IMPROVEMENTS IN THE CONSTRUCTION, ADAPTATION, AND METHOD OF PRESERVATION OF STEAM SUPER- HEATING APPARATUS
Year: 1879

page_text: LETTERS PATENT to Gerald Clarence Hopper, Clerk to Brandon and Morgan-:
Brown, of 38, Southampton Buildings, London, and 1, Rue Laffitte, Paris,
Engineers, and Patent Agents, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION, ADAPTATION, AND METHOD OF PRESERVATION OF STEAM SUPER-
HEATING APPARATUS." A communication from abroad by Louis Marie
Theophile Riot, and Baron Raymond Sellière, both of Paris, France.
PROVISIONAL SPECIFICATION left by the said Gerald Clarence Hopper at
the Office of the Commissioners of Patents on the 20th September 1879.
GERALD CLARENCE HOPPER, Clerk to Brandon and Morgan-Brown, of 38, South-
ampton Buildings, London, and 1, Rue Laffitte, Paris, Engineers, and Patent
Agents. "IMPROVEMENTS IN THE CONSTRUCTION, ADAPTATION, AND METHOD OF
PRESERVATION OF STEAM SUPERHEATING APPARATUS." [A communication from
abroad by Louis Marie Theophile Riot, and Baron Raymond Sellière, both of Paris,
France.]
The object of this Invention is to produce a superheating apparatus, which
combines great efficiency with absolute safety, durability, and easy manipulation.
For this purpose one or more superheating coils are employed, which are arranged
in the hottest part of the furnace as far as is practicable without their coming in
contact with the oxidizing part of the flame, and without obstructing the
circulation of the gases of combustion.
These coils may be made of any metal which is a good conductor of heat and
capable of resisting the temperature to which it is exposed in the furnace; peculiar
means of arranging and supporting the coil in the furnace are employed, varying
more or less with the different classes of boilers to which the superheating apparatus
is adapted.
For locomotive and portable engines the coil is arranged in the top of the fire-
box, and its ends are bent so that they both project to a certain distance beyond
one of its sides. The area circumscribing the coil out to the ends is not larger
than the horizontal area of the firebox, so that the coil can be lifted bodily upwards
into the latter. When arrived at the proper height it is moved sideways, so that
its ends extend through tubes set for the purpose in the firebox and its jacket.
:

page_text: These ends are connected with the bent extremities of two pipes, which latter are
passed clear through the firebox and jacket from one side to the opposite side
immediately below the coil, so that after the connection is effected the coil is
supported by these pipes. The free ends of the supporting pipes are connected one
with the pipe taking the saturated steam from the dome of the boiler, and the
other with the pipe leading the superheated steam away from the coil.
On stationary boilers where the space between the grate and the boiler is
generally so narrow that the coil would be exposed to the direct flames, a small
arch is constructed over the grate with a central hole for the passage of the gases
of combustion, and the coil is placed upon this arch which thus serves not only as
a support, but also as a shield to protect the coil from the oxidizing flame. The
ends of the coil as above stated are connected by suitable pipes one with the dome
of the boiler, and the other with the steam chest of the cylinder.
Another arrangement for stationary boilers more specially designed for cases
where the superheating apparatus has to be adapted to boilers in actual use, which
it is desired to leave as much as possible in their original state, consists in placing
the coil behind the fire bridge and supporting it on small blocks of refractory
material, so that it is fully exposed to the heat of the gases of combustion passing
under the boiler, whilst the direct flames do not arrive at that point. This forms
also a very favorable arrangement for marine boilers where the large flue formed in
the boiler constitutes a combustion chamber in exactly the same manner as the
masonry of a stationary boiler.
In order to protect the coil during the time of getting up steam, and during the
stoppages of the engine water from the boiler is circulated therein, preferably, in a
direction opposite to the way of the steam. To ensure this circulation a check
valve is arranged which allows the water to pass without obstruction from the
boiler into the coil, but which prevents it from flowing back in the opposite
direction. This arrangement is necessary because if the comparatively cold water
is admitted into the highly heated coil this gives rise to a sudden formation of a
large amount of steam, whereby a back pressure is created sufficient to force all
the water, and even some of the steam back into the boiler.
