IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD AND IN THE MANUFACTURE OF CARBONIC ACID SUITABLE FOR USE IN THIS AND OTHER PROCESSES, AND IN THE APPARATUS EMPLOYED IN SUCH MANUFACTURES, PARTS OF WHICH ARE applicablE TO OTHER PURPOSES."
Year: 1882

page_text: LETTERS PATENT to Edward Vincent Gardner, of Burners College, Bernors
Street, Oxford Street, in the County of Middlesex, Professor of Chemistry, for
an Invention of "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD
AND IN THE MANUFACTURE OF CARBONIC ACID SUITABLE FOR USE IN THIS
AND OTHER PROCESSES, AND IN THE APPARATUS EMPLOYED IN SUCH
MANUFACTURES, PARTS OF WHICH ARE applicablE TO OTHER PURPOSES."
"
PROVISIONAL SPECIFICATION left by the said Edward Vincent Gardner
at the Office of the Commissioners of Patents on the 15th February 1882.
EDWARD VINCENT GARDNER, of Berners College, Borners Street, Oxford Street,
in the County of Middlesex, Professor of Chemistry. "IMPROVEMENTS IN THE
MANUFACTURE OF WHITE LEAD AND IN THE MANUFACTURE OF CARBONIC ACID
SUITABLE FOR USE IN THIS AND OTHER PROCESSES, AND IN THE APPARATUS
EMPLOYED IN SUCH MANUFACTURES, PARTS OF WHICH ARE APPLICABLE TO OTHER
PURPOSES."
My improvements consist in certain modes of treating blue lead so as to convert
it into white lead whether the process bo carried out in closed or open spaces, also
in improved methods of generating the gases and vapours required in the process
of converting blue lead into white lead, and also in improved methods of bringing
the various materials to act and react on cach other at certain temperatures and in
certain conditions of humidity and dryness, also in improved methods of arranging
the lead to be converted so as to form in arrangement with other bodies to which
it is related in electrical affinity an electrical combination, and in this state exposing
it to the action of the chemical agents and also in electrifying the agents employed
in producing white lead. By these means I further oxpedite the proceeding and
perfect the process of converting blue lead into white lead. Also in improved
means of preparing and treating the white lead when manufactured by the above
named or any other incthods. Also in improved construction of the apparatus
employed and in the combinations of such apparatus whereby the process of

page_text: converting blue lead into white lead is rendered inore manageable and certain and
whereby it may be carried out without offensive or injurious accompaniments,
with ease and convenience to all engaged and with very great economy.
The principles involved, in this Invention, for making white lead, are:-
First. To bring together certain agents used in manufacturing white lead at a
proper temperature under certain conditions favourable to the complete diffusion
and commingling of them at one general temperature and degree of humidity and
dryness to act upon the metal to be converted into white lead; and in the method
of using them in this process.
Secondly. In increasing the activity of the chemical action of the various
materials upon each other by arranging them in an electrical series or by causing
them to be excited by electrical discharges when acting on each other in the
process of converting blue lead into white lead.
Thirdly. By certain improved arrangements of the apparatus employed in the
manufacture of white lead by which I more effectually carry out the process of
converting blue lead into white lead, and in doing so in a more convenient
economical and perfect manner than is usual.
Fourthly. By improved method of treating the article when manufactured
and by improved appliances doing away with the necessity of handling the
materials in the course of preparation and after white lead has been produced from
blue lead.
Fifthly. In certain improved methods of producing the carbonic acid gas needed
in this and other processes of manufacture..
Sixthly. In the general arrangement of apparatus in a factory to make white
lead.
Seventhly. In the separate use of some of the apparatus described for various
purposes and their combinations for various purposes and for the purposes
imentioned and described for conversion of blue lead into white lead.
Eighthly. In the preparations and treatment of the lead to be converted into
whito lend.
Remarks upon the nature of the substances dealt with in the said improvements.
It is well to notice that the conditions which are observed and fulfilled in the
arrangements I am about to describe are founded upon a study of the nature and
properties as well as the behaviour of the substances concerned under certain
methods of treatment.
There are several oxides of lead which may be formed under special conditions.
First P O the same oxido combined with water or-Pb H² 0³; secondly Pb O
the same oxide combined with water or Pb H2O2-In the hydrated form theso
oxides combine readily with carbonic acid, but they do not combine readily with
carbonic acid when dehydrated. The hydrates are most readily formed at about
120° or 130° Fahrenheit and are decomposed after they are formed if heated to -
212° Fahrenheit.
These oxides and their hydrates combine with acetic acid to form acetate and
sub-acetate of lead and with nitric acid to form nitrate and subnitrate of
lead. Lead submitted to the action of air, vapour of water and acetic acid or
nitric acid or a mixture of these acids and air, or oxygen with proper precautions
forms sub acetate or subnitrate of lead, and this subacetate or subnitrate of lead
readily absorbs carbonic acid and forms carbonate of lead, sufficient acetic acid or
nitric acid or a mixture of these and air and watery vapour must be constantly
supplied to form the subsalts of lead to carry on the operation of converting blue
lead into white lead, but an excess of these agents, or an insufficiency of them will
in either case prevent the formation of the subacetate or subnitrate and conse-
quently of the subcarbonate. For example. Too little air, acetic acid and
aqueous vapour prevents the formation of the hydrated sub-acetate and consequently
sub-carbonate of lead. Too much acetic acid and aqueous vapour and too little
air forms an acetate on the surface of the lead, which by the excess of water
dissolves and wastes and washes the lead; it also varnishes the surface of the lead

page_text: with a coating of acetate and checks if not completely prevents the formation of
subacetate of lead and consequently carbonate and sub-carbonate of lead and
similarly with nitric acid and the formation of nitrates of lead.
This process of
forming the hydrated subacetate or subnitrate of lead is most energetic at a
temperature of 120° to 130° Fahrenheit. If beneath this temperature a much
longer time is occupied in carrying out the process of conversion; above this
temperature the delicate subacetate of lead or subnitrate of lead at first formed
suffers loss of water until at 212° Fahrenheit it is completely dehydrated. At a
temperature above 135° Fahrenheit the power of forming carbonates and sub-
carbonates is lessened and at 212° Fahrenheit considerably diminished.
The carbonate itself is dehydrated at 212° Fahrenheit and is decomposed at a
higher temperature. To obtain white lead of excellent quality for its various uses
we must produce a substance which possesses sufficient body to cover surfaces to
which it may be applied as paint, and it must also possess sufficient base to
combine with the oil of the paint to form a vehicle or varnish to retain and hold
the body on the surface. This is found to be the case with sub-carbonate of lead,
or especially with a compound constituted of two or three equivalents of carbonate
of lead with one equivalent of hydrated oxide of that metal. The object of this
invention is to produce such a compound very rapidly and conveniently and at a
much less cost than is the case with any process of manufacture at present con-
ducted and to enable the maker to vary, by simple means, the composition of the
manufacture to suit special purposes with ease and certainty.
Conditions favourable to this process.
Lead to be attacked by chemical agents should possess a clean surface. If the
surface of the lead is chemically clean so much the better. The surface of the lead
should be extended as much as possible and exposed to the action of the gases and
vapours at a certain heat for its conversion into white lead. It should be if the
most favourable conditions are sought at a temperature of about 120° to 135°
Fahrenheit and to carry on the chemical action tnost favourably the lead during
its conversion should present a granulated coating, that is the coating formned by
the chemical agents should be granular and not continuous in its character. It
should be porous and not of a continuous varnish like or vitreous character. To
rapidly carry on the chemical action the chemical agents should be well diffused
and commingled throughout each other, and the blue lead should be so exposed as
to be open to their attack on all parts of its surface equally and all should be at
and kept at a proper temperature, and at a proper degree of humidity. Too dry a
heat prevents the process of conversion. Too moist an atmosphere wastes the
inaterials and arrests their action.
The conditions therefore which are most favourable will be a certain humid
atmosphere of well diffused and commingled vapours or gases acting on metallic
lend exposed to them under certain conditions of treatment at a temperature of
from 110° to 135° Fahrenheit.
These favourable conditions can be further augmented by certain electrical
arrangements in connection with them.
In the use of paraffine, petroleum, benzine or light oil of paraffine or petroleum
and various carbonaceous substances or mixtures of them alone or mixed with air
or some oxidizing substance free from sulphur and capable of furnishing com-
paratively speaking pure carbonic acid without at the same time producing any
objectionable compounds for obtaining carbonic acid for many purposes and for
using the carbonic acid so obtained in the process of converting blue lead into
white lead.

