Electric Incandescent Lamps of Glowing Refractory Substances.
Year: 1899

page_text: PRONISIONAL SPECIFICATION.
Electric Incandescent Lamps of Glowing Refractory Substances.
I, ALFRED HOWARD, of 10, Clifford's Inn, London, E.C., Solicitor, do hereby
declare the nature of this invention to be as follows:-
This invention consists in adapting and using suitable electrolytes and refractory
substances as incandescent bodies radiating light.
Partly or mainly the novel features are improvements upon the features of the
Jablochkoff lamp described in the Specification No. 1996 of A.D. 1877
"
The first features of novelty are connected with improvements in the holding
part of the electrodes or terminals of the electric conductors. The next features
relate to the improvement of Jablochkoff's system of igniting" or lighting up,
that is to say the conversion by heat of non-conductors into active conductors.
Other features relate to the substance, construction, composition, and form of the
bodies to be used as the radiating source of light. The remaining features are for
shielding the glowing electrolyte from superficial cooling or at least mininiising
the cooling and simultaneously reducing the electrical resistance. The body
of the electrolytic substance which when glowing radiates light is hereafter termed
the candle.
Ordinary metallic conductors are used but the terminals actually in contact with
the refractory substance or substances called the candle are to be specially
modified to fit them for their peculiarly difficult functions. The candle being a
thin rod or plate (liable to retain but little strength when heated) a mere vice
retaining the candle by end thrust is unsuitable, whilst the use of metallic cement
or solder will not suit for the facile, perhaps almost daily, insertion of a cheap
fresh candle and fuse or match. Consequently by this invention the terminals
are adapted each to clamp or else closely encompass one end of the candle and
every terminal must be so proportioned in its mass of copper, hard brass, or other
suitable metal that it will resist fusion where it encompasses the glowing candle
and yet not resist the preliminary heating of the candle necessary to convert the
non-conducting electrolyte into an active conductor at suitable electrical pressures.
Because experiment seems to show that there are disadvantages and difficulties
in lighting up by the use of an electrically heated small carbonaceous fuse in
the case of domestic lamps, this invention helps such electrical fuses by com-
bining therewith ingredients, envelopes, or plates of hot and actively burning
substances (of which celluloid, xylonite, &c. are offered as examples) but exclud-
ing of course all dangerously detonating compounds. Where the heating power
suffices to dispense with the electric are resulting from a melted fuse then a
non-conducting combustion match may be used, and the same ignited by a metallic
fuse or otherwise; or a piece of magnesium wire wrapped around the candle may
be used with or without any of the other devices, different arrangements suiting
different electrolytic substances used as candles according to their size and
according to the higher or lower electrical pressures employed.
Kaoline, porcelain, magnesia, lime and mixed sulphates of lime and barium have
been more or less tried; this invention only brings forward the novel feature of
moulding and bonding these and such like substances into firmer candles than

page_text: formerly by giving the same a firmer or, tougher core or a firmer and tougher
skin. For such purpose true porcelain is bad but the hardest stoneware is better,
yet mica, asbestos, steatite and pumice promise still better results and can be
better claimed as novel for the uses intended. Mica especially is to perform a
still more useful and novel function; a refractory substance of high resistance it
is to be used as a kind of holding envelope, core, table or tray as well as a
stiffening support to such frail but good light-yielding electrolytes as are now
commonly employed for the mantles of incandescent gas lights. Doctor W. Nernst
has introduced the use of oxides of the rarer earths in special mixture as electro-
lytes in a form called filaments, but which are such stout filaments as to be rather
rods at least or cylinders in his Specification of Letters Patent 19424 of 1897;
now by this invention the strength of the supported candle is in the mica envelope
or support but the incandescent compounds which are found to have less electrical
resistance than and more light radiating power than mica are in the very novel
form of thinly attached films or layers or upheld matter and they are made capable
of bearing temperatures which could not be otherwise employed and sustained
successfully.
