Improvements in Electric Incandescence Lamps.
Year: 1899

page_text: Date of Application, 1st Nov., 1899
Complete Specification Left. 23rd July 1900-Accepted. 1st Sept. 1900
[Communicated from abroad by LA SOCIÉTÉ DE COMMENTRY-FOURCHAMBAULT ET
DECAZEVILLE, of 16, Place Vendome, Paris, in the Republic of France.]
Improvements in Electric Incandescence Lamps.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention to be as follows:-
Numerous experiments have heretofore been made with the object of sub-
stituting for the platinum which conveys the current to the filaments of incan-
descent lamps, a less costly metal.
The adaptability or alloys of steel and nickel for the above mentioned purpose
has been particularly considered, but in applying such alloys in practice serious
dimiculties have been encountered so that it has been found necessary to modify
the ordinary method of manufacturing these lamps as well as the construction
with regard to the fixing of the conductors. It is this particular method and
the constructional arrangement resulting therefrom that forms the subject of
the present application.
Nickeled steel is far from being as refractory as platinum and the result is
that it becomes brittle and oxidizes when introduced into the flame of a blow-
lamp. Again nickeled steel when heated to a high temperature, evolves a large
amount of vapour which is interposed between the glass and the metal and
thus prevents the attainment of a tight seal or joint which is necessary for
maintaining the vacuum in the bulb.
To obviate these two defects I so arrange nickeled steel wire that it is not
touched by the flame. This is accomplished by inserting the wire in a glass tube
which is heated to the temperature equal to but not exceeding that required for
softening the glass. The glass thus softened is caused to closely surround the
metal by contraction, or it may be applied to the metal by the aid of pincers or a
like tool, or by other suitable means, in such a manner as to form a tight joint.
The surplus of the glass-tube may if desired be then removed and the result, will
be a combination of glass and metal which can be easily joined to the bulb.
It is advantageous to employ as far as possible a very thin glass-tube so that the
softening of the glass may be rapidly effected. By this means the work is more
quickly performed while at the same time the inconveniences arising from the
heating of the metal are reduced to a minimum.
One arrangement which may be adopted for carrying out the method herein-
before set forth consists in blowing two small tubes to one end of a larger tube
terminated by a bell-mouthed portion which latter is subsequently welded to
the bulb. A nickeled steel wire is then inserted in each of the small tubes and
the latter contracted around the metal wire in the manner herein before explained.
The carbon-filament is next fixed to the conducting nickeled steel wires in the
D77

page_text: usual manner and finally the whole is joined to and enclosed in the bulb as is
well known. The manufacture of the incandescent lamp is completed in the
ordinary manner.
The alloys of steel and nickel employed in the above combination of glass,
steel and nickel may be one of the following two groups:
(1) The group containing from 29 to 30% of nickel.
(2) The group containing from 43 to 45% of nickel.
Ordinarily the alloys of the second group are employed for the manufacture of
the improved lamps, these alloys are less oxidizable than those of the first group.
The percentage of nickel is such as to obtain an alloy having the same coefficient
of expansion as the glass of which the bulb is made.
The herein before mentioned percentages in nickel are suitable for alloys con-
taining a very small proportion of manganese, chromium and other metals fre-
quently employed in metallurgy. But the coefficient of expansion of the alloys
tends to increase in the same proportion as the percentage of these metals, such
increase may however be compensated by an increase in the percentage of nickel
for the first group and a decrease for the second group. Generally speaking an
alloy having the coefficient of expansion of a certain glass can be obtained by
adding appropriate quantities of iron, nickel chromium manganese and so forth
to the alloy of steel and nickel which contains about 36% of nickel of which the
expansion coefficient is approximately nil.
The invention therefore permits of the manufacture of incandescent lamps
without the use of platinum which considerably reduces the cost of the lamp.
Various trials have been made with the object of limiting the use of platinum
in such lamps by employing conductors composed of three parts soldered together
end to end, in such a manner that only the portion traversing the glass is of
platinum. This arrangement however increases the cost of manufacture, while
the low price of the above mentioned alloy permits of its employment for the
whole conductor extending from the contact for the current to the filament.
Moreover the invention is not limited, as is the case with platinum, to the
employment of bulbs having a predetermined coefficient of expansion, that of
platinum, since alloys can be provided having any desired coefficient of expansion.
Dated this let doy of Navamo 1900
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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:-
Numerous experiments have heretofore been made with the object of sub-
stituting a less costly metal for the platinum which conveys the current to the
filaments of incandescent electric lamps.
The adaptability of alloys of steel and nickel for the above mentioned purpose
has been particularly considered, but in applying such 'alloys in practice serious
difficulties have been encountered so that it has been found necessary to modify
the ordinary method of manufacturing these lamps. It is this particular method
of manufacturing that forms the subject of the present application.
Nickel steel is far from being as refractory as platinum, and the result is,

