IMPROVEMENTS IN THE MEANS AND APPARATUS FOR GENERATING FLUID TO WORK ENGINES SO AS TO DEVELOPE GREAT POWER IN PROPORTION TO BULK AND WEIGHT,
Year: 1875

page_text: LETTERS PATENT to Matthew Piers Watt Boulton, of Tew Park,
in the County of Oxford, for the Invention of "IMPROVEMENTS IN
THE MEANS AND APPARATUS FOR GENERATING FLUID TO WORK ENGINES
SO AS TO DEVELOPE GREAT POWER IN PROPORTION TO BULK AND WEIGHT,
PROVISIONAL SPECIFICATION left by the said Matthew Piers Watt
Boulton at the Office of the Commissioners of Patents, with his
Petition, on the 17th February 1875.
I, MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of
Oxford, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN THE MEANS AND APPARATUS FOR GENERATING FLUID TO WORK
ENGINES SO AS TO DEVELOPE GREAT POWER IN PROPORTION TO BULK AND WEIGHT,
MORE PARTICULARLY APPLICABLE TO AERIAL LOCOMOTION," to be as follows:—
This Invention relates to engines in which heat is employed for the
production of motive power, and has for its object to make an engine
of small weight in proportion to its power, such as might be employed.

page_text: for purposes of aerial locomotion where lightness of engine is an object
of primary importance, and the cost of material employed a secondary
one. For this purpose I generate in a chamber under pressure oxygen
or some gas or vapour containing oxygen, such as nitrous oxide, or
vapour or products of nitric acid, and convey this into a combustion 5
chamber into which some combustible matter is introduced. This may
be an inflammable gas or vapour, such as vapour of petroleum, or of
some hydrocarbon generated in a chamber under pressure, or it may ·
be a solid combustible substance, such as charcoal or cotton wool.
The inflammable materials undergo combustion in the combustion 1
chamber, and the heat of this combustion serves to produce the oxygen
or gas containing it, and also to generate the inflammable gas or vapour
when this is the combustible matter employed.
The products of the combustion are cooled by being brought into
contact with water or other liquid which they turn into steam or vapour, 1
and the mixed resulting fluid having the temperature desired is employed
to work an engine.
I proceed to describe more particularly a construction of apparatus
for performing the operations generally stated above, and in this
description I shall suppose vapour of petroleum, and the products 2
evolved from nitrate of ammonia to be the matters employed for
producing combustion. The apparatus for generating the working
· fluid consists of two portions, one in which the combustion is main-
tained and the inflammable vapour and products of the nitrate are
produced, and the other in which the products of combustion impart 2
heat to water or other liquid, thereby generating steam or vapour.
Above the combustion chamber I provide an apparatus for intro-
ducing the nitrate of ammonia; this is fitted with two valves or slides
like those of a shot belt, having a space between them, the one valve
or slide being closed when the other is open, so that the charge of $
nitrate of ammonia is introduced without permitting escape of fluid
from the interior except to a small extent. Other known modes for
introducing charges into close vessels may be employed in place of that
above described. The nitrate of ammonia introduced in this manner
falls upon a plate above the combustion chamber which receives heat &
from the combustion beneath. Upon this it is decomposed, and the
resulting products containing oxygen in a form capable of supporting

