Improvements in Illuminating Conductors for Incandescent Electric Lamps.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Illuminating Conductors for Incandescent Electric
Lamps.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Chartered Patent Agent, do hereby
declare the nature of this invention (as communicated to me fom abroad by
Dr. Carl Auer von Welsbach, of IV. Schleifmuhlgasse, 4, Vienna, Austila,)
to be as follows:
-
My invention relates to an improved type of filaments for use as the illumi-
nating conductors in incandescent lamps
I have found that when a mixture is taken of osmium and a refractory oxide
or oxides such as thorium oxide, zircon oxide, or the oxides of the rare earths
or other refractory oxide, it can be raised to a very high temperature without the
osmium becoming oxidised, provided the mixture is properly made Under these
circumstances bodies of a very peculiar type appear to be formed out of the osmium
and the oxides They have usually a grey metallic appearance and even when
cold are good conductors. When raised to a high temperature by electrical
heating, they give out light in a manner which makes them specially suited for
the ригрове above mentioned.
I manufacture these filaments by taking finely divided osmium and a refractory
oxide (such for instance as thorium oxide) or a salt of such an oxide which is
decomposed by heat and leaves only the oxide as residue These bodies are mixed
together into a paste with a dilute solution of sugar or other organic substance as
binding material. The paste is worked and kneaded until it is quite uniform in
consistency and is then pressed rolled or squeezed into fine threads or other con-
venient shapes
This
These are then dried in the air and gradually heated electrically in air until the
first products of the decomposition of the organic material pass off. They are then
raised to incandescence in a reducing atmosphere containing water vapour.
is done gradually with the result that the carbon 18 burned away and a mixture
or compound of the osmium and oxide or oxides is left behind, forming an
illuminating conductor of the shape chosen.
In the above I have briefly described the mode of manufacture, which can
however be varied By means of it I obtain a filament of osmium and refractory
oxide peculiarly suited for use in electric incandescent lampe.
It is to be understood that in place of osmium, other metals of the platinum
group, or their alloys, may be used.
Dated this 11th day of June 1898.

page_text: Improvements in Illuminating Conductors for Incandescent Electric
Lamps.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings,
Chancery Lane, in the County of London, Chartered Patent Agent, do hereby
declare the nature of this invention (as communicated to me from abroad by
Dr. Carl Auer von Welsbach, of IV Schleifmuhlgasse, 4, Vienna, Austria,)
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement; —
My invention relates to improved types of filament for use as the illuminating
conductors in incandescent electric lamps
I have found that when a mixture is taken of osmium and some refractory
oxide or oxides anch as thorium oxide or zirconium oxide or the oxides of any of
the other rare earths such a mixture can be raised to a very high temperature
without the osmium becoming oxidized and indeed the melting point of these
oxides may be reached without any oxidation of the osmium taking place
result of heating such a mixture to the extent indicated above is to produce from
the osmium and the refractory oxides bodies of a peculiar character varying in
colour from black to a metallic grey and behaving as good conductors of electricity
when cold.
The
The bodies formed as above have a remarkable capacity for resisting very
high temperatures especially when the refractory oxide which has been used
in the mixture is non volatile at high temperature It is from these bodies that
I manufacture the filaments which are the subject of this invention and in the
manufacture of such filaments I proceed as follows-
I mix finely divided osmium with a refractory oxide (such as thorium oxide)
or with a salt which, when heated strongly, leaves the oxide behind as a residue,
and bind the whole together as a paste with a little concentrated solution of sugar
or other organic substance which is suitable for the purpose
The proportions may be varied within certain limits For example there may
be 3 parts by weight of finely divided osmium to 1 part of finely divided thorium
oxide with sufficient sugar solution to make a suitable paste This would be suitable
for a current of 100 volta. For currents of higher tension such as 300 volts
the thorium oxide and osmium should be in approximately equal quantities.
The paste is then worked and kneaded until it is quite uniform in consistence
and is then formed by pressure forcing through a die or otherwise into the desired
form which may be that of a filament or thin plate The threads or plates which
are thus produced are then dried in the air and afterwards gradually heated in the
ai by passing a current through them until the first products of the combustion
of the organic binding material have passed off They are then gradually.
heated to incandescence in a reducing atmosphere containing water-vapour
the current through the filament increases and the temperature rises the carbon
compounds are burnt up and the osmium and the resistant oxide are left behind
in a thread or plate like form.
AB
The proportion of thorium oxide in the mixture of thorium oxide osmium and
carbonaceous material must not be indefinitely increased, it must be kept within
Buch limits that the filament will still act as a conductor to a current of the
required strength when in a cold condition, even after the carbon has been
consumed.
Also the proportion of sugar or other organic binding material of the mixture→

page_text: although to a certain extent variable must not be taken higher than is absolutely
necessary for binding together the separate particles of the mixture.
Pure osmium should preferably be employed for the compound of thorium
oxide, osmium and organic binding material, but osmium mixed or alloyed with
other platinum metals, such as ridium and ruthenium, as components of the
mixture may be advantageously used, it is however to be noted that the melting
point of osmium is considerably lowered by the addition of a considerable pro-
portion of other more easily fusible metals of the platinum group
Also for the thorium oxide in the said compound of thorium oxide, osmium and
organic binding material may be either partially or wholly substituted zirconium
oxide or the Ytterite earths. Also instead of thorium oxide may be used thorium
nitrate, or generally any salt of thorium that is reduced by heat to the condition
of oxide
I may fill the lamps which are used to contain the filament with a reducing
gas or with a gas which has no action on the hot filament or with a mixture of
such gases or I may enclose the filament in an exhausted bulb
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim 18.-
1 The production of filaments or plates for incandescent electric lamps from a
paste obtained by mixing osmium or some other resistant metal of the platinum
group, with some refractory oxide or a salt which when strongly heated leaves
the oxide behind as a residue and an organic binding material and driving off
the organic and volatile constituents by heat aubstantially as described.
2 The herein described process for making the illuminating conductors of
incandescent electric lamps
3 Illuminating conductors for incandescent electric lamps made as described
T
111
1000
ABEL & IMRAY,
Agents for the Applicant