical effect is as follows: The
electrolytic bath may be prepared by dissolving one half pound each of sodium nitrate
and ammonium nitrate in one gallon of water, and then saturating the solution thus
formed with carbon dioxide which can be done in various ways. Sodium and
ammonium carbonates may be used in the place of the nitrates, but in that case nitric
acid must be added until the bath is about neutral which results in the larger portion
of the carbon dioxide being driven off during effervescence. The electrolyte is then
placed in a suitable vessel or tank and electrodes of metallic lead are immersed in the
same. The electrodes are then connected to a source of electric current sufficient to
cause about fifteen amperes per square foot of anode surface to pass. The white lead
begins to fall then, very rapidly. Since carbon dioxide is taken up from the bath to
form the hydrated carbonate of lead, it is of course necessary to have the bath
replenished with additional carbon dioxide as the process continues. This may be
done in several ways. Porous pots filled with sodium or ammonium carbonate may be
placed in the bath and these substances will slowly dissolve out into the bath for the
purpose of supplying the latter with the required carbon dioxide. This method how-
ever involves the ultimate over-saturation of the bath with sodium hydrate and free
ammonia which are of no use when once formed and only tend to interfere with the
most advantageous working of my process. I prefer to supply the carbon dioxide in
some other way and obviously the best method will be one which will supply it
unaccompanied by any other material.
A convenient way of doing this is by burning limestone, washing the gas produced
by the disassociation of the constituents of the lime stone and supplying such gas
directly to the bath by any suitable means. In this case no detrimental effect takes
place in the electrolyte and the latter remains in a normal condition while the pre-
cipitation of the white lead is obviously going on under the electrolytic action of the
electric current.
Where the electrolyte is made up of sodium and ammonium nitrates in water and
the solution is saturated with carbon dioxide in its free state the reactions taking
place upon the passage of the electric current with lead electrodes may be described
as follows:
The electrolyte is decomposed yielding at the anode nitrogen pentoxide, ozone and

page_text: oxygen and at the cathode, sodium hydrate ammonia and hydrogen. The lead anode
is attacked by the powerful oxidizing and nascent nitrogen pentoxide (NO) and
ozone, but nitrogen pentoxide in the presence of water is decomposed to form
nitric acid (H NO,). During the double decomposition which takes place nitric
acid (H NO) and plumbic acid or lead hydroxide PLO (OH), are formed. The
nitric acid combines with the free ammonium and sodium hydrates (formed at the
cathode) to again form ammonium and sodium nitrate, while the plumbic acid is
procipitatod on combining with the free carbon dioxide present to form the hydrated
carbonate of lead 2 PO (O, + Pb (OH),. Thus it is seen that although the
electrolyte is decomposed by electrolysis it is regenerated by the chemical reactions
taking place and the only loss sustained is carbon dioxide and water which can be
readily supplied.
The white lead is from time to time removed from the tank washed and dried and
on mixing with a suitable vehicle into a paint it is found to have much greater
covering properties that ordinary commercial white lead formed by dissolving lead in
acetic acid in the presence of carbonic acid since the latter is slightly crystalline and
less opaque than the hydrated carbonate produced by the action of carbon dioxide on
plumbic acid.
For
I have given the formula of what I consider the most practical and economical
electrolyte but I wish to stato that I do not confine the scope of my invention thereto
as various solutions may be employed without departing from my invention.
instance may use the nitrate or carbonate of any of the alkaline metals or earths.
Likewise the particular means adapted for the introduction of carbon dioxide into the
electrolyte may be varied from those given such for instance as the action of diluted
sulphuric acid on sodium or calcium carbonate and in either of these cases the residue
becomes a marketable product. The bath or electrolyte may be weaker or stronger
in the proportion of dissolved salts to the gallon of water without materially affecting
the results. The temperature of the electrolyte is best at about 60° Fahr.
or 16° (.
Dated this 12th day of November 1889.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to the Manufacture of White Lead.
1, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The object of the present invention is the commercial manufacture by the agency
of an electric current, of white lead in the form of the hydrated carbonate, which
can thus be effected quickly and uniformly instead of the tedious oxidation process
herein before generally used. The invention comprises the preparation of the electro-
lyte, the electrodes and the various steps of the process substantially as hereinafter
fully described and claimed.
The invention consists in electrically dissolving a lead electrode in an electrolyte
containing nascent or free carbon dioxide, whereby the lead compound formed by
electrolytic action is precipitated to form hydrated carbonate of lead or pure white
lead which is then removed washed and dried.
One method of carrying my invention into practical effect is as follows: The
electrolytic bath may be prepared by dissolving one half-pound each of sodium nitrate
and ammonium nitrate in one gallon of water, and then saturating the solution thus
formed with carbon dioxide which can be done in various ways. Sodium and
ammoniam carbonates may be used in the place of the nitrates, but in that case