page_text: combustion pass by a duct or passage into the combustion chamber
I beneath. Otherwise, the nitrate of ammonia may be injected into the
chamber in a liquid state by a pump. For this purpose it may be
melted by heat, or a strong solution of it made in hot water. The water
thus mixed with it is converted by the heat of the combustion into
steam, which, together with that otherwise produced from it, is
serviceable in working the engine.
The heating of the water used for the solution may be effected by the
heat of the combustion chamber acting on the vessel containing the
water exterior to the combustion chamber. The heat of the combustion
chamber also generates the vapour of the petroleum, for which purpose
it may be applied in various ways. For instance, the petroleum is
injected in regulated quantity against a heated plate, forming a portion
of the bottom or side of the combustion chamber. The vapour so
generated passes by a duct into the combustion chamber, where it
meets and mingles with the products from the nitrate of ammonia, and
the mixed fluid undergoes combustion. I prefer to arrange the ducts
in such a manner that the two streams, viz., that coming from the
nitrate of ammonia and that from the petroleum shall impinge against
each other, so as to effect a thorough mixture in order that the com-
bustion may be complete.
Several sets of feed apparatus may be employed for introducing both
the nitrate of ammonia and the petroleum, in order to maintain a
regular supply and a continuous combustion. From the combustion
chamber the hot products of combustion pass into the second chamber
previously mentioned in which they are brought in contact with a liquid
and generate vapour. In the present description I shall suppose the
liquid to be water. The water may be exposed to the action of the hot
gases in various manners. Thus, a jet of water may be caused to play
in the chamber producing spray therein, as in the condenser of a steam
engine. Otherwise the products of combustion may be forced through
perforated tubes or passages immersed in the water so as to rise through
the water in numerous bubbles. And any other known contrivance
for exposing a large surface of water to the action of air or aeriform
matter may be employed. By the generation of vapour in this chamber
the products of combustion are cooled to the extent desired, and the
resulting fluid having the temperature desired is conducted to an engine
and performs work therein.

page_text: If nitric acid is used as the source of the oxygen, then it is introduced
and heated by a plate, as has been previously described in the case of.
petroleum. I prefer to cause its vapour to pass over a highly heated
plate before it enters the combustion chamber. This plate is over the
combustion chamber and heated by it. Those parts of the apparatus :
which come in contact with the nitric acid or its vapour, or gaseous
products, should be of such a nature as not to be acted on by these,
thus they may be composed of porcelain or glass, or metal may be
employed coated with some metal or glaze which resists the action
of the acid. In order to prevent injury to the packing of the pump
which introduces the nitric acid I prefer to force a liquid into the
stuffing box of its plunger at a pressure somewhat exceeding that
to which the nitric acid is subjected. The liquid thus injected excludes
the nitric acid from the stuffing box, a certain portion of it passing into
the nitric acid in the pump. If the liquid thus injected is water the
steam generated from it in the combustion chamber performs sub-
sequently useful work in the engine. If it is of the nature of oil or
grease its vapour serves to maintain the combustion. Stuffing boxes
or bearings or other parts of the engine may be treated in a similar
manner. Nitrate of ammonia may be used in conjunction with nitric
acid in order to supply the oxygen needed for the combustion.
Instead of nitrate of ammonia nitrate of potash or nitrate of soda,
or chlorate of potash might be employed as sources of oxygen; but
these salts in decomposing leave a solid deposit which necessitates
the use of a scraper for its removal. It is evident moreover that
the matter of this deposit is a useless source of weight which it is
highly desirable to avoid. Hence there is much advantage in employing
material such as nitrate of ammonia or nitric acid, which when heated
is entirely converted into gaseous products serviceable in working the
engine. If solid material is employed for fuel it is important to
employ one which burns without producing any considerable amount
of ashes or impurities. Cotton wool and similar substances afford
material of this kind.
The solid fuel is introduced by means of a feed apparatus like that
previously described for the introduction of nitrate of ammonia. The
fuel employed may be gun cotton or other vegetable matter similarly
prepared, in which case less oxygen produced as above described is used,
such a quantity only being introduced as is needed to complete the

page_text: combustion. There is advantage in introducing the gun cotton in a
moist condition, and I prefer also after its introduction to cause it to
pass through a tube of considerable length, kept cool by water between
the place of its introduction and the combustion chamber. Generally
however I prefer to employ fuel of a perfectly non-explosive character
by the use of apparatus such as I have already described.
By the construction above described, in which hot gases are employed'
to act on water and generate steam in the manner explained, an engine
may be made capable of exerting great power for a certain limited time
with small weight. But the proportion of power to weight may be much
increased by employing the heat to evaporate some liquid of low boiling.
point such as a liquefied gas. By this means a very high pressure can be
obtained at a low temperature, and thus a higher pressure can be used
than with an ordinary steam engine where a limit is practically set to
increase of pressure owing to increase of heat. Also when liquefied gases
are used a store of power or energy is provided by means of mechanical
agency or pressure previously excrted, which store is drawn upon when
the engine is at work.
In the following description I shall suppose the liquid employed to bel
liquefied carbonic acid, otherwise called carbonic anhydride :-A store of
this is provided and a portion of it is continuously injected or introduced
into a chamber in which it is acted on by the hot gases as previously.
explained for the case of water, so as to be converted into vapour or
aeriform fluid. The mixture of this with the gaseous products of com-.
bustion, having the temperature desired is used to work an engine.
The parts of the engine with which the working fluid comes in contact
should be composed of or coated with a material not acted on by the
acid in it, for which purpose glass, porcelain, and certain metals may be
employed.
If the store of liquid acid or anhyride is kept in a vessel at high
pressure at the ordinary atmospheric temperature it will exert an
exceedingly high pressure, and the vessel containing it must be very
strong and must be a serious source of weight. This disadvantage is,
avoided by reducing the temperature of the store of anhydride to such a
low degree that it is not more volatile than water is at the ordinary
temperature of the atmosphere, in which case it can be kept in a light
vessel of small strength. It is necessary that the liquid having once

