New-York tribune., 1906-09-17
METALLIC FILAMENT LAMPS.

Many efforts have been made i'm the last five
or ten years successfully TO replace the carbon
thread OF an incandescent electric lamp with
one OF metal or an oxide of metal. The basis of
one rather notable venture was magnesa, which
emitted a brilliant light. hut which could be
made available only with the aid of more
complicated mechanism than Edison required.
Something has been done. too. with Osnium and
tantalum, both rare metals. exhibiting qualities
that afforded encoura cement 20 the inventors.
In order 20 use tantaum to advantage il has
been found necessary TO spin il out to fla
ment of extraordinary slenderneSs and to wind
this tiny fingers into sort Of cats cradle.
The latest experiments 10 attract attention are
those made with tungsten. an element which is
cheaper than tantalum. and which when added
in the proper quantities TO steel imparts TO the
latter exceptional hardness.
From an extended account of the work done
with tungsten, contained in a recent issue Of
The Electrical World" II appears that a con-
siderable variety of processes has been EN-
plOyed in the production Of a filament OF that
material. Such details are of value chiefly
to those who care for the technicalities OF elec-
trio lighting Other facts are presented, how
ever OF great general interest. for the success
which has been attained hints at n revolution
I'm popular practice. Laboratory tests in Vienna
and CharOttenburg prove that with tungsten
two or three times as much light can De naO
from a given amount Of current as is emitted
by the carbon lamp. A few years ago IL was
not feasible 10 more than about dozen
16-candlepOwer lamps with one horsepower.
Fifteen 10 the horsepower is now common
ratio. and if the fiaments coated with
graphite by special process. nineteen can be
used, but no more without sacrifice of bright
ness. II seems to he beyond question that at
least thirty-eight tungsten lamps. of the same
degree of briliancy. can he operated by the
same draft upon the engine room.
Something besides economy in current con
sumption must of course be considered. In re-
spect TO the durability of the tungsten 1lament
much is yet TO be learned. but II seems to have
shown it's superiority TO both carbon and tanta-
lum. On the other hand. nothing is yet known
about the price at which the tungsten lamp will
be sold and this must he determined before any
body can tell whether he will save money by
making a change. Moreover. the experiments
which have been reported thus far have been
made with lamps OF 40 and 60 candlepower In
order to adapt the tungsten fament 10 lamps
of the brightness most commonly demanded it
will be necessary 10 make fresh trials. Indeed.
il is possible that a modification of the central
station equipment may be deemed expedient.
Hence the immediate substitution of the new
lamp for the Edison lamp is out of the ques-
ton. The arc light will probably be the first
one 10 feel the effect of competition. Never
theless The Electrical World" a periodical
which Is not given TO rash utterances expresses
the opinion that 'the tungsten lamp must ulti-
mately prevail" and Silvanus p. Thompson a
leading British authority. declares that "the
carbon flament is doomed by the coming metal
'1ic flament"