Improvements in the Manufacture of Refractory Substance, and Apparatus therefor.
Year: 1895

page_text: Date of Application, 10th Aug., 1895
Complete Specification Left, 11th May, 1896-Accepted, 8th Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Refractory Substance, and
Apparatus therefor.
1 ERNEST ALBERT PELLET, of 34 Boulevard de Clichy, Paris, France,
Electrician, do hereby declare the nature of this invention to be as follows:-
This invention relates to the treatment of magnesia for the production of articles
of a refractory character, specially designed for use in arc lamps. The magnesia
is treated in such a way as to produce articles of any desired shape and of an
extremely hard and almost infusible character suitable for carbon pencils of an arc
lainp to bear against while burning. By this means arc lamps can be made of a
very simple nature and all the usual and expensive and complicated mechanisın
now usual for feeding the carbons done away with, it being only necessary for the
carbons to be carried in a tube and held against the refractory substance by weight
or spring appliance the face of the refractory substance being brought to incan-
descence by the heat from the point of the carbon when burning, increases and
improves the light.
In the preparation of the said refractory substance I proceed as follows: I take
carbonate of magnesia and purify it as much as possible by subjecting it to a high
heat for say twenty hours, after this the magnesia is pulverised, and if not
immediately used stored in a diy place, the articles desired are moulded from this
dry powder alone by great pressure in suitable moulds. After moulding the articles
are placed in a plumbago or other suitable crucible with powdered charcoal, and
baked in a muffle furnace at as high a heat as can be obtained; the heat is brought
to its highest intensity gradually during twelve hours and kept at the same for
twenty four hours, the draught to the furnace being then gradually reduced to
none at all, and the furnace being then hermetically sealed, the fire is allowed to
die out, and gradually cool. When cold, the articles are withdrawn from the
crucible and are ready for use. The fuel preferred to be used is gas carbon broken
into small pieces.
To economise the heat from the furnace as much as possible, the magnesia in the
first instance is pressed into bricks, and then are built up inside, to be acted upon
by the heat for the preliminary purifying of the magnesia. The arrangement of
furnace is as follows: I first form a pit in the earth, which I brick round inside
with firebricks. Within this pit I arrange the furnace as follows: I press the
powdered magnesia into bricks, with which I build up the wall of the furnace,
leaving a space between the outside and inside of fire bricks, which is filled up
with powdered charcoal. The object of this arrangement is to utilize the heat for
the preliminary purifying of the magnesia. The top of the furnace is covered by a
loose cover. The crucible is placed within the wall of magnesian bricks, and rests
upon a pedestal of fire clay upon the bars of the grate. The moulded articles are
placed in the crucible as follows: First a layer of powdered charcoal, then a layer
of moulded articles, then a layer of charcoal, and so on; and when full, the cover
put on. The interior of furnace is then filled up with gas carbon broken small,
a necessary quantity of wood being first put in to light the carbon by.
1005
FREDERIC PRINCE,
Agent for Applicant.

page_text: Improvements in the Manufacture of Refractory Substance, and
Apparatus therefor.
I, ERNEST ALBERT PELLET, of 34 Boulevard de Clichy, Paris France,
Electrician, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
This invention relates to the treatment of carbonate of magnesia for the
production of articles of a refractory character specially designed for use in arc
lampe. The carbonate of magnesia is treated in such a way as to produce articles
of any desired shape and of an extremely hard and almost infusible character
suitable for carbon pencils of arc lamps to bear against while burning.
By this means are lamps can be made of very simple nature and all the usual
and expensive and complicated mechanism now usual for feeding the carbons
done away with, it being only necessary for the carbons to be carried in a tube and
held against the refractory substance by weight or spring appliance, the face of
the refractory substance being brought to incandescence by the heat from the point
of the carbon when burning, increases and improves the light.
In the preparation of the said refractory substance I proceed as follows: I take
carbonate of magnesia and purify it as much as possible by subjecting it to a high
heat for say twenty hours, after this the carbonate of magnesia is pulverised, and
if not immediately used, must be stored in a dry place, the articles desired are
moulded from this dry powder alone by great pressure in suitable moulds. After
moulding the articles are placed in a plumbago or other suitable crucible with
powdered charcoal, and baked in a muffle furnace at as high a heat as can be
obtained the heat is brought to its highest intensity gradually during twelve
hours and kept at the same for twenty four hours: the draught to the furnace
being then gradually reduced to none at all, and the furnace being then hermetically
sealed up, the fire is allowed to die out, and gradually cool. When cold the
articles are withdrawn from the crucible and are ready for use. The fuel preferred
to be used is gas carbon broken into small pieces.
To economise the heat from the furnace as much as possible, the carbonate of
magnesia in the first instance is pressed into bricks, which are used to build up the
walls of the furnace for the preliminary purifying.
The accompanying drawings illustrate the arrangement of furnace :
A pit is made in the earth A, lined with fire bricks B: C, blocks of compressed
carbonate of magnesia, of which the sides of the furnace are built up: D, a loose
fitting cover E, a pedestal to support furnace and grate bars F; G, the crucible
made with an airtight cover H: J, block of fire brick for the crucible to rest
upon K, broken gas carbon or graphite. The blocks used in are lamps are short
lengths like pieces of carbon pencil. In Fig. 2, the crucible is shewn charged with
same embedded in charcoal powder: L, illustrating the blocks and M, the powder.
In charging a crucible, first a layer of charcoal powder, then a layer of blocks, and
so on, the cover H, being then put on, the crucible is stood upon the pedestal J,
the magnesian bricks C, built up, the interior filled with the gas carbon K, a
certain quantity of wood being first put in to light the fuel, and the cover D put
on. This cover carries a chimney N. The space between the outside of the
magnesian bricks C, and the firebricks B, is filled up with carbon or charcoal dust O,
and covered over with earth P: Q, doors to feed in further supplies of fuel.

page_text: Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. The treatment of carbonate of magnesia for the production of refractory
material in desired forms, consisting of taking powdered carbonate of magnesia, as
pure as possible, moulding the same into desired forms by pressure, baking such
forms in a hermetically sealed crucible with charcoal powder: all substantially as
herein before described.
2. In the arrangement of furnace for economising the heat for the preliminary
heating of the magnesia, building the wall of the furnace with bricks made of
compressed carbonate of magnesia, and filling up the space between the outside
of such bricks and the outside of the fire bricks B, with charcoal dust O :
substantially as hereinbefore described and set forth.
Dated this 11th day of May 1896.
FREDERIC PRINCE,
37 Cursitor Street, London, E.C., Agent for Applicant.