page_text: been cooled to this low temperature should be maintained at the same.
For this purpose the vessel in which it is kept is surrounded by some
light material which obstructs the transmission of heat. Snow surrounded
by flannel or powdered charcoal or cotton wool may be suitably employed
for the purpose.
The store of liquid being surrounded by such an
envelope only a small portion of heat can be transmitted to it from the
atmosphere or from the outside. The heat so transmitted can be
removed by allowing a portion of the liquid anhydride to evaporate,
whereby refrigerating action to the extent desired may be constantly.
maintained. But in order to lessen the evaporation needed for this
purpose I prefer in the first instance before the working of the engine
begins to refrigerate the anhydride so far that a portion of it is solidified,
so that the heat transmitted while the engine is at work may take effect
in melting the solid portion without raising the temperature of the
surrounding liquid.
.
The first cooling of the receptacle may be effected by the use of the
liquid anhydride or acid and other refrigerating agents, according to
various known methods. The receptacle having been cooled portions of
liquid acid can be introduced into it from any desired number of small
generating vessels, and a store of the desired quantity of refrigerated acid
may thus be obtained, not more volatile, nor exerting more pressure
than water at ordinary atmospheric temperatures. A portion of the
intensely cold liquid is continually drawn out from this store by a pump
and injected into the heating chamber previously described, in which it
is exposed to heat and converted into vapour as previously explained.
The pressure of the working fluid may be adjusted as desired, since
the vapour of the acid or anhydride may be superheated to any extent
desired, that is to say, its temperature may be raised from any desired
point so as to take effect in increase of its volume instead of increase of
its pressure.
A temperature of the working fluid similar to that
employed in ordinary steam engines may be suitably employed.
Liquefied nitrous oxide might be employed instead of carbonic acid, and it
would have some advantage on account of its vapour or gas not acting
on metal, but it would have the disadvantage of greater cost.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Matthew Piers Watt Boulton in the Great Seal
Patent Office on the 16th August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MATTHEW
PIERS WATT BOULTON, of Tew Park, in the County of Oxford, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of February, in
the year of our Lord One thousand eight hundred and seventy-five, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Matthew Piers Watt
Boulton, Her special license that I, the said Matthew Piers Watt
Boulton, my executors, administrators, and assigns, or such others as I,
the said Matthew Piers Watt Boulton, 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 "IMPROVEMENTS IN THE MEANS AND
APPARATUS FOR GENERATING FLUID TO WORK ENGINES SO AS TO DEVELOPE GREAT
POWER IN PROPORTION TO BULK AND WEIGHT, MORE PARTICULARLY APPLICABLE TO
AERIAL LOCOMOTION," upon the condition (amongst others) that I, the said
Matthew Piers Watt Boulton, 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 same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Matthew Piers Watt Boulton, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, reference being had to the
accompanying Sheet of Drawings, and to the figures and letters marked
thereon, that is to say :-
ง
This Invention relates to engines in which heat is employed for the
production of motive power, and has for its object to make an engine of

