IMPROVEMENTS IN ELECTRIC LAMPS OR LIGHTING APPARATUS AND IN THE MANHECTORE OR LIAMENTA COURA 114 PROVISIONAL SPECIFICATIONACTURE OF LIGHT-EMITTING CONDUCTORS FOR SAME
Year: 1882

page_text: LETTERS PATENT to Josè Manuel Boullon, of Golden Square in the County of
Middlesex, Isaac Probert, of Ponton Place, Walworth Rond in the County of
Surrey, Electrical Engineer and Alfred Walter Soward of Serjeants Inn
Fleet Street in the City of London Analytical and Consulting Chemist, for an
Invention of "IMPROVEMENTS IN ELECTRIC LAMPS OR LIGHTING APPARATUS
AND IN THE MANHECTORE OR LIAMENTA COURA
114
PROVISIONAL SPECIFICATION left by the said Josè Manuel Boullon,
Isaac Probert and Alfred Walter Soward at the Office of the Commissioners
of Patents on the 10th November 1882.
JOSÉ MANUEL BOULLON, of Golden Square, in the County of Middlesex, ISAAC
PROBERT of Penton Place, Walworth Road, in the County of Surrey, Electrical
Engineer, and ALFRED WALTER SOWARD, of Serjeants Inn, Fleet Street, in the
City of London, Analytical and Consulting Chemist, "IMPROVEMENTS IN ELECTRIC
LAMPS OR LIGHTING APPARATUS, AND IN THE MANUFACTURE OF LIGHT-EMITTING
CONDUCTORS FOR THE SAME
"
Our Invention relates chiefly to that kind of electric lighting apparatus in which
a filament of carbon, or of silicon, is rendered incandescent by the passage of an
electric current through the same, but it is partly applicable to are lamps.
We will first describe our improvements in the manufacture of light-emitting
conductors to be used with or as a part of electric lamps. According to one part
of our said Invention we take paper or any suitable vegetable fibre, thread, or
fabric, and treat it with some suitable solvent of cellulose, such as ammoniacal
solution of oxide or carbonate of copper or concentrated hydrochloric acid. After
separation of this solution from the undissolved impurities, by decantation or
filtration, we add a suitable substance such as an acid (in the case of the copper
Bolution), or water, (in the case of hydrochloric acid) by which operation the cellulose,
previously held in solution is precipitated. This precipitated substance we remove
from the supernatant liquid by any of the ordinary well-known means, and, having
dried it, we submit it to such pressure as may be necessary to make it cohere into
Prine Gd1

page_text: a solid mass. From this mass we cut or otherwise prepare filaments or pencils of
the required shape, which we submit to a heat sufficiently intense to carbonize the
cellulose. Or we may take the pasty mass left on removal of the supernatant
liquid and place it in properly shaped grooves or recesses forming moulds cut in
the surface of some such substance as iron. We then cover the grooved plate with
another plate and subject the whole to a heat sufficiently intense to carbonize the
cellulose. In some cases we prefer to provide the upper plate with a projection
which will fit into, but not completely fill, the groove or mould in the plate
below;
then having filled the groove with the pasty mass as hereinbefore described,
we place the projection of the upper plate upon the groove or mould and subject
the whole to pressure. We then carbonize as before.
Our object in this process is to obtain a carbon fibre free from impurities.
Vegetable fibres, and substances of vegetable origin rich in cellulose have heretofore
been used for this purpose but we carry the principle involved in this selection to
its logical conclusion and employ pure cellulose.
We sometimes submit this pure cellulose to the process known as "parchmentising"
that is to say we subject it to the action of a mixture of sulphuric acid of about
Sp. Gr. 18, two parts, and water, one part, or of a concentrated solution of zinc
chloride, if the former method is used, we afterwards wash the prepared cellulose
first with dilute ammonia, and then with water.
According to another part of our invention we take a suitable carbonaceous gas,
such as marsh-gas, and subject it in the following manner to the action of an
electric spark, produced by any suitable generator of high tension electricity, that
is to say, we provide a globular or other shaped covering of glass into which the
metallic conductors pass in the usual manner. We prefer to use platinum as the
electrodes, the ends thereof being brought to a suitable distance from each other in
the globe. The carbonaceous-gas is decomposed by the spark, and a bridge-of
-carbon-is-gradually_deposited until the space separating the said platinum
electrodes between which the spark passes is completely arched over. This bridge-
forms the filament to be used as the light-emitting conductor, the lamp being
ready for use as soon as the said bridge of carbon has been deposited connecting
the two ends of the platinum, or in some cases we may make the said filament
in a separate globe or vessel and insert it, and the electrodes, afterwards within
the lamp with which it is to be used.
