Year: 1888

page_text: Date of Application, 15th Aug., 1888
Complete Specification Left, 24th Apr., 1889
Complete Specification Accepted, 25th May, 1889
1, JOHN SCUDAMORE DELLON OI Hatton rarden
Gentleman do bereby declare the nature of this invention to be as follows:-
My Invention has for its object the obtaining a dense and homogeneous carbon for
use in electric lamps.
Heretofore the carbonizing process has been generally carried on by means of
heating the packed carbons or filiaments in coal or coke fires the carbons being usually
enclosed in crucibles of plumbago or other refractory material and heated by surrounding
such crucible with coal or coke sometimes employing an air blast to increase the heat.
When heated in such a manner however the heat cannot be raised to the high degree
of intensity which is necessary to produce the compactness of texture and the homo-
geneity desirable to ensure the uniformity durability and full efficiency of the filaments
and to prevent the blackening of the globes of the lamps by disintegration of the
carbon by the electric current and it has been a usual practice to deposit upon filaments
so prepared especially when made of parchmentized thread in which irregularities must
so readily occur a coating of hard and compact carbon by passing the electric current
through them whilst surrounded by a hydrocarbon gas. Filaments so prepared have
the defect of not being homogeneous throughout the core being comparatively soft
porous non-durable and inefficient whilst the outside coating or jacket is inelastic and
hard and of an entirely different character consequently there is unequal expansion
and contraction greater liability to break or crack when in use and to deteriorate
rapidly at the points of inequality. By heating filiaments (especially those of a non-
structural character such as are manufactured from properly prepared gelatinous
cellulose) to a very bigh degree of heat, filaments are obtained of extreme compactness
hardness and evenness and of a superior quality as to efficiency, durability and non-
blackening of the globes, but the necessary degree of heat cannot be attained in the
presence of coke or coal as such fuel at so high a temperature as is required, attacks
any crucible which can be used, fluxing or fusing it down and destroying its contents.

page_text: "
I therefore employ for the purpose a specially constructed furnace in which I burn
preferably what is generally known as heavy oil," or I may use petroleum or any
suitable oil or oily compound, with the addition of a blast, of air or of steam, or. I may
employ oxyhydrogen or a mixture of oxygen and other gas, by the use of which heating
agents the crucibles and their contents are preserved from attack and can be raised
to a degree of heat which is otherwise unattainable without bringing about their
destruction. I prefer to use two crucibles one inside the other with a layer of
graphite or carbon powder between them, the inner crucible containing the filaments
carefully packed in the usual manner.
Dated this 11th day of Amanst 1000
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C.,
Agents.

page_text: COMPLETE SPECIFICATION
Improvements in the Manufacture of Carbons for Incandescent
Electric Lamps.
I JOHN SCUDAMORE SELLON of Hatton Garden in the County of Middlesex 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:-
My Invention has for its object the obtaining a dense and homogeneous carbon
for use in incandescent electric lamps. Heretofore the carbonizing process has been
carried on by heating the packed carbons or filaments in coal or coke fires the
carbons being usually enclosed in crucibles of plumbago or other refractory material
and heated by surrounding such crucible with coal or coke sometimes employing
an air blast to increase the heat. When heated in such a manner however the heat
cannot be raised to the high degree of intensity which is necessary to produce the
compactness of texture and the homogeneity desirable to ensure the uniformity
durability and full efficiency of the carbons or filaments and to prevent the blackening
of the globes of the lamps by disintegration of the carbon by the electric current
and it has been a usual practice to deposit upon filaments so prepared especially
when made of parchmentized thread in which irregularities unavoidably occur, a
coating of carbon by passing an electric current through them whilst they are
surrounded by a hydrocarbon gas. Filaments or carbons so prepared have the
defect of not being homogeneous throughout the core being comparatively soft,
porous, non-durable and inefficient whilst the outside coating or jacket is inelastic
and hard and of a character entirely different from that of the core consequently there
is unequal expansion and contraction between the core and the coating and liability to
break or crack when in use and to deteriorate rapidly at the points of inequality.
By heating carbons or filaments (especially those of a non structural character
such as are manufactured from properly prepared gelatinous cellulose) as hereinafter
described to a very high degree of heat over and beyond that obtainable by heating
by means of coal or coke as aforesaid filaments are obtained of extreme compactness
hardness and evenness and of a quality as to efficiency durability and non blackening
of the globes superior to that of the carbons or filaments produced as aforesaid but
the necessary degree of heat cannot be attained in the presence of coke or coal as
such fuel at so high a temperature (even if attainable) as is required clinkers upon
and attacks any crucible which can be used ultimately fluxing or fusing it down and
destroying its contents. I therefore according to my Invention employ for the purpose
a suitably constructed furnace in which I burn preferably what is generally known as
heavy oil or I may use petroleum or any suitable oil or oily compound with the
addition of a blast of air or steam and with or without the further application of oxygen.
Or I may employ a mixture of oxygen and other suitable gas such as coal gas by the
use of which heating agents the crucibles and their contents are practically preserved
from injury and can be raised to a degree of heat which is otherwise unattainable
«

page_text: without bringing about their destruction. I prefer to use two crucibles one inside the
other with a layer of graphite or carbon powder between them the inner crucible
containing the filaments carefully packed in the usual manner.
The accompanying drawing shews in front elevation in Figure 1 and in vertical
section in Figure 2 a furnace arranged for the purposes of my Invention as applied to
burning oil in conjunction with a blast of air or steam with or without the additional
application of oxygen. A is the furnace in which is placed the packed crucible B
with a cover luted on in the usual manner, preferably with an inner crucible packed
with filaments and embedded in carbon in the outer crucible. C is a pipe through
which oil flows from an overhead tank through the valves e drop by drop or in a thin
continuous stream into the funnels d by which it is led into the pipes e at the nozzles
of which it is ignited and burns inside the furnace. A blast of air or steam is supplied
by a pipe and issues with the oil at the points of ignition. The oxygen is generally
used for a short period only towards the end of the operation in order to finish up with
the most intense heat possible and is applied by means of a tube (attached to a cylinder
of compressed oxygen or from a gasometer of oxygen) through one of the openings of
the feeding grid. It is necessary that the heating up should be very gradual the
operation if properly carried out taking several hours.
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 :-
In the manufacture of carbons or filaments for incandescent electric lamps the
employment of a furnace or heater in which "heavy oil" or petroleum or other suitable
oil or coal gas or other suitable heating gas is employed together with a blast of air or
steam with or without the addition of oxygen.