IMPROVEMENTS IN THERMO-ELECTRIC PILES
Year: 1874

page_text: "
LETTERS PATENT to Charles Clamond, of Boulevard de Strasbourg;
No. 23, at Paris, Engineer, for the Invention of "IMPROVEMENTS IN
THERMO-ELECTRIC PILES."
3.
Scaled the 25th September 1874, and dated the 6th April 1874.
PROVISIONAL SPECIFICATION left by the said Charles Clamond at
the Office of the Commissioners of Patents, with his Petition, on
6th April 1874.
I, CHARLES CLAMOND, of Boulevard de Strasbourg, No. 23, at Paris,
5 Engineer, do hereby declare the nature of the said Invention for " IM-
PROVEMENTS IN THERMO-ELECTRIC PILES," to be as follows:-
> This Invention relates to,
Firstly. A method of sealing or of separating thermo-electric-negative
plates.
0. Secondly: The formation of thermo-electric bars in a mould previously
heated almost to the point of fusion of the thermo-electric substance.

page_text: Thirdly. An arrangement for heating by gas, according to the con-
struction of the apparatus, to permit of the employment of a cylindrical
Bunsen or atmospheric burner, with a supply of additional air from the
outside.
struction of the apparatus, to permit of the employment of a cylindrical
Bunsen or atmospheric burner, with a supply of additional air from the
outside.
Fourthly. Building up and binding the pile proper between two ring |
plates united by bars and rods.
Fifthly. A special arrangement for heating by coke by the aid of a
radiating cylinder of a moveable bar, and of a feed receiver.
It is optional to apply these improvements to all kinds of thermo-
electric generators of all forms and dimensions, and whatever be the 1
thermo-electric substance employed.
The Invention is based upon the thermo-electric generator patented
in England by Mess". Mure and Clamond, on the 7th of October, 1868,
No. 3060, under the title of -" Improved -Means and Apparatus for
Generating Electricity by Heat," but differs from it with respect to the 1
construction of the bars and the method of applying the heat.
'
All the thermo-electric bars hitherto constructed only retain-their
virtue for a very short time.
Under the continual action of heat and of the alternate or successivė
heating and cooling to which the bars are subjected, they acquire an a
interior resistance, which goes on increasing (although the clectric force
is the same), and which eventually becomes such that the current
engendered by the heat no longer gives but a very feeble and inap-
preciable quantity of clectricity. Sometimes there occurs even a com-
plete dissolution of the continuity, which renders the electric performance a
next to nothing.
I have observed that this principal defect was owing to two causes,-
First. The surface of the metallic plate by contact with the metal or
crystallized mineral, oxydized and became a resistant to the passage of
the current.
And, Secondly. The crystallized bar, metallic or not, split or cracked
itself. These cracks, imperceptible to the naked eye, grew larger, and
the oxydization penetrated to the interior of the bar, which became more

page_text: in the part of the bar exposed to the heat.
And, Secondly. By a particular method of casting the bars in hot.
moulds.
When it is a question of thermo-electric piles of large dimensions I
give by preference to the whole of the bars a rectilinear 'disposition or
arrangement instead of a circular form.
The detailed explanation of my improvements will be well under-
stood by the following description:-Elements are grouped in a super-
posed manner, and isolated one from another by mica or amianthus, and
form by their superposition a cylinder, the interior of which has to be
heated.
This heating I effect in the following manner:-A tube of refractory
earth with perforations upon its circumference at intervals to form a
kind of lengthened cap is placed in the interior of the pile, leaving a
space between its outer side and the inside ends or extremities of bars.
This interval communicates at the top with the exterior air, and at the
bottom it communicates with the ambient air by means of holes formed
in a cylindrical portion of the support. A tube for the conduct of gas
leads to a Bunsen burner, which causes the gas to mingle with 'the
incoming air.
11.
The mixture of the gas and air takes place in the refractory cap, and
comes away at different heights through the orifices which lead it into
the annular space, where it is burnt in contact with the burning air
coming from the inferior annular space. This air being thus previously
heated renders .combustion very advantageous. The bars are also heated
at the time by the radiation of the refractory tube, which is heated to a
red heat, and by the contact of the flame and the products of combus-
tion in rising towards the chimney. Each bar is provided with pole
plates serving to take up or receive the electric current.
The method of uniting these plates to the electrode depends upon the
nature of the current one wishes to develope, and also upon the tension