To prevent the water from entering the coil while the engine is working, an
arrangement is used which may consist either of a slide forming a separate valve
or of a screw stem carrying a handwheel, and which latter when screwed inward
presses against and locks the check valve firmly down on its seat.
This latter arrangement is more adapted for cases where the check valve can be
placed in such a position as to be within easy reach of the engineer; whilst the
first arrangement is preferable in cases where this part of the mechanism cannot be
made easily accessible, for instance in locomotives, in which case the slide may be
attached to a connecting rod of any length required. This slide valve is preferably
so arranged that when open to let the water pass from the boiler into the coil it
closes a port with which the pipe for leading the superheated steam away from the coil
toward the cylinder communicates, so that the water cannot enter and fill that
pipe. This however is not essential, and in all cases there is a purging cock
arranged between the coil and the check valve, which permits of rapidly emptying
the coil and the pipe leading off the superheated steam (if the water has entered
therein) as soon as it is desired to start the engine, whereupon suitably arranged
cocks, valves, or slides being opened saturated steam from the dome of the boiler is
admitted into the coil at the end opposite to that from which the water has
entered.
When the feed water contains lime or other similar matters there exists danger,
that such matters may precipitate on the check valve or on its seat, so that a tight
contact between these parts would be prevented. If a small quantity of water
thus leaking through the valve when closed would come in contact with the super-
heated steam it would of course evaporate rapidly, and thus resaturate the steam.
The screw stem above described for locking the check valve in this case would not
be sufficiently effective, and the slide valve mentioned would wear too quickly when

page_text: hard granules contained in the water would be introduced between its face and its
seat. For these reasons a special construction is preferable (when impure feed
water has to be used), which consists in arranging an ordinary cock in the pipe
admitting the water from the boiler into the coil between the check valve and
the coil.
In some cases it, is found advantageous to use superheated steam mixed with
saturated steam instead of superheated steam alone, and cases may even occur
where at a given moment it becomes desirable to use saturated steam alone.
For this purpose a double slide valve is combined with the apparatus, so as to
give the engineer exact control of the kind of steam which he intends to use at any
given moment. This slide valve is formed with three ports, two of which
terminate in a single passage leading the steam towards the cylinders, whilst the
third admits the superheated steam_coming from the coil into a cavity formed in
the underface of the slide valve. The saturated' steam is constantly admitted in
the box in which the double slide valve moves. This latter is capable of assuming
four different positions, viz., for closing the steam off entirely from the cylinders,
for admitting only, superheated steam, for admitting only saturated steam, and for
admitting both superheated and saturated steam into the cylinders.
'
The destructive chemical influences to which metals are subjected when exposed
to a high temperature are avoided by coating those parts of the apparatus, which
are exposed to the contact of the gases of combustion with a layer of metallic non
volatile peroxide, which has in a high degree the power of conducting the heat
whilst it shields the metal against the direct contact of the gases of combustion.
For example a composition of about two parts by weight of metallic peroxide, and
one part by weight of clay mixed together and transformed into a thick paste by the
addition of water when applied to the coil or the other parts of the apparatus
exposed to the fire either before or after they are arranged in their proper position
gives excellent results:

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gerald Clarence Hopper in the Great Seal Patent Office on the 16th
February 1880.
"
GERALD CLARENCE HOPPER, Clerk to Brandon and Morgan-Brown, of 38, South-
ampton Buildings, London, and 1, Rue Laffitte, Paris, Engineers and Patent
Agents: IMPROVEMENTS IN THE CONSTRUCTION, ADAPTATION, AND METHOD OF
PRESERVATION OF STEAM SUPERHEATING APPARATUS." (A communication from
abroad by Louis Marie Theophile Riot, and Baron Raymond Sellière, both of Paris,
France.)
The improvements, the subject of this Patent, are based in part upon those
described in the Specifications of former Letters Patent granted respectively to
. A. M. Clark, dated November 15th 1877, No. 4283, and to W. Morgan-Brown,
dated February 25th 1879, No. 763.
The object of this Invention is to produce a superheating apparatus which
combines great efficiency with absolute safety, durability, and easy manipulation.
