Improvements in and Apparatus for Obtaining Oxygen and Nitrogen from Atmospheric Air.
Year: 1892

page_text: Date of Application, 20th June, 1892
Complete Specification Left. 20th Apr. 1893-Accepted, 17th June, 1993
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for Obtaining Oxygen and Nitrogen
from Atmospheric Air.
1, LEONARD CHAPMAN, of 232 Camberwell New Road, in the County of
London, Engineer, do hereby declare the nature of this invention to be as
follows:
My invention relates to processes wherein a lower metallic oxide (such for
example as manganese iron or chromium in a lower stage of oxidation) and a base
are heated together in the presence of air so as to form a compound (such as a
manganate a ferrate or a chromate of the base for example) which when subjected
to the action of steam is decomposed and gives off oxygen.
Great difficulty has hitherto been experienced in conducting such processes
owing to the separation of the materials the lower metallic oxide (I will presume it
to be lower oxide of manganese for the purposes of this description) remaining solid
at the temperature at which the process is conducted whilst the base employed
(which for the purposes of description I will presume to be caustic soda) is fused
or liquified at this temperature so that they separate and the air and steam passed
thereover do not act properly to effect the chemical changes necessary in the
process.
According to my invention I employ the oxide of manganese (or the like) in a
finely divided or powdered form and I keep it suspended in the fused soda (or the
like) whilst the air and steam are passed therethrough so that the said air and
steam respectively come into intimate contact with the oxide of manganese and the
soda. I prefer to employ the air and steam themselves as the means whereby the
suspension of the divided or powdered oxide of manganese is obtained by passing
the air and steam in at the lower part of the charge of such materials so that as the
air and the steam pass upwards therethrough they keep the oxide of manganese
suspended in the fused soda whilst the said air and steam respectively act thereon
and the necessary chemical changes are thereby effected in a most efficient manner.
I may employ the lower oxides either alone or two or more together and I may
use one base or several different kinds of bases together and with the materials I
may use a chemically indifferent but readily fusible material to assist in the fusion
of the mass, or in the bringing of the mass into the most favourable condition for
the proper conduct of the process.
A further objection to the processes as hitherto conducted has been that owing
to the air present in the retorts and in the pipes or passages connected therewith,
the oxygen first obtained off is contaminated with this air. I remove this air
before the obtainment of oxygen is commenced and this I can conveniently effect
by admitting steam into the air spaces in the vessel and pipes or passages to remove
the air before commencing to de-oxidize.
The following is a more detailed description of the means by which my invention
may be performed and of apparatus suited for its practical application but I do not
limit myself to the precise details.
The substances (the oxide of manganese being in a finely divided or powdered
state) are placed in a closed vessel (or vessels) into which a pipe, (which serves
alternately as inlet for the per-oxidizing air and for the de-oxidizing steam) passes
nearly to the bottom of the vessel.
The vessel is provided with an outlet for the escape of nitrogen and unabsorbed
oxygen during the period of per-oxidation and of steam and oxygen during the
period of de-oxidation. The vessel is further provided with a secondary steam
inlet, into its upper part for the purpose of clearing the space in the vessel and in

page_text: the delivery pipe or passage of air before de-oxidising. For admitting steam for
the same purpose to the inlet pipe (the interior of which is shut off by the contents
of the vessel from communication with the interior of the vessel) a small steam pipe
enters the upper part of the inlet pipe and extends down nearly to the level of the
materials in the vessel.
The vessel is heated in any suitable way for instance by being set in a furnace
or furnaces heated by generator gas to a temperature necessary for the purposes of
the process.
The per-oxidation of the contents is effected by passing air, (which should be
previously freed as far as possible of moisture and carbonic acid and heated) into
the inlet pipe, from which it is discharged in jets or a divided state into the vessel
at the lower part thereof and in passing upwards through the materials causes
considerable agitation and brings about intimate contact between the air and the
particles of oxide held in suspension in the fused mass. The nitrogen and the
unabsorbed oxygen escape by the outlet pipe past a pressure regulating valve to
the open air, or they may be usefully employed for creating draught for heating or
for other purposes.
After the above described per-oxidation bas proceeded sufficiently far for
practical purposes and before commencing to decompose or de-oxidize the
manganate formed, I drive out the air remaining in the upper part of the vessel
and in the pipes after the per-oxidation and this I effect by steam admitted above
the surface of the materials in the vessels and escaping to the open air.
