AN IMPROVED HEATING APPARATUS
Year: 1866

page_text: LETTERS PATENT to William Robert Lake, of the "International Patent
Office," No. 8, Southampton. Buildings, Chancery Lane, in the County
of Middlesex, Consulting Engineer, for the Invention of "AN IMPROVED
HEATING APPARATUS."-A communication from abroad by Sidney Smith,
of Greenfield Massachusetts. United States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 16th August 1866, pursuant to the 9th Section of
the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the "International Patent Office," No. 8, Southampton
Buildings, Chancery Lane, in the County of Middlesex, Consulting Engineer,
send greeting.
WHEREAS I am in possession of an Invention for "Ax IMPROVED
HEATING APPARATUS," and have petitioned Her Majesty to grant unto me,
my executors, administrators, and assigns, Her Royal Letters Patent for
the same, and have made solemn Declaration that the same has been com-
municated to me from abroad by Sidney Smith, of Greenfield, Massachusetts,
United States of America.

page_text: NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and in what
manner the same is to be performed, in and by the following statement,
reference being had to the accompanying Drawings forming part of this
Specification:-
Before giving a minute description of the construction and operation of my
apparatus I deem it proper briefly to recount the principles upon which the
results attained depend, principles which have hitherto been unrecognized and
unknown, and to point out the difference which exists between them and the
principles controlling all the methods hitherto in use.
I have discovered that in order to produce perfect combustion within the
fire chamber of a stove or furnace it is necessary to convert the fuel into a
gaseous form without admixture with nitrogen, and to produce the most
thorough mingling of these inflammable gases with the supporter of com-
bustion by introducing the latter to the former at a high degree of temperature,
and in the most minutely divided condition only.
And my Invention consists, first, in constructing the fire chamber of a stove
or furnace in such a manner that the fuel shall be almost or entirely con-
verted into gas before being brought in contact with the oxygen required to
produce combustion.
And, second, in constructing the walls of the fire chamber so that the
atmospheric air shall be introduced throughut the extent of the walls in a
great number of minute streams at a high temperature, and thus most
thoroughly mingled with the inflammable gases from the fuel.
Reference is. bere made only to that continuous process carried on in stoves
and furnaces for the purpose of converting fuel into heat...
Under this restriction what is ordinarily termed combustion consists of two
processes; first, destructive distillation, by which fuel is converted from a
solid or a liquid into a gaseous form; and, second, true combustion, which is
the chemical union of those resultant gases with oxygen. By all methods
hitherto discovered the required oxygen has been supplied by the admission of
atmospheric air, to the fuel, and to produce the best result it has been required
that the largest possible volume of air should be passed through the mass of
fuel. It has never been possible to introduce sufficient oxygen to consume
the whole quantity of gas generated by the first-named process, because
oxygen composes only one-fifth part of the volume of the atmosperic air
introduced, and 'the remaining four-fifths nitrogen passes through the mass of
fuel unchanged, displacing and carrying with it unconsumed a proportionate

page_text: volume of the inflammable gas from the fuel. The more vehement the com-
bustion the greater will be the quantity of gas generated, and the vehemence
of combustion depends upon the quantity of oxygen brought in contact with
the incandescent gas from the fuel within a given time. The quantity of
oxygen is in proportion to the volume of atmospheric air introduced, and
every atom of oxygen which unites with any substance for which it has an
affinity liberates and sets free four atoms of nitrogen, so that the more
vehement the combustion the greater will be the quantity of nitrogen set free.
and the greater will be the quantity of inflammable gas which will pas off
unconsumed.
By the principles underlying my discovery those results are radically
changed. Instead of the largest possible volume of atmospheric air admitted
to the fuel I exclude it entirely, or admit only sufficient to maintain incan-
descence. By the methods hitherto in use the gases unconsumed in the
midst of the fuel, or by the oxygen which passes through the mass of fuel,
rise diluted with free nitrogen; by my method they rise nearly or quite free
from nitrogen, and therefore in the most favorable condition to unite in
combustion with the oxygen of the atmosphere.
Nitrogen is totally deficient in power to support combustion, and as is
abundantly proved by the phenonema of combustion in pure oxygen gas and
in atmospheric air, its presence merely impedes combustion; this is not
because the oxygen is less active, but because the atoms of nitrogen will be
interposed between the atoms of oxygen and the atoms of the object of its
affinity. This result is strikingly illustrated by the effect of powdered glass
mixed with gunpowder, or wood spirit mixed with nitro-glycerine.
It follows
then, as a matter perfectly evident, that the larger the amount of nitrogen
present the greater will be the difficulty of combustion, and if the inflammable
gases distilled from the incandescent fuel in the fire chamber rise diluted with
free nitrogen those gases will unite less readily than would be the case were
the free nitrogen not present.
The vehemence of combustion depends upon the rapidity of the union of
the inflammable gases with the oxygen of the atmosphere, and the rapidity
of this union depends upon the facility with which they are brought in contact
and caused to mingle, and the equality of their temperatures. Homogeneous
union is effected with facility in proportion to the minuteness of the sub-
division of the elements to be united, and in the case of gases equality in
temperature is also important, as is evidenced by the apparent difficulty with
which currents of air unite with each other when they differ in temperature,
and in the matter of combustion the advantage of the introduction of heated

