IMPROVEMENTS IN APPA- PROVISIONAL SPECIFICATION
Year: 1881

page_text: LETTERS PATENT to Arthur French St. George, of 40, Southampton Buildings,
in the County of Middlesex, for an Invention of "IMPROVEMENTS IN APPA-
PROVISIONAL SPECIFICATION left by the said Arthur French St. George
at the Office of the Commissioners of Patents on the 11th November 1881.
ARTHUR FRENCH ST. GEORGE, of 40, Southampton Buildings, in the County of
Middlesex. IMPROVEMENTS IN APPARATUS FOR PRODUCING LIGHT BY MEANS
16
OF ELECTRICITY."
My Invention relates to that form of electric lamp or apparatus in which light
is obtained by means of electricity, in which a suitable body, such as platinum
wire or carbon is rendered intensely incandescent by the resistance which it offers
to the passage through it of a current of electricity.
In such electric light it has heretofore been usual to enclose the body rendered
incandescent as described in a hollow transparent globe. or vessel, from which the
air is exhausted as completely as possible in order that the combination of such air
with the incandescent body and the consequent disintegration and destruction of
the latter may be avoided; or for the same purpose it has been proposed to replace
the air in the transparent globe or vessel by nitrogen or other inert gas or
vapour.
My present Invention has for its object methods of constructing the incandescent
lamp so that it is simpler, cheaper, and more readily made than in the methods
beretofore ordinarily used, the necessity for removing the air or substituting for it
inert gas or vapour being avoided.
For this purpose I take a piece of glass or other analogous vitreous substance of
suitable shape and I heat it until it has become sufficiently soft or viscous, and
into the soft mass I insert a piece of platinum, carbon, or other suitable material
sufficiently capable of conducting a current of electricity and of becoming incan-
descent by the passage through it of such current. The platinum, carbon, or other
such conducting material may be in the form of a wire, ribbon, or other convenient
LD

page_text: shape, and may be heated before being inserted into the soft mass of glass or other
substance described. The extremities of the conducting material or of larger
conducting pieces attached to them are allowed to protrude from the glass, and are
connected to the conducting wires, through which the current of electricity is
passed from any convenient and suitable generating apparatus.
The glass with the contained conducting body may be straight, curved, or of
any desired shape, and when it has cooled the conducting body is completely
embedded in its substance, the process of so embedding it having been performed
with care, so as to prevent the presence of bubbles or films of air or gas, which if
in contact with the conducting body when incandescent might tend to combine
with and disintegrate the latter.
I prefer to use glass toughened or annealed, and such toughening or annealing
may be conveniently effected by plunging the glass with its contained conducting
body into a bath of oil or other suitable annealing fluid and then gradually passing
a current of electricity through the conducting body until the latter has attained
sufficiently complete incandescence, the current of electricity being then gradually
stopped and the glass allowed slowly to cool.
The glass or analogous vitreous substance may be of any kind or quality
sufficiently transparent, and capable of resisting the heat without combining with
and disintegrating the conducting body.
The lamp made as described may be enclosed in a transparent protecting globe
or cover. The parts where connection is made with the electric current may be
immersed in a liquid to keep them cool and prevent access of air.
By my novel method of constructing apparatus for obtaining incandescent light
by means of electricity the necessity for providing a vacuum or an inert gas or
vapour round the incandescent conducting body is avoided, the latter being in
contact only with the glass or other analogous substance which surrounds it.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur French St. George in the Great Seal Patent Office on the
11th May 1882.
ARTHUR FRENCH ST. GEORGE, of 40, Southampton Buildings, in the County of
Middlesex. "IMPROVEMENTS IN APPARATUS FOR PRODUCING LIGHT BY MEANS
OF ELECTRICITY."
My present Invention relates to that form of electric lamp or apparatus for
obtaining light by means of electricity, in which a suitable body, such as platinum
wire or carbon, is rendered intensely incandescent by the resistance which it offers
to the passage through it of a current of electricity produced by any suitable
means.
In such form of electric light fit has heretofore been usual to enclose the body
rendered incandescent by the passage through it of a current of electricity as
described in a hollow globe or vessel of transparent glass, from which the air is
exhausted as completely as possible in order that the combination of such air with
the incandescent wire, carbon, or other body, and its consequent disintegration and
destruction may be prevented; or for the same purpose it has been proposed to
replace the air in the transparent globe or vessel by nitrogen or other inert gas or
vapour.
My present Invention has for its object novel methods of constructing the
incandescent lamp or light, so that the external globe or vessel from which the air
is exhausted or replaced by nitrogen or other inert gas or vapour is unnecessary,
and so that the lamp is simpler, cheaper, and more readily made than in the
methods heretofore ordinarily used.
My Invention consists substantially in embedding the platinum wire, carbon, or
other body, by the incandescense of which light is to be obtained in a bar or mass
of glass or other analogous vitreous substance in such manner that the contact of
air with the wire, carbon, or other incandescent body is entirely prevented by the
presence of the glass or vitreous substance.
Where ordinary glass is to be used for the purpose described a piece of suitable
shape may be taken and heated until sufficiently soft, the conducting platinum
wire or other conductor being then inserted into it, and the glass being then
pressed down into close contact with the wire, the ends of which are left pro-
jecting. A current of electricity of- moderate strength may be passed through the
wire, which becomes sufficiently incandescent to emit light.
Where however a great degree of heat and consequent incandescence is required,
I prefer, instead of using ordinary glass in the way described, to adopt the following
method
I take as a conducting body which is to become incandescent a filament of
carbon, preferably a vegetable fibre, carefully carbonized in any of the usual well
known ways, and I enclose this filament in an inner envelope of glass or vitreous
substance, prepared in the following manner:-I take very finely powdered flint
which I mix with a sufficient proportion of silicate of sodium or other metallic
silicate or silicic acid, to form a vitreous substance when submitted to sufficient
heat, and I mix them with a sufficient quantity of glycerine to form a paste which
will not be liable to crack when it is arranged round the carbon filament which it
is to envelope.
In order to give the vitreous paste its proper form and to properly enclose and
retain within it the carbon filament, I form an outer tube or case embracing the
vitreous envelope and retaining it in its proper placo and shape. For this purpose

