Year: 1887

page_text: Date of Application, 18th Mar., 1887
Complete Left, 19th Dec., 1887
Complete Accepted, 17th Mar., 1888
We ARTHUR FRENCH ST. GEORGE of Redhill in the County of Surrey, Electrician
and CHRISTEN Rus BONNE of 26 Mark Lane London Merchant, do hereby declare
the nature of this invention to be as follows :-
Our invention has for its object improvements in the manufacture and method of
arrangement of electric lamps for giving light by the incandescence of a continuous
electric conductor of metal or carbon or other suitable material contained in a vessel
from which the air has been as nearly as possible exhausted. In the working and
use of such lamps as ordinarily heretofore constructed and used it has been found
that a pencil thread wire or filament of carbon as perfectly solid and homogeneous in
structure as it has heretofore been found possible to construct constitutes the most
efficient and durable conductor of suitable electrical resistance to be rendered incan-
descent and luminous by the passing of an electric current through it. And in somo
cases heretofore in order to produce as nearly as possible a solid thread or filament
of carbon nearly homogeneous in structure a thread or filament of suitable material
such as animal vegetable or other fibre of natural or artificial structure has been
converted into a thread or filament of carbon by heating it in a closed retort containing
carbon and placed in a furnace. The thread or filament of carbon so formed has
been found to be not sufficiently uniform solid and homogeneous in structure
throughout and it is necessary to render it more uniforın and more nearly homo-
geneous by filling up its pores with carbon and it is preferable further to treat the
filament with sufficient carbon to completely cover up and over the pores and by so
doing adding to the bulk and increasing the diameter of the filament. This has been
accomplished by various processes as for instance by placing the carbon thread which
it is desired to render more uniform in structure in a carbon gas liquid or vapour
and by electrically heating the filament to deposit finely divided carbon in its pores
and this process has been in some cases continued until a considerable amount of
carbon has been deposited not only in the pores but over the whole surface of the
carbon filament. This process may be continued almost indefinitely to the building
up of carbons of any required thickness.

page_text: We have observed in the working of electric lamps with filaments composed of a
carbon thread treated with a filling up of the pores with or covering of deposited
carbon as for instance by the process above mentioned that the most useful. portion of
the carbon treated carbon filament is that portion which has been deposited in the
form of finely divided uniform carbon in or over the pores or surface of the original
porous filament the latter not contributing of itself proportionately to the production
of the desired light radiating effect of the whole compound filament. This in
consequence of its afore mentioned heterogeneous character in the absence of a cooling
or filling up of carbon.
According to our invention we do not employ a thread or filament or any form of
carbon produced by the heating of a suitable material in a retort in a furnace. We
employ and manufacture by a novel process a minute tube of homogeneous carbon of
sufficient length. We make such tubes of any suitable dimensions as for instance
carbon tubes from a twenty fifth (th) to a one thousandth (th) part of an inch
in diameter and several inches in length can be constructed according to our invention
and sometimes we construct such tubes in horseshoe, circular, elliptic, spiral or other
bent shapes and of any desired shape in cross section as for instance flattened, elliptic,
fluted or square tubes. In order to accomplish this part of our invention we take a
thin wire of platinum or platinum alloy rather longer than the required length of the
carbon tube that is to be made and we deposit upon the wire a layer of black platinum
preferably by immersion in a bath of platinum chloride solution connected to a
battery until the platinum wire attains a soot like appearance nearly or quite black.
The wire so prepared we thoroughly cleanse by rinsing in water taking care if
possible not to handle tho wire with the fingers or to touch its surface at all except at
the ends which should be scraped bright and clean to be held in good connexion by
metal clamps. The prepared wire is then immersed in a carbon gas liquid or vapour
and by connecting an electric current to the clamps and passing it through the wire
the latter is heated preferably white to incandescence and the carbon of the gas liquid
or vapour is deposited in a finely divided state in the rough surface of the black layer
of platinum upon the wire. This process is carefully continued until sufficient
carbon has been deposited to form a shell of carbon all around the platinised platinum
wire and completely enveloping it. The strength of current should be increased
from time to time as the process is continued for the carbon increasing in bulk it
becomes necessary to employ a more powerful current in order to render the whole of
it sufficiently hot to obtain a further deposit of carbon from the gas liquid or vapour
in which it is immersed. We then immerse the wire so treated with carbon in a
bath of acid such as aqua regia which attacks most readily the film of black deposited
platinum between the platinum wire and the shell of carbon. The platinum wire
thus becomes loosened sufficiently to enable it to be withdrawn leaving a perfect tubo
of carbon. The tube should then be thoroughly cleansed and all traces of platinum
and acid removed by immersion in acid and in water or by immersion in a galvanic bath
connected to a battery arranged so that all traces of metal shall be electrically separated
from the carbon and thrown down in the bath.
Sometimes it is necessary to dissolve away the whole of the platinum wire and its
platinum coating as for instance when difficulty is experienced in withdrawing the
wire from the carbon shell and sometimes we prefer to remove the platinum by
electrically heating the whole to such a temperature as to explode or volatilise the
platinum from within the carbon the outlet for such action being the ends of the
carbon. Thoroughly cleansed and dried the carbon tube is ready to be mounted in a
lamp. We connect the ends of the carbon tube rigidly to two metallic wires or rods
and we use copper or other metal that offers as small resistance to the electric current
as possible and does not become heated by the electric current in preference to
platinum as the latter offers great electric resistance and becomes hot. We take a
bulb of glass having three apertures or tubes one serving the purpose of the tube
through which the air is exhausted from the bulb when the carbon has been mounted
inside. The other two tubes or apertures we close by means of discs or diaphragms
of platinum sheet or foil which are secured each to its tube or aperture of the bulb

