IMPROVEMENTS IN INCANDESCENT ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Jasper Wetter, of New Wandsworth, Surrey for an
invention of IMPROVEMENTS IN INCANDESCENT ELECTRIC LAMPS
A com-
munication from abroad by Lucien Nothomb, of Bruxelles, Belgium
PROVISIONAL SPECIFICATION left by the said Jasper Wetter at the
Office of the Commissioners of Patents on the 24th May 1882.
JASPER WETTER, of New Wandsworth, Surrey, IMPROVEMENTS IN INCANDESCENT
ELECTRIC LAMPS, a communication from abroad by Lucien Nothomb, of Bruxelles,
Belgium,
This invention consists essentially in the nature of the carbon filament and of.
the surrounding atmosphere, in the mode of fixing and in the composition of a
cement for connecting the wires to the carbon.
The incandescing conductor is formed by animal parchment or cellulose carbonised
in an atmosphere carburetted by any suitable means. The cellulose is thus impreg
nated with carbon.
The carbon is fixed to two copper wires by means of a special cement composed
of spongy platinum or iron and any organic matter, preferably molasses or sugar,
which in carbonising produces a very hard and dense carbon. In order to ensure
a perfect contact the copper wire is wound several times around the carbon and the
connection rendered more solid by cement.
The short copper wires terminate at the opposite end in two short platinum wires
passing out of the glass globe and terminating outside with two eyelets by which
the lamp can be hooked to any suitable bracket.
In order to increase the resistance of the glass globe against the pressure of the
external atmosphere I balance the said pressure by filling the inside with a gas
which has no effect on the combustion of the carbon filament, for instance nitrogen
or hydrogen.
•

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Jasper Wetter in the Great Seal Patent Office on the
13th September 1882.
JASPER WETTER, of New Wandsworth, Surrey "IMPROVEMENTS IN INCAN-
DESCENT ELECTRIC LAMPS," a communication from abroad by Lucien Nothomb, of
Bruxelles, Belgium
This lamp, consists chiefly of a special carbon filament which becomes incan-
descent by the passage of the current, and a glass globe from which the oxygen
has been removed The vacuum, which should be as perfect as possible, is obtained
by a mercury pump. The carbon filament is made of cellulose; I use a very
porous wood-fibre, preferably Spanish cane, cut into filaments by a machine and
varying in length according to the strength of the lamp and in thickness from 0.3
to 1 millimetre and upward.
The filaments thus produced are subsequently compressed by a hydraulic press
in order to increase their solidity. Afterwards the filaments are placed in steel
moulds which are subjected to strong pressure and heated to dull red heat for about
an hour in order to commence the carbonisation of the wood.
This operation. is subsequently completed by the electric current.
Instead of cellulose I may use animal' parchment.
The accompanying drawing represents a lamp embodying this invention.
After the filament F, whatever its nature may be, has been prepared, I fix it on
the conductors D, D' each of which is of copper and terminates in a short coil CC¹.
The two ends of the filament are introduced into these conductors and fixed there
by a cement composed as hereinafter described.
The copper conductors are cemented to two platinum wires E, E' passing through
the neck of the lamp and terminating in two eyelets H H¹³, after which carbon is
deposited in the pores of the carbon filament, either by continuing the carbonisa-
tion in a carburetted atmosphere, or by coating the filament with a solution of
purified india-rubber in ether.
I also increase the initial thickness of the filament by about one millimetre,
according to the desired intensity of the lamp. Afterwards I introduce the
filament mounted on its conductors into the lamp, cement the platinum wires to
the globe and pass a current through the lamp while the globe is put in com-
munication with the mercury pump. As soon as the light has reached a sufficient
intensity and all carbonic acid has been removed I close the globe M and the lamp
is completed.
The lamp may contain one or more filaments, all independent from each
other.
The cement for fixing the copper conductors is preferably composed as
follows:-
graphite
calcined borax
linseed oil varnish
"
50 parts
17
"
19

page_text: CLAIMS.
1. The nature and the preparation of filaments of incandescent electric lamps,
made of cellulose or animal parchment, impregnated with carbon, substantially as
described.
2. The nature or composition of the cement for fixing the filaments of incan-
descent lamps to the conductors, and the shape of the conductors, substantially as
described.
In Witness whereof I the said Jasper Wetter have hereunto set my hand
and seal this fourth day of September A.D. 1882.
T WITTED