The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1879-12-21


is an induction coil such as are used by peri
patetic showmen ut fairs and other places when they
give electric shocks to inquiring sightseers at 50
much per shock. It is operated by two cells of bat
terry. D. and wires lead from to the glass tubing T.
from which the air has previously been extracted,
and the passage Of the electric through the
tubing gives out light. This plan Is analogous to
what is known as the Geisler tube arrangement the
difference being in the form OF the tube and the ex-
smallness Of the bore and also in the degree
of vacuum produced. Mr.. Edison succeeded by
this arrangement in obtaining light OF several
candle power with q moderately powerful induction
coil. The light. however. not the sought
after Professionally by the inventor. and it took
its place in that part OF his laboratory occupied by
inventions not In use.
osM1UMIRDIUM.
Once more Mr.. Edison made q departure. he
moulded powdered metallic oxides In the form Of
sticks aud subjected them to very high tempera-
ture. In this connection he obtained very fne re-
suits from the native alloy of osmium-irdum called
iridosmine. which alloy he used in the form OF
powder enclosed in tube Of zircon. Tho electric
current passing through the same brought 1t to .
beautiful incandescence.
CARBON PLATINUM.
The inventors next important move was the adop-
substances to be made incandescent. He caused
slender rod Of carbon to rest upon another Of plat
mum. tho infsriorty of contact between the two ut
their point of meeting producing resistance to the
passage of the electric current and causing the
bon to become highly incandescent while tho plati
mum attained only dull red heat The carbon rod
was kept pressing upon the platinum by weight
ingeniousiy arranged dozen or more forms Of
this lamp were made; but. after all the inventor was
obliged to return to platinum the substance most
suitable all things considered. for being made in
candescent. For two months he worked ut platinum
day and night, only to find that platinum no had
been using it, entirely worthless for tncandes-
cent lighting. To many expcrimenters this would
have proved discouragement perhaps fatal. but it
had the effect only Of increasing Edison's deter
mination.
THE CRACKS PLATINUM.
After scores of new experiments he arrived at the
true causes Of the defects and fastened to apply
the remedy. have found. he writes. that when
wires sheets Of platinum. iridium or other metal
lie conductors of electricity that fuse at high
perature exposed to high temperature
their melting point in air for several hours by pass
ing current of electricity through them and then
allowed to cool. the metal Is found to be rup-
tured. and under the microscope thero revealed
myriads of cracks in various directions. many of
also discovered that. contrary to tho received notion
platinum platinum and iridium alloy loses weight
when exposed to the heat of a candle; that
heated 1t to lose weight; that the loss Is
80 great hydrogen flame is tinged green. After
time the metal falls to pieces hence wire sheets
OF platinum or platinum and iridium alloy
known in commerce useless for giving light by
incandescence-
F.rst-Becaa,se the loss Of weight makes 10 expon-
sive and unreliable and causes the burner to DO
rapidly destroyed.
SecoRd-Becauso its electrical resistance changes
by loss in weight. and it's ghtgiving power for tho
total surface Is greatly reduced by tho cracks or
ruptures.
The melting point also il determined by the weak.
est spot of the metal.
PLATINUM IN vAcUo.
BY my invention or discovery am able to prevent
the deterorat of tho platinum or its alloys by
cutting of intcrcepting the atmospheric action.
A spiral wire other forms of platinum is placed in
q glass tube or bulb with tho wire its ends
passing through and sealed in the glass. aud the air
Is exhausted from the glass. The platinum wires of
the spiral are then connected to magneto-eectric
machine battery. the current of which be
trocd by tho addition of resistance. Sufficient cur
rent allowed to pass through the wire bring 1t
to about $50 degrees Fahrenheit Is then allowed to
remain at this temperature Tor ten or fifteen min
utes. While thus heated both tho air and gases
confined In the metal are expelled by the heat or
withdrawn by the vacuum action.
While this air or the gases passing out OF tho
metal Tho mercury pump is kept continually work
ing.
After the expiration of about fifteen minutes the
current passing through the metal is augmented so
that its temperature will be about 800 deg Fahrenheit
aud IL Ia allowed to ROMAN at this temperature for
another ten or fifteen minutes.
The mercury pump is to DO worked continuously
and tho temperature OF the spiral raised at intervals
of ton or fifteen minutes until 10 attains vivid IN.
candoscencc and the glass is contracted where 1t has
passed to the pump and melted together.
BRILLIANT RESULTS.
The wire is now ia perfect vacuum and in a state
heretofore unknown, for 10 may have its tempera-
ture raised to a mos; dazzling incandcsconcc. emit
ting light of twenty five standard candles, whereas
before treatment the same radisting surface gave .
light of only about three standard candles. Tho
wires after being thus free from gases found to
have polish exceeding that OF silver and obtainable
by no other means. No cracks can be after
tho spiral has been raised suddenly to
many times by tho current. and tho most delicate
balance fails to show any loss OF weight in the wire
even after IL is burning for many hours continu-
ously. have further discovered that IL an alloy
Of platinum aud iridium coated with the oxide VI