An Improved Manufacture of Incandescence-mantles and the like for Gas and other Burners.
Year: 1895

page_text: Date of Application, 4th June, 1895-Accepted, 13th July, 1895
ແ
COMIT LET
An Improved Manufacture of Incandescence-mantles and the like
for Gas and other Burners.
I, Dr. OSKAR KNÖFLER, of Englische Strasse 24 Charlottenburg, in the
Empire of Germany, Chemist, 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:-
The manufacture of practically useful incandescent substances or bodies (such as
mantles) for incandescence gas-lighting, giving the largest surface for the smallest
weight, has hitherto been almost exclusively carried out on the principles made
known by Von Auer.
According thereto, porous filaments or threads of combustible bodies, such as
cotton, as a rule in tubular form, are impregnated with solutions or emulsions
of suitable metallic oxides or salts, especially salts of the group known as the
rare earths," then dried, and burned; whereby such earths remain behind in
continuously connected solid masses, having the original form of the threads and
tissues. Experience has shown that only by the employment of solutions of the
salts named can incandescent bodies of good durability be obtained. This is
explicable by a kind of pseudo-morphosis.
"
Since the cotton-threads, which practically are solely employel for this purpose,
consist of short filaments twisted together, so that, in accordance with the foregoing
explanation, the "mantles or threads of incandescent-substances must also consist
of short threads of oxide only holding together in consequence of an intimate
twisting; and hence, according to all probability, threads or tissues of materially
greater stability, i.e. strength and durability, would be produced, if instead of
subsequently impregnating the finished threads and tissues, as hitherto one could
instead similarly impregnate, with the matter to be incandesced, threads made
endless, which would hold the inorganic incandescent material in corpore so to say.
This is what I have succeeded in doing.
"
:
It has recently been made possible, (as is well-known, in particular, by the labours
of Chardonnet), to produce threads and tissues-which hitherto could only be
obtained from organic vegetable or animal filaments-out of "inorganic"
cellulose, i.e. collodion. Chardonnet obtains his "artificial silk" by compressing
extremely concentrated collodion-solution through capillary tubes, and allowing the
threads to pass through water, whereby the alcohol and ether-are rapidly removed,
and the threads are so "fixed as to admit of being directly reeled, without the
threads subsequently adhering together.
"
In a similar manner I have produced my "in corpore impregnated threads."
I add, to the collodion solution, the corresponding salts (which I find are best
dissolved in alcohol) holding the oxide (or mass of salts) which subsequently
constitute the incandescent body. Substances insoluble in alcohol may be finely
comminuted for mixture with the collodion by trituration. The mixture of
collodion with inorganic substances, thus obtained, and to which, according to
requirement, any other organic substances can be added, in a solid state or in
a state of solution (such as e.g. sugar, camphor, &c.,) is now forced through a series
of capillary tubes by pressure, or drawn through the same by suction or aspiration,
and the resulting threads are either fixed in hot air, or by being allowed to pass
through water; or the fixing may take place by the threads being allowed to pass
through fluids, such as petroleum-ether, benzol, toluol, carbonic disulphide, or
others, which possess the property of appropriating alcohol and-ether without..in.

page_text: the threads.
Chasing the organic salts, evenly distributed throughout
In this way are obtained filaments which cau at once, without further treatment
or preparation, be reeled, spun and woven.
The fixing by water is the simplest and cheapest. For the purpose of preventing
the setting free of any of the salts contained in the threads to he fixed, an alkali or,
better, ammonia is added to the water, which immediately forms a superficial
oxyhydrate coating on the thread, favourable to its preservation.
The burning of such threads or of any fabrics therewith woven, however, when
other organic substances, such as camphor, sugar, etc., have not been mixed with
them, takes place so energetically that it is extremely difficult to obtain really good,
sound, durable incandescent substances or bodies. For that reason the threads
must be denitrated before being burnt. The auxiliary substances which have
hitherto most generally been used in the water-solution, are in this case not very
well adapted for the purpose, because the water is apt to draw out some part of the
inorganic salts incorporated with the threads. This difficulty may be met by
mixing with the fixing-solution above-named (benzin, benzol, &c.) some formal-
dehyde (hydroxylamin), ammonium-sulphide, or the like, so that fixing and
denitrating may take place simultaneously.
It is however better to allow the denitrating solution to take effect for a longer
period, and therefore to let the single, spun, or woven threads remain longer in the
denitrating fluid.
But what has proved itself best is immediate denitration with sulphur alkalies,
especially with ammonium-sulphide, which has been dissolved in water or more
advantageously, in diluted alcohol. In this manner, even tolerably stout threads
may be completely denitrated in half-an-hour.
Made of such denitrated artificial threads or tissues, incandescent mantles are
found to be distinguished by quite exceptional firmness and durability. They are
much better and more easily formed than any other mantles, and, in comparison
with these others, beyond stability, they offer the further advantage that no
substances exercising any deleterious effect on their light-emission capacity are
present an advantage entirely unattainable in other mantles; inasmuch as cotton
mantles even if washed with hydrochloric acid still retain about 0.5 of one per cent.
of ash, which as totally inert material always decreases the light-emitting capacity
of the "incandescent-earths," and also prejudicially affects the stability of the
incandescent mantles.
The essential difference between my process and that which has commonly been
heretofore practised is self-evident, for it has been the custom to impregnate
prepared threads or tissues, made of natural filamentous fibres, subsequently with
incrganic incandescent material; whereas I at once form impregnated artificial
threads (inorganic) and spin or weave these.
As inorganic additions to collodion all suitable and appropriate materials,
soluble or insoluble salts, may be used, which, when the threads or tissues are
burnt out, leave behind an oxide sufficiently refractory not to melt in flame,
besides being stable and possessing a high light-emission capacity in the incan-
descent state. The most firm and durable threads result from the use of salts
which are soluble in alcohol, and particularly nitrates, e.y. thorium-nitrate.
From the collodion illuminating-salt mixture (oxide) other permanent forms
besides endless threads may be made, especially when camphor is added. But,
owing to the material alteration in volume consequent on burning, these have
never given me such firm and durable substances, as I have obtained from the
endless threads above described.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. The production of incandescent bodies for illuminating
purposes from

page_text: individual or spun and eventually wrought or woven threads which are made after
the manner of the so-called artificial silk from collodion previously mixed with
suitable and appropriate oxides oxide-mixtures salts or similar compounds of the
same.
2. In the process described in Claim 1 preparing the collodion by mixing with it
other organic substances e.g. camphor cane-sugar and the like.
3. In the process described in Claim 1 fixing the endless threads by passing them
through a fluid such as benzine benzol or the like which has the capacity to absorb
or withdraw alcohol and ether without the other salts mixed therewith..
4. In the process described in Claims 1 and 3 the addition of ammonium-sulphide
formaldehyde (hydroxylamin), or any other reducing agent having the like effect
to the fixing fluid for the purpose of directly denitrating the thread.
5. In the process described in Claims 1 and 3 the direct denitration of the
completed or prepared thread or tissue by means of ammonium-sulphide or any
other reducing agent having a similar effect used most advantageously in a dilute
alkaline solution.
6. An incandescence-mantle or the like product of the process or processes
hereinbefore described.
Dated this 4th day of June 1895.
BOULT & WADE,
Agents for the Applicant.