Improvements in the Manufacture of Incandescent Electric Lamps and of Carbon Rods therefor.
Year: 1887

page_text: Date of Application, 23rd Sept., 1887
Complete Specification Left, 25th June, 1888
Complete Specification Accepted, 7th Sept., 1888
Improvements in the Manufacture of Incandescent Electric Lamps
and of Carbon Rods therefor.
I, GEMINIANO ZANNI, of 1 Courtney Road, Drayton Park, in the County of
Middlesex, Electrician, do hereby declare the nature of this invention to be as
follows
My invention relates to the manufacture of incandescent electric lamps and of
carbon rods therefor.
In the Specification of former Letters Patent granted to me and dated 10th
June A.D. 1882, No. 2741 I have described a method of manufacturing hollow carbon
rods for incandescent electric lamps. One object of my present invention is to provide
for the treatment of such hollow carbon rods to increase their electrical resistance and
illuminating power. The hollow carbon rods which employ are of much larger
diameter than the carbon filaments generally used in incandescent electric lamps,
consequently when a high degree of resistance is imparted to them, they will afford a
much more brilliant light than the ordinary carbon filaments.
In the Specification of former Letters Patont dated 10th July A.D. 1886, No. 9042,
are described lamps provided with two or more carbon rods connected by a conductor
or conductors which are attached to a central glass rod or stem united at each end to
the glass bulb or globe.
Another object of my present invention is to so construct such lamps as to diminish
the conduction of heat to the globe or bulb and to obviate any liability to fracture of
the said rods or of the central glass rod or stem by expansion and contraction.
A further object of my said invention is to reduce the cost of incandescent lamps
by the employment therein of wires or conductors which are much cheaper than the
platinum wires generally used.
My said invention, moreover, comprises other improvements hereinafter described.
In carrying my said invention into practice, I can use hollow carbon rods which are
made from paper or other material by rolling the said material upon a mandrel, or
forming it into hollow rods in any other convenient manner, and then carbonizing the
hollow rods thus formed.
Or I can use rods consisting of straw or other natural products treated, for example,
as described in my said former Specification No. 2741. In some instances, however,

page_text: I manufacture carbon rods from macaroni of about one twentieth part of an inch,
more or less, in diameter. For this purpose, I cut the macaroni into pieces of the
required length and carbonize them by any well-known or suitable means. If desired
they are formed into spirals or other suitable shapes while they are in a plastic state.
To increase the resistance and illuminating power of the carbon rods, I use a
solution of oxide of zirconium and oxide of lanthanum mixed in suitable proportions,
these proportions and the strength of the said solution being varied according to the
resistance required and the illuminating power which it is desired to impart to the said
rods. By preference I employ an aqueous solution of the nitrates or acetates of the
said oxides. I treat the hollow rods, or the material from which they are to be made
by means of this solution and thus form thereon a coating of an earthy nature, thereby
greatly increasing the resistance of the carbon rods and making them capable of
becoming highly incandescent when the electric current is passed through them in the
treatment by ammonia gas. The said rods are, moreover, by this treatment rendered
more durable than the ordinary filaments. They may be tested under the atmospheric
pressure instead of in a vacuum, and if any flaws exist in them, they will give way at
once, if not they will last for a long time. I prefer to cleanse the paper or other
material previously to treating it as above described, by washing it in bydrochloric
acid. I carbonize the said rods in a crucible, or in any other convenient manner, and
then subject them to "flashing" by ammonia gas, to further increase their illuminating
power or capability of being rendered incandescent.
I can also treat solid rods or filaments in the manner above set forth for the purpose
of increasing their resistance and illuminating power.
When it is desired to increase the illuminating power of the rods without imparting
to them a high degree of resistance, 1 treat the said rods, or the material from which
they are to be made, with a solution of nitrate of magnesia.
To obviate any liability to fracture of the carbon rods by expansion and contraction
in lamps of the kind or class described in the said former Specification No. 9042, I,
according to my present invention, arrange the said cross conductor or conductors to
slide upon the central glass rod or stem, and thus accommodate themselves to the
varying length of the rods when subjected to expansion and contraction. Moreover I
attach the said glass rod or stem at one end only, preferably to the leading-in wires so
that it is not sealed to the bulb at any point, the free end of the said rod or stem
fitting into the point or free end of the bulb. Conduction of heat to the bulb is thus
avoided or diminished and liability to breakage of the bulb by expansion of the said
rod or stem is obviated. The said central rod or stem and the carbon rods can more-
over expand and contract freely and without liability to breakage. I find it
advantageous to make the said conductor or conductors of wire which is made to
encircle the glass rod or stem and is twisted together on each side thereof and then
connected to the carbon rods in any convenient manner.
