Improved Filaments for Electric Incandescent Lamps.
Year: 1898

page_text: Date of Application, 20th Sept., 1893--Accepted, 24th June, 1899
COMPLETE SPECIFICATION.
Improved Filaments for Electric Incandescent Lamps.
I, FRITZ DANNERT, Chemist, of 30, Spenerstrasse, Berlin, in the Empire of
Germany, do hereby declare the nature of this invention and what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement:-
This invention for improved filaments for electric incandescent lamps has for
its object to provide filaments having a greater power of emitting light than those
hitherto employed, and to thereby effect a better electric lighting.
The leading novel and fundamental principle in the production of these fila-
ments is as follows:-For the securing of a completely homogeneous resistance
with great intensity of light, the
that is to
say,
hitherto
customary
material
cellulose prepared in the form of
a paste
capable of being ejected from a syringe has added to it metallic salt
solutions of such a kind (1) as contain metal the oxides of which have a great
power of emitting light (2) are capable of combining with the paste like cellulose
preparation so as to form a complete substance or mass capable of being ejected
from a syringe. This substance or mass is as in the usual way ejected or spirted
out in thread-like form, the threads or filaments, after the usual intermediate
operations are carbonised in the muffle or in the crucible and can thereupon be
inserted in the bulb of the incandescent lamp and be made use of. As an example
the following will serve: To cellulose reduced to the paste like form by means
of concentrated acetic acid, magnesium acetate is added-this latter being pre-
ferably produced fresh by putting magnesia usta into concentrated acetic acid and
this being continued (that is to say the addition above named) as long as the form
is retained of a substance capable of being ejected in the manner mentioned,
and from this homogeneous
stirred up
mixture the intended filaments or
threads are produced, which when fully prepared give absolutely homogeneous
threads or filaments with very considerable power of emitting light.
.
It is obvious that, instead of two separate solutions being made and mixed
together, it is possible to add to the non-saturated solution, for example to the
cellulose, the metallic salts, or oxide also, until a certain considerable saturation
results; the oxide being converted into a salt.
As a matter of course the light varies in colour and character according to the
metallic salts chosen.
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
1. The process for the production of filaments for electric incandescent lamps,
the distinguishing feature of which is that for the forming of the filaments, use
is made of homogeneous combinations formed out of cellulose prepared separately

page_text: and mixed with metallic solutions or metallic salts, the metallic oxides of which
possess great power of emitting light.
2. The improved filaments for incandescent lamps substantially as described.
Dated this 20th day of September 1898.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, Agents.