Where a fibre prepared in this manner is adopted we prefer to use a plain glass
globe with platinum electrodes fused in. We also prefer to support the lamp by a
flexible spring so as to prevent, as far as possible, the breaking of the fibre by
excessive vibration.
"
Other inventors have utilized the carbon deposited from gas to render their
fibres, prepared by other means, more homogeneous and it has heretofore been
sought to use the carbon thus obtained by depositing it upon a soluble metal and
then dissolving away the metal. We deposit our carbon upon an electric spark
which leaves, in any place required, a carbon fibre unsurpassable in purity.
Instead of a carbonaceous gas, we may employ a siliceous gas, such as silicon
methane, and obtain from it by its decomposition, a fibre of pure silicon to be used
in the same manner as the filament.
According to another feature of our invention we employ carbonaceous substances
of animal origin, and carbonize then by any of the well known means to be used
as conductors for electric lamps.
In establishing the contact between the end of a carbon filament and the end
of another carbon filament or with the conductor conveying the current, we prefer
to proceed in the following manner-
We make a hole in the flattened extremity of the conducting wire, or in the
ends of the "metallic connecting pieces" hereinafter referred to in the description
of the method of constructing our lamp. We then roll up the flattened part into
a form somewhat resembling the character or symbol known as the "Bass" or
"F clef" in music, or that portion of the "Treble clef" which curls around

page_text: the "g." We then slightly twist the inner end, and pass the end of our fibre
through the hole above referred to. On releasing this inner end, the elasticity of
the flattened extremity causes it to press firmly against the fibre. We then apply
to the joint a conducting paste. This we make by heating together a metallic
powder with cellulose and black-lead or sometimes we use pure carbonized cellulose
alone.
1
In the construction of our lamp for the use of filaments prepared from cellulose
or similar material wo proceed as follows, that is to say :—
We take a hollow pillar or tube of glass, closed at one end, and provided at
the top, and at a point below with rings of glass surrounding the pillar and held
at a small distance therefrom by glass arms. These rings are provided with radial
indentations. Metallic connecting pieces, preferably of copper, and flat, are bent
around the rings in the said indentations. To the ends of these connecting pieces
the fibres are attached as herein before described. Of these fibres we use as many
as may be thought desirable, and as will appear from the details of construction
we join them "in series." One of the conducting wires is led through the hollow
pillar to its top, where it unites with a piece of platinum wire which passes
through the glass and is fused to it. The other conducting wire is of platinum and
passes through, and is fused to, a funnel shaped enlargement with which the
bottom of the hollow pillar is provided. We then blow a glass bulb, of suitable size
and shape, having a contracted neck. This bulb is divided into two parts, and
the hollow pillar with its fibres is passed into that part having the contracted
neck, so that the funnel drops into the neck. The funnel and the neck are then
fused together, tho portion of the globe previously removed is also restored to its
place and there fused. The usual leading tube for attachment to the vacuum
apparatus is provided.
Another plan we adopt is as follows
We take a glazed, or unglazed, hollow porcelain pillar, provided with enlarge-
ments in place of the rings used with our glass pillar already described. These
enlargements are perforated, and through the holes wo pass metallic connecting
pieces to which the fibres are attached as before described. In place of using these
connecting pieces, we may fill the holes with conducting paste and insert the ends
of the fibres, and in some cases tho pasto may have within it a wire or other
metallic core to increase the conductivity thereof. This pillar fits on the end of
a glass stem which is fused into the bottom of the lamp globe. A ring of india-
rubber is interposed between the porcelain and the glass. The contracted neck
of the globe is filled with cement, surmounted by a non-conducting and infusible
washer.
We exhaust our lamps by any of the well known means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
"
by the said Josè Manuel Boullon, Isaac Probert and Alfred Walter Soward in
the Great Seal Patent Office on the 10th May 1883.
JOSE MANUEL BOULLON, of Golden Square, in the County of Middlesex, ISAAC
PROBERT, of Penton Place, Walworth Road, in the County of Surrey, Electrical
Engineer, and ALFRED WALTER SOWARD, of Serjeant's Inn, Fleet Street, in the
City of London, Analytical and consulting Chemist, "IMPROVEMENTS IN ELECTRIC-
LAMPS OR LIGHTING APPARATUS AND IN THE MANUFACTURE OF LIGHT-EMITTING
CONDUCTORS FOR THE SAME
"
Our invention relates to that kind of electric lighting apparatus in which a
filament of carbon or other material is rendered incandescent by the passage of an
electric current through the same.