page_text: treating and preparing the white lead after I bave manufactured it, and my
improved method of manufacturing carbonic acid applicable to the above process
and to other purposes.
Part of my improvement relates to open stacks or chambers in which the process
of converting blue lead into white lead is carried out and to the arrangement con-
nected with them; other of my improvements are applicable to and relate to
closed chambers used in converting blue lead into white lead and to the arrange-
ments connected with them, and to the processes carried out in them.
I prefer for carrying out my invention in converting blue lead into white lead
to employ a closed but not an air-tight chamber. This chamber is ventilated or
relieved so as to enable the incoming gases and vapours to enter it easily by means
of an exit valve and pipe or an exit shaft connected with the chamber and com-
municating with the exterior air and regulated by a damper or valve or in any
convenient manner. The gases and vapours within the chamber can find their
way out by this exit shaft only by pressure from within the chamber, thus the
interior of the chamber is preserved from disturbance by the formation of currents
within its atmosphere and yet a perfect circulation of the gases and vapours is
kept up.
To warm the interior of this chamber which is constructed of any material that
will resist the action of the vapours and gases, and which is not too absorbent;
I make the bottom of the chamber of such a form and shape as shall form a tank
to hold water or steam and this water or steam or both is kept at any temperature
by steam within it, a coil, for instance, which coil is attached to and is supplied
with steam from a boiler.. I contrive this tank so that its contents shall be
protected from any great pressure and consequently it never
can exceed
212° Fahrenheit in temperature or thereabouts. I can as it will be easily under-
stood regulate the heat of the contents of this tank and preserve them at any
temperature by regulating the supply of steam traversing the coil within the tank
and so in measure regulate the temperature of the chamber. I sometimes so
construct the converting chamber that not only its bottom but its sides also are so
formed as to make heating tanks and regulators of temperature in a similar way to
the bottom tank and by similar means. I may make the skeleton of the converting
chamber of iron cast or wrought and the tank or tanks of the saine materials and
face the iron with glass, slate, tiles, pewter, glazed bricks or any suitable substance.
I can make it of tinned copper or of tinned brass or of pewter partly or entirely in
these cases it needs no lining or facing with other materials. I sometimes employ
wooden chambers or wooden chambers lined in a similar manner to that above
referred to with any of these or some suitable substances according to con-
Biderations of convenience or economy. The chambers are constructed so as to
allow of proper observations being made of the materials under conversion. They
are also so made as to open at the top to allow of their contents being lifted out or
placed in by means of a crane or some such suitable means as will be further
described but I can employ chambers of any suitable form. I employ thermometers
or some such usual thermometric means of denoting and regulating the temperature
of the atmosphere existing within the converting chamber.
In my improved mode of manufacture of white lead and in my improved con-
struction of the apparatus and combination of apparatus employed therein the
gases and vapours generated outside the chamber are conducted to the interior by
means of suitable pipes. The gases and vapours generated outside the chamber
are first raised to a proper temperature by my improved arrangement of apparatus,
that is to a temperature which is beyond that of the inside of the chamber so as to
allow for any cooling effect and for the friction of the gases in passing the pipes
and the distributors attached to the converting chamber. The gases and vapours
are expanded and diffused and commingled by being heated previous to entering
the converting chamber and do not rob the interior of the chamber of heat upon
entering it so that the heat of the chamber is kept constant and can further operate
to expand and diffuse the gases and vapours in contact with the lead within the

page_text: chamber. I find that in practice sufficient command is not obtained of the gases
or vapours or any of them if they are generated inside the chamber. I arrange
the lead within the chamber on trays or shelves or frames in any convenient
arrangement so as to allow the full surrounding of the material to be converted by
the gases and vapours and so as to prevent any direct eddies or currents being
formed or meeting the substance within the chamber. I prefer framed supports
like to a dinner waggon for holding the lead or other material, and I arrange so as
to lift these framed supports into or out of the chamber bodily with their contents
without having to handle them or I arrange shelves or trays on any convenient
support inside the chamber if more convenient to do so. The shelves or supports
or trays if they are made use of to hold the lead are formed so as to have their
bottom surfaces made of artificial graphite or hard coke such as is used for electrical
plates in batteries or of plates or blocks made of a composite of coko or coal
anthracite clay and bitumen in certain proportions prepared and baked, or I
employ plates of graphite, hard coke, platinum or of some such materials as are in
similar electrical relations to lead, I may use plates of any of theso as traybottoms,
or I may put on the shelves or on the bottoms of the trays which are to hold the bluo
lead to be converted into white lead, plates of these materials, I sometimes arrango
that the lead to be converted into white lead, shall be arranged on the shelves or
in the trays so as to be in such conjunction with pieces of carbon or one of these
materials and thus form a true electrical arrangement. In this method the shelves
or the bottoms of the trays need not be of carbon or other electrical relation to the
lead but of any convenient material, I sometimes use ozonised air or oxygen or I
employ electrical influence and by electric discharges passed through the gases and
vapours within the chamber make use of the power of electricity to render the
chemical agents more active, but certain difficulties and practical inconveniences
that may arise in some operations lead me to employ pieces of carbon or other
materials which generate in conjunction with the lead electrical currents in the
manner already explained as being more ready and more easy of application. But
I can use any convenient method of employing the aid of electrical action.
I can adapt this electrical plan to an ordinary "stack" in the Dutch process of
making white lead from blue lead. In doing this I make the pots, for containing
the acetous liquid and the lead to be converted, of the electrical carbon, metals or
compounds, or of those materials which I have already mentioned as electrically
related to load, or I place electrical carbon plates or other suitable plates inside the
ordinary earthenware pots to sustain the lead which is to be converted, or I line
the pots with some of these materials partially or entirely and thus apply the
principle to the ordinary "stack" plant. I also improve the making of white
lead in the "stack" method or "Dutch process by making use of a supply of
carbonic acid gas other than that procured by the decomposition of dung, Tan or
such like material or in addition to it, and this I do by sending a current of that
gas and air or oxygen or a mixture of these gases through the stack at a certain
temperature.
"
I also raise the heat of the stack to the necessary temperature for converting
blue lead into white lead by means of steam pipes arranged throughout the stack
to raise its temperature to the proper point for converting blue lead into white
lead. Sometimes I depend upon the heated supply of gases to raise the stack to
the proper heat and to preserve that heat and at other times I depend upon the
steam heat and use the gases at the ordinary temperature but I may use both steam
and gases and the gases either heated or not as convenient. The carbonic acid
may be obtained for this operation in any suitable way but I prefer my improved
method of procuring this gas which I have hereinafter described that
s by the
oxidation in any convenient manner of Paraffine, Petroleum, Benzoline, and other
carbonaceous substance or of these mixed with air, or oxygen, or some oxidating
material, or mixture of any of these in the manner I describe and I thus greatly
expedite the manufacture of white lead in a stack by the use of the electrical
arrangement described and by supplying the necessary gases at a proper tempera-

page_text: ture. The electrical arrangement will alone greatly improve the process of making
white lead in a stack and this combined with the heating and supply of gases will
much further expedite and improve the process.
The gases and vapours generated and supplied to the interior of the chamber are
heated to a proper temperature before entering the chamber.
The acetic acid and nitric acid or the mixture of theso acids and aqueous vapours
are produced and generated in a vessel so arranged that its contents are kept at a
certain heat point by having the acid solution of a specific gravity equal to about
1.003 (distilled water being taken as the unit of comparison) made by mixing
vinegar and water or by mixing acetic acid and water or acetic and nitric acid and
water. By a convenient adaptation of the air or oxygen supply pipe the current
of air or oxygen passes through or in contact with the boiling acid solution, and
mixing with the vapours within the vessel in which the vapours are generated
passes intermingled with them through a conducting pipe into the chamber and
therein the mixed gas and vapour are distributed through distributing pipes. I
usually employ a solution of acetic acid and water but I sometimes employ a
mixture of acetic acid and nitric acid in various proportions in place of the acetic
solution alone, in such proportion of the mixed acids that by addition of wator the
specific gravity of the mixture shall be as when acetic acid alone is used, that is to
say, about 1·003 specific gravity.
I may vaporize the acid solution otherwise than by boiling it by an outward
source of heat that is I may make use of a current of steam or steam mixed with
air or oxygen or both at a certain temperature, and by driving this through or in
contact with the acid solution carry on its vaporization and the commingling of
the vapours and gases and these supply the chamber with the necessary gases and
vapours at a proper temperature or I may make use of, for the same purpose,
evaporation of heated currents of carbonic acid, air, oxygen or a mixture of these
bodies and these effectually carry on the proper provision and supply of the
converting chamber.
I may prepare the carbonic acid by any of the methods made use of for making
that gas. But as I need it for my purpose fairly pure I take care to observe certain
precautions in its manufacture. When I generate it from chalk and carbon, in a
furnace I arrange additionally to the usual plan that the escaping gas from the
furnace shall be fully oxidized that no carbonic oxide shall pass into the chamber
this I do by making air openings at the uptake from the furnace, and allowing air
or oxygen or a mixture of these gases to pass and meet with the gases coming
from the furnace to the delivery pipes and fully oxidize them. Carbonic oxide is
a very poisonous and dangerous gas, and would be likely to occasion fatal results
if accidentally breathed and it is quite useless in the process of lead conversion.
By oxidation this gas is converted into carbonic acid and becomes serviceable. I
cleanse and purify the carbonic acid made in any convenient manner, not only in
the usual way by passing it through a vessel containing water, but I further
cleanse it and raise it to the proper heat and expanded condition required in my
improved method of making white lead from blue lead by passing it through or in
contact with hot water or a hot solution of carbonate of soda in water in any
convenient way eventually delivering it through delivery tubes to the interior of
the chamber and the distributing pipes contained therein.
There are any
practical inconveniences attending the production and purification of carbonic acid
by the above or by any of the usual chemical methods of setting the substance free
from compounds containing it. They are also expensive processes and need
expensive machines to generate and purify the gas so manufactured.
I have a novel and simple method of generating carbonic acid, and this is by
burning Paraffine, Petroleum or light oils of paraffine or Petroleum, Benzol, or
Benzine or hydrocarbons or carbonaceous liquids, gases or solids capable in their
combination with oxygen of producing carbonic acid free from sulphur and other
deleterious substances. These I can employ alone or mixed together, or any one,