For this purpose one or more superheating coils are employed, which are arranged
in the hottest part of the furnace as far as is practicable without their coming.
in contact with the oxidizing part of the flame, and without obstructing the circula-
tion of the gases of combustion.
These coils may be made of any metal which is a good conductor of heat, and
. capable of resisting the temperature to which it is exposed in the furnace. Iron and
steel are good materials for the purpose. The coil should be formed of lap welded
tube of 1 to inches bore, and should consist of one single length of tube made
in one single piece so as to avoid joints. Peculiar means of arranging and supporting
the coil in the furnace are employed, varying more or less with the different classes
of boilers to which the superheating apparatus is adapted.
For locomotive and portable engines the coil is arranged on the top of the fire
box, and its ends are bent so that they both project to a certain distance beyond
one of its sides. The area circumscribing the coil out to the end is not larger than
the horizontal area of the fire box, so that the coil can be lifted bodily upwards
into the latter. When arrived at the proper height it is moved sideways, so that
its ends extend through tubes set for the purpose in the fire box and its jacket.
These ends are connected with the bent extremities of the two pipes, which latter
are passed clear through the fire box and jacket from one side to the oppposite side
immediately below the coil, so that after the connection is effected the coil is sup-
ported by these pipes. The free ends of the supporting pipes are connected, one
with the pipe which takes the saturated steam from the dome of the boiler, and the
other with the pipe which leads the superheated steam away from the coil.
In stationary boilers, where the space between the grate and the boiler is generally
so narrow that the coil would be exposed to the direct flames, a small arch is con-
structed over the grate with a central hole for the passage of the gases of combustion,
and the coil is placed upon this arch, which thus serves not only as a support but
also as a shield to protect the coil from the oxidizing flame. The ends of the coil,
as above stated, are connected by suitable pipes, one with the dome of the boiler,
and the other with the steam chest of the cylinder.
Another arrangement for stationary boilers, specially designed for cases where
the superheating apparatus has to be adapted to boilers in actual use which it is
desired to leave as much as possible in their original state, consists in placing the
coil behind the fire bridge, and supporting it on small blocks of refractory material,
so that it is fully exposed to the heat of the gases of combustion passing under the
boiler, whilst the direct flames do not reach that point.
This forms also a very favorable arrangement for marine boilers where the large
flue formed in the boiler constitutes a combustion chamber in exactly the same
manner as the masonry of a stationary boiler.

page_text: In order to protect the coil during the time of getting up the steam and during
the stoppages of the engine water from the boiler is circulated therein, preferably
in a direction opposite to the way of the steam. To ensure this circulation a check
valve is arranged, as hereinafter described, which allows the water to pass without
obstruction from the boiler into the coil, but which prevents it flowing back in the
opposite direction. This arrangement is necessary, because if the comparatively
cold water is admitted into the highly heated coil a large amount of steam is sud-
denly formed, whereby a back pressure is created sufficient to force all the water
and even some of the steam back into the boiler.
To prevent the water entering the coil while the engine is working an arrange-'
ment is used which may consist either of a slide forming a separate valve, or of a
screw stem carrying a hand wheel, and which latter when screwed inward presses
against and locks the check valve firmly down on its seat. This latter arrange-
ment is more adapted for cases where the check valve can be placed in such position
as to be within easy reach of the engineer, whilst the first arrangement is preferable
in cases where this part of the mechanism can not be made easily accessible, for
instance in locomotives, in which case the slide may be attached to a connecting
rod of any length required. This slide valve is preferably so arranged that when
open to let the water pass from the boiler into the coil it closes a port with which
the pipe for leading the superheated steam away from the coil towards the cylinder
communicates, so that the water cannot enter and fill that pipe. This however is
not essential, and in all cases there is a purging cock arranged between the coil and
the check valve, which permits of the coil and the pipe which leads off the super-
heated steam (if the water has entered therein) being rapidly emptied as soon as it
is desired to start the engine, whereupon suitably arranged cocks, valves, or slides
being opened saturated steam from the dome of the boiler is admitted into the coil
at the end opposite to that from which the water has entered.