page_text: and upon the quantity of it. One of the plates may be sealed flatwise
as usual to the exterior or cold part of the bar, the other being in con-
tact with the bars in the interior or hot part.
In the moulding operation the metallic plate first placed in the moulds
is provided with a little appendage, which, while the metal is flowing"
through or into the mould, will be sealed or fastened to the material of
which the bar is composed. This appendage is a metallic ring soldered
to the plate and formed in a plate somewhat narrower than the plate,
or else it is taken even into a part of the plate, which is hollowed for the
purpose, another portion being thrown back again and beaten down to
double its thickness.
The width of the ring should be smaller by about half than that of the
plate, these plates, scraped or tinned, being placed in the mould and
conveniently arranged. The metal or mineral envelopes or surrounds
the ring, which penetrates to the interior, constituting thus a core which
forms one with a mass of the bar, and which ensures an intimate and
permanent contact between the plate and the bar.
}
As a material from which to construct the bars I avail myself of all
thermo-electric substances whatever, and especially of the metallic alloy,
said by M. Marcus to be composed of about 2 parts of antimony to 1 part
zinc.
Now whatever be the substance employed so long as it is cast in cold
moulds it is impossible to prevent it cracking interiorly, that is due to the
defect in the homogeneity of the crytalline covering, and in consequence
of the inequality of the dilitation which occasions the ruptures and
crackings in the bar. On contact with the cold sides or walls of the
mould, the exterior coating of the melted metal or mineral hardens
quickly, and undergoes a kind of hardening which contracts it, while the
interior of the bar is still liquid and is congealed very slowly.. It follows
as a natural consequence that the crystallization is not uniform and
regular.
My method entirely avoids these inconveniences; it consists in pre-
viously heating the moulds to a degree very near to the point of fusion
of the metal or mineral. These latter melted to a liquid in the crucible
are poured into the heated moulds, which are placed afterwards in a middle

page_text: course, where they are allowed to cool slowly. I thus obtain bars which
are perfectly homogeneous, and in consequence do not crack or split.
For ensuring the proper arrangement of the elements of the pile I
support them between two ring plates. These ring plates are bound
firmly to the central discs by arms traversed at their extremities by
button rods serving for cross bars. The inferior or lower plate is cast in
a piece with the foot supports.
When I heat by coke for generating thermo-electricity the coke is
enclosed in a cylindrical column of iron concentric to the pile, and of a
diameter narrower than the interior diameter in order to reserve an
annular space between the two for the radiation of the heat. The coke
rests upon a fixed or moveable bar, which admits of the necessary air for
the combustion, the products escaping by a lateral conduit to the
chimney. The products can however be made to circulate in the spaco
before passing away.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Clamond in the Great Seal Patent Office
on the 1st October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
CLAMOND, of Boulevard de Strasbourg, No. 23, at Paris, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of April, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, tho said Charles Clamond, Her special licence,
that I, the said Charles Clamond, my executors, administrators, and
assigns, or such others as I, the said Charles Clamond, my executors,