page_text: or any mixture of them mixed with air, or with oxygen, or any other oxidizing
substance for producing carbonic acid.
In my present arrangement for making white lead from blue lead I employ a
Inimp or lamps with oxidizing arrangements, or some arrangement by which I can
burn and fully oxidize the hydro-carbon substances above referred to or a mixture
of them alone or with air or oxidizing materials and produce at once at a low cost
and with great convenience carbonic acid gas at a proper temperature and of
comparative purity.
The carbonic acid so produced I conduct by proper pipes through a purifier or
saturator and evaporator to the interior of the converting chamber and I there
distribute it alone or mixed with the other gases and vapours by means of proper
distributing pipes and apparatus as will be well understood.
The carbonic acid gas generated by the above substances during their oxidation
in my improved process can be employed for many purposes for which carbonic acid
in a cheap form is needed.
The "saturating evaporator" is a vessel arranged to carry out my improved
method of making use of carbonic acid gas produced from carbonaceous materials
herein before mentioned and for purifying and conducting the gas so produced to
the converting chamber.
It is a vessel made of any suitable material and is divided by a partition which
forms it into two chambers an upper and a lower chamber. The lower chamber is
divided by a partition dependant from the upper one into two parts. To one of
the chambers a pipe is attached for conducting the products of combustion from a
lamp or burner into the interior of the saturating evaporator. The lamp or burner
consumes some of the materials herein before mentioned for producing carbonic
acid gas which is produced and conducted by the said pipe through the interior of
the saturator. This pipe is fitted with another through which may be passed air,
oxygen, or a mixture of these gases so as to mix with the products of combustion
and pass with them through the chambers of the saturator. The products of com-
bustion and the air oxygen and so on find their way by another tube after passing
through the interior of the saturating evaporator into the interior of the converting
chamber or other apparatus. The vessel or chambers of the saturating evaporator
contain solutions to be evaporated or for purifying the carbonic acid gas. Some-
times these solutions to be evaporated or for purifying the gas are contained not
only in the vessels or chambers, but also in a series of shallow containers so as to
expose a large surface to the action of the heated gases and the vessels are some-
times fitted with tubes so that the heated gases and vapours in passing through
the tubes, from the combustion of the hydrocarbons may be brought in contact
with the fluids in the vessels and containers and may evaporate and become
saturated with them. Sometimes this saturating evaporator is used as a fumigator
or vaporiser by generating gases within it by the heat of the combustion of the
fluids in the lamps or burners or by passing gases in a heated condition through it
when its Containers and vessels contain fluids for fumigating, or odourising and
disinfecting. By charging the vessel and containers with carburetting fluids and
passing gas or air through this apparatus it fulfills the functions of a carburetter.
In converting blue lead into white lead I employ it for evaporating the acid and
aqueous vapours and for supplying mixed with them the carbonic acid gas at a
proper heat and degree of humidity. It is suitable to be used for producing and
purifying carbonic acid alone and for treating substances contained within it with
the hot carbonic acid and hot gases and vapours generated by the combustion of
paraftine, or other hydrocarbons as hereinbefore mentioned.
It is evident the form of the apparatus may be diversified to meet various
considerations of purpose or convenience, without material departure from the
principles of construction above described.
Having thus explained and detailed some of the various parts of my improved
apparatus and processes I will now proceed to particularize my manner of proceeding
in their use in converting blue lead into white lead. I first prepare the converting

page_text: chamber and dispose of all the necessary arrangements for filling it with the blue
lead and I fill it with prepared lead.
For the purpose of this Invention I employ lead cast or rolled or of any suitable
condition or shape and 1 may dip the lead in acetic acid or nitric acid and water
prior to placing it in the converting chamber, but I prefer to granulate the lead
and to dip it after granulation in acetic acid and water or in nitric acid and water
or in a mixture of acetic and nitric acid and water but I find that a mixture of
these acids or one of them with a solution of acetate of lead or nitrate of lead or
both is better and I find it better to granulate and prepare the lead for conversion
at one operation as follows. I have a slab of stone, slate or iron about two or threo
inches thick and this I place in a tank or vessel and fill the tank or vessel with the
fluid for granulation until the fluid rises three inches above the upper surface of the
slab. I then melt the lead in any convenient manner and obtain the molten metal for
granulation at a red heat I then pour the molten metal by any suitable contrivance
into the granulating fluid contained in the tank or vessel and in such manner I
pour it that it shall fall through the fluid on to the slab within the tank or vessel.
I thus granulate it and produce what I call "spongy lead." The lead is in this
manner not only granulated but it is eminently fitted for the process of conversion
without further dipping or preparation. The granulating fluid I employ is a
mixture of acetic or nitric acid and acetate or nitrate of lead and water and this
gives the spongy lead an excellent preparation in the process of granulation.
I prepare lead for conversion into blue lead and prior to its treatment in the
converting chamber in the following manner. I heat metallic lead in any suitable
form granulated or otherwise and graphite, carbon, coke, platinum or some such
electro negative to lead in a mixture of acetate of lead, and nitric acid and water.
I find the following proportions succeed in this process very well, namely about
40 parts by weight of water about 1 part of nitric acid and about 1 part of
acetate of lead, I do not confine myself to theso proportions and I may generate
the nitric acid in any convenient way as by nitrate of soda or potash and sulpuric
acid. I prepare the metallic lead in any suitable form, by heating it with carbon,
graphite, coke, platinum or other electro negative to lead. Acetic acid and nitric acid
and water in the proportions of about 40 parts by weight of water, about 1 part of
nitric acid and about 24 of acetic acid. In either process the lead is attacked and
subacetate or subnitrate or oxide or suboxide of lead will be formed. I submit the
lead and electro negative substance to the action of the hot fluid mixture for one or
two hours, the lead is then removed from the solution or mixture, and is thus prepared
for being converted into white lead in the process of conversion in the converting
chamber, the materials remaining in the vessel after the lead has been removed can be
used with a fresh supply of lead for preparing fresh quantities of the metallic lead,
thus more lead is placed in the solution and mixture of materials and the process is
repeated, and this may be continued until no more oxide of lead is formed in the
process; at which stage an addition of about 1 part of nitric acid about 10 parts of
water and about 8 parts of acetic acid is to be made to the solution or mixture to
renew its power of action in the formation of the oxide and suboxide and sub-salts
of lead in repeating the process. Having filled the converting chamber I then close
the same and turn steam on to the tank or tanks of this chamber and I keep up
the steam supply until the temperature of the interior of the chamber denotes 120°
Fahrenheit on the thermometer. The lead is then arranged on the trays or on
the frames or on other supports then when loaded they aro lifted bodily by a hoist
and let down through the top of the converting chamber which is opened to receive
them to their places within it or the lead is inserted or introduced in any other
convenient manner. When the converting chamber is furnished with its proper
charge of blue lead the chamber is again closed. The supply of steam is continued
until the temperature within the chamber rises again to 120° Fahrenheit or there-
abouts and it is kept at that temperature for three or four hours, in fact, until the
whole of the contents of the converting chamber are of one uniform temperature,
when this is obtained the vapour of acetic acid, and the vapour of water, or the

page_text: vapour of the mixed acids and water (acetic and Nitric) and atinospheric air or
oxygen, or a mixture of these gases is supplied, at a proper heat and passed into
the converting chamber by the supply pipes and distributed within by the
distributing pipes or apparatus. The supply of acetic acid nitric acid or of mixed
acids, watery vapour and air and so on as lastly described is kept up at a moderate
rate, the temperature of the chamber must not be allowed to fall below 110°
Fahrenheit and not to mount above 125° Fahrenheit which is fittest, at this stage
the heat can be easily governed and regulated. The nitric acid and acetic acid for
use in this process may be obtained directly from their corresponding salts of soda,
potash or lime by the action of sulphuric acid and sent direct into the converting
chamber when more convenient to do so. The hot vapours and gases coming
into the converting chamber tend to preserve the heat of its contents or
even to raise their temperature, so that it may require that the steam
should be shut off from the tank or tanks of the chamber, and the supply
of the hot gases and vapours lessened so as to diminish the general
temperature of the gases and vapours within the converting chamber and to proserve
them at about 120° Fahrenheit and this is continued for 24 hours. The elevation
of the temperature if necessary at any time may be effected by increasing the
evaporation and the passage of the gases and vapours into the converting chambor
if the chamber is deficient in them or it may be attained by the action of the
steam, steam being supplied to the tank or tanks of the converting chamber. It is
well to regulate the supply of vapours and the temperature so that there shall not
be much condensation or excess of fluid within the converting chamber, on the one
hand, and on the other so that there shall not be a dry thirsty atmosphere within
it. A moist foggy atmosphere is the best and can always be easily secured and
preserved at the proper humidity and temperature by a due regulation of steam
heating, and of the evaporation of the gases and vapours into the converting
chainber, after 24 hours the heat may be allowed to rise in the converting chamber
to about 125° Fahrenheit and may even be allowed to proceed to about
130° Fahrenheit without absolute injury to the process provided that the atmo-
sphere within the converting chamber is not allowed to become dry and thirsty
but 125° Fahrenheit is the most safe and sure. This second stage is continued for
another period of 24 hours. The temperature may now vary between 120° and
130° Fahrenheit and must not be allowed to go above that or the material will
suffer. After forty eight hours treatment as stated a current of carbonic acid or of
carbonic acid and air or oxygen provided in any of the methods I have described
or in any convenient way and heated to a proper temperature is passed into the
converting chamber by the pipes and distributed within by the distributing pipes
or apparatus. This supply of carbonic acid or of that gas and air or oxygen is
continued for two hours, the supply of the acetic or aceto-nitric vapours and
aqueous vapour and air or oxygen being continued through the same period with
the carbonic acid gas, after 2 hours passing of the carbonic acid the supply is shut off
and the acetic or aceto-nitric vapours and aqueous vapour and air or oxygen con-
tinued as before for another four hours and so on; the supply of carbonic acid gas
and so on as before, for two hours being once in every six hours. The acetic or
acetonitric vapours and aqueous vapour and air or oxygen being continued the
whole time with the noted precautions. The supply of air or oxygen may be
obtained in any convenient way as the process of formation of white lead advances
in about four or five days granulation and efflorescence of the lead will be observed
on the surface of the lead or exfoliation of the lead will commence the supply of
carbonic acid and so on as before is to be increased to two hours every four hours
or to four hours every six hours, and the continuous supply of acetic or aceto-nitric
vapours and aqueous vapour and air or oxygen may be increased also with due
observance of the precautions mentioned saving that as the incrustation of white
5 lead thickens on the surface of the lead the temperature may be allowed to rise
and a range of temperature between 125° and 130° Fahrenheit may be employed
and will be found beneficial to the process. In about seven to fourteen days or

