Method of Effecting in Electric Glow Lamps an Airtight Union between Entering Wires, Made of Non-precious Metal, and the Glass Globe.
Year: 1892

page_text: Date of Application, 16th Dec., 1892
Complete Specification Left, 15th Sept., 1893-Accepted, 18th Nov., 1893
PROVISIONAL, SPECIFICATION.
Method of Effecting in Electric Glow Lamps an Airtight Union
between Entering Wires, Made of Non-precious Metal, and the
Glass Globe.
I, PAUL SCHARF, of I Wipplinger Strasse, No. 38, Vienna, Austria, Engineer,
do hereby declare the nature of this invention to be as follows:-
For supplying electric current to the carbon loop or other incandescence body
contained in the glass globe of electric glow lamps, the parts of the metallic con-
ductors which pass through the neck of the globe have heretofore generally been
made of platinum, because no other metal or alloy possesses the following properties
of platinum:
1, an expansion coefficient nearly identical with that of glass; 2, non oxidizable
nature, and 3, power of supporting the heat of the blow pipe without melting; the
combination of these three properties alone allow of the melting of the glass
effectually on to the wires in such manner as to afford an effective and permanent
closure of the globe.
Experiments heretofore made to employ non-precious metals in place of platinum
have not proved successful, because the intimate union of the glass with such wires
could only be effected by complicated processes that were too dear to be of
advantage.
The present invention relates to a simple method for producing an intimate union
between wires of non-precious metals, such as copper and iron, with the glass globe
of a glow lamp.
This method consists in first securing the said wires carrying the incandescence
body in the glass globe by melting in the manner usual with platinum wire, and
then coating the parts of the wires, where they issue through the glass, with a
layer of a compound consisting of precious metal, in form of fine powder mixed
with adhesive material, and after drying this layer, melting or burning such metal
on to the wires and the surrounding glass, so as to produce a perfect air tight
closure at the point of issue of the wires. After this has been done, it is advan-
tageous to melt some solder on to the layer of precious metal, after treating this
with suitable soldering acid. In carrying out the invention, the wires that project
out through the glass are best cut off flush with the latter, and the powdered
precious metal mixed intimately with either thick turpentine oil, soft resin, Canada
balsam or copaiva balsam or the like, is applied round the wire, dried, and then
burnt in, after this has been effected, the soft solder can be at once applied.
As however by this means the subsequent soldering on of the thin conducting
wires of soft copper, such as are used with all glow lamps, and which are
generally imbedded in gypsum, would be rendered difficult, it is advantageous
to proceed as follows. A thin copper wire is stretched directly over the two
points of entrance of the before mentioned wires into the glass, which have been
coated with precious metal, after which the soft solder is applied to both places
so as to fix the said thin wire thereto, and the piece of thin wire extending
across from the one soldered place to the other is then cut away.
By this means both the hermetic closure of the glass globe and the effectual
securing of the conducting contact between the wires of the lamp and the external
conducting wires is insured. The glass globe can afterwards be exhausted of air
in the usual manner.
For effectually uniting the wires of non precious metal to the glass of the
lamp, two methods can be employed, as is the case with platinum wires.
According to one method, each wire is enclosed in a thin coating of glass,

page_text: which, on heating, easily unites with the glass of the globe, using preferably
small glass tubes for this purpose, made of the same kind of glass as the globe.
These two tubes, after being melted on to the wires, might then be connected
by a transverse bar of glass melted thereon, which will facilitate the subsequent
operations. The lamp globe is then slit open at the neck, the incandescence
body together with its glass-coated supporting wires is introduced through such
slit, and the neck of the globe is melted on to the glass coating of the wires, and to
the uniting bar thereof, when such is used. The small glass tubes must be so
arranged as to project slightly beyond the glass of the globe, in order that they
may have melted glass coiled round them so as to strengthen them.
According to the second method, the wires are directly united to the glass of the
globe, for which purpose these are introduced, together with the incandescence
body, through the slit neck of the globe, and after heating the latter to a plastic
condition, it is squeezed on to the wires. A broad flat strip of glass is thus formed
on the neck of the globe, through which the wires pass. The air tight closure is in
both cases effected as above described.
Dated this 16th day of December 1892.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Method of Effecting in Electric Glow Lamps an Airtight Union
between Entering Wires, Made of Non-precious Metal, and the
Glass Globe.
I, PAUL SCHARF, of I Wipplinger Strasse No. 38 Vienna, Austria, Engineer,
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 :-
In electric incandescent lamps, hitherto in use, for supplying the current to the
carbon filament or other body which is to be made incandescent, the part of the
metallic conductor which passes through the glass-bulb of the lamp, has nearly
always been made of platinum, because no other metal or alloy unites in itself the
three following qualities of platinum:
1. It has nearly the same coefficient of expansion as the glass.
2. It does not oxidize.
3. It does not melt at the temperature produced by the glass blower's lamp.
These three conditions must absolutely be united simultaneously in order to
enable the sealing of the conductors in the glass bulb to be effected and to insure a
permanent and air tight closing of the latter.
The attempts made hitherto to replace the platinum by common metals have
given no satisfactory results, because complicated operations too costly for profit-
able use, were required for connecting tightly the conductors to the glass bulb.
This invention has for its object a simple process for securing tightly wires of
common metal (iron, nickel, copper) to the glass bulb of the lamp.
This process is carried out as follows:-After the leading-in wires of common
metal have been sealed into the glass exactly in the same manner as platinum wires,
the glass at the places of exit of these wires, is covered with a coating of precious
metal, which is allowed to dry and is afterwards heated in the flame of a Bunsen
burner, for the purpose of obtaining an air-tight closing.
After preparing in this manner the places of exit of the leading-in-wires, these
places are covered preferably after moistening with soldering water, with soft
solder (tin solder).
pre-
In the accompanying sheet of drawings Figs. 1-3 illustrate the method of
paring the leading-in-wires carrying the carbon filament for the purpose of sealing
them into the lamp.