page_text: oxygen is abundantly proved, by the hot blast of Neilson. By restricting the
supply of air to the fuel to a quantity sufficient only to maintain incandescence
destructive distillation is effected without combustion, and the resultant gases
rise from the fuel by their own levity, and in a condition almost free from
nitrogen. When these gases are ignited by mixture with the oxygen of the
atmosphere immediately above the fuel the supply of air to the mass of fuel
may be entirely cut off, the heat from the burning gas then being sufficient to
maintain incandescence.
From these premises it will be apparent that if the fuel be converted into
gas, and this gas without any previous mixture with free nitrogen be brought
in contact with atmospheric air at a high temperature and in minute streams,
perfect combustion must be produced, and it is to carry out in practice these
hitherto unrecognized principles that my Invention has been made..
Having now set forth the nature of my discovery and Invention, and having
indicated the natural laws or principles upon which it depends, and pointed
out the difference existing between them and the principles hitherto re-
cognized, I will describe a stove constructed according to and embodying
these principles.
☐ DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a vertical section through the centre of a stove constructed
according to my plan; Fig. 2 is a horizontal plan of the same on
line X, X, of Fig. 1; Fig. 3 is a perspective view of a portion of a fire
chamber showing a central tube and internal construction; Fig. 4 is a
vertical section of a fire chamber constructed according to my plan applied
to a steam boiler.
The wall A of the fire chamber is constructed of any suitable material, but
from motives of economy I prefer cast iron. This wall is throughout its
extent perforated with as large a number of minute holes as the material
used will permit to be made, and may be constructed with as may parts or
sections as may be necessary or convenient. To relieve it in expanding and
contracting I think it advisable to construct it with vertical corrugations, as
shown. The fire chamber may be round, square, or in any other form
required, and should extend a considerable distance above the surface of the
fuel. For convenience in removing ashes, &c. without extinguishing the fire,
a grate B is placed at the bottom of the fire chamber; this grate has
beneath it a tight chamber C, with a movable trap or bottom D, retained in
position by the crane R, or any other suitable device. When ashes accumulate.
upon the grate they are shaken through, the grate being moved by any con-