page_text: by blowing the glass on the edge or periphery of the platinum diaphragm airtight or
by sealing round the edge of the diaphragm with a suitable cement which we prefer
to make of powdered flint mixed with sodium silicate to a paste and the joint is
heated in a flame after it is thoroughly dry. To the centre of the platinum
diaphragms we solder one of the metal wires or legs above mentioned to carry the
carbon inside the glass bulb and this we accomplish by threading the carbon into
the bulb with its metal legs by way of one aperture and then dropping the carbon
into such a position as to allow its metal legs to protrude and to be soldered each to
its diaphragin before scaling the latter into its aperture or tube. The diaphragms we
use to carry the conducting wires or legs allow of expansion and contraction of the
glass bulb by changes of temperature and we sometimes employ bulged or corrugated
diaphragms so that when the glass bulb expands and contracts the diaphragms yield
to the pressure and strain exerted and cracking of the glass bulb which has been
observed in lamps consisting of a receiver made entirely of glass through which the
leading wires pass is obviated.
Sometimes we allow the metallic legs of the carbon to protrude through the
diaphragms each leg being soldered all round and to the diaphragm. The open tube
is then connected to a pumping apparatus and the bulb exhausted of air producing
as nearly as possible a perfect vacuum and the tube is then closed and blown off.
Sometimes we employ diaphragms of other metal than platinum. In some cases
we close the exhaust tube of the glass bulb by means of a platinum diaphragm
pierced with a hole which we close up with melted solder admitted to it at exhaustion
point from a branch tube and bulb fitted with a valve or we close the hole by electrical
fusion by means of conducting wires from a battery brought close to the point of
sealing and in vacuum.
13
23
1

page_text: of Manufacturing the same.
We ARTHUR FRENCH ST. GEORGE of Redhill in the County of Surrey Electrician
and CHRISTEN RIIS BONNE of 26 Mark Lane London, Merchant 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 :-
Our invention has for its object improvements in the manufacture and method of
arrangement of electric lamps for giving light by the incandescence of a continuous
electric conductor of metal or carbon or other suitable material contained in a vessel
from which the air has been as nearly as possible exhausted.
In the working and use of such lamps as ordinarily heretofore constructed and
used it has been found that a pencil thread wire or filament of carbon as perfectly
solid and homogeneous in structure as it has heretofore been found possible to
construct constitutes the most efficient and durable conductor of suitable electrical
resistance to be rendered incandescent and luminous by the passing of an electric
current through it. And in some cases heretofore in order to produce as nearly as
possible a solid thread or filament of carbon nearly homogeneous in structure a thread
or filament of suitable material such as animal vegetable or other fibre of natural or
artificial structure has been converted into a thread or filament of carbon by heating
The thread or
it in a closed retort containing carbon and placed in a furnace.
filament of carbon so formed has been found to be not sufficiently uniform solid and
homogeneous in structure throughout and it is necessary to render it more uniform
and more nearly homogeneous by filling up its pores with carbon and it is preferable
further to treat the filament with sufficient carbon to completely cover up and over
the pores and by so doing adding to the bulk and increasing the diameter of the
filament. This has been accomplished by various processes as for instance by placing
the carbon thread which it is desired to render more uniform in structure in a carbon
gas liquid or vapour and by electrically heating the filament to deposit finely divided
carbon in its pores and this process has been in some cases continued until a con-
siderable amount of carbon has been deposited not only in the pores but over the whole
surface of the carbon filament.
This process may be continued almost indefinitely to the building up of carbons of
any required thickness. We have observed in the working of electric lamps with
filaments composed of a carbon thread with a filling up of the pores with or covering
of deposited carbon as for instance by the process above mentioned that the most
useful portion of the carbon treated .carbon filament is that portion which has been
deposited in the form of finely divided uniform carbon in or over the pores or surface
of the original porous filament the latter not contributing of itself proportionately in
the production of the desired light radiating effect of the whole compound filament.
This in consequence of its aforementioned heterogeneous character in the absence of a