The de-oxidation or decomposition of the manganate formed during the period of
per-oxidation is effected by admitting dry steam to the inlet pipe, from which it
emerges in a finely divided state at the bottom of the vessel. Great agitation
takes place here again and the particles of manganate formed during the period of
per-oxidation are brought into intimate contact with the steain. The oxygen and
unabsorbed steam escape by the outlet pipes to a cooling apparatus, in which the
-steam condenses and drains off in the form of water, while the oxygen passes in to
the gas holder.
I prefer to use two or a greater number of vessels so that whilst the contents
of some of the vessels are being per-oxidized those of the others are being
de-oxidized.
The admission of air to the bottom of the vessels of blow through steam to the
pipes and to the upper parts of the containers and of dry steam to the bottom of
the containers as well as the emission of the excess-air during per oxidation, of
steam and air while blowing through and of steam and oxygen, to the condenser
during de-oxidation may with advantage be controlled mechanically by automatic
apparatus adjustable as to duration of each operation.
An installation of the simplest form for producing oxygen by the above described
process consists of two vessels set in a furnace, the contents of one vessel being
per-oxidized while those of the others are being de-oxidized.
In such an arrangement the main inlet pipe and the outlet pipe of each vessel is
connected to one of four separate compartments in the main casting of the auto-
matic machine, each of which is provided with two ports or openings, the one
communicating with a steam chest and the other with an air chamber. Midway
between these four compartments a fifth compartment is formed which is, however
subdivided by a partition into two separate cells each provided with a port, one
opening into the steam chest, the other into the air chamber. The cell, the port
of which opens into the steam chest, is connected by a pipe to the condenser and
the cell communicating with the air cbest is connected by a pipe to the pressure
regulating valve, through which the excess air escapes during the period of per
oxidation.
The port faces of both steam chest and air chamber are thus each pierced with.
five ports, the middle one being in each case the exhaust, the outside ones the inlet
and the intermediate ones the outlet ports.
Each port face is fitted with a valve which may be a common slide valve of such

page_text: a length, that at the extremity of its travel in either direction it admits steam or
air as the case may be to an outside port only and provided with an exhaust cavity
long enough only to effect communication between the middle exhaust port and one
of the intermediate outlet ports.
These two main valves are moved at intervals simultaneously in opposite
directions and admit air to, and allow of the escape of the excess of air and nitrogen
from the vessel the contents of which are being per oxidized, and admit steam to
and provide for the escape of steam and oxygen from the vessel the contents of
which are being de-oxidized.
To provide for the removal of air from the upper part of the vessel I may
employ in connection with the main air chamber a secondary air chamber, into
which all air supplied by the pump or blower is delivered. A slide valve in this
secondary air chamber controls two inlet ports and one exhaust port. One of the
inlet ports leads directly into the main air chamber, the other to a secondary escape
pipe fitted with a pressure regulating valve set to the same pressure as the similar
valve on the exhaust pipe of the main air slide. The exhaust port is connected by
a pipe with a small inlet in the cover of the vessel. The ports and the slide valve
of this secondary air chamber are so arranged that when the valve is at one
extremity of its travel, air is passing direct from the pump through the secondary
air chamber to the main air chamber, while the port opening to the secondary
escape pipe as well as the exhaust port connected to the cover of the container is
closed. When this slide valve is at the other extremity of its stroke, the port
leading to the secondary escape pipe is open and that leading to the main air
chamber is closed to the inlet of, air but is communicating through the exhaust
cavity in the slide valve with the exhaust port connected with the small inlet in
the cover of the vessel.
Shortly before the main air and steam slides are timed to shift, the secondary air
slide, which has hitherto allowed of direct communication between the two air
chambers is moved (preferably by automatic mechanism) to the other extremity of
its stroke, thereby cutting off the supply of air to the main air chest and allowing
communication by way of its exhaust cavity between the inlet port to the main air
chest and the exhaust port communicating with the unoccupied space above the
level of the contents of the vessel while at the same time the supply of air from the
pump or blower is directed into the secondary outlet pipe whence it escapes past a
pressure regulating valve.
