IMPROVEMENTS IN AND IN APPARATUS FOR PRODUCING THE ELECTRIC LIGHT, AND IN THE MANUFACTURE OF CARBONS THEREFOR
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
AND IN APPARATUS FOR PRODUCING THE ELECTRIC LIGHT, AND IN THE
MANUFACTURE OF CARBONS THEREFOR." A communication from abroad by
Madame Josephine de Changy, née de Deyn, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 10th October 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN AND IN APPARATUS FOR PRODUCING THE
ELECTRIC LIGHT, AND IN THE MANUFACTURE OF CARBONS THEREFOR." [A com-
munication from abroad by Madame Josephine de Changy, née de Deyn, of Paris,
France.]
This Invention relates to improvements in electric lighting by the incandescence
system in vacuo or otherwise, and it has for its object to render the carbon or other
electrode incandescent without being traversed by the current in the direction of
its length.
One electrode only is employed, but the arrangements for carrying out the
Invention may be considerably varied.
In order that the Invention may be more readily understood, I have represented
in the accompanying Drawings several arrangements of lamps on this principle by
way of illustration. Figure 1 shows a lamp in which the carbon pencil is
introduced in a spiral cage of platinum wire or equivalent material included in the
circuit, and Figure 2 shows the same kind of lamp adapted for suspension from
a ceiling or otherwise; Figure 3 represents a lamp in which the point of the
carbon pencil rests upon two conducting blocks insulated from each other;
Figure 4 shows a lamp in which the point of the carbon pencil rests between two
inclined electrodes of platinum or other conducting material supported upon an
insulated or insulating block; Figure represents a lamp in which the point of
the carbon pencil rests against the peripheries of two revolving discs forming the
two poles.

page_text: Referring to Figures 1 and 3, a is a spiral of platinum formed of single or
multiple wire connected to the posts b, c, and communicating by them and the
plates d, e, with the terminals f, g; h is an insulated arm carrying a guide through
which the carbon j passes, the carbon resting by its own weight in the spiral a of
platinum wire and becoming incandescent by the radiation produced by the
incandescence of the wire.
In Figure 3 the carbon pencil j rests upon two blocks of carbon k, which alone
are placed in the circuit, the said blocks being bevelled to form a V shaped cavity
for the carbon to rest in, and which may be coated with platinum at the point of
contact with the carbon j. The carbon pencil passes through a guide Ɩ, which
slides on a suitable support; f, g, are the terminals. The point of the carbon j
when placed in the V cavity becomes incandescent and produces a very fine fixed
light.
In, Figure 4 the carbon ; is introduced in a similar manner between two inclined
metallic or carbon electrodes m, m, mounted upon an insulated block n, or one of
insulating refractory material, such as magnesia, lime, kaolin, &c.
The point of the carbon ; closes the circuit and produces the result above
described; f, g, terminals.
In Figure 5 the carbon j rests between and against the peripheries of two metal
discs p, p, which are made to revolve in opposite directions so as to constantly
change the point of contact. The discs are driven by clockwork q or other
mechanism in the lower part of the apparatus, and are placed sufficiently far apart
to prevent the formation of an arc between them; they are also insulated from one
another, and for this purpose the pinions r, s, should be either insulated or made
of ebonite or other nonconducting material; f, g, terminals. The carbons may be
regulated in any other manner than as described, such as by means of springs,
weights, &c.
The above described system of lighting is also applicable to incandescent vacuum
lamps.
The Invention also relates to the manufacture of the carbons employed in the
lamps, and consists in absorbing in porous substances of vegetable or mineral
origin matters capable of producing carbon by calcination in a closed vessel or in
vacuo. I may use a thread of pure flax or hemp, cotton plaited, or other vegetable
material, or pumice stone, or other similar substance capable of absorbing matters
which by calcination will deposit carbon in their pores. The absorbent materials
are immersed in a boiling bath of hydrocarbon or fatty matter, holding in solution
resins, tars, or other matters rich in carbon, and when thoroughly impregnated are
blackleaded and brought to the desired form for the pencils. The pencils are then
placed in crucibles or other vessels of refractory material, and surrounded either
with powdered vegetable carbon or lamp black, and the vessels or crucibles being
then luted are heated to a cherry red for about five hours. If lamp black be used
it should have been previously calcined. After being thoroughly cooled the pencils
whatever may be their form are dipped into a hot solution of saccharine syrup,
and after drying are again calcined, as before described, the operation being
repeated according to the degree of hardness to be obtained.