page_text: covering or filling up of carbon.
thread or filament or any form
material in a retort in a furnace.
According to our invention we do not employ a
of carbon produced by the heating of a suitable
We employ and manufacture by a novel process a
minute tube of homogeneous carbon of sufficient length.
We make such tubes of any suitable dimensions as for instance carbon tubes from
a twenty fifth (th) of an inch to a one thousandth part of an inch in diameter and
several inches in longth can he constructed according to our invention and sometimes
we construct such tubes in horseshoe circular elliptic spiral or other bent shapes and
of any desired shape in cross section as for instance flattened elliptic fluted or square
tubes. In order to accomplish this part of our invention we take a thin wire of
platinum or platinum alloy rather longer than the required length of the carbon tube
that is to be made and we deposit upon this wire a layer of black platinum preferably
by immersion in a bath of platinum chloride solution connected to a battery until the
platinum wire attains a soot like appearance nearly or quite black. The wire so
prepared we thoroughly cleanse by rinsing in water taking care possible not to
handle the wire with the fingers nor to touch its surface at all except at the ends
which we scrape bright and clean and insert in suitable metallic clamps for electrical
connexions. The prepared wire we then immerse in a carbon gas liquid or vapour
and by connecting an electric current to the clamps and thus passing it through the
wire we heat the latter preferably white to incandescence and the carbon of the gas
liquid or vapour is deposited in a finely divided state in the rough surface of the
porous layer of black platinum upon the wire. This process is carefully continued
until sufficient carbon has been deposited to form a shell of carbon all around the
platinised platinum wire and completely enveloping it. The strength of current is
preferably increased from time to time as the process is continued for the carbon
increasing in bulk it becomes necessary to employ a more powerful current in order
to render the whole of it sufficiently hot to obtain a further deposit of carbon from
the gas, liquid or vapour in which it is immersed.
We immerse the wire so treated with carbon in a bath of acid such as aqua regia
which attacks most readily the film of black deposited platinum between the platinum
wire and the shell of carbon. The platinum wire thus becomes loosened without
further immersion in acid to enable it to be withdrawn leaving a perfect tube of
carbon. The tube should then be thoroughly cleansed and all traces of platinum or
acid or impurities removed by immersion in acid and in water or by immersion in a
galvanic bath connected to a battery arranged so that all traces of metal shall be
electrically separated from the carbon and thrown down. Sometimes it is necessary
to dissolve away the whole of the platinum wire and its coating as for instance when
any difficulty is experienced in withdrawing the wire from the carbon shell and
sometimes we prefer to remove the platinum by electrically heating the whole to such
a temperature as to explode or burn away or volatilise the platinum from within the
carbon the outlet for such action being the ends of the carbon. Thoroughly cleansed
and dried the carbon tube is ready to be mounted in a lamp. We connect the ends
of the carbon tube rigidly to two metallic wires or rods and we use copper or other
metal that offers as small resistance to the electric current as possible and does not
become heated by the electric current in preference to platinum as the latter offers
great electric resistance and becomes hot. We take a bulb of glass having three
apertures or tubes one serving the purpose of an exhaust tube through which the air
is to be exhausted from the bulb when the carbon has been mounted in proper position
within the glass bulb. The other two tubes or apertures we close by means of dises
or diaphragms of platinum or other metal sheet or foil. When we employ discs of
platinum sheet or foil we secure each disc to its aperture or tube of the glass bulb by
blowing the glass to it at the edges but when we employ copper or other metals for
the discs we seal round the edge of each disc a cement securing it to the glass
bulb at the aperture of the bulb or the tube therefrom. We prefer to make the
cement of finely powdered flint or kaolin mixed with sodium silicate solution to
a paste and in such condition we apply it to the bulb luting the discs all round
to it