This pressure regulating valve in rising opens a small valve which admits steam
through a pipe to the interior of the main inlet pipe to the vessel in which it is
discharged close to the level of the molten mass therein. The steam does not
however penetrate the molten mass, but retraces the path followed by the incoming
air prior to the cutting off of the supply by the secondary air slide, until after
passing through the port or opening connecting the main and secondary air
chambers, it is directed by the cavity of the slide valve in the secondary air
chamber through the exhaust port and connecting pipe to the upper part of the
vessel whence it escapes by the outlet pipe past the cavity in the main air slide and
the main escape pipe to the open air taking with it the air left over from the period
of per oxidation in the inlet and outlet piping and in the unoccupied space in the
vessel.
After this blow through has continued for a short time, the main slides and the
secondary air slide shift simultaneously the latter admitting the supply of air from
the pump or blower again to the main air chest whence it is sent into the other
vessel, and closing the port leading to the secondary escape pipe with the result
that the pressure regulating valve on this pipe closes and at the same time shuts
the small steam valve on the blow through pipe, and as the steam slide moves
simultaneously with the main air slide dry steam now passes into the vessel which
has just been purged of air by blowing through.
Such an automatic apparatus can be employed in connection with an installation
of more than two vessels, provided that each vessel is connected to one of the iulet

page_text: mains and one of the outlet mains coming from and returning to the automatic
apparatus, and that each vessel is so coupled with the blow through steam pipe
and with the exhaust port of the secondary air chamber as to receive a jet of
steam back through its inlet pipe into the vacant part of the container as above
described.
Nitrogen may also be obtained by the above described process in the following
manner.
A gasholder or other receptacle is filled with air, and this air is employed to
per-oxidize the contents of the vessels. The oxygen extracted is delivered to the
oxygen gas holder or is allowed to escape, but the nitrogen and excess of air
unabsorbed by the contents of the vessels during the periods of per-oxidation, is
returned to the gas holder or receptacle whence it was withdrawn, instead of being
allowed to escape. The per-oxidation and de-oxidation of the contents of the
vessels is continued as when making oxygen only until practically all the oxygen
contained originally in the gas holder or receptacle filled with air has been
extracted, and practically pure nitrogen alone remains.
Dated this 20th day of June 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for Obtaining Oxygen and Nitrogen
from Atmospheric Air.
I LEONARD CHAPMAN of 14 Flodden Road Camberwell late of 232 Camberwell
New Road, in the County of London Engineer do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
My invention relates to processes wherein a lower metallic oxide (such for
example as manganese, iron or chromium in a lower stage of oxidation) and a
base are heated together in the presence of air so as to form a compound (such as
a manganate, a ferrate or a chromate of the base for example) which when
subjected to the action of steam is decomposed and gives off oxygen.
Great difficulty has hitherto been experienced in conducting such processes
owing to the separation of the materials the lower metallic oxide (I will presume
it to be lower oxide of manganese for the purposes of this description) remaining
solid at the temperature at which the process is conducted whilst the base employed
(which for the purposes of description I will presume to be caustic soda) is fused
or liquified at this temperature so that the materials become into such a condition
that the air and steam do not act properly to effect the chemical changes necessary
in the process. According to my invention I employ the oxide of manganese (or
the like) in a finely divided or powdered form and I keep it suspended in the
fused soda (or the like) so that the charge is practically in the condition of a
liquid whilst the air and also whilst steam are passed therethrough so that the said
air and steam respectively come into intimate contact with the charge 1 prefer to
employ the air and steam themselves as the means whereby the suspension of the
divided or powdered oxide of manganese or the practically liquid condition of the
charge is obtained by passing the air and steam in at the lower part of the charge
of such materials so that as the air and the steam respectively pass upwards
therethrough they keep the charge in the requisite conditions as aforesaid and
the necessary chemical changes are thereby effected in a most efficient manner.
I may employ the lower oxides either alone or two or more together and I may
use one or more than one base and I may use with the materials a chemically
indifferent but readily fusible material such for example as sulphate of soda or
borate or silicate of soda or of potash to assist in the fusion of the mass or in the

page_text: oringing of the mass to OST
the process.
YOU
A further objection to the processes as hitherto conducted has been that owing.
to the air present in the retorts an! in the pipes or passages connected therewith,
the oxygen first obtained is contaminated with this air I remove this air before
the obtainment of oxygen is commenced and in cases where the per-oxidizing air
is forced through the contents of the vessel I can conveniently effect this by
admitting steam into the air spaces in the vessel and pipes or passages to remove.
the air before commencing to de-oxidize. When the per-oxidizing air is drawn
through the contents of the vessel I can effect the removal of the air by shutting
off the supply of air before de-oxidation is commenced and allowing the exhauster
or the vacuum pump to create as good a vacuum as possible above the level of the
contents of the vessel.
