The daily Gate City. [volume] (Keokuk, Iowa) 1855-1916, 1911-10-17
PROGRESS OF ELECTRIC LIGHTS.

PROGRESS OF ELECTRIC LIGHTS.
An article of considerable interest
on the subject of "The Progress OF the
Electric Light" appears in Science
Progress, an English publication, and
is written by Maurice Solomon. A. G.
la. l.. M. l. E. E. He points out that
about FIVE years ago the best lamp for
ordinary indoor lighting was the car
bon filament lamp. This lamp was
invented In 1878, and many improve
ments were made in it. When new,
the carbon filament lamp should con-
sumo between three and four watts
per candle. 1t has life OF about
| / 900 hours, during which it consumes
on an average from 4 to 40 watts per
candle
In 1898 the Nernst lamp was in
vented. It's filament is made OF mix
ture of oxides which become conduct
| ing at moderately high temperature.
To heat the filament up to the re
quisite temperature porcelain spiral
T s wound openly round it. and fine
platinum wire is closely wound round
the porcelain The current flows
through the platinum wire and thus
heats the filament Of the lamp. AS
soon as the filament becomes hot
enough the current begins to flow
through it, and works cut out which
breaks the platinum wire circuit. An
other complication is that as the
Nernst f1lament falls in resistance Its
Temperature rises, and 1t has to be
run in series with special resistance.
Thus although the Nernst lamp was
far more economical than the car
bon filament lamp, it was SO complt-
Gated that 1t was never used ex-
tensively.
In 1905 the first metallic f1lament
lamp appeared, the Osmium lamp.
But it was not great success chiefly
because the filament is so brittle when
Icold.
The Osmium lamp was quickly fol-
lowed by the tantalum lamp, brought
Iout by Messrs Siemens and Halshire.
These metallic flament lamps look
lust like carbon filament lamps, but
with a different filament. For the
ltantalum lamp the average consump-
tion in watts per candle Is 1.85 for
!, direct current lamps and two watts
for alternating lamps; that is. 1t con
. sumes about half the energy OIL the
: carbon flament lamp, and it was q
I great success.
/ But the next advance came almost
J. Immediately. The tungsten lamp, call
Y ed the Osram lamp, was brought Out
/ by the Welsbach Company. and con
sumes between LIZ and Ia watts pei
candle, during life of at least 1,50C
= hours.
;. There is point in the life of lamp
4 called the smashing point" when II
a is more economical to discard the
4 lamp, as it begins to consume 30 much
l. energy; this is the economical life
J. But in practice it is not easy to tel
r when this point has been reached, ant
6 the figures given refer to the "usefu
Y life" of a lamp, that is to the tim
n when the candle power given falls t
about so per cent of it's original value
This useful life" Is longer than tn
;. the Economical life," but the loss |
9 not great; it does not, however, pa
to run lamp. when It's candle powe
!, falls more than this.
/. The arc lamp, used for outdoo
a lighting and for very large interior
o has also been much improved. Thi
~ lamp consists of an arc burning b.
). tween two carbon rods. In the ope
q arc 1t is enclosed in a glass globe
a. protect it from wind, etc: and in tn
q closed arc it is enclosed in fairly a
!, tight globe, carbonic acid Is given o
and fills the globe and the carbon
burn moro slowly. Thus, although II
,f closed arc consumes more enere
q than the open arc (2.3 watts pr
"a candle against Ia to IL watts p'
"a candle), the carbons last longer al
n the arc does not take SO much tril
,r ming.
d. The first noteworthy improveme
at consisted in the invention OF hollo
v. carbons filled with some volatile su
IN stance which, vaporizing, lowered Il
no resistance of the arc and steadied
TO- The first satisfactory fame arc w
ty made by Bremen. 1S98-l9o0; improy
"a ments were made subsequently al
re- now the fame carbon has core fro
he ope-third to one-half the diameter
/. the carbon. This core consists OF c;
bon, potassium silicate, and fluorid
lot calcium fuoride gives yellow far
yn and strontium fuoride red one. T
at fiuoride volatilizes and lowers t
he resistance of the arc, and thus max
he it possible to work with longer OF
Ia a great advantage in many ways.
cir The yellow flame arc consumes 70
ep- and the white fame arc seven wat
srs per candle. The fame arc is tn
asst much more economical than the op
Of or the enclosed arcs, which consur
err IL to Ia and 2.9 watts per candle
po spectiyely. But when comparing I
hn cost of the arc lamp with the metal
vas filament lamp it is necessary
g