page_text: To the centre of each disc to be so fitted we solder or cement with the paste a
metal wire or leg to carry the carbon inside the bulb and this we accomplish by
threading the carbon (a horseshoe filament for instance) into the bulb with its metal
leg by way of one aperture and then dropping the carbon into such a position as to
allow its metal legs to protrude and to be soldered each to its diaphragm before
sealing the latter into its aperture or tube. The diaphragms or discs of inetal that
we employ to carry the legs or wires and carbon attached thereto are of sufficient
flexibility to allow of expansion and contraction of the glass bulb by changes of
temperature arising in its working as a lamp or otherwise. By this device we avoid
cracking or failure by leakage of the lamp which in lamps of other construction than
this our invention has been observed to occur as for instance in lamps consisting of a
receiver made entirely of glass through which the leading wires pass. Sometimes
we arrange the metallic legs of the carbon so as to protrude each through its
diaphragm and we solder or cement cach to its diaphragmi. Sometimes we arrange
the ends of the carbon so as to protrude each carbon end through its diaphragm and
secured to it by the paste or by electro deposit of metal and soldering on either or
both. The open tube of the glass bulb we connect to a suitable pumping apparatus
and when the bulb has been sufficiently exhausted of air we blow off the exhaust tube
in the ordinarily well understood manner. According to our invention we sometimes
close the exhaust part of the bulb by means of a metallic disc or diaphragm blown
on or cemented to the bulb as hereinbefore described and pierced with a hole which
we close up with inelied solder admitted to it by a branch tube or in other convenient
manner on attaining proper exhaustion or we close the hole by electrical fusion of
metal by means of electrical heating at the point of sealing and in vacuum.
We sometimes construct and arrange a lamp according to our invention with only
one aperture and one diaphragm fitted thereto also an exhaust tube the single
diaphragm carrying both the conducting wires and one or both of the latter we
insulate from electrical contact with each other and the diaphragm by means of a
small tube or collar or block of insulating material preferably glass which we slip
over the wire leg where it passes through the diaphragm as shown at D' in Figure 1,
of the Drawings. Before exhausting lamps constructed according to our invention
we thoroughly dry, bake or burn the paste joints in order to render them perfectly
air tight and rigid and sometimes we varnish or glase the joints after drying & baking
to make them more reliable.
Figure 1 shows in section an incandescent lamp constructed according to our
invention. A is the glass globe, B is a circular disc or diaphragm of metal foil luted
to the globe with cement at C, C.
D, Dare the joints of cement or solder luting the wire legs E, E to and passing
through the diaphragm B. D' is a glass tube insulating one of the wire legs E, E
from electrical contact with the metal diaphragm B.
F, F are joints of the metal legs E, E, with the carbon filament G.
Figure 2 shows in plan the disc or diaphragm B. C, C the ring shaped luting of
cement or solder. Dthe cement or solder luting of one of the wire legs. D₁ the
cement luting and glass tube insulator.
Figure 3 shews in section enlarged the diaphragm and wire legs attached.
Figure 4 shews in section an incandescent lamp constructed according to our
invention with two diaphragms sealing two tubes of the globe H, H.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed-we declare that what wo
claim is
1. The method of construction of a filament, thread, wire, pencil or rod of carbon
of tubular cross section by electrically heating the platinum substantially as and for
the purposes set forth and described.

page_text: 2. The combination of a carbon filament, thread, wire, pencil or rod within a
receiver made of glass having one or more apertures closed by means of one or more
discs or diaphragms of metal foil or sheet secured as described and through which
the electric leading wires pass and to which they are secured as described and from
which receiver the air is exhausted substantially as and for the purposes set forth.
3. The method of securing the leading wires to the metallic foil diaphragm or
diaphragms by means of the paste herein described substantially as and for the purposes
set forth.
4. The method herein described of securing to and insulating from the metallic
diaphragm one or more of the electric leading wires by means of the pasto herein
described.
5. The method herein described of sealing the glass receiver at one or more of its
apertures by means of the metallic foil discs or diaphragms secured thereto as
described in order to preserve a vacuum within the receiver as and for the purposes
described.