This sandwiching of materials between plates of mica and the like seems to
bring other indirect advantages of possibly very high value owing presumably
to the current passing through the attached or upheld electrolyte with better
results than when the same matter is moulded into a thicker rod-like filament
pipe or cylinder. Besides adding stiffness and strength such mica or similar
envelopes plates, or cores supply a reserve of heat against atmospheric cooling
when centrally situated and an external shield or skin when outwardly applied.
Besides this enveloping connection this invention proposes to use a sleeve of
glass to shield the compound candle; this sleeve is a short glass tube removable
on to one side whilst lighting up and replaceable as a cover to the horizontal
candle protecting the same from air currents with their inevitable dust.
Dated this 3rd day of March 1899.
Electric Incandescent Lamps of Glowing Refractory Substances.
I, ALFRED HOWARD, of 10, Clifford's Inn, in the City of London, Solicitor, 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:
candle" by
The conducting terminals are to hold the glowing refractory
gripping each an end thereof instead of being attached thereto by brazing,
metallic cement, or solder. A screw clamp is the form of gripping apparatus
preferred but to make the same more effective for a very small candle in the
form, say, of a thin strip of mica, the latter should be metallized (at least at the
ends) after one of the well known ways in which ornamental glass and pottery
wares are ornamented with metallic gilt or gilt-like metallic films. After the
high resistance refractory electrolytic material or substance has thus had its
ends (if not more--that is to say even perhaps as far as the middle) coated with
a metallic film, it may be easily further enveloped in a thicker metallic coating
either by a repetition of the process or by ordinary electro-deposition. The metals
most obviously applicable for such purposes are magnesium and aluminium
because their rapid oxidation in air when sufficiently heated will create in situ
the very oxides which are reckoned amongst the best refractory electrolytes for
incandescent purposes, though a difference of opinion has been expressed as to
their light emitting properties unless reinforced by the help of the other elements

page_text: specially introduced into (or accidentally inherent in). the mineral substances
out of which incandescent gas mantles are made. Furthermore the above-men-
tioned metallic film has a temporary useful effect as an initial conductor during
the lighting up process before the full body heat of incandescence is obtained..
However magnesium and aluminium appear not to be the only metals useful in
this way although they seem to be the best for specially short-life". replaceable
cheap candles. Other metals including nickel, platiumin and other difficultly fusible
metals and alloys can be used for similarly metallizing the foundation filaments or
compounds with good effects. This is probably attributable to the special conduc-
tivity of metallic oxides thus situated in connection with metallic particles, and
refractory electrolytic foundations simultaneously existing at the critical moment
of lighting up (at least this appears to be the case with those oxides which. do.
not too readily vaporize or become dissipated under the heat of incandescence).
With regard to the mere metallized ends of candles, they will make the contract
of the candle at the terminal holders more electrically. uniform and effective in.
connection with the novel gripping method of attachment, but this same kind of.
treatment comes in again just as usefully in standardising the resistances and.
making uniform the voltages of different power candles; this would be of course
effected by increasing or varying the density and character of the said films and
especially their disposition and the amount of their extension from the terminal
clamps towards or through the central incandescing portion of the candle. Such.
films again may be more or less in the actual metallic state, being more or less.
perfectly or imperfectly reduced oxides and salts (that is to say more or less.
compounds of metallic particles with other particles partly in a chemically and
partly in a mechanically combined state.) All this developement as far as it was
not foreshadowed in the Provisional Specification's description of the structure;
and composition of the candle is not here being claimed in itself as a distinct and
inherent feature of the invention; it is here placed on record as naturally
emanating from experiments to perfect the invention as first provisionally disclosed
and now hereby to be completed and formally claimed.
