A NEW OR IMPROVED MODE OF AND APPARATUS FOR CHARGING ATMOSPHERIC AIR WITH OXYGEN
Year: 1869

page_text: LETTERS PATENT to Jules Theodore Anatole Mallet, Engineer, of
13, Boulevart St. Martin, Paris, for the Invention of "A NEW OR
IMPROVED MODE OF AND APPARATUS FOR CHARGING ATMOSPHERIC AIR WITH
OXYGEN."
Sealed the 1st January 1870, and dated the 15th July 1869.
PROVISIONAL SPECIFICATION left by the said Jules Theodore Anatole
Mallet at the Office of the Commissioners of Patents, with his
Petition, on the 15th July 1869.
I, JULES THEODORE ANATOLE MALLET, Engineer, of 13, Boulevart
St. Martin, Paris, do hereby declare the nature of the said Invention
for "A NEW OR IMPROVED MODE OF AND APPARATUS FOR CHARGING ATMOSPHERIC.
AIR WITH OXYGEN," to be as follows:-
My invention relates to a method of charging air with oxygen to any.
desired extent, for which purpose I avail myself of the different degrees.
of solubility of oxygen and azote in water. Water absorbs forty-six
thousandths of its volume of oxygen and twenty-five thousandths only:
of azote. When these gases are mixed, as in atmospheric air, their

page_text: respective solubility should be multiplied by the proportion they occupy
in the mixture. Thus atmospheric air when dissolved in pure water
gives the following result:-
Oxygen
Azote
0.046 × 0.33 0.015, 0.48
0.025x0.67 0.017, 0.52
By dissolving it a third time the air will contain 62 per cent., and after
a. fourth time, 75 per cent. of oxygen.
In carrying out my Invention practically the air would be forced at
varying pressures, not exceeding 150 pounds per square inch, into
metallic reservoirs filled with water so arranged that the air and water
shall be in immediate contact. This may be done, for example, by
making the vessels of great depth, and injecting air therein in small jets
or currents, or by employing agitators of any kind. One portion of the
gas becomes dissolved, and the undissolved portion returns for acting
on the piston of the air pump or other piston with which it is connected
for the purpose of regaining the power absorbed by the compression.
When the water has been sufficiently saturated with the gases the latter
are caused to pass into another receiver similar to the first. Previous
to this, however, the gases pass through a pump or cylinder with piston
and slide valve, which first receives their effective pressure, and then
when there is no longer an excess of pressure forces them into the second
chamber. Between the second and third chamber is disposed a pump
similar to the foregoing, and the same is the case for the whole series,
until the last, which is also provided with a cylinder and piston for
receiving the power due to the pressure that the gases will lose before
passing to the gasometer.
By means of the above arrangements almost the whole of the power
employed for compressing the gases in the water is recovered, except
that necessarily expended in friction and vis inertia. With eight
solutions air containing 97 per cent. of oxygen and three per cent. of
azote (or nearly pure oxygen) may be obtained; but for metallurgical
purposes it is sufficient to use air with 48 per cent. of oxygen obtained

page_text: by two dissolutions; or 33 per cent. of oxygen (the result of one solution)
would in some cases be sufficient.
This Invention thus consists, 1st, in the separation of the gazeous
elements of air for the purpose of enriching it in oxygen by saturating
it under pressure in water; these saturations are repeated more or less
often according to the proportion of oxygen required.
And, 2ndly. In the arrangement of apparatus herein-before described
by means of which the motive power absorbed by the compression of the
gases is almost wholly regained.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Jules Theodore Anatole Mallet in the Great Seal
Patent Office on the 13th January 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULES
THEODORE ANATOLE MALLET, Engineer, of 13, Boulevart St. Martin,
Paris, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of July, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Jules Theodore Anatole Mallet, Her
special licence that I, the said Jules Theodore Anatole Mallet, my
executors, administrators, and assigns, or such others as I, the said
Jules Theodore Anatole Mallet, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "A NEW OR IMPROVED MODE OF
APPARATUS FOR CHARGING ATMOSPHERIC AIR WITH OXYGEN," upon the con-
dition (amongst others) that I, the said Jules Theodore Anatole Mallet,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the saine to be filed in the