page_text: small weight in proportion to its power, such as might be employed for
purposes of aerial locomotion, where lightness of engine is an object of
primary importance, and the cost of material employed a secondary one.
For this purpose I generate in a chamber under pressure oxygen, or
some gas or vapour containing oxygen, such as nitrous oxide, or vapour
or products of nitric acid, and convey this into a combustion chamber
into which some combustible matter is introduced. This may be an
inflammable gas or vapour, such as vapour of petroleum or of some
hydrocarbon generated in a chamber under pressure, or it may be a solid
combustible substance, such as charcoal or cotton wool.
The inflammable materials undergo combustion in the combustion
chamber, and the heat of this combustion serves to produce the oxygen
or gas containing it, and also to generate the inflammable gas or vapour
when this is the combustible matter employed.
The products of combustion are cooled by being brought into contact 1
with water or other liquid, which they turn into steam or vapour, and
the mixed resulting fluid having the temperature desired is employed to
work an engine.
I proceed to describe more particularly a construction of apparatus
for performing the operations generally stated above, and in this 2
description I shall suppose vapour of petroleum and the products
evolved from nitrate of ammonia to be the matters employed for pro-
ducing combustion. The apparatus for generating the working fluid
consists of two portions, one in which the combustion is maintained and
the inflammable vapour and products of the nitrate are produced, and 2
the other in which the products of combustion impart heat to water or
other liquid, thereby generating steam or vapour.
Above the combustion chamber I provide an apparatus for intro-
ducing the nitrate of ammonia. This is fitted with two valves or slides
like those of a shot belt, having a space between them, the one valve or 3
slide being closed when the other is open, so that the charge of nitrate of
ammonia is introduced without permitting escape of fluid from the
interior except to a small extent. Other known modes of introducing
charges into close vessels may be employed in place of that above
described. The nitrate of ammonia introduced in this manner falls 3
upon a plate above the combustion chamber which receives heat from
the combustion beneath. Upon this it is decomposed, and the resulting

page_text: products containing oxygen in a form capable of supporting combustion
pass by a duct or passage into the combustion chamber beneath. Other-
wise the nitrate of ammonia may be injected into the chamber in a
liquid state by a pump. For this purpose it may be melted by heat or a
strong solution of it made in hot water. The water thus mixed with
it is converted by the heat of the combustion into steam, which together
with that otherwise produced from it is generally serviceable in working
the engine.
The heating of the water used for the solution may be effected by the
heat of the combustion chamber. acting on the vessel containing the
water exterior to the combustion chamber. The heat of the combustion
chamber also generates the vapour of the petroleum, for which purpose
it may be applied in various ways. For instance, the petroleum is
injected in regulated quantity against a heated plate, forming a portion
of the bottom or side of the combustion chamber. The vapour so
generated passes by a duct into the combustion chamber, where it meets
and mingles with the products from the nitrate of ammonia and the
mixed fluid undergoes combustion. I prefer to arrange the ducts in
such a manner that the two streams, viz., that coming from the nitrate
of ammonia and that from the petroleum shall impinge against each
other so as to effect a thorough mixture in order that the combustion
may be complete.
Several sets of feed apparatus may be employed for introducing
both the nitrate of ammonia and the petroleum in order to maintain a
regular supply and a continuous combustion. From the combustion
chamber the hot products of combustion pass into the second chamber
previously mentioned, in which they are brought in contact with a
liquid and generate vapour. In the present description I shall suppose
the liquid to be water. The water may be exposed to the action of the
hot gases in various manners. Thus a jet of water may be caused to
play in the chamber, producing spray therein as in the condenser of a
steam engine. Otherwise the products of combustion may be forced
through perforated tubes or passages immersed in the water so as to rise
through the water in numerous bubbles. And any other known con-
trivance for exposing a large surface of water to the action of air or
aeriform matter may be employed. By the generation of vapour in this
chamber the products of combustion are cooled to the extent desired,