It appears that the lighting up of refractory electrolytic "candles" or filaments
of second class" conductors has hitherto been effected by means of an extreme
initial heating and or by extra high voltages. Now it is well known that
immediately the resistance is thus broken down or overcome the filament or candle.
is in danger of being disintegrated by an excess of current. Some recent inven-
tions obviate the troubles which thus arise by the automatic insertion of high
resistances. Now my second feature of novelty improves matters after the manner
of Lieutenant Paul Jablochkoff's conducting or igniting "match." I apply a
high degree of rapid preliminary heating in a form admitting of the lamp being
lighted up as nearly as possible by a current not so much as otherwise in excess
of the feeding current to be afterwards maintained. For this purpose the sub-
stances used by me are (1) magnesium in lieu of or in addition to Jabockhoff's
carbonaceous igniting match and (2) celluloid compounds as mere high tem-
perature flaming heaters whether started by the arcing of a fuse (carbonaceous or,
metallic-magnesium or the like), or by an externally applied flame. The mere.
heating adjuncts of the candle" or filament proper are assisted by the action
of the before mentioned metallic gilt-like deposits or coatings which help to
afford an initial low resistance to the current of a low measurement until changed
by the incandescing heat of the ignited candle which simultaneously changes:
the unignited candle's high internal resistance for a lowered ignited or incan-
descing résistance. Thus the loss of one counterbalancing the gain of the other
something approximating uniformity prevails and the problem of solving the
difficulty of introducing an electrolytic incandescing candle becomes less com-
plicated.
"
61
"
**
The next feature of novelty consists in using mica as the candle or as the core
foundation filament or basis of a more or less compound "candle." Steatite or
pumice may be used instead of native mica, or cemented compounds of all or any
;

page_text: of such substances may be used. To make a candle with a mica basis or core
and refractory metal or metallic earth oxide or other similar incandescing film
(more or less an overlay or more or less a combination) the surface of the filament,
rod or plate may be coated with various nitrates, acetates, sulphates, chlorides, or
the like partially or wholly reduced by burning or heating as well as by blending 5
with borax, borates.or. other. known reducing and reducible agents. By a careful
process of repeated incandescing (electrolytically or by flame heat) the con-
stituents or components of a candle can be condensed bonded and improved, the
practical life of the candle being thereby lengthened. The .common substance
ordinary called mica, whether magnesian "potash" or other mica, possessing a 1
laminated or foliaceous structure and being disposed to swell and separate into a
mass of tissues on heating, it becomes both possible and necessary to consolidate.
and bond the candle of such materials by treating the foundation filament by
suitable coatings of reducing and reducible agents. The metallizing as well as
the other coating or mized mineralizing of the surface of such candles comes in
especially useful in connection with the formation of a compound candle upon a
mica foundation as herein contemplated and described.
.
:"
Because the filament of the refractory incandescent material called the "candle
is a short and thin rod or plate glowing with extreme heat, it is excessively liable
to superficial cooling by air-currents so that it should be guarded by some kind
of shade or globe. Over and above any ordinary globe or shade for safe guarding
and general protection, I propose to shield the "candle" very closely by a remove-
able small sleeve of glass. Such sleeve of glass is simply a short straight length
of tube, open at each end; it is to be removeable by sliding on to one side out of
the way whilst lighting up and easily replaceable immediately afterwards as a
protecting cover surrounding the candle without touching the same.
It is contemplated to manufacture some specially cheap candles so suited to
a form of lamp holding the same in a manner facilitating their removal, and
replacement, that it will be feasible and economical to renew the lamp candle
daily or as often as the lamp is to be fresh lighted up. It may be pointed out, that
this feature alone thus constitutes the present invention a novel developement of
Jabloclikoff's old invention in a direction very different to that of other recent
inventions. Of course the general features of novelty are also intended to be
applied to "candles" or filaments destined for a longer life than the specially
cheap, and ephemeral candles.
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:-
::
candle to
1. The facile attachment of the special refractory electrolytic
the terminals of the leads (obviating the use of and inevitable trouble with
soldered ends) substantially as above described.
2. The improved igniting "match" or flaming heater including the employment
of magnesium and of celluloid with or without an arcing fuse substantially as
above described.
3. The use of mica as the substance or foundation of my electrolytic candle
substantially as above described.
4. The use of mica, steatite, or pumice treated coated, and enveloped with
metallic particles, mineral matter, metallic oxides, salts, or compounds sub-
stantially as above described.
5. The combination of the refractory foundation with the overlayed glowing
(light emitting) electrolyte manufactured in situ substantially as above described.
6. The glass cylindrical protecting tube or shield for the candle shaped and
applied substantially as above described.
1000
.