To give greater stiffness to the pencil a metal or other core may be used; for
example, I may spin upon a platinum wire a more or less thick covering of flax
or hemp either pure or previously treated in the ordinary manner of making
parchment paper; or I may wind a strip of paper around the core, the covering
being treated in the manner above described by immersion in a bath and calci-
nation after having given it the desired form.
The carbons produced in the above manner may according to their size and the
nature of their core or support be employed for lighting either in vacuo or not.
The arrangements are susceptible of considerable variation to suit these different
cases, and the Drawings represent incandescence lamps provided with carbons of
the kind above described.
Figure 6 represents a lamp in which the carbon a is hollow and connected to a

page_text: platinum wire b, which may either pass through the interior of the carbon or
be wound round it, the ends of the wire being connected to two copper
conductors c.
In Figure 7 the carbon a is attached to two conductors b, b, passing through a
part c, which admits of their being readily withdrawn from the lamp.
In Figure 8 the carbon is straight and connected at each end to metallic
conductors b.
In Figure 9 the carbon a is twisted in any suitable manner and attached by its
extremities to conductors b, b.
The carbons are in all cases contained in glass bulbs d exhausted of air or
containing any suitable atmosphere.
It is preferred to employ the following substances in the manufacture of the
carbons, viz., piassava, sorghum grass, alfa, rattan, and rattan pith, couch grass,
rushes, reeds, and all kinds of straw or reeds capable of being carbonized by
calcination. These substances are first steeped in mono-hydrated sulphuric acid
diluted with half its quantity of water, and after being sufficiently washed and
dried are plunged in a bath of
boiled for four hours, allowed to cool in the bath, and then withdrawn and dried,
after having been first washed to remove any syrup which may remain on their
surface. After being thoroughly dried the matters thus prepared are subjected to
a first carbonization in a crucible filled with powdered vegetable charcoal, calcined
lampblack, or other similar substance raised to a dull red heat. After four hours'
calcination the carbons, which have been previously brought to the desired form,
are again dipped in the above mentioned bath and after being completely dried are
calcined again, but at a cherry red heat. It is necessary to repeat the operations
twice more in the same manner, the temperature being so graduated as to reach a
white heat at the fourth operation. Each calciuation should occupy at least four
hours and be very gradual.
Each end of the carbon should by preference be previously introduced into a
short piece of perforated rattan to facilitate its attachment in the lamp.
The carbons may be indefinitely varied in form, according to the purpose for
which they are intended.
The proportions of the bath may be varied, and this bath of sugar may be
replaced by one composed of oil and resin, colophony, or other analogous substance,
or a bath of spirits of turpentine or hydrocarbons and gumlac or other substanco
soluble therein, or by the baths and method previously described.
Besides the substances herein before specified I may employ the following woods
for the manufacture of the carbons, viz.:- - Chestnut, beech, mahogany, plane, red
and white pear, sandal, pine, or white woods, and generally all long fibred woods
free from knots, such as ash, white mulberry, and rosewood; I however prefer
those first mentioned.
I may also employ ivory (elephant or hippopotamus tooth), vegetable ivory and
bone. These several substances are first cut up into very thin sheets like veneers
and then in the case of the vegetable substances placed in a bath of mono-hydrated
sulphuric acid diluted in half the quantity of water and rinsed. In the case of
ivory or other animal substance it is first boiled in spirits of turpentine or its
equivalent and calcined without evaporating at a graduated heat, the several
operations being repeated according to the result desired. After drying, the
substances are heated in the saccharine bath previously mentioned and calcined in
a similar way after having been first made of the form desired either by bending
or stamping out. After the first calcination the materials are plunged a second

page_text: time in the same baths in order to impart the desired hardness to the carbons and
again calcined.
I make the globe of incandescence lamps in the form of an elongated ovoid of
which the diameter should not exceed 51, to 6 centimetres. Such a lamp is
shown in Figure 10. The tubular neck a is formed with an enlargement 6 for
engaging with the clips c, forming contacts. The carbon attachments are formed
of a steel tube, upon which is spun a tube of glass enamel d. At the upper part a
platinum wire is soldered with silver or platinum, said wire being itself connected
by a glass tube e united to the enamel sheath d, while the latter and the platinum
are united to the frame of the lamp.