page_text: and the resulting fluid having the temperature desired is conducted to
an engine and performs work therein.
If nitric acid is used as the source of the oxygen then it is introduced
and heated by a plate, as has been previously described in the case of
petroleum. I prefer to cause its vapour to pass over a highly heated
plate before it enters the combustion chamber. This plate is over the
combustion chamber and heated by it. Those parts of the apparatus
which come in contact with the nitric acid or its vapour or gaseous pro-
ducts should be of such a nature as not to be acted on by these. Thus
they may be composed of porcelain or glass, or metal may be employed
coated with some metal or glaze which resists the action of the acid. In
order to prevent injury to the packing of the pump which introduces the
nitric acid I prefer to force a liquid into the stuffing box of its plunger
at a pressure somewhat exceeding that to which the nitric acid is sub-
jected. The liquid thus injected excludes the nitric acid from the stuffing
box, a certain portion of it passing into the nitric acid in the pump. If
the liquid thus injected is water the steam generated from it in the com-
bustion chamber performs subsequently useful work in the engine; if it
is of the nature of oil or grease its vapour serves to maintain the com-
bustion. Stuffing boxes or bearings of other parts of the engine may be
treated in a similar manner. Nitrate of ammonia may be used in
conjunction with nitric acid in order to supply the oxygen needed for
the combustion.
Instead of nitrate of ammonia nitrate of potash or nitrate of soda or
chlorate of potash might be employed as sources of oxygen, but these
salts in decomposing leave a solid deposit, which necessitates the
use of a scraper for its removal. It is evident, moreover, that the
matter of this deposit is a useless source of weight, which it is highly
desirable to avoid. Hence there is much advantage in employing
material such as nitrate of ammonia or nitric acid, which when heated is
entirely converted into gaseous products generally serviceable in working
the engine. If solid material is employed for fuel it is important to
employ one which burns without producing any considerable amount of
ashes or impurities. Cotton, wool, and other fibrous material, and also
pure preparations of charcoal or carbon afford material of this kind.
The solid fuel is introduced by means of a feed apparatus like that
previously described for the introduction of nitrate of ammonia. The

page_text: fuel employed may be gun cotton or other vegetable matter similarly
prepared, in which case less oxygen produced as above described is used,
such a quantity only being introduced as is needed to complete the com-
bustion. There is advantage in introducing the gun cotton in a moist
condition, and I prefer also after its introduction to cause it to pass
through a tube of considerable length, kept cool by water, between the
place of its introduction and the combustion chamber.
Generally,
however, I prefer to employ fuel of a perfectly non-explosive character
by the use of apparatus such as I have already described.
By the construction above described, in which hot gases are employed
to act on water and generate steam in the manner explained, an engine
may be made capable of exerting great power for a certain limited time
with small weight. But the proportion of power to weight may be much
increased by employing the heat to evaporate some liquid of low boiling
point, such as liquefied gas. By this means a very high pressure can be
obtained at a low temperature, and thus a higher pressure can be used
than with an ordinary steam engine, where a limit is practically set to
increase of pressure owing to increase of heat. Also when liquefied gases
are used a store of power or energy is provided by means of mechanical
agency or pressure previously exerted, which store is drawn upon when
the engine is at work.
In the following description I shall suppose the liquid employed to be
liquefied carbonic acid, otherwise called carbonic anhydride. A store of
this is provided, and a portion of it is continuously injected or introduced
into a chamber, in which it is acted on by the hot gases, as previously
explained for the case of water, so as to be converted into vapour or
aeriform fluid. The mixture of this with the gaseous products of com-
bustion having the temperature desired is used to work an engine. The
parts of the engine with which the working fluid comes in contact should
be composed of or coated with a material not acted on by the acid
in it, for which purpose glass, porcelain, and certain metals may be
employed.
If the store of liquid acid or anhydride is kept in a vessel at high
pressure at the ordinary atmospheric temperature it will exert an exceed-
ingly high pressure, and the vessel containing it must be very strong,
and must be a serious source of weight. This disadvantage is avoided
by reducing the temperature of the store of anhydride to such a low,