When the feed water contains lime or other similar matters there is danger that
such matters may precipitate on the check valve or on its seat, so that a close
contact between the parts would be prevented. If a small quantity of water thus
leaking through the valve when closed should come in contact with the superheated
steam it would of course evaporate rapidly, and thus resaturate the steam. The
screw stem above described for locking the check valve in this case would not be
sufficiently effective, and the slide valve above mentioned would wear too quickly
when hard granules contained in the water were introduced between its face and
its seat. For these reasons a special construction is preferable (when impure feed
water has to be used), which consists in arranging an ordinary cock in the pipe
which admits the water from the boiler into the coil, between the check valve and
the coil.
In some cases it is found advantageous to use superheated steam mixed with
saturated steam, instead of superheated steam alone, and cases may even occur
where at a given moment it becomes desirable to use saturated steam alone. For
this purpose a double slide valve is combined with the apparatus, so as to give the
engineer exact control of the kind of steam which he wishes to use at any given
moment. This slide valve is formed of three ports, two of which terminate in a
single passage leading the steam towards the cylinders, whilst the third admits the
superheated steam coming from the coil into the cavity formed in the under face of
the slide valve. The saturated steam is constantly admitted into the box in which
the double slide valve moves. The latter is capable of assuming four different
positions, viz., for closing the steam off entirely from the cylinders, for admitting
only superheated steam; for admitting only saturated steam, and for admitting both
superheated and saturated steam into the cylinders.
The improved apparatus can be applied to various classes of boilers now in
general use. The accompanying Drawings illustrate the construction of the
apparatus and shew, as example, its adaptation to locomotives, Figures 1 2, 3, 4, 5,
to two different types of stationary boilers, Figures 6, 7, and 8, 9, and to three
types of marine boilers, Figures 10, 11, Figure 12 and Figure 13. The principles
▸

page_text: being always the same the description of these Figures will suffice to
clearly indicate the manner in which the apparatus may be adapted to other kinds
of boilers known.
Similar letters of reference indicate corresponding parts in all the Figures.
ADAPTATION TO LOCOMOTIVES.-FIGURES 1, 2, 3, 4, 5.
Figure 1 is a plan of a locomotive boiler with the fire box in section; Figure 2
is a longitudinal section on the line A, A, Figure 1, of the same; Figure 3 is a
cross section through the fire box on the line B, B, Figure 1; Figure 4 is a similar
cross section on the line C, C; Figure 5 is a detail in section.
In this case the superheating coil 1 is arranged at the top of the fire box. It is
flat and bent in the shape of a rectangular parallelogram with rounded corners, the
longer side of this parallelogram being nearly as long as the fire box. Both ends
2, 2, of this coil are bent slightly downward and then extend horizontally again
a short distance beyond one of the long sides of the parallelogram, so that the
width of the fire box is still a little larger than the width of the coil from the
opposite side out to the ends. It follows from these dimensions that the entire coil
can be lifted bodily upward into the fire box, and when it has reached the proper
height it is moved sideways so that its ends extend out through tubes 3, set for
this purpose in the jacket of the fire box as represented. It is not, however
absolutely necessary that the width of the coil measured from the ends (2, 2,) to the
opposite side be smaller than the width of the fire box. It will readily be
understood that if the width of the coil measured as explained be a little more than
that of the fire box the coil can easily be introduced into position by slightly
inclining it and then lifting it until the ends 2, 2, come opposite the tubes
3, 3, and by then introducing these ends into the tubes and moving the coil slightly
upwards at the opposite side and at the same time sideways until the ends 2, 2,
project a little beyond the exterior of the jacket. On the same level with these
tubes at a suitable distance therefrom two similar tubes are set in the jacket, and
directly opposite thereto in the other side of the fire box two further tubes 3, 3,
are similarly arranged. Through these latter tubes 3, 3, are passed two pipes 4, 5,
which are bent at one of their extremities and connected to the ends 2 of the coil
extending out through the tubes 3. The other ends of the pipes 4, 5, are connected
one, 4, to the pipe 6, leading into the dome of the boiler from whence the steam to
be superheated is taken, and the other, 5, to a valve casing 7 of cast iron or other
suitable metal. A pipe 8 leads the superheated steam which it receives from the
pipe 5 towards the cylinder. The valve casing 7 is formed with two ports, which
are both covered and opened by one slide 9 operated by a suitable connecting rod,
not shewn, attached to its stem 10, and leading to the platform of the locomotive
within reach of the engineer. One of these ports establishes communication
between the pipes 5 and 8, whilst the other when opened admits water from a
separate compartment of the casing 7 into the coil 1. The water enters this com-
partment, arriving by the pipe 11 from the boiler in consequence of its gravity,
the water level in the boiler being under all ordinary conditions higher than the
casing 7. Before arriving however at the slide valve port this water has to open
and flow past a check valve 12, arranged as shewn, so that it can always pass into
the coil, providing the valve 9 is open, but so that it can never flow backwards if a
pressure be created in the coil stronger than that in the boiler. A purging cock 13
fitted to the casing serves to allow the escape of the water contained in the coil 1
and in the pipe 8 (if any has been admitted there) before steam is admitted into
the former to be superheated.