A vacuum is obtained in these lamps by means of an air pump traversing a
large sulphuric acid receiver. The air is let in several times, being passed
previously through a series of vessels containing a hygrometric substance, such as
chloride of calcium, caustic potash, &c. When the vacuum is sufficient an electric
current is passed through, so as to bring the carbon to a cherry red heat for a
certain time before sealing the lamp.
The incandescent lamps may also be arranged in either of the following
ways: (1) a glass filament may be twisted into the same form as the carbon and
disposed parallel within it or crosswise, whether of horseshoe, spiral, letter, or other
forms, and whether white or colored glass be employed; (2) a wire or strip of
platinum may be bent or shaped to the form of the carbon, but smaller, and
arranged as in the former case either crosswise or parallel therewith.
The introduction in the carbon of whatever form of a metallic or other substance.
increases its temperature and serves as a reflector without increasing the expen-
diture of electricity.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
8th April 1882.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN AND IN APPARATUS FOR PRODUCING THE
ELECTRIC LIGHT, AND IN THE MANUFACTURE OF CARBONS THEREFOR." A com-
munication from abroad by Madame Josephine de Changy, née de Deyn, of Paris,
France.
This Invention relates to improvements in electric lighting by incandescence, in
vacuo or otherwise, and it has for its object to render the carbon or other electrode
incandescent without being traversed lengthwise by the current.
One electrode only is employed, but the arrangements for carrying out the
Invention may be considerably varied.
In order that the Invention may be more readily understood, I have
represented in the accompanying Drawings several arrangements of lamps on this
principle by way of illustration. Figure 1 shows a lamp in which the carbon
pencil is introduced into a cage or basket, formed by a spiral of platinum wire or
equivalent material connected by its extremities to the two poles of the circuit, and
Figure 2 shows the same kind of lamp adapted for suspension from a ceiling or
otherwise; Figure 3 represents a lamp in which the point of the carbon
pencil rests upon two conducting blocks insulated from each other; Figure 4 shows
a lamp in which the point of the carbon pencil rests between two inclined
electrodes of platinum or other conducting material supported upon an insulated
or insulating block of refractory material; Figure 5 represents a lamp in which the
point of the carbon pencil rests against the peripheries of two revolving discs
forming the two poles.
Referring to Figures 1 and 3, a is a spiral or cage formed of a single or multiple
platinum wire connected to the posts b, c, and communicating by them and the
plates d, e, with the terminals f, g; h is an insulated arm carrying a guide through
which the carbon passes, the carbon resting by its own weight in the platinum
spiral a and becoming incandescent by the radiation produced by the incandescence
of the wire.
In Figure 3 the carbon pencil j rests upon two blocks of carbon k, which alone.
are placed in the circuit, the said blocks being bevelled to form a V shaped cavity
for the carbon to rest in, and which may or may not be coated with platinum at
the point of contact of the carbon j.
The carbon pencil passes through a guide which slides on a suitable support;
f, g, are the terminals. The point of the carbon j when placed in the V shaped
cavity becomes incandescent and produces a very fine fixed light.
In Figure 4 the carbon j is introduced in a similar manner between two inclined
metallic or carbon electrodes m, m, resting upon an insulated block n or one of
insulating refractory material, such as magnesia, lime, kaolin, &c.
The point of the carbon ; closes the circuit and produces the result above
described; f, g, are the terminals.
In Figure 5 the carbon j rests between and against the peripheries of two metal
discs p, p, which are made to revolve in opposite directions so as to constantly
change the point of contact. The discs are driven by clockwork g or other
mechanism in the lower part of the apparatus, and are placed sufficiently far apart
to prevent the formation of an are between their circumferences; they are also
insulated from one another, and for this purpose the pinions r, s, should be either

page_text: insulated or made of ebonite or other nonconducting material; f, g, terminals.
The carbons may be regulated in any other manner than as described, such as by
means of springs, weights, &c.
The above described system of lighting is also applicable to incandescence
vacuum lamps.
