Improvements in Electric Arc Lighting.
Year: 1890

page_text: Date of Application, 15th Feb., 1890
Complete Specification Left, 5th Nov., 1890-Accepted, 6th Dec., 1890
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lighting.
I, LLEWELLYN SAUNDERSON, of 10 De Vesci Terrace, Kingstown, in the County of
Dublin, Gentleman, do hereby declare the nature of this invention to be as follows :-
:-
In the Specification of a former Patent granted to me dated the 28th day of
September 1888 No. 13987 I described a method of electric are lighting in which
hydro-carbon vapour was introduced into the arc through one or both of the carbons
made hollow for that purpose.
My present invention relates to improvements upon the invention described in that
Specification.
In order to prevent the hydro-carbon from being absorbed by the porous carbon
electrode and saturating the same and so to escape in vapour before it reaches the
arc I line the interior passage in the electrode with an enamel consisting of hard
pitch or bitumen dissolved in a solvent. This enamel I apply with a brush and allow
it to harden. In the same way 1 coat the end of the electrode where the same is
inserted into the box and the exterior surface of the carbon may be similarly coated
if desired. Thus the hydro-carbon liquid is kept from contact with the porous surface
of the electrode.
'
In order to prevent the passage of the electric current through the heated carbon
of the electrode from decomposing the hydro-carbon and producing a deposit of
carbon tending to fill up and stop the hole through the electrode I introduce into
the hole above the wick (which I insert into the lower part of the hole) filaments
or pieces of asbestos or other non-conductor of electricity which prevent the deposit
of carbon and keep the hole open.
In cases where the carbon electrodes are of such a length that the heat generated
at their ends furthest away from the arc is not found to be of sufficient power to
vapourize the hydro-carbon in sufficient quantity I either use a heated wire or con-
ductor in or about the said ends of the carbons in order to accelerate vapourization,
or I force a minute quantity of hydro-carbon vapour through the said ends of the
carbons by means of a pump or equivalent mechanism, or I heat hydro-carbon in a
closed vessel from which the vapour passes by the force of the expansion in through
the said ends of the carbons.
Dated this 14th day of February 1890.
D
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lighting.
I, LLEWELLYN SAUNDERSON, of 10 De Vesci Terrace, Kingstown in the County of
Dublin, Gentleman, 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:-
In the Specification of a former Patent granted to me dated the 28th day of
September 1888, No. 15987 I described a method of electric are lighting in which
hydro-carbon vapour was introduced into the arc through one or both of the carbons
made hollow. for that purpose.
My present invention relates to improvements upon the invention described in that
Specification. These improvements are illustrated by the drawings annexed.
In Figure 1 of the drawings A represents in longitudinal section a carbon electrode
with a passage through it from end to end; it is here shown enclosed in a casing of
copper B which also forms a closed receptacle at the end of the electrode for the
Pine R71