page_text: Great Seal Patent Office within six calendar months next and imme.
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Jules Theodore Anatole Mallet,
do hereby declare the nature of my said Invention, and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement; reference being had to
the Sheet of Drawings hereunto annexed, and to the letters and figures
marked thereon (that is to say) :-
My Invention relates to a method of increasing the proportion of
oxygen in atmospheric air to any desired extent by physical and
mechanical means without the aid of any chemical action.
The improvements are based on the known principle of the difference
of solubility in water or other liquid of the oxygen and azote of which
air is composed.
One volume of water will dissolve twenty-five thousandths of its
volume of azote while it will dissolve forty-six thousandths of oxygen.
When the two gases are mixed, as in the air, their respective solubility
remains the same but must be multiplied by the pressure of each of
the gases in the mixture, viz., 0-79 for the azote, and 0.21 for the oxygen,
which is thus stated:-
Azote
Oxygen
-
0.025 x 0.79=0-0197
0.046x0.21
0.67
0.0097, 0.33.
Direct analysis proves that the above is the correct composition of air
dissolved in water, and air is proved for this and other reasons to be but
a simple mixture and not a compound of azote and oxygen. It is also
known that if oxygen, be allowed to remain in contact with water
containing air in solution an exchange is effected, that is to say, a
supplementary amount of oxygen becomes dissolved, while a portion of
the azote is disengaged.
The above principles have never heretofore been applied as means for
increasing the amount of oxygen in air.
The following is the mode of operation:-I take a closed vessel filled
with water, as at A in the accompanying Drawing, into which atmo-
spheric air is introduced under pressure and is there dissolved, the
conditions being such that the whole of the oxygen contained in the
air introduced is dissolved; this condition is not however indispensable,

page_text: although simplifying the explanation. On the solution being effected
and the undissolved azote discharged the pressure is removed and the
dissolved gas allowed to escape, when it will be found to be composed as
above indicated and in greater or less volume according to the pressure
employed. The gaseous mixture or slightly enriched air is then
injected into water contained in a second vessel B (or it may be into the
vessel first used if it is not desired to use separate receivers for each
compression), and the operation repeated, and so on.
The following table gives the proportions of oxygen after each
operation. It will be seen that after eight compressions the mixture
will contain 0.973 of oxygen, which is the highest limit attainable, and
practically four compressions will be sufficient, when the air obtained
will contain 0-75 of oxygen. For certain metallurgical purposes two
compressions may suffice producing air containing 0.47 of oxygen, at or
about which point it will re-ignite an incandescent body, this being
a distinctive feature of oxygen.
Atmospheric air Azote

page_text: The volumes indicated should be multiplied by the pressure at which
the solution of the gases is effected.
The following table also indicates the successive volumes obtained,
commencing at the first vessel, the water capacity of which is represented
by 1000 with an effective pressure of 5 atmospheres, it being supposed
that the whole of the oxygen is dissolved at each operation. It will be
understood that if the pressure varies from 5 atmospheres the volumes
given in the table must be increased or diminished accordingly.
I have indicated the results of six solutions, although these might be
increased to eight, but with little practical advantage.
Number of compressions
1.
2.
3.
4.
5.
6.
Capacity of reservoir or
volume of water
- 1000°
647.
440. 341.
282.
250°
Volume of gas introduced 231
147.
100°
78-2
64.7
57.
Volume of oxygen dissolved
48.5
48.5
48.5
48.5
48.5
48.5
Volume of azote dissolved
98.5
51-5
29.7
16-2
8.5
4-8
Both combined
-
147. 100°
78.2
64.7
57.
53.3
Volume of azote escaping
84.
47.
21.8
13.5
7.7
3.7
Thus it is seen that with four successive solutions I obtain with five
atmospheres 64-7, and with six solutions 53.3 of mixed gases. At ten
atmospheres these amounts would be doubled.
Before proceeding to describe the apparatus I use for enriching air
with oxygen I would first observe that from the foregoing it will be seen
that water, air, and motive power are required to obtain the desired

page_text: effect, the same water being used throughout, while the air costs nothing,
thus the supply of the motive power is the only consideration.
Supposing the air to be compressed in successive receivers filled with
water the cost of the motive power employed for this purpose would
render the air thus enriched very expensive, and in order to obviate this
I save a great portion of the power expended by utilizing the elastic.
force of the gases after compression. This I claim as an important
feature of my Invention. Further, there is no danger of the water
becoming heated by the compression of the air (which would tend to
diminish the solubility of the gases), as the expansion of the latter after
compression produces a corresponding fall in the temperature, and this
may be utilized for preventing all injurious effects.
I have in the Drawing accompanying this Specification represented an
apparatus having three recipients only, by whose aid the air will contain
on its issue therefrom 0.625 of oxygen with an effective pressure of five
atmospheres. The arrangements are the same when a larger number of
receivers is employed. The first receiver A has a capacity of about 10
cubic yards, the second seven, and the third receiver five cubic yards;
with these dimensions I obtain 78.2 of gas after each operation. It
is of advantage to make the receivers as deep as possible in order that
the solution of the gases may be more perfectly effected.
I will suppose the receiver to be about 32 feet in depth, which,
although increasing the pressure of the water, will render the action more
complete. The depth however may be such as experience will determine,.
and the action may also be assisted by mechanically acting agitators..
Further, instead of employing a single receiver of great depth there may
be several placed in juxtaposition, through which the gases would pass
successively, as in a Woolf's apparatus.
The first pump a draws in atmospheric air and forces it by means of a
pipe h (provided with a valve p to prevent the water returning to the
pump) in at the lower part of receiver A. The air is here caused to pass:
through a plate m filled with minute perforations so as to be infinitely
subdivided in its passage. Several of these perforated plates may, if
desired, be disposed at various points, so as to further subdivide the gases
in case they should become re-united in large globules. If the perfora-
tions be made 1/25th of an inch in diameter, and the whole of the globules
in the same vertical line were to unite and form a cylinder 1/25th of an