The Invention also relates to the manufacture of the carbons employed in the
lamps, and consists in causing porous substances of vegetable or mineral origin to
absorb matters capable of yielding carbon by calcination in a closed vessel or in
vacuo. To this end I use pure linen or hemp thread, plaited cotton, or other
vegetable material, or pumice stone or other similar substance capable of absorbing
matters, which by calcination will deposit carbon in their pores. The absorbent
materials are immersed in a boiling bath of hydrocarbon or fatty matter, holding
in solution resins, tars, or other matters rich in carbon, and when thoroughly
impregnated are blackleaded and brought to the desired form for the. pencils. The
pencils are then placed in crucibles or other vessels of refractory material, and
surrounded either with powdered vegetable carbon or lamp black, and the vessels
or crucibles being then luted are heated to a cherry red for about 5 hours. If
lamp black be used it should have been previously calcined.
After being
thoroughly cooled, the pencils, whatever may be their form, are dipped into a hot
solution of saccharine syrup, and after drying are again calcined as before
described, the operation being repeated according to the degree of hardness to be
obtained.
To give greater stiffness to the pencil a metal or other core may be used; for
example, I may spin upon a platinum wire a more or less thick covering of flax or
hemp either pure or previously treated in the ordinary manner of making parch-
ment paper, or I may wind a strip of paper around the core, the covering being
treated in the manner above described by immersion in a bath and calcination
after having given it the desired form.
or
The carbons produced in the above manner may, according to their size and the
nature of their core or support, be employed for lighting either in vacuo
otherwise. The arrangements are susceptible of considerable variation to suit these
different cases, and the Drawings represent incandescence lamps provided with
carbons of the kind above described.
Figure 6 represents a lamp in which the carbon a is hollow, and connected to a
platinum wire b, which may either pass through the interior of the carbon or be
wound round it, the ends of the wire being connected to two copper wires c.
In Figure 7 the carbon a is attached to two wires b, b, passing through a forked
leg c to the exterior of the lamp.
In Figure 8 the carbon is straight, and connected at each end to metallic
conductors b.
In Figure 9 the carbon a is looped or bent to any suitable form, and attached by
its extremities to conductors b, b.
The carbons are in all cases contained in glass bulbs d exhausted of air, or
containing any suitable atmosphere, the conductors passing through to the
exterior.
It is preferred to employ the following substances in the manufacture of the
carbons, viz., piassava, sorghum grass, alfa, rattan, and rattan pith, couch grass,
rushes, reeds, and all kinds of straw or reeds capable of being carbonized by
calcination. These substances are first steeped in mono-hydrated sulphuric acid
diluted with one half its quantity of water, and after being sufficiently washed and
dried are plunged in a bath of

page_text: surface. After being thoroughly dried the matters thus prepared are subjected to
a first carbonization in a crucible filled with powdered vegetable charcoal, calcined
lamp black, or other similar substance raised to a dull red heat. After four hours'
calcination the carbons, which have been previously brought to the desired form,
are again dipped in the above mentioned bath, and after being completely dried
are calcined again, but this time at a cherry red heat. It is necessary to repeat
the operations twice more in the same manner, the temperature being so graduated as
to reach a white heat at the fourth operation.
Each calcination should occupy at least four hours, and be very gradual. Each
end of the carbon should by preference be in the first place introduced into a short
piece of perforated rattan for the purpose of mounting it in the lamp.
The carbons may be indefinitely varied in form, according to the purpose for
which they are intended.
The proportions of the bath may be varied, and this bath of sugar may be
replaced by one composed of oil and resin, colophony, or other analogous substance,
or a bath of spirit of turpentine or hydrocarbons and gumlac or other gum soluble
therein, or by the baths and method previously described.
Besides the substances hereinbefore specified I may employ the following woods
for the manufacture of the carbons, viz. :-Chestnut, beech, mahogany, plane, red
and white pear, sandal, pine, or white woods, and generally all long fibred woods
free from knots, such as ash, white mulberry, and rose wood; I however prefer
those first mentioned.
I may also employ ivory (elephant or hippopotamus tooth), vegetable ivory, and
bone. These several substances are first cut up into very thin slips like veneers,
and then in the case of the vegetable substances placed in a bath of mono-hydrated
sulphuric acid diluted with one half its quantity of water and rinsed. After drying,
the substances are treated in the saccharine bath previously mentioned and calcined
in a similar way, after having been first brought to the form desired, either by
bending or stamping out. After the first calcination they are plunged a second
time in the same baths in order to impart the desired hardness to the carbons and
again calcined. In the case of ivory or other animal substance it is also cut into
thin slips, and is then boiled in spirits of turpentine or its equivalent, and after-
wards calcined without being evaporated at a graduated heat, these several operations
being repeated according to the result desired.