page_text: reception of paraffin, vaseline, albo carbon (naphthaline) or the like. d is a wick of
asbestos passing part of the way along the hollow in the electrode into which it is
tightly packed so that the hydro-carbon may not be able to pass too freely. is an
asbestos thread hereinafter referred to. The carbon here shown may be used either
as an upper or lower electrode.
In order to prevent the hydro-carbon from being absorbed by the porous carbon
.electrode and saturating the same and so to escape in vapour before it reaches the are
I line the interior passage in the electrode with an enamel consisting of hard pitch
or bitumen dissolved in a solvent. This enamel I apply with a brush and allow it to
harden. In the same way I coat the end of the electrode where the same is insorted
into the box and the exterior surface of the carbon may be similarly coated if desired.
Thus the hydro-carbon liquid is kept from contact with the porous surface of the
electrode.
Another part of my invention relates to means for preventing deposit being formed
in the passage through the electrode.
In the absence of suitable precautions it has been found that the passage of the
electric current through the heated carbon of the electrode decomposes the hydro-
carbon and produces a deposit of carbon which after a time fills up and stops the hole
through the electrode, so that no vapour can pass. To prevent this I introduce into
the hole above the wick a filaments of asbestos 6 or other refractory non-metallic fibre
may be employed but asbestos is preferred.
The asbestos is in the form of a fine loosely twisted thread, it is much smaller in
diameter than the passage in the electrode and it drops easily into it. The presence
of this thread when the electrode is in use prevents the deposit of carbon and keeps
the hole open. This part of my invention is very applicable to cases in which coal
gas is supplied through the hollow electrode in place of hydro-carbon vapour.
Another part of my invention relates to means by which the generation of vapour
from a liquid or solid hydro-carbon is facilitated.
In cases where the carbon electrodes are of such a length that their ends furthest
away from the arc do not become sufficiently heated to vaporize the hydro-carbon in
sufficient quantity 1 provide a conductor by which the heat of the arc is conveyed to
the hydro-carbon more freely. This conductor may take various forms but a casing
of copper around the carbon electrode such as is shown at B is preferred.
Figure 2 shows another arrangement in which my several improvements are
applied. In this case the hydro-carbon receptacle is not formed by the copper
casing B but is a separate metallic vessel E through which a slotted tube C passes.
These parts are shown separately by the Figures 2 and 2° they form a socket or
holder into and upon which the carbon electrode fits. The wick d is stiffened by a
spiral of iron wire around it and it passes down into the tube Camongst the hydro-
carbon as the drawing indicates. f is an air hole in the vessel E. G is a carbon
cylinder to prevent the conduction of heat to the carbon holder. H is the part which
is held in the clamp of the lamp.
Figure 3 shows an arrangement more especially suitable for an upper electrode; it
resembles Figure 1 except that a tube C2 is provided in the hydro-carbon receptacle;
the vapour is unable to pass to the passage through the electrode except by this tube.
The tube C² is tightly packed with a wick d in place of having this wick within the
carbon. The asbestos thread b is provided to prevent deposition of carbon in the
passage by which the vapour passes to the arc. This electrode may either be used
with a lower electrode such as herein shown or with one which is plain or
unperforated.
Figure 4 shows an arrangement somewhat similar to Figure 2, but adapted for the
use of a permanently liquid hydro-carbon which is supplied from a reservoir L by a
pipe M. The liquid enters the pipe C which in this case is closed at the sides; the
upper part of the tube at J forms a vapourizing chamber.
Figure 5 shows an arrangement which admits of the use of liquid hydrocarbon with
an upper carbon electrode, the vapourising chamber J is loosely packed with asbestos.
Figure 6 is a modification of Figure 5; an additional vapourising chamber is

page_text: provided at a short distance from the carbon; this is intended for use in cases where
the heat immediately above the carbon is inconveniently high. The hydrocarbon
liquid is supplied from a bird fountain vessel K.
Figure 7 shows an arrangement for the supply of vapour to the interior of the
electrode. Here a vapourizing chamber J in the form of a hollow metal ring loosely
packed with asbestos surrounding either or both electrodes is permanently fixed a
short distance either above or below the focus of electric arc. The vapour generated
in the chamber is led to the end of the carbon farthest away from electric arc " by a
spiral or flexible tube."
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In electric are lighting, a hollow carbon electrode; hydrocarbon vapour or gas
supplied to the are through the hollow carbon electrode; and an internal lining of
enainel preventing the hydrocarbon penetrating into the substance of the electrode as
herein set forth.
2. In electric are lighting; a hollow carbon electrode; hydrocarbon vapour or gas
supplied to the are through the hollow carbon electrode; and a thread or filament of
asbestos or other refractory non-metallic material contained loosely within the hollow
carbon electrode and serving to prevent the obstruction of the passage by the deposition
of carbon therein.
3. In electric are lighting, the combination consisting of carbon electrodes (one or
both hollow) connected with an electric source and usual devices for the production
of the electric are between the electrodes; a tightly fitting fibrous plug inserted a
short way up the hollow electrode; a thread of asbestos or refractory fibrous material
loosely placed in a space within the electrode between the fibrous plug or packing at
one end and the arc at the other and means for supplying hydrocarbon to the plug or
packing at the end furthest away from the arc.
4. In electric are lighting; a hollow carbon electrode; a chamber containing
hydrocarbon at the end of the electrode remote from the arc; and a metallic con-
ductor formed as a casing around the electrode or otherwise, extending along it ;
the whole so arranged that heat conducted froin the are to the hydrocarbon causes
vapour to be generated which by the hollow in the electrode passes to the arc.
Dated this Eleventh day of October 1890.
LLEWELLYN SAUNDERSON.