page_text: thereabouts the process will be completed and the blue lead will be entirely con-
verted into white lead I may also prepare a white lead for some purposes most
useful because very rich in carbonate of lead and this I do by dispensing with the
vapours above referred to and with the acetic or aceto-nitric acid vapours for
finishing the process and I send on to the chamber at this stage a current of
carbonic acid gas at a proper temperature, or of carbonic acid gas and air or oxygon
or both and with or without water vapour, according to the condition of the
contents of the chamber. In this manner I complete the converting process.
I may finish by placing the white lead and water and passing the carbonic acid or
the mixture of the said gas or gases above mentioned through it.
When I employ my saturating evaporator it will be understood that I may then
dispense with the whole or a part of the separate apparatus described for supplying
acetic, aceto-nitric and aqueous vapours, air or oxygen, and carbonic acid or I may
employ it in combination with one or all of them. I may first evaporate the acetic
or accto-nitric acid and aqueous vapour by a lamp arranged in the apparatus and
send the vapours and air through a union pipe to an exit opening in the body of
the apparatus to first supply the contents of the converting chamber and after-
wards shutting off the lamp and employing an oxidizing lamp burner containing
the paraffine or other hydro-carbon to supply the necessary evaporation of acid
or acids and watery vapour and to furnish the carbonic acid gas and air or
oxygen or mixture of these as required in the process above described, and in
this case the process can be complete and continuous by the use of this one
apparatus until the operation is finished.
When I require a white-lead rich in the hydrated oxide of lead I proceed as
follows after the process of the conversion which I have described is completed or
nearly completed. I discontinue the acid vapour and carbonic acid supply and
I send into the chamber a jet of steam at a low pressure or of steam and air mixed
for a few hours to act on the contents of the chamber before they are removed. In
this manner I finish the treatment in the chamber of such a sample. With some
description of lead I have found it beneficial to the process of conversion to use
nitric acid vapour and air or oxygen and watery vapour in place of that of acetic
acid and vapour and air or oxygen and watery vapour also in some cases to use the
nitric acid vapour in place of acetic acid vapour for the first 24 hours treatment
and after such treatment I continue with acetic acid vapour air or oxygen and
watery vapour or with acetic and nitric acid vapour mixed and air or oxygen and
watery vapour to completion of the process of conversion.
When the process of conversion is completed the converting chamber is opened
and the frames or supports containing the white lead are lifted out by the hoisting
apparatus and by it are transferred to the grinding apparatus direct or are by it
placed on a trolley for removal, or are otherwise suitably dealt with.
The comminuting, pulverizing or grinding of the material is effected in any
suitable way or in an improved apparatus of my invention hereinafter described.
This apparatus or mill is constructed of metal or wood or some suitable material.
It consists of a cylinder revolving in an enclosed chamber. The upper part of the
enclosed chamber is fitted with a hopper which can also be enclosed. The white
lead brought from the converting chamber is thrown into the hopper and falls into
the cylinder. The cylinder is a skeleton and is built longitudinally of iron rods or
wooden staves fastened at certain distances from each other so as to leave spaces
between them. Thus when the cylinder is revolved the contents are thrown
violently about and are thus comminuted or ground to powder. This action is
increased by having a few wooden or leaden balls in the cylinder to increase the
action. The white lead thus exposed to the comminuting process falls through the
spaces of the cylinder into a seive which is kept in agitation and from this seive it
falls into a second cylinder similar to the first, the core remains behind and is
delivered from the machine. The spaces of this second cylinder are narrower and 5
it is further pounded therein during its motion or it falls into a pair of horizontal
stones and is ground to fine powder. From the second cylinder or mill if not

page_text: fine enough it falls into another finer sieve placed beneath the second cylinder
or mill and from this sieve into a receptacle the core again remaining behind. The
whole of this apparatus is enclosed, for instance, the cylinders the sieves and other
parts so that no powder or dust can escape during the operation of grinding and
sifting. If desirable water or oil or both inay be used in grinding the white lead
but is not always necessary, or the white lead produced may be washed dried and
ground in the usual manner.
I dispose of the whole apparatus and plant in a factory for making white lead in
a novel manner. I build the chambers in a circle and in the centre I erect a hoist
or crane. At one part of the circle is the factory entrance, at the other and
opposite part is the mill and store.
The chambers occupy the space to complete the circle on either side of the
entrance and mill and store, the chambers are, by preference, usually arranged to
open at their tops.
In this manner by so combining the hoist or crane, the chambers, and the mill
and stores I can convey the materials from any part of the factory to any other
part where operations are conducted with little inanuel labour. Thus I can direct
the hoist to the store, load it, and it can transfer its load (for instance a frame of
trays containing lead) to any chamber by a circular motion given to it, in liko
manner the crane or hoist can convey the contents of any chamber to the mill or
store, or any materials from any one part to another; as for instance from the
entrance to the store or to the mill, or to any chamber, or vice-versa.
The white lead produced in the manner and by the arrangements I have men-
tioned is of such a character of purity both in its constitution and colour and free
from surface or other discoloration so that it does not always as white lead usually
does, need to be first sorted washed and ground in water to cleanse it and improve
its colour and then to be afterwards stirred and dried and when thus brought to
uniformity of colour and texture to be again ground to powder and ground with oil
to form the usual white lead basic body for paints.
White lead prepared in the manner and by the improved process herein before
described may be ground to powder alone or with oil or water and will produce
the finest white lead both in color and body without any interme liute treatment.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Vincent Garner in the Great Seal Patent Office on the
15th August 1882.
EDWARD VINCENT GARDNER of Berners College, Berners Street, Oxford Street,
in the County of Middlesex, Professor of Chemistry. "IMPROVEMENTS IN THE
MANUFACTURE OF WHITE LEAD AND IN THE MANUFACTURE OF CARBONIC ACID
SUITABLE FOR USE IN THIS AND OTHER PROCESSES, AND IN THE APPARATUS
EMPLOYED IN SUCH MANUFACTURES PARTS OF WHICH ARE APPLICABLE TO
OTHER PURPOSES.
"
The improvements constituting my said Invention consist in certain modes of
treating blue lead so as to convert it into white lead whether the process be carried
out in closed or open chambers or spaces, and in an improved method of generating
carbonic acid gas required in the process of converting blue lead into white lend.
The said improvements refer particularly to improved methods of bringing the
various materials employed to act and react on each other at certain temperatures
and in certain conditions of humidity and dryness, Also to improved methods of
arranging the lead to be converted so as to form, in arrangement with other bodies
to which it is related in Electrical affinity, an Electrical combination and exposing
it to the action of the chemical agents; to the employment of ozonised materials in
producing white lead by which means I expedite the process, and to improvements
in the construction of apparatus employed whereby the process of converting blue
lead into white lead is rendered more manageable and certain and whereby it may
be carried out, without offensive or injurious accompaniments, with ease and
convenience to all engaged and with very great economy. The principles involved
in this Invention are:-
First The preparation and treatment of the lead to be converted into white
lead, by bringing together certain agents, used in manufacturing white lead, at a
proper temperature under certain conditions favourable to the complete diffusion
and commingling of them at one general temperature and degree of humidity and
dryness to act upon the metal to be converted into white lead. And in the method
of using them in the process.
Secondly-In increasing the activity of the chemical action of the various
materials upon each other by arranging them in an electrical series or by causing
them to be excited by ozonised materials in the process of converting blue into
white lead.
Thirdly By certain improved arrangements of the apparatus employed in the
manufacture of white lead by which I carry out the process of converting blue lead
into white lead in a more convenient economical and perfect manner than is usual,
Fourthly By improved method of treating white lead in course of manufacture
and by improved appliances doing away with the necessity of handling the material
in the course of preparation, and also after it has been produced from blue lead.
Fifthly In certain improved methods of producing the carbonic acid gas needed
in this and other processes as in the manufacture of various carbonated compounds
and in the conversion of carbonates into bi-carbonates.
REMARKS UPON THE NATURE OF THE SUBSTANCES DEALT WITH IN THE SAID
INVENTION.
It is well to notice that the conditions which are observed and fulfilled in the
arrangements I ain about to describe are founded upon a study of the nature and
properties as well as the behaviour of the substances concerned under certain
inethods of treatment.
There are several oxides of lead which may be formed under special conditions-

