New-York tribune., 1879-09-03
MP EnIsnN,s DISCOVERIES.


Much interest was evinced In regard to an I'm
oortaut paper by Mr.. Thomas A. Edison on " The
Phenomena of Heating Metal IL Nacuo by Mesns oi
nm Electric Current" Ia the absence Of MI Edison
Professor +. II. Upton read the paper from the
writer's exquisite manuscript.
In the course Of my experiments on electric lighting
have developed striking phenomena atisng rom
the heating Of metals by flames and by the electric cur
rent espe ciay wires OF platinum ana platinum aIOyed
with ird,um These experiments still IN progress.
The first fact observed that Patirum lost weight
when heated In flame OF hydrogen, that the metal
rsored the fame green and that these two results con-
t'nued until the whole OF the platinum In contact with
the name had disappeared. platinum wire 5000
of an inch IN diameter and weight BOG mii-
sramines was punched together ana suspended
IN hydrogen dame. Ii lost weight ~ the rate OF frac
tion ess than mlgramine pet hour AZ long as u
was suspended In the flame. When platinum wire Is
stretched between clampingposts and arranged to
pass through hydrogen flame. il is colored "A light
green when the temperature Of the wire is raised
above that OF the fame by pasay current through IT,
Tie flame - coloIed a deep green. -
nlstnnm Wire when heated by the electric current
placed bctween two clsmPng-pOsts wire olcoo
cram,nes THIS wire, after II brought 10 incan-
desceneo tventy minutes by the CURRENT lost one
milllTamme. The same wire wss then raised 10 mean
desrepce; FOR twenty minutes IL gave Il loss
Of th-eo milli igramues AitcrwMd II was Kept
inoa descent FOR hour and ten minutes, at
which time II weighed 3Bs nihgrammee,a total loss OF
+ milhgrampes. Another wire Weighing 343 MILL
,r,antoes WAS moderately incandescsnt Tor nine
fonrs aftcr which t weighed 301 millgrammes, show
Ing total iO>s o; AZ mlgrammes,
< platinum wire 1900 Of an inch in diam
oter wss wound in the form OF a spiral ls Of an Al,
g. diameter AID Z inch Ia length The Two ehIs OF
Tue spiral were secured 70 Ssinplhs .poS's; % so % o
whole apparatus was covered with glass shAae "a
inches m diameter and inches high Upon brinsnl the
spiral to for twenty minutes that part V
TIE globe IN llpe with the SIDES Of the spirai became
sghIIy rkened In Ave hours the dcpos, became ~
thick tAst The iDcabdesotut spfai couh hot ps seen
through the deposit This AIM which Was most perfect
consisted % platinum. aud i nave no doubt uut tlat
iarge plstes Of glass might be coated economically by
placinl them each side OF large sheet OF platinum
kept ncsmdetccnt by the electric current ms ioss IN
e-nied yery serious obstacle 10 the use OF metallic
wires FOR giving light by, incandescenoe' but
'nls %as Ssc Ssssccertsined ] coated the wire form
ing the spiral with the "xide Of magnesium,
by dustlng upon II finely powdered acetate OF m"sne-
the heat aud there remained strongy adherebt coat
ing OF tho oxide This spral coated covered with
glass shade and brought To tneantescence for several
glass there O deposlt OF be oxide of nsgne>ia
Prom this and other experiments became
Wasbing action of the air upon the spiral !
that the loss OF weight an and the coiorStion
OF ;hc hydrogen hame was also Que 10 tne away
OF the surface OF the plstina by the a.ton produced
by the impact of the stream or gases npon ,he nkhy
surface and not 10 voiallatioh as coni
have not " led the expefimeet that metallic sodium
canno yOlsE-d IN high vacua by the neat ue'i,eu
from incandescent platinum; any enec' s@' ena'
tnx action OF the residual air. Alter TIE
experiment iet described placed spiral OF platinum
IN the receiver OF common airpump ana aitahgod y,
while tue receiver was exhausted AT pressure OF Two
mmetres spiral kept at incapdescence for two
bOurs before the deposit wac supc,ent 10 become Nis
Sie In another OF xperlmeBt at higher exhaustion IL
S.ouired fye hours before n dopesi became visible
In sesied siass bulb exhausted BY spreasei pump