page_text: venient means, into the chamber C, from which they may be removed when
convenient. The bottom D is designed to be kept closed, except while per-
mitting the ashes within the chamber C to escape, as it is not desired that any
draught should ever be permitted to enter through the grate B. The wall A
I find convenient to construct in the following manner:-At the back of
the pattern I make conical indentations as numerous as possible without
weakening the casting. These indentations extend nearly through to the
front surface, and mark the positions of the perforations which admit the air
to support combustion within the fire chamber. When the casting from this
pattern is completed the perforations are made by a hammer and punch, a
slight blow being sufficient to break through the film of metal which covers
the indentations; by this means the edges of the perforations are made
ragged and uneven, which has proved very beneficial, as the entering current
is broken up thereby. At a distance of two or three inches from the bottom
is the flange E, projecting one-half or three-fourths of an inch from the
highest points, of the back surface; or I sometimes prefer to make the lower
part of the wall without perforations, as shown at F, Fig. 4, so that no
draught will at any time enter the mass of the fuel, and I may thus dispense
with the valve M; in this case the fuel will be ignited from its upper surface
by the use of some light combustible material, the burning gas from which
will radiate sufficient heat to raise in a short time the temperature of the
more refractory fuel to a point of incandescence, a temperature which will
afterwards be maintained by the combustion of the gases distilled from the
fuel while at that temperature. Surrounding the wall A, and at a distance of
balf or three-fourths of an inch therefrom, I place the jacket G, which may
be made of thin metallic plates perforated with a great number of minute
holes; ordinary perforated tin having holes about one sixty-fourth of an inch
in diameter, and placed as close together as possible, answers the required
conditions of this jacket very well. Between the jacket G and the outer case
or wall H is a space of four or five inches, or more in large structures, into
which the external air is admitted through any suitable arrangement of valves
which are susceptible of adjustment and control; this I accomplish in
the stove represented in Figs, 1, 2, and 3 by perforating the bottom plate I
and covering the perforations with the flat valve. ring J, by the move-
ment of which the perforations through the plate I may be partially or
wholly closed.
If the flange E is employed, and the lower portion of the wall A is per-
forated, the space between the wall A and the jacket G will be divided by -
said.flange E into two apartments K and L, and around the lower part of

page_text: the jacket G is placed the valve ring M, by means of which the orifices
through the jacket into the apartment L may be closed; this valve ring may
be operated by the rod N, or by any other suitable and convenient means.
The upper edges of the wall A and jacket G are to be joined to the side or
case H by the plate O, or its equivalent, and there should be no openings
through the upper part of case H, excepting such as are necessary for the
purpose of admitting fuel, &c., and such openings should be constructed so as
to close very tightly, and not admit air direct from the surrounding atmo-
sphere. When I desire a fire in my stove a small quantity of fuel is placed
in the chamber and ignited in the ordinary way. If coal is the fuel used the
quantity should not exceed that required to cover the bottom of the fire
chamber to a depth of two or three inches, unless the heater be very large.
All access of draught is cut off except through the perforations of the walls.
As the volume of air permitted to pass through the fuel is very small the
combustion there is barely sufficient to raise the mass of fuel to a degree of
temperature sufficient to produce destructive distillation. The gases which
are set free by this process rise by their own levity, and mixing with the
atmospheric air which enters through the perforated walls above the fuel
become ignited and consumed. The combustion of this free gas within the
fire chamber very soon heats the wall A, so that the air passing through its
perforations is heated to a certain degree before coming in contact with the
hot gases within; but no single wall will raise the temperature of the air
passing through its perforations to a temperature sufficiently bigh to secure
the most rapid and vehement combustion. Atmospheric air does not absorb
heat readily; it is excessively elastic and mobile, and hence the simple
presence of a very hot body will not unaided quickly raise the temperature
of the surrounding air. To produce perfect combustion it is required that the
oxygen to support the combustion should be raised to a temperature as
nearly equal to the temperature of the gas to be consumed as possible, and to
so raise its temperature means must be provided by which the required caloric
may be imparted almost instantaneously, because the flow of the draught is
very rapid. Those means are provided in the use of the perforated jacket G,
which possesses two essential functions; first, it encloses a narrow space in
which there can be but little flow and counterflow of the confined air in
currents, hence the radiated caloric is not carried away to be distributed
through a large volume of air, and that which has passed through this thin
sheet is reverberated from the inner surface of the jacket; second, it is per-
forated with a very large number of minute holes, through which the air flows
in minute streams into the intensely heated space K, each atom of oxygen