page_text: First-Pb O-and the same oxide combined with water P 2 HO2-Secondly—
PbO-and the same oxide combined with water-P. 6 H2O*. In the hydrated form
these oxides combine readily with carbonic acid, but they do not combine readily
with carbonic acid when dehydrated. The hydrates are most readily formed at
about 120° or 130° Fahrenheit and are decomposed after they are formed if heated
to 212° Fahrenheit.
These oxides and their hydrates combine with acetic acid to form acetate and
sub-acetate of lead, and with nitric acid to form nitrate and subnitrate of lead.
Lead, submitted to the action of air, watery vapour, and acetic acid or nitric
acid or of a mixture of these acids, with air or oxygen, with proper precautions,
forms subacetate or subnitrate of lead, and this sub-acetate or sub-nitrate of lead
readily absorbs carbonic acid and forms carbonate of lead and subcarbonate of
lead.
Sufficient acetic acid or nitric acid or a mixture of these and air or oxygen and
watery vapour must be constantly supplied to form the subsalts of lead to carry on
the operation of converting blue lead into white lead but an excess of these agents
or an insufficiency of them will in either case prevent the formation of the subacetate
or subnitrate and consequently of the subcarbonates-For example.
Too little air, acetic acid and aqueous vapour prevents the formation of the
hydrated subacetate and consequently sub-carbonate of lead. Too much acetic acid
and aqueous vapour and too little air forms an acetate on the surface of the lead
which by the excess of water dissolves and wastes and washes the lead; it also
varnishes the surface of the lead with a coating of acetate and checks if not
completely prevents the formation of subacetato of lead and consequently the
formation of carbonate and subcarbonate of lead; and similarly with nitric acid
and the formation of nitrate and subnitrate. This process of forming the hydrated
subacetate or subnitrate of lead is most energetic at a temperature of 120° to 130°
Fahrenheit. If beneath this temperature a much longer time is occupied in
carrying out the process of conversion, above this temperature the delicate
subacetate of lead or subnitrate of lead at first formed suffers loss of water until
at 212° Fahrenheit it is completely dehydrated. At a temperature abovo 135°
Fahrenheit the power of forming carbonate and subcarbonates is lessened and at
212° Fahrenheit considerably diminished. The carbonate itself is dehydrated at
212° Fahrenheit and is decomposed at a higher temperature.
To obtain a white lead of excellent quality for its various uses it is necessary to
produce a substance which possesses sufficient body to cover surfaces to which it
may be applied as paint and it must.also possess sufficient base to combine the oil of
the paint to form a vehicle or varnish to retain and hold the body on the surface.
This is found to be the case with subcarbonate of lead or especially with a compound
constituted of two or three equivalents of carbonate of lead with one equivalent of
hydrated oxide of that metal. The object of this Invention is to produce such a
compound very rapidly and conveniently and at a much less cost than is the case
with any process of manufacture at present conducted and to enable the Maker to
vary by simple means the composition of the manufacture to suit special purposes
with ease and certainty.
CONDITIONS FAVORABLE TO THIS INVENTION.
Lead to be attacked by chemical agents should possess a clean surface. If the
surface of the lead is chemically clean so much the better. The surface of the lead
should be extended as much as possible and exposed to the action of the gases
intim haut frm its conversion into white lead

page_text: character. To rapidly carry on the chemical action the chemical agents should be
well diffused and commingled throughout each other and'the blue lead should be so
exposed as to be open to their attack on all parts of its surface equally and all
should be at and kept at a proper temperature and at a proper degree of humidity.
Too dry a heat prevents the process of conversion. Too moist an atmosphere wastes
the materials and arrests their action. The conditions therefore which are most
favorable will be a certain humid atmosphere of well diffused and commingled
vapours or gases acting on metallic lead exposed to them under certain conditions
of treatment at a temperature of from 110° to 135° Fahrenheit.
These favorable conditions can be further augmented by certain electrical
arrangements in connection with them.
In the use of paraffin, petroleum, benzine or light oil of paraffin or petroleum
or other suitable carbonaceous substances free from sulphur, or of mixtures of such
carbonaceous substances alone or mixed with air or some oxidizing substance and
capable of furnishing comparatively speaking pure carbonic acid without at the
same time producing any objectionable compounds and in the construction and
arrangement of apparatus for using the carbonic acid so obtained in the process of
converting blue lead into white lead.
I will now proceed to describe the mode of applying the various improvements
in the method of preparing and converting blue lead into white lead, the improved
apparatus, and the improved method of manufacturing carbonic acid gas applicable
to the above process and to other purposes.
Certain of the improvements above referred to are applicable to open stacks or
chambers in which the process of converting blue lead into white lead is carried
out whilst others are applicable to and relate to, closed chambers.
I prefer for carrying out my invention in converting blue lead into white lead
to employ a closed but not an airtight chamber. This chamber is ventilated or
relieved so as to enable the incoming gases and vapours to enter it without
hindrance and to escape by means of an exit valve and pipe or an exit shaft
connected with the chainber and cominunicating with the exterior air and regulated
by a damper or valve or in any convenient manner. The gases and vapours within
the chamber can find their way out by this exit shaft only, by slight pressure or
expansion from within the chamber thus the interior of the chamber is preserved
from disturbance by preventing the formation of currents within its atmosphero
and yet a perfect circulation of the gases and vapours is kept up.
To warm the interior of this chamber which is constructed of any material that
will resist the action of the vapours and gases and which is not too absorbent; I
make the bottom of the chamber of such a form and shape as shall form a heating
vessel to hold water or steam and this water or steam or both is or are kept at the
required temperature, by steam within a coil or pipe, or by other means. I so
contrive the said vessel that its contents shall be protected from any excess of
pressure and consequently it seldom exceeds 212° Fahrenheit in temperature, or
thereabouts. I can, as will be easily understood, regulate the heat of the contents
of this heating vessel and preserve them at any temperature and so in measure
regulate the temperature of the chamber. I sometimes so construct the converting
chamber that not only the bottom but the sides also are so constructed as to form
heating vessels or coils and regulators of temperature and by similar means I may
make the skeleton of the converting chamber of iron cast or wrought and the
heating vessels of the same material and face the iron with glass, slate, tiles,
pewter, glazed bricks or any suitable substance, I can make it of tinned copper or
of tinned brass, or of pewter, partly or entirely, in these cases it needs no lining
or facing with other materials. I sometimes employ wooden chambers or wooden
chambers lined with any of the said materials and titted with coils for steam or I
carbonize the wood either by heat or by the action of sulphuric acid or some
strong acid solution, according to various considerations as will be well understood.
The chambers are constructed so as to allow of proper observations being made of
the materials under conversion. They are also in some cases so made as to open

page_text: at the top to allow of their contents being lifted out or placed in by means of a
crane or some such suitable means; Although I prefer to employ chambers
constructed as lastly described, chambers of any suitable form may be used.
Thermometers or some such usual thermometric means of denoting the temperature
of the atmosphere existing within the converting chamber are suitably arranged.
In my improved mode of manufacturing white lead, and in my improved con-
struction of the apparatus, employed therein, the gases and vapours generated
outside the chamber are conducted to the interior by means of suitable pipes.
The gases and vapours generated outside the converting chamber are first raised
to a proper temperature by the arrangement of apparatus hereinafter described,
that is to say to a temperature which is beyond that of the inside of the chainber
so as to allow for any cooling effect and for the friction of the gases in passing
through the pipes and the distributors attached to the converting chamber. The
gases and vapours are expanded and diffused and commingled by being thus heated
and they do not rob the interior of the chamber of heat upon entering it, so that
the heat of the chamber is kept constant and can operate to further expand and
diffuse the gases and vapours in contact with the lead within the chamber. I find
that in practice sufficient command is not obtained if the gases or vapours or any of
them are generated inside the chamber.
I arrange the lead within the chamber in trays or on shelves or frames in any
convenient manner so as to allow the lead to be surrounded and thereby converted
by the gases and vapours employed as hereinafter described and so as to prevent
any direct eddies or currents being formed or meeting the substance within the
chamber. I prefer framed supports, like to a dinner waggon for holding the lead
or other material and I sometimes arrange such supports so that they may be
lifted into, or out of, the chamber bodily with their contents without having to
handle them or I arrange shelves or trays on any convenient support or supports
inside the chamber if more convenient to do so. The shelves or supports or trays,
if they are made use of to hold the lead, are formed so as to have their bottoin
surfaces made of artificial graphite or hard coke, such as is used for electrical plates
in batteries, or of plates or blocks made of a composite of coke or coal with
anthracite, clay and bitumen or of coke and free burning coal in certain pro-
portions prepared and baked or I employ plates of graphite, hard coke, platinum or
of carbonized and platonized materials or some such materials as are in similar
electrical relations to lead. I inay use any of these materials for making the trays
and so on or I employ them as tray bottoms putting plates of them on the shelves
or on the bottoms of the trays which are to hold the blue lead to be converted
into white lead. I sometimes arrange that the lead to be converted into white
lead shall be placed on the shelves or in the trays so as to be in such conjunction
with pieces of carbon or some one of these materials as to form an electrical
arrangement. In this method the shelves or the bottoms of the trays need not be
of carbon or other material in electrical relation to the lead but of any convenient
material. I sometimes use ozonised materials such as air or oxygen and so on, but
certain difficulties and practical inconveniences that may arise in preparing ozonised
materials lead me to prefer to employ carbon or other materials which generate in
conjunction with the lead electrical currents as being more ready and more easy of
application. But I can use any convenient method of employing the aid of
electrical action.
J
I can adapt this electrical plan to any ordinary "stack" for instance to the
Dutch process of making white lead from blue lead. In doing this I make the pots,
for containing the acetous liquid, and the lead to be converted, of the electrical
carbon, metals or compounds or of those materials I have already referred to as
electrically related to lead or I place electrical carbon plates or other suitable
plates inside the ordinary carthenware pots to sustain the lead which is to be
converted or I line the pots with some of these materials partially or entirely and
thus apply the principle to the ordinary stack" plant. In some cases I further
improve the making of white lead in the "stack" process or Dutch method of
of

