The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1905-05-14

cent lamp, Is n metallic chemical cle-
ment, an obscure member of the chemi-
cal group of metals to which blsmuths
and anthony belong Tantalum Is II
heavy metal, about seventeen times as
heavy ans water, being heavier than mcr-
curry, but not so heavy as gold. 1t is |
about as hard as mild steel. whom pre-
pared for lamp filamcnts, and rs strong |
rs very good steel. 1t remains solid up
to a peculiarly high temperature. whence
It's selection as n proper substance for
an incandcsccnt filament. |
AS a constituent OF n number OF min
erals tantalum Is found In various locall-
ties, as in Massachusetts and In the
mica district OF Western North Carolina,
and TO n limited degree in the mineral
columbltc in Amelia county. Va. AS.
however, q pound Of tnntalum furnishes
material for twenty thousand lamps de-
malid for large quantities Of ores may
| perhaps not become urgent. (The pau
| city OF material In the ordinary carbon
| filament lamp Is strikngly expressed ny
! I3disons remark, when on first walking
| into tho grounds OF the Pan-tmcrican
| Exposition ut Buffalo and seeing Stier-
inger'a Incompatible exterior illuminn-
| ton Of the buildings, he exclaimed:
Magnificent! and all of It done with q
| little pile OF carbon filnments you could
| nut in hat" 1t takes only short
| computation 10 SHOW liie vi 'SSettSs 80 -
| the comment.)
| In construction tho tnntalum lamp
| differs materially from the ordinary car
! bon finment lamp In universal use LOT
| domestic lighting, though IN size ana app
| pearancc it Is equivalent to the type
| With frosted bulb. The filamcnt designed
| for the customary pressure OF 1l0volts.a
/ Instead Of being six or seven inches
! long is about two feet. 10 suspend this
| long filament there are two star-shaped
l supports an upper and lower, ABOUT
| an inch apart, each with n dozen arms
i terminating In hooks. over which UP ana
! down the filnment Is lea In zlg-zas
course not unlike the =. cord ABOUT an
| imaginary drum. The flament Is very
| slender, about two thousandths OF an
/ inch in diameter. To render the support
less apparent frosted bulb Is USED.
In quality OF light the tantalum lamp
is conspicuously good; in fact is a nota-4i
bic Improvement over the ordinary IN
! candescent lamp. AS the result o. ~. nv,
i hiph temperaturo at which the metal
/ sfila,nent can DO worked a clear white
i light replaces the yellowish or orange OF
! the present incandescent light. so PERM
l cious in It's effect on judgment OF color,
1 Az the modern demand becomes IN
4 creasingly Imperative that the light USED
in interior illuminationFat night sha,i ps
equivalent in quality to the sunlGht
. Of daytime. the desirability Will be a IS
precated Of dlsplacing tie present ms
candescent lighting by less jaundiced
substitutes.
4 Economy OF power expenditure IN light
4 ing, while, OF course, highly Important
! has mistakenly as is now recognized.
i heen nlaced before quality of the light
produced. In the incendescent filament'
4 however. the two go generally together.
Z I'm The tantalum lamp the consumption OF
) mower is / Z TO 20 watts per candle. "hlle
lin present average practice the Ordinary
q carbon fllament lansp calls for ABOUT Do
watts per candle Chat Is one morse
power Of 746 watts, sustains fourteen
lamps of the usual sixteen candic noMe OWL
Z LTc be sure with very steady pressure
1 the carbon filament lamp is protitahlS
! rim Mt 80 watts per candle, with I'M
proyement, too in the quality OF tiie
Il light. Higher efficiency than this, now
ever. renders the useful life OF the lamp
. unprofitably short. !,
81 In candle power the tantalum lamp -
less favora bly, circumstanced us canole
newer Of twenty-five to twenty-five is less
accountable than the time-houored sixteen
y of the carbon flamcnt lamp. a very wea'
noint IN electric lighting has always peeh
&Iinability to get lesser light units, attacn-
able to the commercial mains at GOOD
efficiency. The Ncrnst lamp Tor. instance
!: is SO high In candle power nifty LOT tn :
single glover as to be almost a. 'ie .Ll
4 hetween the lncandescent and the u! :
iamn Tho tantalum lamp. particularly
for domestic use, suffers In being npoYe
"a tbor than below the common lamp. u,
In tlength Of useful life, several huHdftu
Il to,,rs Of burning the tantalum lamp Is
substantially equal to the common calu Vl.l
II fIlament lamp. In the first 10" ltu '.'l .
OF burning ineboth cases the CANOE IVY. =. -
increases slightly. A long stationary
,,,1
falls away without equivalent decrease =
consumption OF energy, SO that n polil,
10 reached where economy requires ti'a
tho old lamp be exchanged Tor ne"
The tantalum fiament generally EroW'
brittle and has the disadvantage OF pe'
Ing unable to resist severe 'ns s,;rn
I shock in the later rort'ol 80 - ~ ~.
carbon filament lamp Is Its high sehsl 't
5 nose 10 change Of electric pressure. =
/, i,oht at n point remote from the po"tt
: hnmsa Or s,lb-station ordinarily IS AZ loWt
nIectr,c press,re in the middle eVen''.t
. thnn at midnight, on account Oh uiop ~,
nress,lre due to the large cnrrent ~ ~. 80,
g p,ains at time of heavy Lighting !o.iu
M .,o,, yorintion of pressure the tahta
Inn Lamp is less sensitive, since ~, ~.
g a,ant rio resistance becomes greater as "
: measure, and consequently INC tei''pst'
* ture of the fament rises 40 IN,
a curiously diverse company MY ~,
4 substances now adopted as praclle'p.'
i for incandcscent filaments' ihe ontu w
of the ordinary. filament IS non-'n ~
.au,n clement Or perhaps, we should re
Q gard Il : ,seml-metallc. The Vernst ma
n ,,ant IS not an element at NIL hut
chemical compound. and is not cohdMe
tnr mntil It is heated. The osinum OF, ~ -
o a nv or osmium lamp is a metal o
gold platinum group Tantalmm otsr as nn,
y aa,ann,np 10 another chemical GROUP
!, INTO into ,Ic selection o. an illumin nan !
,,.o,,,e, Of considerations enter, size
the light unit, portability, cleanliness !, y !.
a s adjustablity in amount Of light
safety, Independence, quality OF llsn ,4,
their relative Importance VARYING w
circumstances. The 'anlalui, ,a'', ,,sh !,
clcan ana safe and gives white l'gh'
1t, is reasonably portable In tethere'
SORT of way, is economical In consumptio'