In the manufacture of the filament or light-emitting conductor for an electric
incandescence lamp, the following points, amongst others, must be considered, that
is to say: First. The light-emitting conductor should have a high electrical
resistance and a small mass and surface, for the following reasons, vis:-
The heat generated in the conductor varies directly with. tho resistance of the
same. The higher the resistance, therefore, the greater is the amount of heat
generated in the said conductor by a given current, a correspondingly greater
electromotive force being used to produce the current. The temperature of the
conductor in which the heat is-generated depends partly upon-the mass. of the said
conductor and partly upon the extent of the radiating surface thereof. The smaller
the mass of the conductor the more concentrated-is-the-heat-;-the-smaller-the-
radiative surface the more is the radiation impeded. Both the concentration of
the heat and the hindering of the radiation produce an augmentation of temperature.
The light emitted by the conductor, as is well known, varies not directly with, but
increases much more rapidly than, the temperature. It follows, therefore, that to
obtain a high efficiency, that is to say, to obtain much light in proportion to the
heat developed, the temperature produced should be high. It follows also that, to
obtain a high temperature with a small current, a filament or conductor having a
small mass and surface should be used. The conductor which, for a given resistance,
has the smallest mass and surfaco is spherical, but such a conductor, having the
necessary resistance, is not obtainable in practice. An approximation to perfection
is obtained by making the filament very thin and correspondingly short. But, in
order that such filaments shall endure, the points which are hereinafter considered
must be particularly attended to.
Secondly. The filament should be absolutely homogeneous, that is, it should be
made from a single substance in a state of chemical purity. If the filament is made
from a mixture of several substances, or if (which is in effect the same) the
substance used for the preparation of the filament is not chemically pure, the life
of the filament is short, because the effect of the electric current and the heat
produced by the passage thereof is to rapidly disintegrate the material of the
filament.
Thirdly. The molecular state of the filament should be such that the passage
of the electric current will produce as little as possible molecular strain. The
material of the filament should, if possible, be thrown permanently into the
molecular state which all materials tend to assume when an electric current is
passed through them.
Having stated some of the principles which should be considered in making
light-emitting conductors for electric incandescence lamps, we will now proceed to
describe our improvements in the manufacture of such light-emitting conductors.

page_text: According to one part of our said invention, we manufacture light-emitting
conductors in the following manner, that is to say:-We take a suitable gas or
vapor and subject it, as hereinafter described, to the action of the electric spark
which may be produced by any suitable generator of high tension electricity. For
this purpose wo provide a globular or other suitably shaped vessel or casing of
glass, in which we insert metallic conductors or electrodes. We prefer to use
platinum for the said electrodes, the ends thereof being arranged at a suitable
distance from each other within the globe. These metallic electrodes may be either
solid or tubular; if made tubular, we make the interior ends conical and closed at
the point, and the conical part is provided with apertures. In some cases
carbonaceous gas or vapor, such as marsh gas, or coal gas, is introduced into the
glass vessel and decomposed by the passage of electric sparks through the same,
A slight deposit of carbon takes place upon the end of one of the electrodes, which
deposit is gradually built up by means of a rapid succession or continuous flow of
sparks, and a bridge of carbon is thus formed, so that the space separating the said
metallic electrodes, between which the spark passes, is completely arched over.
This bridge forms the filament to be used as the light-emitting conductor. After
exhausting and sealing the glass vessel in any of the usual manners the lamp is
ready for use. But, when the metallic electrodes are made tubular, we inject into
them a suitable conducting paste after the filament is completed; this paste passes
through the tubes and issues from the apertures at their conical ends and surrounds
the parts where the ends of the filaments are attached, thereby making a more
efficient connection between the electrodes and the filaments, We then close
the exterior ends of the metallic tubes with melted glass or other suitable
material.
Carbon deposited from gas has been heretofore employed to render filaments
prepared by other means more homogeneous, and it has heretofore been sought to
use the carbon thus obtained by depositing it upon a metal and then deflagrating
the metal away, or by depositing it upon a soluble metal and then dissolving
away the metal, But we deposit our carbon gradually by means of the
electric spark, thereby forming a carbon filament unsurpassable in purity, whose
molecular constitution is such (the filaments having been formed under the
influence of the electric current) that the prolonged action of electric currents
does not result in disintegration.