page_text: making use of a supply of carbonic acid gas other than that procured by the
decomposition of dung or tan or such like material or in addition to it, and this I
do by sending a current of that gas and air or oxygen or a mixture of these gases
through the stack at a suitable temperature.
I sometimes raise the heat of the stack to the necessary temperature for
converting blue lead into white lead, by means of steam pipes arranged throughout
the stack. Sometimes I depend upon the heated supply of gases to raise the stack
to the proper heat and to preserve that heat, at other times I depend upon the
steain heat and use the gases at the ordinary temperature but I may use both
steam with gases heated or I use either or both of these in addition to the
ordinary means. The carbonic acid may be obtained for this operation in any
suitable way but I prefer my improved method of procuring this gas which I have
hereinafter described or I may obtain it by the oxidation, in any convenient
manner, of paraffin, petroleum, benzoline and other carbonaceous substances or of
these mixed with air or oxygen or some oxidizing material or a mixture of any of
these in the manner I describe. The gases and vapours generated and supplied to
the interior of the chamber are heated to a proper temperature before entering the
chamber.
The vapours of acetic acid or nitric acid or of a mixture of these acids and
aqueous vapours are produced and generated by heat in a vessel so arranged that
its contents are kept at a certain hent point for vapourizing by having the boiling
acid solution of a specific gravity equal to about 1,003 (distilled water being taken
as the unit of comparison) made by mixing vinegar and water or by mixing acetic
acid and water or acetic and nitric acid and water.
By a convenient adaptation of the air or oxygon supply pipe the current of air
or oxygen passes through or in contact with the boiling acid solution and the
carbonic acid supply can be so used and for a similar purposo and sometimes both
the air or oxygen and the carbonic acid supply are so made use of and adopted
and such gases mixing with the vapours within the vessel in which the acid
vapours are generated passes intermingled with thein through a conducting pipe
into the chamber and therein the mixed gas and vapours are distributed through
distributing pipes.
I usually employ a solution of acetic acid and water but I sometimes employ a
mixture of acetic acid and nitric acid and water in various proportions in place of
the acetic solution alone the proportions of the mixed acids being such that by
addition of water the specific gravity of the mixture shall be as when acetic acid
alone is used, that is to say about 1.003.-I may vapourize the acid solution
otherwise than by boiling it by an outward source of Heat. That is I may make
use of a current of Steam or Steam mixed with air or oxygen or of either or both
with carbonic acid at a certain temperature and by causing the same to pass
through or in contact with the acid solution. I effect its vaporization and the
commingling of the vapours and gases and thus supply the Chamber with the
necessary gases and vapours at a proper temperature, or I may make use for the
purpose of evaporation of heated currents of carbonic acid, air oxygen, or a mixture
of these bodies and thus effectually carry on the proper provision and supply of the
converting chamber.
I may prepare the carbonic acid by any of the methods made use of for making
that gas. But as I need it for my purpose fairly pure 1 take care to observe
certain precautions in its manufacture. If I generate it from chalk and carbon in
a furnace I arrange additionally to the usual plan, that the gas or gases escaping
from the furnace shall be fully oxidized that no carbonic oxide shall pass into the
Chamber, this I do by making air openings at the uptake from the furnace and
allowing air or oxygen or a mixture of these gases to pass and meet with the gases
coming from the furnace to the delivery tubes to fully oxidize the gases.
I cleanse and purify the carbonic acid made in this or in any convenient way
not only in the usual way by passing it through a vessel containing water but I
may further cleanse it and at the same time raise it to the proper heat and

page_text: expanded condition required in my improved method of making white Lead from
Blue Lead by passing it through or in contact with hot water or preferably through
or in contact with a hot solution of carbonate of soda in water or through vessels
containing carbonates hot or cold in any convenient way eventually delivering it
through delivery tubes to the interior of tho chamber and the distributing pipes
contained therein. There are many practical inconveniences attending the pro-
duction and purification of carbonic acid by the above or by any of the usual
chemical methods of setting the substance free from compounds containing it.
They are also expensive processes and need expensive machines to generate and
purify the gas so manufactured. Although I may use carbonic acid manufactured
in any suitable way I prefer to employ such gas as manufactured in accordance
with this invention, which manufacture is effected in the following manner. By
allowing petroleum Benzine paraffin and any suitable similar or analagous carbo-
naceous substances to act on chalk or some such suitable carbonate at a high
temperature in a suitable manner. The suitable substance such as petroleum
paraffin and so on is allowed gradually to fall into the retort containing the hot
chalk or carbonate and amongst other substances carbonic acid gas of considerablo
purity is generated I allow a current of air or oxygen to meet the gases thus
produced while still highly heated and fully combust them before they enter the
converting chamber. Carbonic acid so generated is applicable to many other
purposes than the conversion of blue lead into white lead, and the carbonic acid
manufactured as above described is fitted for any such other purpose where a
supply of moderately pure carbonic acid is necessary.
I may simply generate carbonic acid by burning paraffin petroleum or light oils of
paraffin or petroleum, Benzole or Benzine or Hydrocarbon or Carbonaceous Liquids
gases or solids, capable in their combination with oxygen of producing carbonic
acid free from sulphur and other deleterious substances. These I can employ alone
or mixed together, or any one, or any mixture of them combusted with air or with
oxygen or any other oxidizing substance for producing carbonic acid.
In my Invention for making white Lead from blue lead I sometimes employ a
Lamp or Lamps or some arrangement by which I can burn and fully oxidize the
Hydro-carbon substances above referred to or any mixture of them alone with air or
with oxidizing materials and produce at once and at a low cost and with great con-
venienco carbonic acid gas at a proper temperature and of comparative purity. The
carbonic acid so produced I conduct by proper pipes through a purifier or saturator
and evaporator to the interior of the converting chamber and I there distribute it
in this or in some other convenient way alone or mixed with the other gases and
vapours by means of proper distributing pipes and apparatus as will be well
understood.
I sometimes employ bicarbonates such as bicarbonates of soda, potash and so on
for generating pure carbonic acid gas when it is required of great purity. This I
do by beating the bicarbonates to a sufficient heat to drive off the one molecule of
carbonic acid and reduce the bicarbonate to the state of carbonate to be used over
again when bicarbonated by carbonic acid gas, as will be well understood.
Figure 1 represents in longitudinal section an example of an apparatus for
purifying carbonic acid obtained by the employment of a lamp or burner as above
mentioned and for conducting it to the converting Chamber.
A. B. C. D. is a vessel made of tinned copper or of tinned brass, or of pewter or of
some substance lined with rolled tin or some suitable material according to the naturo
of the process. It is divided by a horizontal partition e. f. which forms it into two
Chambers, an upper and lower chamber. The Lower Chamber is divided by a
dependent partition g into two parts. To one of these divisions is attached the
tube or tubes for conducting the products of combustion from a lamp or lamps or
burner or burners into the Vessel. The lamp or burner or lamps or burners
consumes or consume some of the materials I have mentioned and produces carbonic
acid. The tube i attached to h is for the conduct of air, oxygen or any needed gas
or vapour to the interior of the vessel in addition to the products of combustion.
R

page_text: The products of combustion generated by the lamp or lamps or burner or burners
pass by h. into one of the lower chambers and then by the tubes 1. 2. 3. 4. 5 into
the upper chamber. This upper chamber contains water or solution of some
carbonate. This water or solution of carbonate, for instance carbonate of soda, is
warmed by the passing of the heated gas through the pipes. When the gas arrives
at the upper chamber it comes into contact with the water or solution of carbonate
contained in the upper vessel and is cleansed or purified, it then passes down by
the pipes 6. 7. 8. 9. 10. to the other lower chamber out by the pipe K, to the dis-
tributor L into the converting chamber M. The funnel pipe N is for charging the
vessel and the gauge. o. is for regulating the charge: P is a thermometer for
denoting the temperature, Q is a tap or valve for emptying the upper chambers, R. R¹.
are taps for emptying the lower chambers of any leakage. S is a dumper or valve
for regulating the combustion.
In some cases by the use of the apparatus shown in Figure 2 and hereinafter
termed the "saturating evaporator" in converting blue lead into white lead. I can
dispense with the separate acids and aqueous vapour generator and with the inde-
pendent air and carbonic acid supplying and heating apparatus I produce the acid
and aqueous vapours in this apparatus or one similar to it and I send the air or
oxygen and carbonic acid gas in the proper conditions and at a proper temperature
through the apparatus.
It will be observed in my various arrangements I cause the air or oxygen and
carbonic acid to be supplied to the chamber not only at a temperature which
prevents them cooling the contents of the Chainber, but I also supply them saturated
with moisture inasmuch as they have passed through or have come into contact
with boiling solutions, previously to being delivered to the interior of the
chamber.
In this new apparatus which I have invented and will describe I also contrive
that the air or oxygen and carbonic acid shall be delivered from it to the interior
of the chamber at a proper heat and they are also so saturated with aqueous and
acid vapour as not to in any way disturb the contents of the chamber, on the
contrary they are in a perfectly diffused and commingled state and at one regular
and proper expanse and temperature to keep up the supply of gases and vapours to
the chamber without unduly heating or cooling its contents and giving rise to
unequal action in the conversion of the blue lead into white lead. In this Figure
A. B. C. D represent the "saturating evaporator" as used in converting blue lead
into white Lead and made of tinned copper, fino pewter or tinned Brass or some
suitable material which can withstand the corrosive gases and vapours. This is
supported and arranged on metal legs or on some other convenient support and is
also so arranged that the exit tube E can be fitted to the pipes and distributing
apparatus of the converting chamber. The lower part of this vessel is partially
filled with the converting fluid. The converting fluid may be a solution of acetic
acid in water, specific gravity 1003 or a solution of Nitric acid or a mixture of the
two, which is to be gasified or vapourised. The height of the fluid is shown by
the dotted line a. a. The fluid is boiled and evaporated, when necessary by the
lamp for by some suitable means. The height of the fluid is at all times seen by
the gauge g. The gases or vapours generated in this part of the vessel can be sent
in one of two directions, one being directly through the union tube to the exit E
and so to the converting chamber, the other through the apparatus in the direction of
the arrows and through the tube n. to the exit pipe E and so on to the converting
chamber. The union tube and exit E are governed by dampers or valves ii i so
as to send the current in either direction at pleasure. The apparatus is fitted with
two containers K. K. and K'. K¹. so contrived as to contain the liquid to be
evaporated and to direct the current of heated gas in the direction of the arrows
from the inlet tube and hood L. Above the said containers K. K. K. K. is a
larger container having a number of tubes 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12 to
conduct the heated gases and vapours through the fluid it contains so as to
evaporate it. This upper container has a plate m fastened to its lower surface