The following is a more detailed description with reference to the accompanying-
drawings of the means by which my invention may be performed and of apparatus
suited for its practical application but I do not limit myself to the precise details.
Figure 1 shews in diagrammatic form the general arrangement of an apparatus.
constructed according to my invention.
Figure 2 is a plan partly in section of a furnace constructed to accommodate four
vessels in which are contained the oxygen absorbent materials.
Figure 3 is a vertical section of the upper part of the furnace shewing two of
the vessels one being in section.
Figure 4 is a sectional plan of mechanism for automatically carrying on the-
process.
Figure 5 is a sectional elevation and Figure 6 a plan of the arrangement of three.
way cocks shewn in Figure 1.
The substances (the oxide of manganese being in a finely divided or powdered.
state) are placed in a closed vessel (or vessels) into each of which a pipe (which.
serves alternately as inlet for the per-oxidizing air and for the de-oxidizing steam).
passes nearly to the bottom of the vessel.
The vessel is provided with an outlet for the escape of steam (due to the
formation of manganate) of nitrogen and of unabsorbed oxygen during the period
of peroxidation and of steam and oxygen during the period of de-oxidation.
When the per-oxidizing air is forced through the vessel is further provided with a
secondary steam inlet into its upper part for the purpose of clearing the space in.
the vessel and in the delivery pipe or passage of air before de-oxidising. For
admitting steam for the same purpose to the inlet pipe (the interior of which is.
shut off by the contents of the vessel from communication with the interior of the
vessel) a small steam pipe enters the upper part of the inlet pipe and extends down.
nearly to the level of the materials in the vessel.
The vessel or vessels is or are heated in any suitable way for instance by being.
set in a furnace or furnaces heated by generator gas to a temperature necessary for
the purposes of the process.
The per-oxidation of the contents is effected by passing air, (which may be
previously freed as far as possible of moisture and carbonic acid and heated) into.
the inlet pipe from which it is discharged in jets or a divided state into the vessel
at the lower part thereof and in passing upwards through the materials causes
considerable agitation and brings about intimate contact between the air and the
particles of oxide held in suspension in the fused mass. The steam due to the.
formation of the manganate, the nitrogen and the unabsorbed oxygen escape by
the outlet pipe past a pressure regulating valve to the open air or are withdrawn.
by the exhauster or vacuum pump.
After the above described per-oxidation has proceeded sufficiently far for
practical purposes and before commencing to decompose or deoxidize the manganate:
formed, I drive out the air remaining in the upper part of the vessel and in the
pipes after the per-oxidation and this I effect by steam admitted above the surface
of the materials in the vessels and escaping to the open air or by shutting off the

page_text: supply of peroxidizing air and allowing the exhauster or the air pump to continue
evacuating before commencing to de-oxidize according to whether the peroxidizing
air is forced or drawn in.
The de-oxidation or decomposition of the manganate formed during the period
of per-oxidation is effected by admitting dry steam to the inlet pipe, from which it
emerges in a finely divided state at the bottom of the vessel. Great agitation
takes place here again and the particles of the manganate formed during the period
of per-oxidation are brought into intimate contact with the steam.
The oxygen
and unabsorbed steam escape by the outlet pipe to a cooling apparatus, in which
the steam condenses and drains off in the form of water, while the oxygen passes
on to the gas holder.
I prefer to use two or a greater number of vessels so that whilst the contents of
one or of some of the vessels are being per-oxidized those of the other or others are
being de-oxidized. The admission of air to the bottom of the vessels, of blow
through steam to the pipes and to the upper parts of the vessels and of dry steam
to the bottom of the vessels as well as the emission, of the excess air nitrogen and
steam during per-oxidation, of steam and air while blowing through and of steam
and oxygen to the condenser during deoxidation may with advantage be controlled
nechanically by automatic apparatus adjustable as to duration of each operation.
An installation of the simplest form for producing oxygen by the above described
process consists of two vessels set in a furnace, the contents of one vessel being
per-oxidized while those of the other are being deoxidized.
I have however in the drawings shewn an arrangement consisting of four vessels
which generally is a convenient construction two having their contents peroxidized
whilst the contents of the other two are being deoxidized.