Instead of a carbonaceous gas we may employ a siliceous gas or vapor, such as
silicon methane, and obtain, by its decomposition as above described in reference
to carbon filaments, a filament of pure silicon to be used in the same manner
aud for the same purposes as the aforesaid filament of carbon.
In the accompanying drawing we have shown different forms of electric lamps
constructed according to our invention
Figure 1 is a diagram illustrative of a lamp provided with four electrodes and
three deposited filaments, the latter being represented by dotted lines.
Figure 2 is a diagram illustrating a lamp with two metallic conductors passing
through a glass stem and sustaining a single filament.
Figure 3 is a diagram illustrating a lamp having a number of filaments of
carbonized cellulose or other suitable material.
Figure is a side elevation of part of a filament made from cellulose or other
suitable material,
Figure 5 is a diagram illustrating a modified form of lamp having a number of
filaments of carbonized cellulose or other suitable material and
Figure 6 is a side elevation showing a method of connecting the filaments and
conductors.
When a filament prepared by the decomposition of gas or vapor as herein
described is employed, we prefer to use a plain glass globe with platinum electrodes
fused into the same; obviously more than two electrodes may be used and more than
one filament as shown in Figure 1, in which a is the glass globe, b, b are the,

page_text: electrodes inserted therein, and the dotted lines c, c represent the filaments attached
⚫to the said electrodes.
We prefer to support the lamp by means of a flexible spring so as to prevent,
as far as possible, the breaking of the filament or its detachment from the electrodes
by excessive vibration.
We find it advantageous to make the said filaments in a separate vessel and to
insert them and their electrodes afterwards within the lamp or lamps of which they
are to form a part. In preparing our filaments to be used in this manner we pass
the electric spark between electrodes of highly purified graphite. By regulating
the size of the electric spark and the degree of rarefaction of the gas or vapor,
filaments of any desired thinness may be obtained. A finer deposit, that is, one of
Jess thickness and more compact texture is obtained when the gas is considerably
rarefied and the spark very thin, and a deposit of greater thickness is obtained
when the gas is under a higher pressure and a spark of considerable size is
employed. And, if a straight uniform spark is produced, the quality of the
filament will be better than when the spark follows a zigzag path. We have found
filaments of one thousandth (1000) of an inch in thickness very convenient and
advantageous; filaments of this thickness have a resistance of about one negohm
per inch and require a current of about 07 of an ampère to raise them to bright
incandescence.
The filaments so formed we attach to electrodes in any convenient manner and
insert in globular or other shaped vessels of glass in the usual manner; n
method of mounting the filaments which we have found convenient is represented
in the diagram Figure 2, in which a is the globe, b, b are the electrodes, c is the
filament and d is a central glass stem having two metallic conductors e, e inserted
therein. These conductors terminate at, or near, the top of the glass stem d, and
are arranged-to-receive the split metallic tubes fif, each of which has a flexible
-projecting tongue b forming an electrode; to these tongues the filament is attached;
but any equivalent arrangement may be adopted. After exhausting-the-glass-
globe or vessel a, the lamp is ready for use. It is obvious that, in a lamp of this
kind, more than one filament may be used, and, when we use more than one filament,
wo prefer to join the said filaments in "series" and not in " multiple arc."
In order to establish contact between the end of a carbon filament and the
conductor conveying the current, we proceed in the following manner, that is to
say we flatten the extremity of the conducting wire and make an aperture
therein, or in the end of one of the metallic connecting pieces hereinafter referred
to, we then coil the flattened part, as shown in Figure 6, into the form of a volute
or a form somewhat resembling the character or symbol known as the "bass-or
F clef in music, or that portion of the "treble cleff" which curls around the
"G." We then slightly twist the inner end and pass the end of the filament c
through the aperture above referred to. On releasing the said inner end, the
elasticity of the flattened extremity causes it to press firmly against the filament.
We then apply to the joint a conducting paste. This paste we make by heating
together a metallic powder with cellulose and black-lead, or sometimes we use pure
carbonized cellulose alone.