page_text: degree that it is not more volatile than water is at the ordinary tempera-
ture of the atmosphere, in which case it can be kept in a light vessel of
small strength. It is necessary that the liquid, having once been cooled
For this
to this low temperature should be maintained at the same.
purpose the vessel in which it is kept is surrounded by some light
material which obstructs the transmission of heat. Snow surrounded
by flannel or powdered charcoal or cotton wool may be suitably employed
for the purpose. The anhydride itself in the form of snow may form a
portion of the envelope, this snow being subsequently melted and used
in the engine. The store of liquid being surrounded by such an envelope
only a small portion of heat can be transmitted to it from the atmosphere
or from the outside. The heat so transmitted can be removed by allowing
a portion of the liquid anhydride to evaporate, whereby a refrigerating
action to the extent desired may be constantly maintained. But in order
to lessen the evaporation needed for this purpose I prefer in the first
instance, before the working of the engine begins, to refrigerate the
anhydride so far that a portion of it is solidified, so that the heat trans-
mitted while the engine is at work may take effect in melting the solid
portion without raising the temperature of the surrounding liquid.
The first cooling of the receptacle may be effected by the use of the
liquid anhydride or acid and other refrigerating agents, according to
various known methods. The receptacle having been cooled portions of
liquid acid can be introduced into it from any desired number of small
generating vessels, and a store of the desired quantity of refrigerated
acid may thus be obtained and retained at the atmospheric pressure, or
as near it as is desired. A portion of the intensely cold liquid is con-
tinually drawn out from this store by a pump and injected into the
heating chamber previously described, in which it is exposed to heat and
converted into vapour, as previously explained.
The pressure of the working fluid may be adjusted as desired, since
the vapour of the acid or anhydride may be superheated to any extent
desired, that is to say, its temperature may be raised from any desired
point so as to take effect in increase of its volume instead of increase
of its pressure. A temperature of the working fluid similar to
that employed in ordinary steam engines may be suitably employed.
Liquefied nitrous oxide might be employed instead of carbonic acid, and
it would have some advantage on account of its vapour or gas not acting
on metal, but it would have the disadvantage of greater cost.

page_text: The accompanying Drawing represents a vertical section of one form
of apparatus according to my Invention for generating fluid under
pressure for the purpose of working a light engine.
A is a hopper containing nitrate of ammonia, this hopper having a
mouth fitted with double slides a¹, a³, in the manner of a shot belt, so
that by alternately advancing and retracting those slides charges of the
nitrate of ammonia can be fed into the generator without permitting the
escape of gaseous fluid from it. These charges drop on a heated
surface B, whereby the material is decomposed, giving off steam and
nitrous oxide gas. C is a pipe by which petroleum or other liquid
hydrocarbon is forced by a pump so that it enters the generator in a jet
directed against a heated surface D, whereby it is converted into com-
bustible vapour, such portions of the liquid as are not vaporised being
removed by a pipe c. The gaseous products of the nitrate of ammonia
and the combustible vapour pass through orifices 6 and d respectively,
so that they mingle and produce flame in the cavity E which communi-
cates freely with the space F of the generator. In this space a jet of
water G is maintained, and the flame from E playing directly on the
broken and subdivided water of this jet converts a portion of it into
steam, which along with the cooled products of combustion is collected
in the upper part of F, whence the mixed fluid is withdrawn by a pipeƒ
to work an engine. An overflow pipe f¹ is provided to conduct water
back to the pump which feeds the jet when it rises above the desired
level. When instead of using nitrate of ammonia in the solid state I
employ it in the liquid form either in solution or in a fused condition, or
when I employ other liquids which contain a large proportion of oxygen,
such as nitric acid, such liquid may be introduced in a jet upon the
surface B in a manner similar to the jet of petroleum on D.
It is to be understood that the jet G may, as above described, be a
liquefied gas, such as carbonic anhydride instead of water fed from a
store of such liquid kept at a low temperature.
Instead of employing a jet, such as G, for exposing a large surface of
the water or other liquid to be evaporated, the flame from E may be led
through a coil of perforated pipe immersed in the liquid, so that the hot
products of combustion bubble up through the liquid.

page_text: Second. The use for generating working fluid for light engines of a
generator constructed and operating substantially. as herein described in
reference to the accompanying Drawing, in one chamber of which
oxygen producing material is decomposed and combustible vapour is
generated by the heat resulting from the combustion of their mixed
products, and in another chamber of which the hot products of com-
bustion are brought in contact with water or other liquid so as to become
partially cooled and to generate steam or vapour.
Third. The use of liquefied gas, such as carbonic anhydride, for the
purpose of generating working fluid, in the manner above referred to.
Fourth. The method, substantially as herein described, of keeping a
store of such liquefied gas for use in a generator, as above described, in
a light vessel, in which its pressure is maintained by intense cold at or
near that of the atmosphere.
In witness whereof, I, the said Matthew Piers Watt Boulton,
have hereunto set my hand and seal, this Twenty-fourth day of
June, in the year of our Lord One thousand eight hundred and
seventy-five.