page_text: about its centre dipping down and reaching to the bottom of the container K. K¹.
It's end is pierced to permit free circulation to the fluid in K. K. but it directs the
heated gases and vapours upwards through the pipes 1. 2. 3. 4. 5 and 6 into the
vapour space above the tubes and thence down the tubes 7. 8. 9. 10. 11. 12 to the
union tube and exit tube E. The apparatus can be worked with the lamp for
without it. When the lamp is not used that is when the full power of evaporation
is not needed then the heated gases entering at L pass over the surface of the fluid
in the container a. a. and over the surface of the fluid in the containers K, K. K¹. K'.
and through the pipes over the surface of the fluid in the upper vessel or container
and down to the exit E. When desired the lamp f is placed in operation as well as
the oxidizing burner lamp or apparatus under the hood pipe L. The said lamp or
aparatus is for combusting paraffin petroleum or any of the materials or mixtures
which have been hereinbefore mentioned. The products of this combustion alone
or mixed with air or oxygen, which can also be supplied through the lamp or by
the pipe S are conducted up the hood pipe L to carry on the evaporation of the
fluid in the containers within A. B. C. D and commingling and mixing and diffusing
with the vapour and gases contained therein eventually reach the converting
chamber by the exit pipe E. The tank N contains a supply of the fluid to be
evaporated and is connected by the pipes O and O. with the containers inside the
evaporator. These pipes are each of them fitted with taps by which the supply
may be given to the containers. The pipe Oc mmunicates with the upper part of
the vessel or the upper container. The pipe O' with the container K. K. When
the cock in the pipe O' is turned on, the fluid runs from N into K. K. until that
is filled to the top of the funnel pipe P. it then runs down P into the lower con-
tainer K. K. and fills it to the top of the funnel pipe P¹. it then runs down P¹. into
the lower container until this is filled to the level a a when the tap of the pipe O'
is turned off and the flow of the fluid from N is stayed. The gauges R and R¹
enable the operator to see the height of the fluid in the containers and to regulate
the supply. The containers are provided with pipes and taps for emptying them
when it is necessary to do so. It will be understood that by means of this part of my
invention evaporation of the fluid and saturation of the gases used in the process
by the vapours at any given regulated temperature can be easily and economically
effected and preserved in a continuous supply and more or less abundantly as
required for the process in operation. The thermometer T is for ascertaining
the temperature of the interior gases and vapours in order to regulate their
evaporation.
I modify this construction and render the apparatus more powerful, when
necessary, by forming the lower container C. D. (Figure 2) similar to the upper
one, that is I fix in it a number of tubes so that the products of combustion from
the lamp or burner f pass through the tubes in the lower contaiuer C. D. warming
the liquid it contains and entering the space above the liquid a. a. mixes with the
gases and vapours entering at L passes on mixed with them in the direction of the
arrows through the exit E to the chamber.
I sometimes employ more than one lamp or burner such as I use beneath the
pipe L and attach similar pipes to one or both sides of the apparatus. Thus I can
increase the supply of gases and vapours to any extent required. Figures 3 and 4
show two modifications of the "saturating evaporator." In Figure 3, A. B. C. D, is
a boiler filled with tubes a. a. a. This boiler contains the fluid to be evaporated.
The evaporation is effected in any convenient way, in Figure 3 by heat beneath
the boiler A. B. C. D. In Figure 4 by a steam coil within the upright boiler. In
Figure 4 the tubes u. a. a. a. are for conducting the products of combustion from
the carbonic acid producer situated in E, when, desirable through the opening F.
The vapour generated within the boiler, and the carbonic acid gas from E, and air
sent through G, mix together and pass in the opening F either into the converting
chamber or if further evaporation is needed they then enter and pass through the
vessel H. I. J. K. which contains trays or containers of fluid, over which the gases

page_text: and vapours pass heating the fluid and becoming saturated therewith, passing
eventually through L to the converting chamber.
The same letters refer to like parts in Figures 3 and 4.
In Figures 1. 2. 3 and 4 the disposition of the parts of the apparatus is similar
and for similar purposes.
In Figures 3 and 4 the vessels A. B. C. D. can be used alone or in connection
with the vessels H. I. J. K.
With the saturating evaporator I can supply all needed in the conversion of
blue lead into white lead without an independent apparatus to produce each of the
gases and vapours needed in that operation but I may use it in combination with
other apparatus if convenient.
When I apply the said burner or burners for making Carbonic acid gas for other
purposes than that of converting Blue Lead into White Lead I place in the con-
tainers the material to be carbonated and the gas is caused to pass over or through
the material so placed and thus to carbonate it.
Having thus explained and detailed some of the various parts of my improved
apparatus and processes, I will now proceed to particularize my manner of using
them in converting blue lead into white lead.
I first prepare the converting Chamber and dispose of all the necessary arrange-
ments for filling it with the blue lead which I employ in any suitable condition or
shape and I dip the lead prior to placing it in the converting Chamber in acetic
acid or in nitric acid and Acetate or Nitrate of lead and water in a mixture of
acetic and nitric acids and the salt or salts of lead and water. I find it better to
granulate and to prepare the lead for conversion at one operation as follows:-
I have a slab of stone slate or Iron about two or three inches thick and this I place
in a tank or Vessel and fill the tank or vessel with any of the said solutions until
the fluid rises three inches above the upper surface of the slab, I then melt the
lead in any convenient manner and obtain the molten metal for granulation at a low
red heat I then pour the molten metal by any suitable contrivance from a height
of about four to six feet into the granulating fluid contained in the tank or
Vessel and I pour it in such a manner that it shall fall through the fluid on to the
slab within the tank or vessel such slab being so arranged that the metal on coming
into contact therewith is free to pass off into the fluid beneath-1 thus granulate
and produce what I call "spongy lead," in a more suitable condition for conversion
into white lead, than if granulated in water only by the way above described.
The lead in this manner is not only granulated but it is eminently prepared for
the process of conversion without further dipping or preparation.
Although I find the said solutions suitable for spongifying and preparing the lead
in the manner lastly described, I, in some cases, substitute water therefor and spongify
the lead in a similar manner, but in this case the lead undergoes no special preliminary
preparation for conversion into while lead. The lead is then arranged on the
trays or in the frames or on other supports which when loaded are lifted bodily by
a hoist and let down through the top of the converting chamber, which is opened
to receive them, to their places within it, or the lead is introduced in any other
convenient way. When the converting chamber is furnished with its proper charge
of blue lead it is closed and it is heated by the heating apparatus until the
temperature within the chamber rises to 120° Fahrenheit or thereabouts and it is
kept at that temperature for three or four hours, in fact, until the whole of the
contents of the converting chamber are of one uniform temperature. When this
is obtained the acid vapours and the watery vapour (such vapours having, when
desired, mixed with them, atmospheric air or oxygen or a mixture of these gases)
are supplied at a proper heat and passed into the converting Chamber by the supply
pipes and distributed within by the distributing pipes or apparatus The supply of
Acetic acid, nitric acid or of mixed acids watery vapour and air and so on as
herein before described, is kept up at a moderate rate, the temperature of the
chamber must not be allowed to fall below 110° Fahrenheit nor to mount above