page_text: nitric acid must be added until the bath is about neutral which results in the
larger portion of the carbon dioxide being driven off during effervescence. The
electrolyte in then placed in a suitable vessel or tank and electrodes of metallic
lead ore immersed in the same. The electrodes are then connected to a source
of electric current sufficient to cause about fifteen amperes per square foot of
anode surface to pass. The white lead begins to fall then, very rapidly. Since
carbon dioxide is taken up from the bath to form the hydrated carbonate of lead,
it is of course necessary to have the bath replenished with additional carbon dioxide
as the process continues. The may be done in several ways. Porous pots filled with
sodium or ammonium carbonate may be placed in the bath and these substances will
slowly dissolve out into the lath for the purpose of supplying the latter with the
required carbon dioxide. This method however involves the ultimate over-saturation
of the bath with sodium hydrate and free ammonia which are of no use when_once
formed and only tend to interfere with the most advantageous working of my
process. I prefer to supply the carbon dioxide in some other way and obviously
the best method will be one which will supply it unaccompanied by any other
material.
A convenient way of doing this is by burning limestone, washing the gas produced
by the disassociation of the constituents of the lime-stone and supplying such gas
directly to the bath by any suitable means. In this case no detrimental effect takes
place in the electrolyte and the latter remains in a normal condition while the
precipitation of the white lead is obviously going on under the electrolytic action of
the electric current.
When the electrolyte is made up of sodium and ammonium nitrates in water and
the solution is saturated with carbon dioxide in its free state the reactions taking place
upon the passage of the electric current with lead electrodes may be described as
follows:
The electrolyte is decomposed yielding at the anode, nitrogen pentoxide, ozone and
oxygen and at the cathode, sodium hydrate, ammonia and hydrogen. The lead anode
is attacked by the powerful oxidizing and nascent nitrogen pentoxide (N, O₂) and
ozone, but nitrogen pentoxide in the presence of water is decomposed to form
nitric acid (H NO,). During the double decomposition which takes place nitric
acid (NO) and plumbic acid or lead hydroxide PbO (OH) are formed. The
nitric acid combines with the free ammonium and sodium hydrates (formed at the
cathode) to again form ammonium and sodium nitrate, while the plombic acid is pre-
cipitated on combining with the free carbon dioxide present to form the hydrated
carbonate of lead 2 PO CO, + Pb (OH)2.
Thus it is seen that although the electrolyte is decomposed by electrolysis it is
regonerated by the chemical reactions taking place and the only loss sustained is
carbon dioxide and water which can be readily supplied.
The white lead is from time to time removed from the tank washed and dried and
on mixing with a suitable vehicle into a paint it is found to have much greater
covering properties than ordinary commercial white lead formed by dissolving lead
in acetic acid in the presence of carbonic acid, since the latter is slightly crystaline
and less opaque than the hydrated carbonate produced by the action of carbon dioxide
or plumbic acid.
I have given the formula of what I consider the most practical and economical
electrolyte but I wish to state that I do not confine the scope of my invention thereto
as various solutions may be employed without departing from my invention. For
instance I may use the nitrate or carbonate of any of the alkaline metals or earths.
Likewise the particular means adapted for the introduction of carbon dioxide into the
electrolyte may be varied from those given such for instance as the action of diluted
sulphuric acid on sodium or calcium carbonate and in either of these cases the residue
becomes a marketable product. The bath or electrolyte may be weaker or stronger
in the proportion of dissolved salts to the gallon of water without materially
affecting the results. The temperature of the electrolyte is best at about 60° Fahr.
or 16° (

page_text: Having now particularly described and ascertained the nature of the said
invention and in what matter the same is to be performed as communicated to
me by my foreign correspondent I declare that what I claim is :-
First. The process of manufacturing white lead consisting in electrolytically
dissolving a lead anode in alkaline aqueous solution, while supplying the latter with
carbon dioxide.
Second. The process of manufacturing white lead by electrolytically dissolving an
electrode of metallic lead in alkaline solution containing free carbon dioxide.
Third. The process of manufacturing white lead by electrolytically forming an
oxygen compound of lead from a lead electrode in an alkaline solution containing
free carbon dioxide which unites with the oxygen compound of lead to form the
hydrated carbonate of lead.
Fourth. The process of manufacturing white lead consisting in electrically con-
verting lead into hydrated lead carbonate by subjecting an electrolyte of an alkaline
nitrate to electrolysis with laden anodes while the bath is kept saturated with free
carbon dioxide substantially as herein described
That this 20th Ja
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.