page_text: inch in diameter (and this would be the least favorable result), a column of
this diameter would require to be 1400 yards in height to make a quart,
hence a quart of gas would furnish a surface in contact with the water
of nearly 5 square yards, and on these conditions almost the whole of the
oxygen contained in the air introduced may be dissolved. Other means
may also be adopted for lengthening the contact of the gases with the
water. The undissolved portion, consisting of azote, instead of accu-
mulating at the top of receiver A, may pass off at a safety valve weighted
to the desired degree, but it is preferably caused to act on the upper side
of the piston of pump a (conveyed thereto by pipe k), which side is of
diminished area, the bottom and top sides of the piston having areas,
represented by 231 and 86 respectively. The gas is admitted to act on
the top side of the piston by means of a valve, and is then discharged
into the atmosphere, or it may pass to a receiver or gasometer for the
purpose of storing the azote, the process being equally applicable for
producing azote as well as for oxygenating and deoxygenating air. A
valve and excentric on the same rod serve to regulate the admission and
discharge of air below the piston. The pump is operated by a crank and
connecting rod from a shaft connected with any suitable motor. I would
here remark that I may also work below the atmospheric pressure, that
is to say, I may produce a partial vacuum in the receivers in order to
obtain nearly the whole of the gases dissolved in water.
From the above description it will thus be seen that I am enabled to
utilize the power expended in forcing the undissolved gases into the
water, and thus the only power actually expended is that required for
the volume dissolved. The pressure starting at 0 and rising to 5
atmospheres, power is required to effect the compression of 147 of
gas at a mean pressure of 2 atmospheres, to which must be added
the resistance due to the depth of the water. Each of the receivers is
provided with a valve p for preventing the return of the water to the
pumps. The receivers are made of sheet iron glazed or pitched on the
inside to prevent the oxygen in a humid state acting on the metal. The
receiver A thus contains a gazeous mixture represented by 147. about 33
per cent. of which consists of oxygen. Supposing the pressure to cease
in receiver A the dissolved gas will disengage, and there will only remain
that which is in solution at the ordinary pressure, that is to say,
originally contained; but even this may be extracted by producing a

page_text: partial vacuum in the manner before mentioned. The gases disengaged
may either be conveyed to a gazometer or introduced direct into
receiver B until there is an equilibrium of pressure in the two reservoirs,
but it is preferable to employ a second pump b, similar to the first
mentioned, and receiving the gases from A by a pipe and valve and
discharging them into receiver B, the azote undissolved passing to the
top side of the piston, where its pressure is utilized before being dis-
charged into the atmosphere. The solution of the gases in receiver B is
effected in the same manner as in A. It will be seen that not only is
the force expended limited to that necessary for compressing the gases
actually dissolved, but that this power is afterwards recovered, so that
theoretically none of the power is expended. The solution in receiver C
is also effected the same as before, and I would here observe that instead
of conveying the gases direct to a gazometer I may pass them into a
cylinder d, by the aid of which the power due to their expansion is
transmitted to the pump shaft in aid of the driving power; the gases
pass from this cylinder into a gazometer, or into reservoirs for com-
pressed gas. As the water is increased in volume by the solution of
the gases it is necessary to supply a small expansion chamber (not
shown) to each receiver, consisting of a small reservoir containing air,
which is compressed according to the pressure of the liquid; it may, for
example, be a small cylinder containing a piston, either weighted or
provided with springs like the accumulator of an hydraulic press.
Further, as the gases in their exit will necessarily carry some water with
them, a separating vessel is provided in each of the exit pipes of the
receivers to prevent the water passing into the pumps. I have not
indicated any provision to prevent heat due to the compression, which,
as already shown, does not take place in the pumps, because if there is
compression on the one side there is expansion at the other. The
heating of the receiver is also similarly provided for by allowing of
expansion after compression, as before mentioned, and employing a large
proportion of water relatively with that of the gases, that is to say, by
employing moderate pressure the raising of the temperature to any
appreciable degree during compression may be prevented. As regards
the pressure employed, I would remark that experience will show to
what degree I may proceed with convenience; as, however, there may be
some practical difficulty in highly compressing the gases, a pressure of
from 5 to six atmospheres will be found most suitable. The water