In the construction of our lainps for use with filaments prepared from cellulose
or other material, we proceed as hereinafter set forth, that is to say-In the lamp
shown in Figure 3, a is the glass globe, g is a hollow pillar of glass, closed at one
end, and provided at, or near, the top and at a point below, with rings h, h of
glass, surrounding the pillar and held at a suitable distance therefrom by glass
arms . These rings may be provided with radial indentations. The metallic
connecting pieces, preferably of copper and flat, are bent around the rings h and
lie in the said indentations where they exist. To the ends of the said connecting
pieces the filaments c' are attached in any suitable manner. Wo use as many of
these filaments as may be thought desirable, and, as will appear from the details of
construction, we join them in "series" and not in "multiple are." The filaments
"

page_text: may be plain curves or may have a zigzag imposed upon the curve, as shown in
Figure 4. The latter shape we prefer, as, by its uso, a much greater length and
resistance of filament can be utilized in one lamp, and moreover the doubling
back of the filament upon itself places an impediment in the way of the free
radiation of the heat produced by the passage of the electric current, and so causes
an elevation of temperature resulting in the production of an increased amount of
light, thus effecting a considerable economy. The conducting wire k is led through
the hollow pillar to the upper end thereof where it unites with a piece of
platinum wire passed through the glass and fused therein. The other conducting
wire is of platinum and passes through, and is fused to, the funnel-shaped
enlargement g¹ of the hollow pillar g. The glass bulb or globe a is divided into
two parts to permit the hollow pillar g with its filaments c to be inserted so that
the funnel-shaped portion g' fits into the neck a². The funnel-shaped portion and
the neck are then fused together. The portions of the globe previously separated
are then put together again and fused. The usual leading tube for attachment to
the vacuum apparatus is provided.
In another form of lamp we employ a glazed or unglazed hollow porcelain
pillar provided with enlargements in place of the rings used with our glass pillar
above described. These enlargements are perforated, and through the holes we
pass metallic connecting pieces to which the filaments are attached in any suitable
manner. In place of using these connecting pieces we may fill the holes with
conducting pasto and insert the ends of the filaments therein; and, in some cases,
the paste may have within it a wire or other metallic core to increase the
conductivity thereof. Figure 5 shows a lamp constructed according to the last
described method. In this Figure, a is the globe and g² is the porcelain pillar
having the enlargements g³. This pillar fits on the end of a glass stem g¹ made
in the shape of a funnel, which stem is fixed in the bottom of the lamp-globe.
A ring of india-rubber is interposed between the porcelain and the glass. The
contracted neck of the globe may be filled with cement surmounted by a
non-conducting and infusible washer.
We exhaust our lamps by any of the well known means, and the tubes for
attachment to the vacuum apparatus may be in any suitable position.
By employing a number of filaments arranged in series, as shewn in Figure 3 or
Figure 5, we obtain increased resistance in the lamp.
Having thus fully described our said invention and the manner of performing
the same we wish it understood that in manufacturing light emitting conductors
by the decomposition of gas or vapor by the electric spark we do not limit
ourselves to the particular arrangements of the lamps as herein before set forth,
but we claim :-
First The manufacture of light-emitting conductors or filaments for electric
incandescence lamps by the deposition of carbon or other material from gas or
vapor decomposed by the passage of electric sparks through the same.
Second. An electric incandescence lamp consisting of a glass globe or vessel
provided with metallic electrodes between which the filament or filaments have
been formed by the passage of electric sparks through gus or vapor, substantially
as set forth.
Third. In an electric incandescence lamp in which the light-emitting conductor
or filament has been formed us above described by the passage of electric sparks
between two tubular electrodes, the attachment of the filament to the electrodes
by injecting into the latter a conducting paste, the exterior ends of the said
electrodes being afterwards closed, substantially as set forth.
Fourth. In an electric incandescence lamp, the mode of establishing contact
between carbon filaments and electrical conductors by coiling one end of each
conductor, inserting the filament in an aperture therein, and applying the conducting
paste thereto, substantially as set forth.
Fifth. An electric incandescence lamp having a hollow central glass pillar provided

page_text: with glass rings and metallic connecting pieces, or equivalent devices attached
thereto, and light-emitting conductors or filaments joined by the said connecting
pieces in "series," substantially as, and for the purpose, set forth.
Sixth. An electric incandescence lamp having a hollow porcelain pillar provided
with perforated enlargements, metallic connecting pieces to which the filaments
are attached being passed through the perforations of the said enlargements, or
the said perforations being filled with the conducting paste, with or without
metallic cores, and the ends of the filaments being inserted in the said paste, all
substantially as, and for the purpose, set forth.
In witness whereof I the said Alfred Walter Soward, for myself and on 1
behalf of the said Josè Manuel Boullon and Isaac Probert have hereunto
set my hand and seal this Tenth day of May in the year of our Lord
One thousand eight hundred and eighty three
ALFRED. WALTER SOWARD. (L.S.)