The pipe 8 for superheated steam, and another pipe 14 receiving saturated steam
from the boiler, are both connected to a valve casing 15, in which operates a double
slide valve controlled by the engineer by means of a connecting rod. The valve 16
is hollow and of such shape that the superheated steam never enters the space in
which this valve moves, whilst the saturated steam is constantly admitted there

page_text: and serves to keep the double valve on its seat. In this seat are formed in all
three ports, one, 17, for the admission of the superheated steam, and the two others,
18 and 19, which communicate with one single passage 20 leading to the cylinders,
for the delivery of either saturated steam alone, or superheated steam alone, or
both mixed. In the position represented the steam is entirely shut off from the
cylinders; when the double valve is moved to the right saturated steam alone will
be admitted through 18 and 19, when moved a certain distance to the left super-
heated steam alone will be admitted from 17 to 18, and when moved further to the
left both saturated and superheated steam will be admitted, the former through 19
and the latter through 18.
The operation of this apparatus is simple. For working the slide valve 9 must
be in position to cover the water passage in the valve casing 7. The steam passes
from the dome of the boiler through the pipes 6, 4, 2, into the coil 1, becomes super-
heated therein, and passes through the pipe 5, past the valve 9, through the pipe 8,
ports 17, 18, into the passage 20, whence it goes into the cylinders. During the
time that steam is being got up, and during stoppages the double valve 16 is of course
closed and valve 9 is in position to close the passage into the pipe 8, whilst it lets the
water freely enter through the pipe 11, past the check valve 12 into the pipe 5
and the coil 1, where it forms steam which escapes into the dome of the boiler.
A distress cock 21 may be arranged in the pipe 6 so as to intercept communica-
tion between the boiler and the superheating apparatus in case any part of the
latter should be out of order.
It will be observed that this disposition of the parts, either in the manner here
shewn and described or with slight modifications, forms also a very favorable
arrangement for portable engines, particularly the manner of introducing and sup-
porting the coil 1 in the top of the fire box, offers precisely the same advantages as
for locomotives, and is considered a simple, cheap, and efficient method of con-' 1
struction for both classes of boilers; it is therefore not considered necessary to
separately represent in the Drawings the adaptation to portable engines.
ADAPTATION TO STATIONARY BOILERS.-FIGURES 6, 7, AND 8, 9.
These Figures shew the apparatus adapted to two classes of stationary boilers,
Figures 6, 7, shewing a steam generator consisting of two water boilers 22 with
the boiler itself arranged directly above, the fire being under the boilers 22, whilst
Figures 8 and 9 represent a generator in which the two water boilers. 22 are
arranged one above the other, alongside the fire, and the boiler itself directly over
the fire. Figures 6 and 8 are horizontal sections, and Figures 7 and 9 sectional
elevations.