page_text: that it becomes brittle and oxidizes when introduced into the flame of a blow-
lamp. Nickel steel even when it has been annealed in vacuo, evolves when
heated to a high temperature, a large amount of gas which remains interposed
between the glass and the metal and thus prevents the attainment of a tight
seal or joint which is necessary for maintaining the vacuum in the bulb of the
lamp.
To obviate these defects I so arrange nickel steel wire that it does not come
in actual contact with the flame. This is effected by inserting the wire in a
glass tube which is heated to a temperature equal to, but not exceeding, that
required for softening the glass. The glass thus softened is caused to closely
surround the metal by contraction, or it may be applied to the metal by the aid
of pincers or like tool, or by other suitable means, in such a manner as to form
a tight joint. The surplus of the glass-tube may if desired be then removed and
the result will be a combination of glass and metal which can be easily joined to
the bulb. It is advantageous to employ as far as possible a very thin glass-tube
so that the 'softening of the glass may be rapidly effected. By this means the
work is more quickly performed while at the same time the inconveniences
arising from the heating of the metal are reduced to a minimum.
A
One arrangement which may be adapted for carrying out the method herein-
before set forth is illustrated in the accompanying drawing and consists in
blowing two small tubes a a to one end of a larger tube b terminated by a
bell-mouthed portion c which latter is subsequently welded to the bulb A.
nickel steel wire f f is then inserted in each of the small tubes a a and the latter
contracted around the metal wire in the manner herein before explained. The
carbon-filament a is next fixed to the conducting nickel steel wires f f in the
usual manner and finally the whole is joined to and enclosed in the bulb as is well
known. The manufacture of the incandescent lamp is completed in the ordinary
manner.
Instead of the above described arrangement the wire may be first imbedded
in or surrounded by glass, either by dipping it in molten glass, or by putting
glass around it.
The alloys of steel and nickel employed in the above combination of glass,
steel and nickel may be one of the following two groups:
(1) The group containing from 29 to 30% of nickel.
(2) The group containing from 43 to 48% of nickel.
Ordinarily the alloys of the second group are employed in the manufacture of
my improved lamps, such alloys being less oxidizable than those of the first
group. The percentage of nickel is such as to obtain an alloy having the same
coefficient of expansion as the glass of which the bulb is made.
The hereinbefore mentioned percentages in nickel are suitable for alloys con-
taining a very small proportion of manganese, chromium and other metals fre-
quently employed in metallurgy. But the coefficient of expansion of the alloys
tends to increase with the percentage of these metals, such increase may however
be compensated by an increase in the percentage of nickel for the first group
and a decrease for the second group. Generally speaking an alloy having the
coefficient of expansion of a certain glass can be obtained by adding appropriate
quantities of iron, nickel chromium manganese and so forth to the alloy of steel
and nickel which contains about 36% of nickel of which the expansion coefficient
is approximately nil.
The invention therefore permits of the manufacture of incandescent lamps
without the use of platinum which considerably reduces the cost of the lamp.
Various trials have been made with the object of limiting the use of platinum
in such lamps by employing conductors composed of three parts soldered together
end to end, in such a manner that only the portion traversing the glass is of
platinum. This arrangement however increases the cost of manufacture, while
the low price of the above mentioned alloy permits of its employment for the
whole conductor extending from the contact for the current to the filament.

page_text: Nevertheless, as this alloy may be easily soldered, or brazed with other metals,
it can also be used in the above described manner.
Moreover the invention is not limited, as is the case with platinum, to the
employment of bulbs having a predetermined coefficient of expansion, such as
that of platinum, since alloys can be provided baving any desired coefficient of
expansion.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondents, I declare that what I claim is:-
1. A process of manufacture of electric incandescent lamps in which the
connecting wires between the outer head and the filament are made of alloys of
iron and nickel of the special composition as above described, so that their
coefficient of expansion may be the same as that of glass substantially as
described.
2. An electric incandescent lamp constructed substantially as herein before
described and illustrated by the accompanying drawing and for the purpose
specified.
Dated this 92nd d
ST11000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.