Improvements in or relating to the Manufacture of Incandescent Mantles or Filaments for use in Connection with Gas or Electric Incandescent Lamps.
Year: 1893

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c. Act, 1883), as allowed by
the decision of the Comptroller-General of the 18th day of April 1896.
Date of Application, 4th July, 1893-Accepted, 2nd Sept., 1893
COMPLETE SPECIFICATION (AMENDED).
Improvements in or relating to the Manufacture of Incandescent
Mantles or Filaments for use in Connection with Gas or Electric
Incandescent Lamps.
A communication from OTTO HERMANN STEUER of Dresden, Saxony, German
Empire, Merchant.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
The incandescent manties hitherto in use for incandescent gas lamps have the
great disadvantage of being not only extremely fragile but are also unable to adapt
themselves to the variation in the pressure of the gas. The various means suggested
in order to overcome those defects have all failed inasmuch as they usually
interfered with the power of incandescence. It has also been tried to produce a
support or core for the illuminating minerals or metallic salts so as to give the
latter more durability without reducing their lighting power These experiments
have all been a failure because the metallic oxides could not be made to adhere
firmly to the core and invariably scaled off under the action of the heat.
By means of the present invention it is intended to overcome the aforementioned
difficulties and moreover to provide filaments for electric lamps which filaments
produce a better light than the carbon filaments &c. hitherto in use.
The process
as proposed by the inventor for manufacturing the above articles consists mainly in
providing the incandescent material i.e. the minerals or metallic salts with a skeleton
so to speak, capable of intermixing intimately and firmly with the said salts. This
is done by employing a precious metal such as gold or platinum or also a mixture
of both in the form of dust which has been precipitated from a solution containing
a suitable acid. The precipitated matter appears in the form of a spongy porous
mass of finely divided metal in which form it is especially adapted to mix with and
retain the incandescent materials. The mixture may then either be applied to a
core or support which need not necessarily be made of incombustible material, or
it may simply be mixed with a suitable binding medium into a stiff paste so as to
be moulded into proper shape.
The designation of "incandescent material" in the present description applies to

page_text: all minerals and metallic compounds or combinations especially metallic oxides
which have the property of producing light with an otherwise non-illuminating
flame (such as that of a Bunsen burner) or also when under the influence of an
electric current, to send forth a more or less strong light. The term metallic
precipitation means here the precipitation of gold or platinum or of both in the manner
before described.
The filaments for electric lamps are prepared on the same principle as the
incandescent mantles for gas-lamps and it will be sufficient to explain that the
structure in this case is built up of threads containing each if desired a suitable
core in the form of a thread, while in the previous case the article named refers
especially to the well-known hollow form used in connection with incandescent gas
lamps. Besides the hollow form just mentioned other forms such as cones,
semispheres, perforated plates &c. may be used in gas-lamps.
It is well-known that a solution containing gold or platinum becomes decomposed
under the influence of moderately applied heat. In soaking a fabric or other
absorbing material such as paper wood &c. with a solution containing gold or
platinum or both, the metal will be found to deposit in a minutely divided but
coherent state upon the said material forming thereon a very fine fibrous structure
of proportionately great strength and elasticity to serve as a solid core for the
incandescent mantle. The said core is impregnated with light-producing bodies
such as oxide of calcium (quick-lime) or oxide of strontium so as to produce
an incandescent mantle possessing great elasticity and tenacity together with a
tendency to adapt itself to the flame inasmuch as it increases or reduces slightly in
volume according to the variations in pressure of the gas; this feature forming a
very important point as the pressure of the gas can never be regulated very
exactly.
Two solutions containing respectively the metal and the illuminating body may be
mixed together and then applied to the core.
The gold or platinum in solution will at once become precipitated on account of its
weak affinity to the oxygen and thus help to provide a resistant mantle.
This process requires the use of a separate core. If the said core is composed
of combustible material the improved process has the special advantage of requiring
only very small quantities of the precious metals in order to produce an incandescent
mantle which will not be destroyed or at least not become decomposed even after
a comparatively long period.
If no special core is to be used the illuminating bodies and the metallic solution
may be formed into a paste-like mass by using a suitable binding medium such as
flour, starch, paper pulp, powdered cork and the like. The paste is then shaped
into any desired form, as for instance cylindrical, semi-spherical, or flat or in the
form of perforated plates discs &c.
.
In the preparation of the above the binding medium employed may be china
clay or fire-clay &c.
The incandescent mantles manufactured as described give a somewhat reddish
light which becomes more pronounced in proportion to the greater quantity of
precious metal deposited.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner the
same is to be performed, I declare that what I claim is :-
1. The process for producing incandescent mantles for gas and filaments for
electric lamps consisting in submitting a combustible or non-combustible core
to impregnation with luminous matter or metallic salts in a solution containing gold
or platinum or both metals so that the metal becomes deposited on the said core under
the action of heat and thereby forms a porous and sponge-like but strong and elastic
support for and well-mixed with the said luminous matter.
2. The modification of the process characterized in Claim 1 consisting in the use

page_text: of a paste containing the two above mentioned solutions for manufacturing the
incandescent mantle or filament without an inner core.
3. A filament or mantle substantially as described.
Dated this 4th day of July 1893
W. P. THOMPSON & BOULT
Of London, Nottingham, Liverpool and Manchester.
Agents for the Applicant.