I prefer to make the said conductors and the leading-in wires of electro-platinized
copper, which I find adheres to the glass as efficiently as the expensive platinum wires
heretofore employed. I thus considerably reduce the cost of the lamp.
When I desire to increase the resistance of the lamp 1 sometimes connect the carbon
rods by means of a spiral wire or conductor of German silver, or I arrange spiral
wires or conductors of German silver between the carbon rods and the leading in
wires.
It is obvious that some of my present improvements are applicable to other forms
of incandescent lamps than those above referred to. Moreover, the carbon rods,
instead of being straight, can be made of any other suitable shape.
Dated this 23rd day of September 1887
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: and of Carbon Rods therefor.
I, GEMINIANO ZANNI, of 1 Courtney Road, Drayton Park, in the County of
Middlesex, Electrician, do hereby declare the nature of this invention and in what
manuer the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to incandescent electric lamps and comprises improvements in
the construction of such lamps and in the manufacture of carbon rods or illuminating
conductors therefor.
In the specification of former Letters Patent granted to me and dated 10th June
A.D. 1882, No. 2741, I have described a method of manufacturing hollow carbon rods
for incandescent electric lamps. One feature of my present invention is the treatment
of such hollow carbon rods as hereinafter described to increase their electrical resistance
and illuminating power. These hollow carbon rods are of much larger diameter than the
carbon filaments generally used in incandescent electric lamps, consequently, when a
high degree of resistance is imparted to them, they are capable of affording a much
more brilliant light than the said filaments. I also, however, treat solid carbon
rods or filaments by my process to increase their resistance and illuminating power.
In the specification of former Letters Patent dated 10th July A.D. 1886, No. 9042,
there are described lamps provided with two or more carbon rods connected by a
conductor or conductors attached to a central glass rod or stem which is united at each
end to the glass bulb or globe.
Another feature of my present invention is the construction of lamps of this kind
or class in such a manner as to diminish the conduction of heat to the globe or bulb
and to obviate liability to fracture of the said globe or bulb, or of the carbon rods, or
of the central glass rod or stem by expansion and contraction.
I
Another feature of my said invention is the employment, in an incandescent electric
lamp, of platinized wires or conductors of copper, German-silver or other suitable
metal, which wires are much cheaper than the platinum wires generally used.
thus provide for diminishing the cost of the lamp whilst ensuring the adherence of
the leading-in wires to the glass.
Another feature of my said invention is the employment of German-silver wires
between the carbons and the leading-in wires to increase the resistance of the lamp.
I sometimes make the carbon rods from macaroni or from paste prepared for the
purpose with carbon powder, lamp black or the like or with earthy materials and
formed into hollow rods or sticks in the same manner as macaroni. For this purpose
I take sticks or pieces of the macaroni or of the said paste of about one-twentieth
part of an inch, more or less, in diameter, and cut or divide the same into pieces of
the required length and carbonize them by any well-known or suitable means...If

page_text: desired, these pieces are formed into spirals or other suitable shapes while they are in
a plastic state. I treat these carbon rods or illuminating conductors as hereinafter
described to increase their electrical resistance and illuminating power.
I sometimes make the carbon rods from paper or other materials by rolling the
same upon a mandrel or otherwise imparting thereto a tubular formation and then
carbonizing the same, or from straw or other natural products treated for example, as
described in my said former specification No. 2741.
To increase the resistance and illuminating power of the carbon rods I use a
solution of oxide of zirconium and oxide of lanthanum mixed in suitable proportions;
these proportions and the strength of the said solution being varied according to the
resistance and illuminating power which it is desired to impart to the said rods. Or
I use other chemical compounds which will increase the resistance or illuminating
power, or both, of the carbon rods or filaments. I employ, for instance, an aqueous
solution of the nitrates or acetates of zinconium and lanthanum. I treat the carbon
rods, or the material from which they are to be made, by means of this solution and
thus form thereon a coating of an carthy nature, thereby greatly increasing the
resistance of the carbon rods whilst making them capable of becoming highly incan-
descent when the electric current is passed through them in the treatment by flashing
in ammonia or other gas. The said rods when treated by my process are, morcover,
rendered more durable than the ordinary filaments. They may be tested under the
atmospheric pressure instead of in a vacuum, and, if any flaws exist in them,
they will, under such a condition, give way at once, if not they will be efficient for a
long time.