I make the bulbs of incandescence lamps in the form of an elongated ovoid, of
which the greatest transverse diameter should not exceed 5 to 6 centimetres.
Such a lamp is shown in Figure 10. The tubular neck a is formed with a swelling
at 6 for engaging with the metallic clips c, Figure 11, which serve to form contact.
The carbon holder is formed of a steel tube, upon which is spun a tube of glass
enamel d. At the upper part a platinum wire is soldered with silver or platinum,
said wire being itself connected by a glass tube e united to the enamel sheath d,
while the latter and the platinum are united to the sealed end of the neck.
A vacuum is obtained in these lamps by means of an air pump traversing a large
sulphuric acid receiver. The air is let in several times, being passed previously
through a series of vessels containing a hygrometric substance, such as chloride of
calcium, caustic potash, &c. When the vacuum is sufficient an electric current is
passed through in order to heat the carbon to a cherry red for a certain time
before sealing the exhaust tube.
The incandescence lamps may also be arranged in either of the following ways:
-(1.) A twisted glass of the same form as the carbon and disposed parallel within
it or crosswise, whether of horse shoe, spiral, letter, or other forms, and whether
white or colored glass be employed; (2) a wire or strip of platinum may be bent
or shaped to the form of the carbon, but smaller, and arranged as in the former case
either crosswise or parallel therewith.
The introduction within the carbon of whatever form of a metallic or other
substance, increases its temperature and serves as a reflector without increasing the
expenditure of electricity.

page_text: :
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,―
1st. In an incandescence electric lamp burning in vacuo or not, the combination
and arrangement of a cage or basket a, formed of platinum wire, included in the
circuit, and of a carbon which is received and rests in the said cage or basket, and
is rendered incandescent by the incandescence of the wire, substantially as herein-
before described and illustrated in Figures 1 and 2.
2nd. The combination and arrangement of the carbon pencil j, and of the two
carbon electrodes k having bevelled surfaces, upon and between which the pencil j
rests as described, the said electrodes being insulated from one another and
connected to the two poles of the circuit, and their inclined surfaces being platinized
or not, as herein before described and illustrated in Figure 3.
3rd. The combination and arrangement of the carbon pencil j and of the two
inclined electrodes m, m, between which it rests, and of the insulated or insulating
and refractory block or support n against which they abut, substantially as herein-
before described and illustrated in Figure 4.
4th. The combination and arrangement of the carbon pencil and of the two
rotating disc electrodes p, substantially as hereinbefore described and illustrated in
Figure 5, the disc electrodes being rotated by any suitable mechanism.
5th. The process of manufacture of carbons for electric lighting by impregnating
porous substances of vegetable or mineral origin with a hydrocarbon or other
matter rich in carbon, then carbonizing, cooling, and immersing in a hot solution
of saccharine syrup, substantially as herein described for the purpose specified.
6th. The manufacture of carbons produced as herein specified in any form
required for incandescence lamps, such as those represented in Figures 6, 7, 8, and 9
of the Drawings hereunto annexed.
7th. The manufacture of carbons for electric lighting from piassava, sorghum,
alfa, rattan, rattan pith, or couch grass, by immersing in sulphuric acid, washing,
drying, and immersing in a bath of glucose, sugar and water, as herein specified, or
in a bath composed of other substances specified according to the desired resistance
of the carbon.
8th. The manufacture of carbons from long fibred wood free from knots, bone,
or ivory, by cutting the same into thin slips, immersing in a bath of sulphuric
acid, or boiling in spirit of turpentine, cutting out or bending to the definitive
form, calcining, and immersing in a bath, as herein before described for the purpose
specified.
9th. The construction and arrangement of the carbon holder and the form of the
lamp, substantially as herein described and illustrated in Figures 10 and 11.
10th. The construction of the lamp holder adapted to form contact as and for the
purpose described and illustrated in Figures 10 and 11.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Eighth day of April, in the year of our Lord One
thousand eight hundred and eighty two.
A. M. CLARK.
(L.S.)