page_text: Figs. 4 and 5 show two modifications of the system hereinafter described for
securing tightly the wires to the glass.
For carrying out this invention, the leading-in-wires previously sealed into the
glass, and projecting more or less from the latter, are preferably broken or cut off
close to the glass.
The precious metals employed are taken in their pure pulverulent state, mixed
thoroughly with thick oil (thick turpertine oil, soft rosin, Canada balsam or copaiva
balsam) into a thick paste, applied on and round the places of exit of the wires,
then allowed to dry and finally heated to red heat in the flame of a Bunsen-burner.
The soft solder may be laid directly on the baked coating of precious metal, but
it is preferable to proceed in the following way, since the aforesaid method might
render more difficult the subsequent operation of soldering the thin wires (of soft
copper) connecting the leading-in-wires of the lamp to the exterior contact pieces,
and which must be employed in every incandescent lamp (even in those hitherto in
use, having platinum wires) and are generally embedded in plaster.
On the places of exit of the leading-in-wires a (Figs. 4 and 5) coated with the layer
of baked precious metal, a thin copper wire a¹ is stretched, and then the soft solder c
is applied only to those two places, after which the middle part of the wire a',
extending from one pole of the lamp to the other, is cut off and taken away (Figs. 4
and 5).
In this manner an air tight closing of the glass bulb of the lamp is obtained and
at the same time the connection with the copper wires leading to the exterior con-
tact pieces is established, whereupon the air may be pumped out of the lamp in the
usual manner.
In order to seal the leading-in wires of common metal carrying the filament in
the glass bulb, the same process may be used as for platinum wires, namely as
follows.
Each of the wires a is surrounded by a small quantity of glass which, when
properly heated, unites easily with the glass of the lamp, and preferably has the
shape of a small tube b (Fig. 2) surrounding the wire and made of the same glass
as the bulb. These small tubes, after they have been fixed to the wires a, may be
connected to each other by means of a transverse bridge of glass 6' (Fig. 3) in
order to facilitate the subsequent operation.
Then the neck of the globe is heated and widened so as to form a slit, the
filament and the leading-in wires are inserted through the latter, and the small
glass tubes 6 fixed to the wires are sealed to the glass of the lamp by fusion. If a
glass bridge b has been added, the same may be also melted in (as shown in dotted
lines in Fig. 4) or it may be left to remain inside the bulb.
The small glass tubes must project a little from the glass globe in order that it
may be possible to thicken these tubes by surrounding them with additional
quantities of glass.
The leading-in wires a may also be melted directly into the glass bulb, for which
purpose a slit is cut in the neck of the bulb, the filament and the leading-in wires
(if desired connected by a bridge) are inserted into the latter, the neck of the bulb
is heated and finally pressed with force round the wires. A flat and broad belt,
traversed by the conductors, is thus formed on the neck of the glass bulb, as shewn
in Fig. 5.
In all cases the air tight closing of the lamp and the simultaneous soldering of
the exterior contact wires a' are performed in the hereinbefore described manner.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what
claim is :-
In electric incandescent lamps, the method of connecting leading-in wires of
common metal with the glass bulb, consisting in sealing these wires in the bulb in
the manner used for platinum wires, then coating the glass bulb, at the places of
exit of these leading in wires, with a layer of precious metal which is afterwards

page_text: baked, and on which for the purpose of forming an air tight connection between
these wires and the glass bulb, soft solder is applied either directly on the baked
layer of precious metal, or only after the laying on the ends of the leading in wires
of a thin wire, the part of which that extends between the two solder places being
afterwards cut off, substantially as described.
Dated this 15th day of September 1893.
ABEL & IMRAY,
Agents for the Applicant.