IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1884

page_text: "
I GEORGE PITT of Sutton in the County of Surrey, Gentleman, do hereby
declare the nature of my invention for "IMPROVEMENTS IN ELECTRIC LAMPS
A communication from Charles Beck of Paris Engineer to be as follows:-
The present invention has for its object improvements in electric lamps, its
intent is to produce a portable electric lamp having almost the appearance of an
ordinary oil lamp, very durable, maintained at a small cost and giving a brilliant
light.
For this recourse is had to a new combination which consists in utilising the
electric spark in a medium composed of a gaseous mixture of nitrogen and mercurial
vapour in sufficient quantity to easily hold in suspension fine carbonaceous particles
which are also present. The spark produced by a suitable induction machine
between two electrodes in this medium encounters the carbonaceous particles which
in consequence of the high tension of the gas and their own minute dimensions are
drawn in a rapid current which causes them to pass rapidly and repeatedly into
the spark so that at the end of some seconds the globe in the interior of which the
phenomenon occurs is full of a luminous and incandescent atmosphere. Each
carbonaceous particle becomes white and from its small dimensions and as carbon
has a very high radiating power the lamp gives a light sensibly superior to that of
gas. Besides in consequence of the rapidity of the currents the light may be
regarded as constant; finally the carbon cannot be consumed because the medium
in which it is placed is destitute of oxygen and contains azote only which is
unsuited for combustion. The mercurial vapours are intended to increase the
density and the better to maintain the spark,

page_text: I GEORGE PITT of Sutton in the County of Surrey Gentleman do hereby declare
the nature of my invention for "IMPROVEMENTS IN ELECTRIC LAMPS
" A com-
munication from Charles Beck of Paris Engineer and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement:-
==
The present Invention has for its object improvements in electric lamps, its
intent is to produce a portable electric, lamp, having almost the appearance of an
ordinary oil lamp, very durable, maintained at a small cost and giving a brilliant
light.
For this, recourse is had to a new combination which consists in utilising the
electric spark in a medium composed of a gaseous mixture of nitrogen and mercurial
vapour in sufficient quantity to easily hold in suspension fine carbonaceous particles
which are also present. The spark produced by a suitable induction machine
between two electrodes in this medium encounters the carbonaceous particles which
in consequence of the high tension of the gas and their own minute dimensions are
drawn in a rapid current which causes them to pass rapidly and repeatedly into the
spark so that at the end of some seconds the globe in the interior of which the
phenomenon occurs is full of a luminous and incandescent atmosphere. Each
carbonaceous particle becomes white and from its small dimensions and as carbon
has a very high radiating power the lamp gives a light sensibly superior to that of
gas. Besides in consequence of the rapidity of the currents the light may be
regarded as constant; finally the carbon cannot be consumed because the medium
in which it is placed is destitute of oxygen and contains Azote only, which is
unsuited for combustion. The mercurial vapours are intended to increase the
density and the better to maintain the spark.
In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.
:
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a central vertical section through a lamp embodying my
Invention. Figures 2 and 3 are horizontal sections on the lines x- and y-y
respectively; and Figure 4 is a central vertical section through the lamp globe
showing a modified arrangement of the electrodes. Figure 5 is a view showing
the switch separately.
In the drawings A Figure 1 represents a glass globe preferably constructed in
the ordinary manner in which globes for incandescent electric lamps are made and
having the usual aperture at the point d for exhausting the contents. Within the
globe are the electrodes consisting of platinum balls a. a' provided with platinum
wires bb¹ respectively which pass out through the bottom of the globe those
portions of the wires b b which are within the globe A being insulated by glass
sleeves cc respectively which are hermetically sealed at one end to the surface of
the globe and at the other to the neck or base of the electrodes a a¹. The atmo-
sphere of the globe A having been exhausted by any suitable means-such as for
instance an ordinary mercurial pump-I introduce into the interior a quantity, say
to occupy a hundred and fiftieth part of the capacity of the globe, of pure and
perfectly dry charcoal reduced to an impalpable powder (indicated by the dotted
surface c¹) and then charge the remainder of the globe A with nitrogen gas rarefied
1.-