I prefer to cleanse the paper or other material, previously to treating it as above
described, by washing it in hydrochloric acid. I carbonize the rods in a crucible or
in any other convenient manner, and I subject them to "flashing" by ammonia
or other gas to further increase their illuminating power or capability of being
rendered incandescent.
I can treat either hollow or solid rods or filaments in the manner herein set forth
for the purpose of increasing their resistance and illuminating power.
When it is desired to increase the illuminating power of the rods without imparting
to them a high degree of resistance, I treat the said rods, or the material from which
they are to be made with a solution of nitrate of magnesia and phosphate of magnesia
mixed in suitable proportions, or with calcined magnesia mixed with a solution of
acetate or other salt of magnesia.
In the latter case, the carbon rods are dipped into the solution of calcined magnesia
and acetate or other salt of magnesia, and these substances are then decomposed
by heat.
In some instances. I combine with the paste from which the carbon rods are to be made,
plaster of Paris, clay or other suitable substance which will increase the resistance of
the rods, and I then carbonize the said rods in any convenient manner and treat them
with magnesia or other chemical compounds for the purpose of increasing their
-illuminating power.
In the accompanying drawings.
Figure 1 is a front view of a lamp constructed according to the said former.
specification No. 9042. and having my present improvements applied thereto.
Figure 2 is a front view of the carbon rods and parts connected therewith, ready for
insertion into the globe or bulb.
Figure 3 is a perspective view illustrating my improvements applied to a lamp with
four carbon rods, and
Figure 4 is a perspective view illustrating a modification of the said lamp.
a is the globe or bulb; b, bare the platinum wires, which are sealed into the glass
in the usual or other suitable manner. c, c are hollow carbon rods which are preferably
treated as above described to increase their resistance and illuminating power. Solid
rods may, if desired, be substituted for these hollow rods. d is the cross-conductor
connecting the rods c. e is the central glass rod or stem which serves as a support for
-the carbon rods.at their lower end.

page_text: I arrange the said cross-conductor d to slide upon the central glass rod or stem e
and thus accommodate itself to the varying length of the rods c when subjected to
expansion and contraction. Moreover I attach the said glass rod or stem at one end
only, preferably to the leading-in wires by the cross-bar e', so that it is not sealed to
the bulb at any point, the free end of the said rod or stem fitting loosely into the
point a' of the bulb. Conduction of heat to the bulb is thus avoided or diminished
and liability to breakage of the bulb by expansion and contraction of the central rod
or stem is obviated. The said central rod or stem and the carbon rods can, moreover,
expand and contract freely and without liability to breakage.
When four carbon rods are used, as in Figure 3, I employ two cross-conductors d, d'
and arrange them one above another with a space between them, so that each of the
said conductors can move upon the glass stem e without affecting the other conductor.
I find it advantageous to make the said conductor or conductors d, d' of wires which
are made to encircle the glass rod or stem and are twisted together on each side
thereof as in Figure 3, or 4, and then connected to the carbon rods in any convenient
manner; for instance by sockets f.
I prefer to make the said conductors d and the leading-in wires of electro-
platinized copper or other inetal, which I find adhere to the glass as efficiently as the
expensive platinum wires heretofore employed. I thus considerably reduce the cost of
the lamp.
When I desire to increase the resistance of the lamp, I sometimes connect the carbon
rods by means of a spiral wire or conductor of German silver, or I arrange spiral wires
or conductors of German silver between the carbon rods and the leading in wires
as at g.
It is obvious that some of my present improvements are applicable to other forms
of incandescent lamps than those above referred to. Moreover, the carbon rods or
illuminating conductors, instead of being straight, can be made of any other suitable
shape.
It is evident, moreover, that the cross-conductors d can be otherwise held in or
upon the central rod or stem of the lamp whilst leaving them free to move as required
by the expansion and contraction of the parts.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, wish it understood that
I claim
First. The treatment of carbon rods, filaments or illuminating conductors in the
manner hereinbefore described to increase the electrical resistance or the illuminating
power or both the resistance and the illuminating power thereof, as above specified.
Second. An electric lamp comprising two or more carbon rods or illuminating
conductors connected by one or more metal bars or other conductors which, whilst
held against lateral movement, are free to move up and down, substantially as, and
for the purpose, set forth.
Third. The employment, in an electric lamp, of electro-platinized wires or conductors
of copper or other metal, as, and for the purpose, above specified.
Fourth. The employment, in an electric lamp, of spiral or other wires or conductors
of German-silver, as, and for the purpose, above specified.
Data thin with day of June LSSS
G. ZANNI.
Haseltine, Lake & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.