In such an arrangement the main inlet pipes A and the outlet pipes B of each
vessel or pair of vessels are connected to one of four separate compartments 1. 2. 3. 4
in the main casting of the automatic machine, see Figure 4 each of which is
provided with two ports or openings 1ª, 1º, 2º, 2º, 3ª, 3, 4, 4º, the one 1ª 2ª 3ª 4ª
opening at the side at which the steam chest 7 is situated and the other 1b 2b 3b 4b
at the side at which the air chamber 9 is situated. Midway between these four
compartments a fifth compartment is formed, which is, however, sub-divided by a
partition into two separate cells, each provided with a port, one 5ª opening into the
exhaust cavity of the valve 6 in the steam chest 7 and the other (5b) into the
exhaust cavity of the valve 8 in the air chamber 9. The cell, the port 5° of which
opens into the cavity of the valve 8 in the air chest, is connected by a pipe 11 to
the condenser and gas holder and the cell communicating with the cavity of the
valve 6 of the steam chest 7 is connected by a pipe 10 to the pressure regulating
valve, through which the excess air escapes during the period of peroxidation.
The port faces of both steam chest and air chamber are thus each pierced with five
ports, the middle one being in each case the exhaust, the outside ones the inlet and
the intermediate ones the outlet ports.
The valves 6 and 8 may be common slide valves of such a length that at the
extremity of their travel in either direction they admit steam or air as the case
may be to an outside port only, and provided with an exhaust cavity long enough
only to effect communication between the middle exhaust port and one of the
intermediate outlet ports.
These two main valves are moved at intervals simultaneously in opposite
directions and admit air to, and allow of the escape of the excess of air, steam
and nitrogen from the vessel the contents of which are being per-oxidized, and
admit steam to and provide for the escape of steam and oxygen from the vessel the
contents of which are being deoxidized.
To provide for the removal of air from the upper part of the vessel I may
employ in connection with the main air chamber 9 a secondary air chamber 12 into
which all air supplied by the pump or blower is delivered through the pipe 13.
A slide valve 14 in this secondary air chamber 12 controls two inlet ports 15
and 16 and one exhaust port 17. One of the inlet ports (15) leads directly into

page_text: the main air chamber 9 the other to a secondary escape pipe 18 fitted with a
pressure regulating valve shown at 19 in Figure 5 set to about the same pressure
as the escape valve on the main exhaust pipe. The exhaust port 17 is connected
by a pipe 20 to a three way cock 26 which communicates by a pipe 28 (see
Figure 1) with the compartment 28ª and the small holes 28 in the entablature A*
which supports the vessels. The ports and the slide valve of this secondary air
chamber 12 are so arranged that, when the valve is at one extremity of its travel
(as shewn) air is passing direct from the pump through the secondary air
chamber 12 and passage 15 to the main air chamber 9 while the port 16 opening
to the secondary escape pipe 18 as well as the exhaust port 17 communicating by
the pipe 20 and the three way cock 26 with the covers of the vessels is closed.
When this slide valve is at the other extremity of its stroke, the port 16 leading to
the secondary escape pipe 18 is open and the port 15 leading to the main air
chamber 9 is closed to the inlet of air, but is communicating through the exhaust
cavity in the slide valve 14 with the exhaust port 17 connected with the small
inlets in the covers of the vessels as hereinbefore described.
Shortly before the main air and steam slides are reversed, the secondary air
slide 14 which has hitherto allowed of direct communication between the two air
chambers is moved (preferably by automatic mechanism) to the other extremity of
its stroke, thereby cutting off the supply of air to the main air chest 9 and allowing
communication by way of its exhaust cavity between the inlet port 15 to the main
air chest 9 and the exhaust port 17 communicating through the pipe 20 with the
space above the level of the contents of the vessel, while at the same time the
supply of air from the pump or blower is directed through the port 16 into
the secondary outlet pipe 18 whence it escapes past the pressure regulating
valve 19 (see Figure 5).
This pressure regulating valve in rising opens a small valve 21 which admits
steam through a pipe 22 and the three way cock 23 by the pipe 25 and by the
small pipe D see Fig. 3 into the main inlet pipes of the vessels which are under
per-oxidation it being discharged close to the level of the molten mass therein.
