The sun. [volume] (New York [N.Y.]) 1833-1916, 1892-03-13
uaAtKsas1.FFAdG M GiAg sA.NSlns H M y.
Their Cost Can re Reduced 20 One. Fourth
Deposition OF Pure Metals.

,apnAhtktas11aFFdf sieAS Sa.SSlns HFE M rv.;.,
Their Cost Can Ke Reduced "a Oae.Fourth-
| Deposition or Pure Metals.
coryrtyh. 1879 b., s. s. No67m,
A blazing pine knot or the glowing embcr.
OF hearth have in their time enabled n good
many men to read their newspapers and
books Primitive though such illumination
may be. 1t has SON ethin2 in common with the
latest and best light tho electric. Remove an
ember from the crate 80 that the draught will no
longer play upon 1t and instantly It begins to
lose brightness, although lite temperature fails
in nothing like tho same degree. A luminous
ray. from whatever source can only be had
from highly heated surface: and its Intensity
increases much faster than the rise in tenn
| perature which creates II. This truth was
borne out in the early experiments with elcc-
| trcity a. a light-brln2or In seeking a sub
stance which the current might raise to white
heat invento g tried iron and platinum. but
| before othSr could be brought - a sattsfac-
tory radiance. the Intensity OF electric heat ha
melted it. Carbon meantime. was giving n
brilliant light In the arc lamp and the
question rose II there was any means OF
adapting |. t., lncandescent illumination. The
quest for a suitable carbon fllamsnt occupied
years AMI required enormous outlay. Every
characteristic North American fibre WAS test
Brazil, to lnnds remotor still. to gather other
nbres In forest and Jungle: at the end OF many
! thousand experiments finely divided strips OF
| btmb,o were foam to give The bost results.
Further success was reached when artas we'll
rs natl WAS laid under contribution. Paper
| and thread ware chnrrcd with scrupulous caro-.
and a"hon Of the tlncst grain reduced to pow
| der was moulded unlsr pressure into delicate
threads. yielding light OF brilliant quality.
! success.
Precisely how the llaments o, the American
| incandcs 'ent lamps OF to-day are made Is Il
trade secret. Tho manufacturers prefer to
| trust tn" honor OF their en- poyees rather than
tode:en Ion the protection Of tho Patent Office
LAMP IAHtNC.
Certain interesting st cps OF the process, how
aver. are matters ~ public information. The
first cnrbon hlaments ma le seldom lasted
more than ilftv hours, rendering the cost OF
lamn renewal as much n tho cost OF current.
In onde ivor;ng to prolon! the lie OF n lamp It
was noticed hat tho Alameat w ~ brighter at
somc points thin others. indicating n vara.
tion Of siZe. Conld this be rcmciied? Could
the filamaat la nude Of uniform diameter?
Fortunately. yes Several years before. NJ. Du-
PROF., II French chemist. had recorded one OF
thase observations SD common III science.
wairh. barren ut tho time they occur, after
ward sprin: int, fruitfuness through dis
closing relationship to puzzlng problem.
He noticed that carbon heated in an atmo-
sphere OF hydro carbon received a deposit OF
an extremely dense form OF carbon upon its
surface. Hero lay the key to increasing the du-
rabiity OF the lamp fament Immersing it
while luminous In u heavy hydro carbon gas or
liquid it took on a solid coating. and where tho
iilamant was hottest and therefore thinn est the
deposit became thickest In this ingenious
fashion the thread was made to repair its own
defects. with marked Improvement in lasting
quality. To further experimental refine
ment the incandescent lamp owes another
point OF its present excellence. For a lamps
success It is essential that the air be exhausted
from its bulb rs thoroughly as possible. Not
wthstanding tho use Of the best pump. Mr..
Swan. one Of the pioneers OF electric lighting.
detected that his nlnments were attacked by
oxygen 1t occurred to him that perhaps a
little OF this gas might have been loft In the
substance ofthe carbon itself. for he we'll knew
how strong was the nifty between gases and
porous forms Of carbon. Thought he. It may
be that II the hlament were kept aglow during
the PUN ping operation the oxygen could be
dslodged. Experiment proved the soundness
OF his surmise and another advance In lamp
making was scored. In leading the wires
bearing curron. into lamp inventors en-
countered u good deal Of difficulty. This was
overcome on discovery that platinum. whom
heated. has much the sans rate OF expansi-
bllty us glass.
CONTINUOUS AND ALTERNATING CURRENTS.
In producing current for Citing the choice
lies between two plans. that OF n continuous
current usually OF comparatively low voltage.
or pressure. AMI that Of IN alternating one.
usually. but not necessarily. OF high voltage
The alternating current. which may have it's
~ cad tn I
has the Advantage Of lending itself to eronomi-
cal transformation. that is to tho production
Of chan yes in its pressure. 1t can be regulated
also with loss loss Of energy than continu-
Gus electrical stream. The continuous cur
rent when furnished. MS it usually is, at go
volts. is well within tho safety limit. and on
the thros-wirc system supplies incandescent
lamps Mt rs volt. avoidin: the toll exacred
by even the best transformer. This is the cur
rent suitable for compact city circuits with
scattered circle Of custom. such us that OF a
suburban district, the alternating system is
preferred.
L.MrI OF NEW SIMPLICITY.
An arc light being five times as brilliant as
nm in"nndcscent lamp. in proportion to the
current supplied. there is u widespread de-
nM nr an n ari Inmr "t mdeEn," size snita
zen, .Ir:a,ts in this "ransh, = iny,ntion
h,'vi"e than any originated On this side the
"''"1, They have made a iamp"f very con:
tn" rnr-rnt re- iurud in the hest American
mrr As shown ut tho Frankfort Exhibition
Lat summer. this cnntrvuace wis 50 s imply
l"M together t!.at It was not beyond the
cnlarity ~ an intelligent domestic to trim
l.. An npo'tlnt point this. for the German
GUST" II j. thai the company which gen.rateS
~ current does nothing more than deliver
it. IN" customer using such lamps as ho
..i,"p>"S manages them himself Indeed. in
G"rniny. the iay is at hand when electric
~ M viii i" bonxh: mt the Groccr's just rs
ri, IN ~ for Kerosene lamps are now. had no
r,'a ~ vN'":s WHY TN, remainder OF the word
slmud logger lmhini Germany. What bars
the way H. tn" universal use Of the clean. pure
bril!mn' ".trt.i' light An oil lamp or II gas
ict .".urrg its foul aud heated products into
the airrf y house. /, really OF the same cate
& "y %; !!!unlinlnts nS tho primitive pine
kunt. In met. tho pino knot TINT sends its
gs-" M chimney l.. in that respect at least.
duci!uGiy superior.
THE EIECrRIC lIGHT ~ UNIVERSAL USE
The c!e-tric light. perfect as it Ia. would
L no riVn were its cost Drought within an