page_text: "
to about one half its normal density and allow a very small quantity-in fact a
mere trace of metallic mercury in the form of vapor to enter therewith. The
vapor of metallic mercury introduced in the exceedingly minute quantity mentioned
I have found to enhance the operation of the lamp probably by increasing the
5 conducting power of the atmosphere within the globe. The charcoal which I con-
sider best adapted to the purpose is that made from loose cotton or "batting'
purified and dried as perfectly as possible and reduced to an impalpable powder.
After charging the globe as described I seal it hermetically as shown at d and
mount it upon a suitable base V supported by a metallic shell L which serves to
enclose the induction apparatus. The lower portion of the shell L fits snugly within
the top of the jar or vessel B containing the galvanic cell and rests as shown
upon the rim of the jar B. The elements of the galvanic cell (represented by C
and Z) are suspended from a vulcanite disc F by screw caps G H respectively and
may be also braced at their lower ends by means of an annular plate E. The
disc F is secured to the depending rim of the shell L to which is also attached at a
slight distance above a second disc I also of vulcanite and supporting a condenser J.
The condenser is formed in the ordinary manner of alternating sheets of metallic
foil and insulating material the details of which being well understood need not be
particularly described. The wires im from the galvanic cell pass through the
discs F and I and are connected with the condenser in the usual manner. Above
the condenser is a vulcanite cap N which fits within the shell L and supports the
induction coil K and automatic circuit breaker u which may be of any of the well
known forins suitable for producing a rapid succession of discharges or sparks.
Wires ow lead from the poles of the condenser J through the cap N to terminal
points prespectively mounted upon the cap N and adjacent to said points are
two other terminal points R P respectively which are connected with the primary
of the induction coil. The circuit between the points R and 7 and between P
and P is established or broken at will by means of a switch consisting of a segment
of vulcanite M on the under side of which are two strips of copper W W₁ respec-
tively. The segment M is mounted upon a handle S which projects out through
an opening q in the shell L and is pivotted at T. When the switch is in the
central position indicated in Figure 5 the circuit with the coil K is established by
means of the strips W WI; but by turning the handle S in either direction the
circuit is broken. The wires bb leading to the electrodes a a¹ are connected by
means of the binding posts with the secondary coil.
"
The galvanic battery which produces the current may be of any of the well
known types and I therefore do not deem it necessary to give a detailed description
thereof. The use of a "dry pile" is however advantageous when the lamp is
intended to be portable.
The operation of the apparatus is as follows. The switch M being turned so as
to establish the circuit and the battery having been set in operation a rapid
succession of discharges or sparks takes place between the electrodes a a¹. This
action induces a circulation of the atmosphere within the globe A disturbing the
fine particles of carbon and carrying them in suspension into the path of the
electric discharge. They are there located by the passage of the current and as
the circulation continues and the particles are repeatedly subjected to this action
their temperature rises so that ultimately those at any given moment in the path
of the discharge become temporarily incandescent presenting the appearance of a
luminous mist of great brilliancy and if the succession of the discharges be
sufficiently rapid the effect is that of a fixed light.
I contemplate various modifications in form and arrangement of the apparatus
above described. Thus in Figure 4 the electrodes a² a³ are arranged in a vertical
line within the globe A¹ their respective connections b2b being insulated by the
sleeves c2c and the powdered material e¹ being disposed around and upon the
lower electrode a³. So also two or more pairs of electrodes provided with suitable
sources of electric supply may be arranged within the same globe.

page_text: Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is :-
First. The berein before described improvement in the art of electric lighting
which consists in passing an electric discharge through previously comminuted
particles of solid material in a confined inert atmosphere substantially as set forth.
Second. In an electric lamp the combination of the following elements: a closed
translucent envelope or globe charged with a chemically inert gas and containing
also a supply of comminuted refractory material capablo of being rendered incan-
descent by the action of electrical discharges a pair of electrodes arranged within
said globe and provided with conducting wires which extend outside thereof and a
suitablo induction apparatus connected with said wires all substantially in tho
manner set forth.
Third. The herein before described portable electric lamp consisting of the
following elements in combination viz. a jar or vessel containing a galvanic cell a
condenser mounted thereon and in circuit with the poles of said cell an induction
coil and circuit breaker also mounted upon said vessel and having a suitable switch
for establishing and interrupting circuit with said condenser and a closed translucent
globe also mounted upon said vessel and containing a pair of electrodes connected
with the secondary circuit of said induction coil said globe being charged with a
chemically inert gas and with a supply of comminuted refractory material capable
of being rendered incandescent by the electric discharge all substantially as set
forth.