The steam does not, however, penetrate the molten mass, but retraces the path
which was followed by the incoming air prior to the cutting off of the supply by
the secondary air slide 14 until after passing through the port or opening 15 con-
necting the main and secondary air chambers, it is directed by the cavity of the
slide valve 14 in the secondary air chamber 12 through the exhaust port 17 and
connecting pipe 20 and three way cock 26 and by the pipe 28 to the upper part of
the vessels being blown through whence it escapes by the outlet pipe B past the
cavity in the main stean slide 6 and the main escape pipe 10 to the open air,
taking with it the air left over from the period of per-oxidation in the inlet and
outlet piping and in the unoccupied space in the vessel.
After this "blow through" has continued for a short time the main slides 6
and 8 and the secondary air slide 14 shifts simultaneously, the latter admitting the
supply of air from the pump or blower again to the main air chest whence it is sent
into the other vessels which are now under per-oxidation and closing the port
leading to the secondary escape pipe 18 with the result that the pressure regulating
valve 19 on this pipe closes and at the same time shuts the small steam valve 21 on
the blow through pipe 22, and as the steam slide 6 moves simultaneously with the
main air slide 8 dry steam now passes into the vessels which have just been cleared
of air by blowing through.
Such an automatic apparatus can be employed in connection with an installation
of other number than four vessels, provided that each vessel is connected to one of
the inlet mains and one of the outlet mains coming from and returning to the
automatic apparatus, and that each vessel is so coupled with the blow through
steam pipe and with the exhaust port of the secondary air chamber as to receive a
jet of steam back through its inlet pipe into the vacant part of the container as
above described.

page_text: The mechanism for automatically regulating the admission of air and steam to
the retorts, and the escape of nitrogen and excess air, and of oxygen and excess
steam from the same, is actuated by the piston of a steam cylinder the slide valve
of which is moved alternately in opposite directions by a cam 30 mounted on the
shaft 29 and causes the piston to make an outward and an inward stroke alternately
every half revolution of the shaft. On the same shaft is mounted a disc 31 provided
with two tappets each of which in turn moves the valve 14 of the intermediate air
chest in the same direction thereby shutting off the supply of air to the main air
chest 9 and sending it up the secondary escape pipe during a short period prior to
the cam 30 actuating the valve 33 of the steam cylinder 32 and bringing about the
reversal of the positions of the main steam valve 6 and the air valve 8 and of the
two three way cocks 23 and 26. The lever 35 which serves to transmit the motion
of the steam piston to the main valves 6 and 8 also provides for the pushing back
of the intermediate air slide valve 14 into its normal position viz. that in which it
gives full passage of the air to the main air chest.
With the steam piston 34 lever 35 and valves 6, 8 and 14 in the positions shown
in Figures 1 and 4 the cycle of operations is as follows:-
Air is delivered by the fan blower or pump through pipe 13 into the intermediate
air chest 12 thence through port 15 into the main air chest 9 thence through
port 4 into chamber 4 and by the pipe A to the passage A' provided in the
hollow entablature A* whence it emerges through the holes A² therein and through
corresponding holes in the flanges of the vessels or containers and through the
passages A³ into compartments A of the covers of the vessels to the pipes A³
which reach to near the bottom of the vessels. After passing up through the
molten material contained in the vessels the air passes out through the holes B
into the compartments B in the covers of the vessel and by the passage B³ in the
cover the corresponding hole B2 in the entablature to the outlet channel 13¹
formed in the entablature Ax and thence by the pipe B to the compartment 3 of
the automatic gear which it leaves by the port 3 and is directed by the cavity of
the steam chest slide valve through port 5" to escape pipe 10 and thence past a
pressure regulating valve therein to the open air. Meanwhile the shaft 29 has
been slowly revolving and in due course one of the tappets on the disc 31 comes
into contact with the roller on the intermediate air chest valve rod and causes the
intermediate air slide valve 14 to shut off the supply of air to the main air chest 9
and to direct it through port 16 up the secondary escape pipe 18 and in escaping
therefrom raises the cap 19. This cap in rising actuates the lever 20 which by
means of the rod 20° opens the valve 21 and admits live steam by passage 22
through the three way cock 23 to pipe 25 which it traverses and enters compart-
ment 25 of the entablature.