In the case of the generator, Figures 6 and 7, the coil 1 is arranged directly over
the fire, and is there supported by a light arch 23, formed with a central hole 24,
through which the gases of combustion pass. This arch 23 not only serves as a
support but also acts as a shield against the direct radiant heat, an arrangement
which, in this case, is considered advantageous, because the space between the
grate and boilers being too low to allow an arrangement similar to that of
the locomotive, the coil would come too close to the burning fuel. Here also the
saturated steam is taken by a pipe 6 from the dome of the boiler itself, passes
through the coil 1, and thence into the pipe 8, which may lead directly to the steam
chest of the cylinder or to a double slide valve similar to that hereinbefore
described to render the use of mixed steam or of saturated steam alone also
possible.
For the introduction of water into the coil while steam is being got up, or during
stoppages, a pipe 11 leads from, one of the water boilers 22 to that end of the coil 1,
from which the superheated steam is taken, and a check valve 12, similar to that
herein before described, is introduced here to prevent the water from being forced
back wards by a sudden generation of a large quantity of steam in the coil 1. As
means for positively closing the passages of the water during the working a screw

page_text: stem 25 is used here (this arrangement is. represented in section in Figure 11),
which, when screwed inward, presses the check valve 12 tightly on its seat; this
arrangement being rendered convenient by the position within easy reach of the
engineer of this part of the mechanism. The purging cock 13 serves as above for
discharging the water from the coil 1 and pipe 8 when it is desired to start the
engine. The other parts of the apparatus are the same as those described with
reference to the superheater for locomotives, and their operation and manipulation
exactly correspond."
When only calcareous or otherwise impure water can be obtained for feeding
the boiler it is advisable to omit the screw stem in the check valve case and to
effect the positive closing of the water communication in the manner already herein-
before described, that is to say, by an ordinary cock inserted in the pipe 11,
between the check valve case and the pipe 8. This modification is so simple that
it has not been considered necessary to shew it particularly in the Drawings.
The arrangement shewn in Figures 8 and 9 differs from the former only in that
the coil 1 is not placed directly over the grate but behind the fire bridge, an
arrangement which is very convenient in cases where the space between the grate
and the boiler is very low, so that the small arch 23 could not be constructed
without being an impediment to the flames attaining their highest efficiency; also
in cases where superheating apparatus is to be adapted to boilers in actual use,
which it is desired to leave as much as possible in their original state. The coil 1
is here shewn as forming an ellipse supported on blocks 26 formed of refractory
clay at such height as to be fully exposed to the gases of combustion passing under
the boiler. The arrangement of connecting pipes and cocks and of the water
circulating mechanism and its operation are exactly the same as described with
reference to Figures 6 and 7.
ADAPTATION TO MARINE BOILERS.-FIGURES 10, 11, FIGURE 12, AND FIGURE 13..
The arrangement shewn in Figures 10 and 11 differs from the one just described
only in the fact that the coil 1 is situated inside the boiler, the large flue passing
through the boiler forming a combustion chamber exactly in the same manner as
the masonry in Figures 8 and 9.
The principal parts of the apparatus are shewn as applied to the boiler in such
positions as will best explain the system; in practice the valve and other essential
parts will generally be situated at the front of the boiler.
In the arrangement shewn in Figure 12 the coil 1 is placed at the top of the
combustion chamber, and is supported by pipes 4, 5, in the same manner as the coil
in the locomotive represented in Figures 1, 2, 3, and 4.
In the arrangement shewn in Figure 13 the coil 1 is placed vertically at the
back of the combustion chamber, and is of elliptical form.
In both the arrangements, Figures 12 and 13, the slide valve, the connecting
pipes and cocks, and the water circulating mechanism are the same as in the
arrangements previously described.
As regards the proportions of the coil or coils employed it may be stated that
for each horse power a length of superheating tube of 8 inches to a foot is necessary,
according to whether the machine to which it is adapted is a condensing engine or
not, it being always understood that cut off engines are used, as it is the cut off
that prevents the grinding of the sliding parts of the cylinders, which would other-
wise be unavoidable considering the high temperature of the steam used. All the
packings should be asbestos compositions which are capable of resisting the heat.
Except this trifling change any engine can be worked with superheated steam
produced in this apparatus without modifying any of its parts.
When it is necessary to employ more than one coil to produce the amount of
superheated steam required it is important in order to ensure a proper circulation
of steam through each coil that each coil should have its own separate connections
with the.steam and water spaces of the boiler so that each may be supplied inde- i

page_text: pendently therefrom; the several coils may either be connected with a single pipe
for conveying the superheated steam to the steam chest, or, if preferred, there may
be a separate pipe from each coil to the steam chest.