page_text: being as it were separated from its fellows and submitted individually to the
heating process. That caloric will be absorbed much more rapidly by atmo-
spheric air when in this minutely divided state than it would be were large
volumes exposed does not admit of a question. When this heated air flows
through the perforations in the wall A the most vehement combustion results.
From every orifice streams of flame varying in length from one or two inches
to two or three feet curl and twist like tortured serpents. The more numerous
these minute perforations through the wall A the more intense and vehement
is the combustion, so that an experimental wall made of iron minutely per-
forated by punching, was melted and destroyed in a few minutes, and
experiment has shown that by duplicating the perforated jacket G the effect
is intensified, because submitting the air to a second straining into a heated
cbamber raises its temperature still higher, and increases the violence with
which its oxygen unites with the inflammable gases within the fire chamber.
The state of art precludes the possibility of obtaining by these means the very
highest degree of intensity in the combustion of fuel, an ultimatum which in
practice can only be obtained when in constructing the wall A some substance
can be economically used which possesses power to withstand the most intense
heat and still preserve its form when perforated as described.
From the foregoing description it will appear that the opposite walls of the
fire chamber should not be so far removed from each other as to prevent the
meeting in the centre of the jets of air entering from each side; but in large
structures, as the fire boxes of steam boilers, &c., it would be manifestly
inconvenient if not impossible to retain these narrow limits; I therefore
erect towers, like P, Figs. 3 and 4, in the midst of the fire chamber; they
may be in number as many as required, according to the size of the fire
chamber; they are constructed exactly like the walls A, and have within
them the finely perforated wall G, air being admitted through the central
space in the same manner as that already described. If. a plain movable
plate be substituted in place of the grate B, finely comminuted fuel, as saw-
dust, coal dust, and peat powder may be consumed in my stove or furnace with
nearly or quite as much facility as fuel in lamps, because it is not required to
pass any draught through the mass of the fuel, and its temperature is main-
tained at the point of incandescence by heat radiated from the gases undergoing
combustion above its surface.
The character of the combustion produced by my apparatus is very marked;
it bears every feature of combustion in pure oxygen gas, for on throwing
the flame
small bits of shavings or particles of sawdust, or iron filings into
hundreds of brilliant sparks or scintillations (which every chemist has observed

page_text: on lowering particles of carbon or iron into a jar of pure oxygen) are given
out. There are other evidences of the separation of the oxygen from the
nitrogen of the atmosphere, for immediately after passing through the per-
forations a space was observable between the inner surface of the fire-pot and
the point at which the spiral flames commenced where there was no com-
bustion. Now it is evident that this space cannot be filled with combustible
gases, inasmuch as there are jets of air constantly passing through this space,
all of which are heated above the point of ignition, causing these to ignite.
The separation of the oxygen and nitrogen of the atmosphere immediately on
entering the fire chamber has an important tendency to preserve the walls A,
which do not become so hot, and therefore do not oxidize in the vicinity of
the perforations as rapidly as would otherwise be the case.
I am aware that air has been admitted above the fuel in a variety of
methods, and both cold and hot, for the purpose of burning the inflammable
gas which would otherwise escape unconsumed, and I am also aware that air
has been admitted through perforations in the wall of the fire-pot, and through
tubes erected upon the grate; but, as I have explained, the operation of all
of these plans is radically different from mine herein set forth. I am not
aware that a double wall such as described has ever been used, or that the
effect of it has ever been otherwise attained. I am not aware that a fire-pot
with a closed bottom and the draught admitted by minute perforations
through the side walls has ever been used, or that the same effect has ever
been attained by analogous means in the combustion of fuel.
The advantage of my apparatus is the complete and perfect combustion of
the gaseous products of the fuel, giving out at least eight times the quantity of
heat attained by any other method, or amounting to a saving of at least seven-
eighths of the fuel required to produce a given quantity of heat, and without
any proportionate loss in the durability of the apparatus and the combustion
of fuel hitherto unutilized.
Having thus described the said Invention, as communicated to me by my
foreign correspondent, I claim,-
First, a fire chamber constructed in accordance with the principles and
substantially in the manner herein set forth to produce the effect described.
. Second, the combination of the perforated walls A and G, constructed and
located as described to form a fire chamber.
Third, the combination of the perforated walls A and G with the close
bottom D for the purpose set forth.
Fourth, the combination of the perforated walls A and G with the partition E
and damper M for the purpose set forth.

page_text: Fifth, the wall A constructed with the solid portion F for the purpose
described.
In witness whereof, I, the said William Robert Lake, have hereunto
set my hand and seal, this Sixteenth day of August, in the year of our
Lord One thousand eight hundred and sixty-six.
Witness,
WILLIAM ROBERT LAKE. (L.S.)
.GEORGE HASELTINE,
8, Southampton Buildings,
London, W.C.