page_text: exterior air, and at the bottom it is terminated by the lower annular
space c, c. To the plate is joined the cylindrical piece D supporting
the tube B, at the base of which it is arranged. The tube E connected
to the gas conduit debouches underneath. This tube is provided with a
Bunsen burner e, which mixes the gas and the air coming through the
holes o, o. This mixture of air and gas proceeds to the refractory cap
and comes away at different heights through the little orifices b, b, which
leads it into the annular space, where it is burnt in contact with the air
coming from the inferior annular space c. This air being previously
heated renders the combustion very advantageous, and the bars are
rapidly heated by the radiation of the refractory tube, which becomes
red hot, and by the contact of the flames.
Each bar is provided with two plates n and p. for the purpose of
receiving or collecting the electric current. The first n is adapted to the
interior of the negative pole, the second is situated at the exterior of the
positive pole.
"
The method of uniting these plates to the electrodes of the buttons
N. & P depends upon the nature of the current it is desired to develop
" in tension or "in quantity." In the plan, Figure 2, these plates are
shown united "in tension." The plates p, p, are scaled flatwise upon the
.exterior and cold part of the bars.
With respect to the plates n, n, which are in contact with the bars at
the interior and hot part, I seal them in the manner following (see
Figures 3 and 4) :-The metallic plate previously placed in the moulds
is provided with a little appendage, which during the flow will be sealed
and held in the material of the bar. This appendage is a metallic ring r
soldered to the plate n and formed in a little plate somewhat narrower
than the said plate n (see Figure 3), or else it is soldered to the plate n,
hollowed for this purpose at the part 8, which is then folded as shown in
Figure 4.
As material from which to form the bars I avail myself of all thermo-
electric substances whatever, and especially of the metallic alloy called
Marcas, composed of about two parts antimony to one part zinc.
To avoid the cracks and clefts which always result from the employ-
ment of cold moulds in making the bars, I previously heat the moulds

page_text: almost to the point of fusion of the metal or mineral. The latter melted
and agitated in a crucible is poured into the heated moulds, which are
then placed in a cooling medium wherein they will become cool slowly.
The elements of the pile are firmly arranged between two ring plates
t, t, which are bound in a solid manner to the central discs by three
arms v, v, traversed at their extremities by bolt pins u, u, u, serving for
cross bars or stays. The lower frame is cast in a piece with the foot
'supports x,.x.
In some cases the heating can be effected by coke instead of by gas.
This combustible (see Figure 5) is enclosed in a column of cast iron or
of ordinary iron C, concentric to the pile, and of a diameter sufficiently
narrow to preserve an annular space B for the radiation of the heat.
The coke rests upon a bar or. grate G, which admits sufficient air for
the combustion. The coke is charged at the top of the feed receiver H,
and the residues can be removed by opening the grate. G, which is
jointed for the purpose.
For small models the coke can be replaced by charcoal, or by any
artificial agglomerated combustible. The products of combustion escape
through the lateral conduit D towards the chimney F. In this case also
the elements of the pile are maintained between two ring plates t, t,
fastened to the plates by the arms v, v. The lower plate has feet z, z.
And having now described the nature of my said Invention, and
what manner the same is to be performed, I declare that I claim as my
Invention of "Improvements in Thermo-electric Piles,--
First. Sealing or fitting negative plates of thermo-electric piles as
described and as shown in the accompanying Drawings..
Secondly. Casting bars of thermo-electric piles in moulds previously
heated almost to the point of fusion of the thermo-electric material from
.which they are to be made, as described and shown.
Thirdly. Heating thermo-electric piles by gas, especially those piles
or generators in which bars are built up and arranged between two ring
plates united by bolted cross bars, as described and as shown in Figure
1 and 2 of the accompanying Drawings.

page_text: And, Fourthly. The construction and employment of my circular
thermo-electric generators or piles, substantially as described and shown
in the annexed Drawings.
In witness whereof, I, the said Charles Clamond, have hereunto set
my hand and seal, this Eleventh day of September, One thousand
eight hundred and seventy-four.
Witness,
CH. ARMENGAUD,
Civil Engineer,
CHARLES CLAMOND. (L.S.)
Boulevard de Strasbourg, No. 23,
à Paris.