I
Many modifications can be made. in the details without departing from the
principles of the Invention. Some of the parts may be used without the others,
although it is preferable to use the apparatus in substantially the combinations
herein described. The slide valve 9 shewn in connection with the check valve 12.
in the apparatus for locomotives may be used in stationary boilers instead of the
screw stem 25 for locking the check valve 12, or instead of an ordinary cock intro-
duced in the position described, and vice versa. The double slide valve 16 for the
distribution of saturated and superheated steam may in some cases be omitted, or
it may be replaced by another arrangement, but the combination of this valve with.
the apparatus in the form represented is believed to be particularly advantageous."
It is almost unnecessary to mention that the shape in which the coils are formed or
wound is immaterial and depends merely on convenience and the requirements of each
special case, they should be horizontal except in cases where they will be better
heated if arranged vertically.
The destructive chemical influences to which metals are subjected when exposed
to a high temperature are avoided, according to another part of this Invention, by
coating those parts of the apparatus which are exposed to the contact of the gases
of combustion with a layer of metallic non-volatile peroxide which has in a high
degree the power of conducting the heat, whilst it shields the metal against the
direct contact of the gases of combustion. Peroxide of iron is the peroxide which
it is preferred to employ, and it is conveniently applied by forming a composition
consisting of about two parts by weight of the peroxide, and one part by weight of
clay mixed together and transformed into thick paste by the addition of water.
This composition when applied to the coil or other parts of the apparatus exposed
to the fire either before or after they are arranged in their proper position gives
excellent results. The best results are obtained with clay containing alumina and
a small quantity of silica..
And having now described the nature of the said Invention, and in what manner
the same is to be performed, I declare that I claim,-
First. The combination or arrangement of parts forming improved steam super-
heating apparatus adapted for locomotives and for portable engines substantially as
herein before described and represented in Figures 1, 2, 3, 4 and 5 of the annexed
Drawings.
}
i
Second. The combinations or arrangements of parts forming respectively improved
steam superheating apparatus adapted for stationary boilers substantially as herein-.
before described and represented respectively in Figures 6 and 7, and in Figures 8
and 9 of the annexed Drawings.
Third. The combinations or arrangements of parts forming respectively improved
steam superheating apparatus adapted for marine boilers substantially as herein-
before described and represented respectively in Figures 10 and 11, in Figure 12,.
and in Figure 13 of the annexed Drawings.
Fourth. Constructing, mounting, and supporting the superheating coil in the fire
box of locomotive or portable engines by making its ends to pass through the fire
box and its jacket, and connecting these ends with pipes extending clear through
the fire box and jacket, and serving one for feeding the coil with saturated steam
and the other for taking off the superheated steam, substantially as hereinbefore
described and shewn in Figures 1, 2, 3 and 4.
I
Fifth. Constructing steam superheating, apparatus with two or more coils
arranged as far as practicable in the hottest part of the furnace, each of the said
coils having its own separate connections with the boiler, substantially as and for
the purpose herein before described.
Sixth. In steam superheating apparatus arranged substantially as herein before
described I claim the employment of a check valve arranged and acting in the

page_text: manner and for the purpose hereinbefore described and shewn in the annexed
Drawings.
Seventh. In steam superheating apparatus arranged substantially as hereinbefore
described I claim a double slide valve working in a casing with three 'ports, and
capable of occupying four different positions with regard to those ports substantially
in the manner and for the purpose hereinbefore described and shewn in the annexed
Drawings.
Eighth. I claim protecting those parts of steam superheating apparatus which
are made of iron or steel and are exposed to the contact of the heated products of
combustion by coating them with a composition consisting of metallic oxide and
argillaceous substances such as are herein mentioned, substantially in the manner
herein before described.
In witness whereof, I, the said Gerald Clarence Hopper, have hereunto set
my hand and seal, this Twelfth day of February, One thousand eight
hundred and eighty.
GERALD CLARENCE HOPPER. (L.S.)