page_text: 125° Fahrenheit which is fittest at this stage; the heat can be easily governed and
regulated. The nitric acid and acetic acid for use in this process may be obtained
in any convenient manner directly as from their corresponding salts of soda Potashi
or Lime by the action of sulphuric acid and sent direct into the converting chamber
when more convenient to do so. The hot vapours and gases coming into the
converting chamber tend to preserve the heat of its contents or even to raise their
temperature so that it may require that the Steam should be shut off from the
heating apparatus of the chamber and the supply of the hot gases and vapours
lessened so as to diminish the general temperature of the gases and vapours within
the converting chamber and to preserve them at about 120° Fahrenheit and this is
continued for Twenty four hours. The elevation of the temperature if necessary
at any time may be effected by increasing the evaporation and the passage of the
gases and vapours into the converting chamber or it may be obtained by the
action of the Steam supplied to the heating apparatus of the Chamber. Should
¡ electrical discharges be employed to accelerate the process they are passed from
any convenient source and by suitable means through the substance engaged in
converting blue lead into white lead such as air oxygen and so on before they
enter the converting chamber or they are passed through the atmosphere of the
gases and vapours within the converting chamber. Such electrical discharges
being made occasionally so as to excite the chemical energy of the materials
within the Chambers in their action on each other during the process of
conversion.
But in some cases in order to obviate any necessity for such electrical discharges
I place the lead for conversion on supports or trays so arranged as to bring the
lead into action with carbon platinum, platinized materials or some such electro-
negative as will with the lead form a galvano-electric combination and this may be
accomplished in any suitable manner inside the converting Chamber or in tho
manner herein before described.
During the process of conversion it is well to regulate the supply of vapours
and the temperature so that there shall not be much condensation or excess of fluid
within the converting chamber on the one hand, and on the other so that there
shall not be a dry thirsty atmosphere within it.
A moist misty atmosphere is the best and can always be easily secured and
preserved at the proper humidity and temperature by a due regulation of Steam
heating and of the evaporation of the gases and vapours into the converting
chamber. After twenty four hours the heat may be allowed to rise but not to
exceed about 130° Fahrenheit provided that the atmosphere within the converting
Chamber is not allowed to become dry and thirsty. But 125° Fahrenheit is the
most safe and sure heat. This second stage is continued for another period of
twenty four hours.
The temperature may now vary between 120° and 135° Fahrenheit and must
not be allowed to get above 135° nor much below 120° or the material will suffer.
After forty eight hours treatment as stated carbonic acid or carbonic acid and air
or oxygen provided in any of the methods I have described or in any convenient
way and heated to a proper temperature is passed into the converting Chamber by
the pipes and distributed within by the distributing pipes or apparatus. This
supply of carbonic acid or of that gas and air or oxygen is continued for two hours,
the supply of the acid vapours and aqueous vapour and air or oxygen being
continued through the same period with the carbonic acid gas; after two hours
passing of the carbonic acid gas the supply is shut off and the acid vapours and
aqueous vapour and air or oxygen continued as before for another four hours and
So on the carbonic acid gas being supplied as before for two hours in every six
hours. The acid vapours and aqueous vapour and air or oxygen being continued
the whole time. The supply of air or oxygen may be obtained in any convenient
way. As the process of formation of white lead advances in about four or five
days effloresence of the surface of the lead will be observed or exfoliation of the
lead will commence the supply of carbonic acid as before is to be increased to two

page_text: hours every four hours or to four hours every six hours and the continuous supply
of acid vapours and aqueous vapour and air or oxygen may be increased also with
due observation of the precautions already mentioned saving that as the
incrustation of white lead thickens on the surface of the lead, the temperature
should be preserved at about 130° to 135° Fahrenheit. In seven to fourteen days
or thereabouts the process will be completed and the blue lead will be entirely or
for the greater part converted into white lead.
I do not confine myself to the exact periods of time above mentioned; I find that
with my prepared spongy lead I can accomplish the process of conversion in much
less time than seven or fourteen days.
Figure 5 is a longitudinal section of a tray shelf or support. The bottom of the
tray or support is covered with carbon plates or some electro negative to lead and
it is divided and formed into spaces by upright plates, of the same material, the lead
is spread or placed upon the shelf tray or support as shown.
Figure 9 is a top view of a shelf tray or support. 1. 2. 3. 4. 5. 6. 7 are the
carbon or other suitable electro negative plates forming divisions and the spaces
between are occupied with the lead to be converted the lead resting upon similar
plates to the said upright plates. Sometimes the lead to be converted is mixed
with lumps of carbon or other suitable electro-negative material and is placed on
the shelves or trays without any definite regularity of arrangement and many
other analogous dispositions are adopted as most suitable or convenient for use in
especial circumstances.
When the conversion of the contents of the converting Chamber is completed
they are transferred to the grinding apparatus or may be treated in any suitable
way however I prefer to grind or pulverize them by means of a comminuting
apparatus constructed in the following manner.
Figure 7 represents the comminuting or grinding or pulverizing apparatus con-
structed in accordance with this Invention A. B. C. D is an outer framing enclosing
the whole apparatus and preventing the escape of any particles of the material
under operation F. F¹ are two Cylinders of any suitable form pierced with holes
or perforations or made up so as to have a series of longitudinal spaces. When two
Cylinders are employed, which is not always the case the Cylinder F' has the said
spaces much closer together than the Cylinder F. The spaces of the Cylinders are
covered with wire netting or wire gauze so as to form a kind of sieve around the
cylinder through which the comminuted substance falls. Balls of metal, wood or
stone are placed in the Cylinder to assist the pounding action on the material. E is
the exterior hopper closed by doors 1 and 2, and E is the interior hopper. The
material to be pulverized is placed first of all in E. The Cylinder Fis immediately
underneath E, and has a door opened from without, to admit the material from the
hopper E. After charging F the said door is closed. The Cylinder is made to
revolve with its contents and is driven in any suitable way. Underneath the
.Cylinder or below each Cylinder, if two are employed, is a sieve or screen G into
which the substance from the Cylinder or Cylinders falls and is sifted. The
sieves G. G. are actuated by a gaggle or any suitable machinery and are set so
inclined as to deliver the core, which cannot pass their meshes, at a suitable opening
in the Outer framing A. B. C. D. When one Cylinder and Sieve only is employed
.this is all that is necessary. But when two Cylinders and two Sieves are engaged
then a second hopper E¹ receives the material passing from the first sieve G and
conducts it to the second Cylinder F' which is similar in construction to the first
but with finer spaces and which as well as the hopper E' is provided with proper
doors or openings for the passage of the material. The hopper E¹ has a door at H
for sustaining its contents and this door is actuated and opened from without when
the contents are to be dropped into the second Cylinder F¹ through the door or
opening in it which door is also actuated from without. The tinely pounded
substance reaches the receptacle I from which it is occasionally removed or it falls
through an opening in I into a store. The cylinders F and F¹ deliver their core in
any suitable way.

page_text: When a Mill is made use of in conjunction with the Cylinder F the sieve G and
Cylinder may be dispensed with.
Figure 8 is a view of an improved comminuting apparatus, A is a Cylinder of
cast iron or other suitable material revolving on an axis, when driven by the
pulley B. The end of the axis opposite to B, is hollow to allow of the hopper
tube C¹ fitting into it. The material from the hopper falls into C¹ and is pushed
by the piston D into the interior of the Cylinder A. The Cylinder A has openings
on its face E. E covered with metal gratings or gauze for sifting the contents of A.
These gratings are covered with metal plates while comminuting is going on and
these plates are removed when the material is sifted through the gratings or
gauze. The sifted materials fall into a sieve or mill as in the apparatus already
described.
Grinding or comminuting in water can be effected in any of those apparatus
by allowing water to flow in at the top of the case into the Cylinder through the
gratings or gauze as the Cylinder revolves and to flow out into troughs beneath.
The white lead produced in the manner and by the arrangement I have men-
tioned is of such a character of purity both in its constitution and colour and is
free from surface or other discolorations that it does not, as white lead usually
does, need to be first washed and ground in water to cleanse it and improve its
color then to be afterwards stoved and dried and when thus brought to uniformity
of colour and texture to be again ground to powder and ground with oil to form
the usual white lead basic body for paint.
White lead prepared in the manner and by the improved process hereinbefore
described may be ground to powder alone or with oil or water and will be found
excellent both in colour and body without any intermediate treatment.
Having thus described and ascertained the nature of the said Invention and
the, manner in which it is to be performed I would observe in conclusion that
what I consider novel and original and therefore claim as constituting my said
Invention, is.―
First. The preparation of lead by submitting it to the action of a mixture of
acetic acid and acetate or nitrate of lead and water, or in a mixture of nitric acid,
acetate or nitrate of lead and water, or in a mixture of these acids and the said
salts of lead and water, substantially as and for the purposes hereinbefore described
and setforth.
Secondly. The method of granulating or spongifying lead by dropping the molten
metal on to a slab arranged within a tauk, substantially as heroin beforo described
and setforth.
Thirdly. The arrangement of electro negatives to lead such as carbon, platinum
and so on in connection with the lead to be converted into white lead so that they
shall be in electrical relationship to each other, substantially as and for the purposes
herein before described and setforth.
Fourthly. The employment of ozonised materials (such materials being ozonised
before entering the chamber or they may be ozonised within the chamber by
electrical discharges) alone or in combination with the electro-negatives referred to
in the third claim, substantially as and for the purposes herein before described and
setforth.
Fifthly. The method of producing carbonic acid gas by the oxidation of paraffin,
petroleum or other such like carbonaceous substances, substantially as hereinbefore
described and setforth.
Sixthly. The construction and arrangement of the apparatus heroin before termed
the "saturating evaporator" substantially as and for the purposes hereinbefore
setforth and described and shown in Figures 1. 2. 3 and 4 of the accompanying
drawings.
And Seventhly. The employment of the mixed vapours of acetic and nitric
acids and water alone or mixed with air or oxygen or carbonic acid in ordinary

page_text: condition or with ozonised materials substantially as and for the purposes
hereinbefore described and set forth.
In witness whereof I the said Edward Vincent Gardner have hereunto set
my hand and seal this fourteenth day of August in the year of our Lord
One thousand eight hundred and eighty two.
EDWARD V. GARDNER. (L.S.)