page_text: I mix very finely powdered flint with sufficient water to incorporate it into a mass
from which a thin tube of the desired size and diameter is formed by pressing it
round a central core or in other convenient manner. The core is then withdrawn
and the tube is burned in a furnace at as high a temperature as possible.
I then soak it in glycerine in order to prevent adhesion between its inner surface
and the vitreous paste which it is to contain, and I inject or otherwise force into
it a sufficient quantity of the latter to fill it, the carbon filament being afterwards
inserted into it in a position as nearly central as possible, so that the filament is
thoroughly covered and the admission of air absolutely prevented. In some cases
I mix with the vitreous paste, prepared as described, a small quantity of finely
powdered carbon, platinum, or other metal or material, by which when they
become sufficiently hot the light emitted is improved.
Before inserting the carbon filament I coat its ends for a sufficient length with
copper or other good electrical conducting material, so as to prevent incandescence
except at the middle of its length, the ends of the coat formed by the internal
vitreous covering being thus prevented from becoming so hot as to soften and leave
the conductor liable to exposure to the air.
The outer ends of the conductor, coated as described, after emerging from the
coating are connected to the conducting wires from any suitable electrical generator,
so that the electricity may be passed through the carbon filament when desired,
the latter by its resistance becoming intensely hot and consequently sufficiently
incandescent to emit light.
The paste-prepared as described_and_surrounding_the_conductor_also becomes
heated and incandescent, forming a vitreous matter of great durability and
completely protecting the conductor from contact with air, and the external tube
whilst also becoming hot permitting the passage of light, and itself emitting light
does not soften or become viscous, but retains its shape and keeps the internal
vitreous envelope from bending or otherwise altering its shape and injuring the
efficiency of the central incandescent conductor.
Instead of a single carbon conducting filament, two or more such filaments may
bo used, and instead of one outer tube or case, as described, two or more may be
used, increasing in diameter as required, of the material described or of glass or
other analogous vitreous and sufficiently transparent material.
The inside or outside or both of the external tubo, or the entire apparatus, may be
glazed with a coating of vitreous material.
Instead of a straight enclosed filament the latter with its envelopes may be
curved or of any desired shape.
Where, as in the method first described, I use ordinary glass to surround the
internal conducting wire or filament, I prefer to use glass toughened or annealed,
and such toughening or annealing may be effected by plunging the glass with its
contained conducting filament into a bath of oil or other suitable annealing fluid,
and then gradually passing a current of electricity through the filament until the
latter exhibits sufficient incandescence, the current of electricity being then
gradually stopped, and the glass allowed to cool slowly.
Electric lamps made according to my Invention, as described, may be enclosed in
ornamental transparent protecting globes or covers, from which it is not necessary
to exhaust the air.
The accompanying Drawing which is in illustration of my Invention, represents
sections of a straight electric lighting device, constructed in the method above
described.
a is the central internal filament of carbon; b is the envelope surrounding it of
vitreous paste forced into the external refracting flint tube c. The ends of the
conducting filament a are coated with copper or other good conductor except at
the central part, so that the vitreous matter at and near the extremities is
prevented from becoming too much heated.
I am aware that it has been proposed in electric lamps to use carbon conductors
supported upon foundations of lime, the incandescent conductors being themselves

page_text: coated with silicon, the lamps so made being enclosed in a transparent vessel from
which the air is exhausted, and I do not claim as my Invention any such method
of construction, but having described my Invention and the manner in which it is
to be performed, I claim,-
The method of constructing incandescent lamps consisting of one or more carbon
or other conducting filaments, surrounded by an envelope of glass or vitreous
material, which entirely prevents air from obtaining access to the incandescent
part of the conducting filament so that no external transparent exhaust vessel or
globe is required, substantially as hereinbefore described. Also in combination
with the incandescent lamp so constructed, the external shell or tube of flint
surrounding the vitreous envelope round the incandescent conducting filament,
substantially as and for the purpose hereinbefore described and shewn in the
Drawing.
In witness whereof, I, the said Arthur French St. George, have hereunto
set my hand and seal, this 11th day of May, in the year of our Lord
1889
A. F. ST. GEORGE. (L.S.)