From this compartment it passes by holes 25° and through corresponding holes
in the flanges of the vessels and passages 25° in the covers to the upper compart-
ment 25 of the cover and thence by the small central pipe D to the inside of the
inlet pipe A³. This steam does not pass through the molten mass but retraces the
path hitherto followed by the incoming air and is directed by the cavity of
the intermediate air valve 14 and port 17 to the pipe 20 which communicates with
the three way cock 26 and the pipe 28 which conducts the steam back to the
compartment 28 in the entablature whence it passes by holes 28 and corresponding
passages 28 and compartment 28 and the hole 28 in the cover into the space
above the molten mass in the vessel whence it expels the residual air by the
channels B5 B3 B2 and pipe B into the chamber 3 of the automatic gear and
thence by the port 3ª and cavity of valve 6 and port 5ª to the main escape
pipe 10.
The shaft 29 has meanwhile been steadily revolving and the valve 33 of the
steam cylinder 32 is now moved in a direction away from the shaft causing the
piston 34 to move in the same direction and by means of the lever 35 to reverse
the position of the main air and steam valves 8 and 6 and by throwing over the

page_text: bell crank lever 36 by the projecting end 37 of the lever 35 to return the inter-
mediate air valve 14 to its normal position as shown in Figure 4. The air now
resumes its normal course direct into the main air chest and as no air is now
passing up the secondary escape pipe 18, the cap 19 drops and closes the blow
through steam valve 21.
Owing to the position of the valves 6 and 8 and the two three way cocks 23
and 26 having been reversed the air supply is now directed to the other pair of
vessels and steam now passes through pipe A into the pair of vessels the material
in which has just been per-oxidized with the result that oxygen and steam pass
off through the pipe B into the chamber 3 and the cavity of the air slide valve by
port 5b to pipe 11 leading to the condenser or separator and to the gas holder.
Nitrogen may also be obtained by the above described process in the following
manner.
A gas holder or other receptacle is filled with air and this air is employed to
per-oxidize the contents of the vessels. The oxygen extracted is delivered to the
oxygen gas holder or is allowed to escape, but the nitrogen and excess of air
unabsorbed by the contents of the vessels and the steam due to the formation of
manganate during the periods of per-oxidation are returned to the gas holder or
receptacle whence they were withdrawn instead of being allowed to escape the
steam being removed by condensation. The per-oxidation and de-oxidation of
the contents of the vessels is continued as when making oxygen only until
practically all the oxygen contained originally in the gas holder or receptacle filled
with air has been extracted and practically pure nitrogen alone remains.
I prefer to use either manganate of potash with an addition of say one tenth
of its weight of caustic potash or manganese per-oxide and caustic soda in the
proportion of the molecular or combining weights necessary for the formation of
manganate and to add as the chemically indifferent and readily fusible material
hereinbefore mentioned a quantity of sulphate of soda equal in weight to that of
the caustic soda employed.
It is to be noted however that if sulphate of soda be used as the chemically
indifferent material and iron vessels be employed they should be coated internally
with a metal or material not injuriously acted upon by the sulphate of soda.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the obtainment of oxygen or nitrogen from atmospheric air the employment
of a charge of oxygen absorbing and oxygen yielding materials kept suspended or
in what is practically a liquid condition whilst the air and the steam are passed
therethrough substantially as herein before explained.
2. In the obtainment of oxygen or nitrogen from atmospheric air the employment
of a lower metallic oxide or lower metallic oxides in a divided or powdered
condition kept suspended in a fused base or bases whilst air is passed in contact
therewith.
3. In the obtainment of oxygen or nitrogen from atmospheric air the employment
of a lower metallic oxide or lower metallic oxides in a divided or powdered
condition kept suspended in a fused base or bases whilst air is passed therethrough
the charge being also subsequently maintained in a liquid condition whilst steam is
passed therethrough.
4. In the obtainment of oxygen or nitrogen from atmospheric air by the employ-
ment of a charge kept suspended or in what is practically a liquid condition whilst
air and steam are passed therethrough as hereinbefore explained and claimed the
addition to the said charge of a fused chemically indifferent material.
5. The arrangement and combination of parts constituting apparatus for the
obtainment of oxygen or of nitrogen from atmospheric air substantially as herein-
before described and illustrated by the accompanying drawings.
6. The combination with apparatus such as is claimed by the last preceding
R

page_text: claiming clause of automatic gear for reversing the valves substantially as herein-
before described with reference to the accompanying drawings.
Dated the 20th day of April 1893.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.