page_text: capacity of the reservoirs should successively diminish, for if the gas
issuing from one receiver were to be again dissolved in the same quantity
of water the composition of the mixture would be the same only as
before.
I have stated that theoretically there will be no loss of power in
consequence of the mode of utilizing the same, but practically there
must be some loss of power from friction in the tubes and passages.
From experiments I have made I find that with four compressions one
cubic yard at least is obtainable per hour for every horse power applied
on the pump shaft, that is to say, one cubic yard of water containing
75 per cent. of oxygen. To obtain a more highly enriched air more
power would be required.
The apparatus I have described and of the dimensions indicated will
complete an operation, that is to say, one compression and discharge
every five minutes, or 12 an hour, or 647 x 12 = 7764. Each horse power
consumes 4 pounds of coal at 25/ per ton, costing 6/10ths of a penny
per hour, and this with 2/10th of a penny for cost of lubrication makes
a total of 8/10th of a penny as the expense of the motive power per cubic
yard. To this must be added the expense of n attendant for the engine
providing the motive power (the apparatus themselves working auto-
matically), except in cases where the power derived is from motors used
for other purposes (as in factories, for instance) reckoning the wages at
4/ per day, it would be about 6/10th of a penny per cubic yard at 84
cubic yards per day.
The cost of keeping the apparatus in working order is but trifling,
as they are not subjected to high temperatures or any chemical action.
Allowing then one half-penny for this item per cubic yard it will be
seen that under the most unfavourable conditions I still obtain air
containing 75 per cent. of oxygen at a cost not exceeding twopence,
and supposing the motive power to be obtained without cost (whether
hydraulic power or that derived from the waste heat from metallurgical
operations) the expense would be limited to that necessary for keeping
the apparatus in order, and the cost per cubic yard reduced to one half-
penny or less for two solutions only, which is sufficient in most cases
where used for metallurgical purposes.
Instead of having four pumps for the four receivers two only may be
employed, as the receivers act in pairs. In this case the pumps would

page_text: starting of the pumps is effected automatically, and in any suitable
manner.
I may also modify the various parts of the apparatus, for example, I
may only use one receiver for compressing or dissolving, the action being
intermittent; and further I may employ receivers of different forms and
materials, and use mechanically acting stirrers for mixing the gases
and water, which would enable me to reduce the depth of the receivers.
The air enriched, as herein-before mentioned, may serve for lighting,
heating in metallurgical operations, chemical actions, and for hygienic
and other purposes, while the air, deprived of oxygen, may be used more
particularly for the preservation of alimentary substances.
In the foregoing description I have given the figures generally
adopted as indicating the respective solubility of oxygen and azote.
According to Bunsen's more recent researches oxygen is represented by
0.0325 and azote by 0.0161, instead of. 0.046 and 0.025 respectively.
The volumes obtained would thus be rather less than those before given,
but the enriching of the air would be more rapidly effected, which serves
as a compensation.
I would also mention that I may, in certain cases where a diminution
of volume and weight in the apparatus would be of more importance
than the cheapness of the operation, employ alcohol as the liquid for
dissolving the gases. The co-efficients of solubility, according to Bunsen,
is 0.284 for oxygen, and 0.125 for azote; the enriching of the air may
be rapidly effected in but a few operations and with a small volume of
liquid. One disadvantage might result from the liability of the gases
to carry with them a certain quantity of alcoholic vapors, a portion of
which at least would escape and so increase the cost of operating.
The alcohol may be readily recovered by causing the gas to pass
through substances capable of absorbing the same, such as chloride
of calcium for example.
The apparatus would be arranged as before indicated when water is
used, except that the gases before escaping are caused to pass through
condensing and washing apparatus kept at the lowest possible tempera-
ture, so as to retain the greater part of the alcohol; precautions are
also taken to prevent the heating of the apparatus and liquid.
The following table gives the composition of the gases after the
several solutions in alcohol. Theoretically speaking the change of

page_text: liquid will only affect the size of the apparatus, and not the power
employed, which is regained and utilized.
Atmospheric air Azote
0.79
J. T. A. MALLET. (L.S.)