New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1872-12-30

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THE latter experiment is here represented. the
camera b the lens OF leo, and an envelope contain
ing gun.cotton which exploded when adjusted 10
be within the focus formed by the lens The lens
held in the hand OF the Professor and supported
stand above shown, and its frequent tumbes to the
floor were provocative OF much merrlmentl
This mode OF concentrating the rays OF heat-namev,
by lense the same as that hrs employed by the cell
lens OF ice Is something remarkable IL performed
Dy ocoresby III tine Arctic regions with solar light II
cal Light. The lens NAV be cold the ice is and yet
transmit sufficient heat TO ignite various substances,
This looks odd but 1t is easy Of explanation when we
reflect that only those that absorbed tha
produce the impression OF heat shall endeavo,
points This experiment is a difficult and requires
great eanfiou The diamond As you see, is suspended in
a jar The jar is hlled by displacement with Oxygeu
and the diamond then brought within the focus o. the
light from the mirror.
This experiment was twice attempted. In both in
stances the diamond glowed but did not ignite. The
Professor finally forced confess that da-
mond was not a good one"I
SEPARATING LIGHT. HEAT, AND ACTNIc RAYS
Looking these effects, said the lecturer, the question
naturally arises What constituent Of the radiation pro-
duces theml introduce cell Of alum in front Of the
aperture Of the camera causing interfere with the
light passing from the mirror 10 the focus As you OBJ
serve. the light remains 1t but upon placing
no 90, some gun cotton IN the focus II shines brgby
cell is removed the gun cotton explodes.
This experiment succeeded admirably. The instant
the alum cell Withdrawn the gun cotton Exploded
TINS m mt shows V US 0 hat there must be
mited produces the calorinc effect What is TINS CON
stnentl If we bring the lighB 30 focus by means o.
the mirror within the camera, aud then cut of all light
certain effects VIII follow Which VIII give rs clue
Chemical combination exers an enormous influence ON
the lumnleIOus ether Every person in this brilliant
audience is radiant with these and the reason why
we cannot see them Is that the vibrations slow
which is mechanical mixture Of nitrogen and oxygen,
When tSe Is % e an 81 re-
ducon OF temperature because OF the amount OF heat
Fadaed by earth into space The elementary OOiles
such oxygen hydrogen, chlorine, brOmine etc. are
remarkably transparent to the rays of heat. Let Us
what Will result from using with our apparatus
iodine dissolved In bsulphide OF carbon.
THE solution OF iodine in carbon was placed in posi-
tiOn previous TO which the spectrum from the carbon
points thrown upon the screen. When the solution
Of the iodine weak only the green Of the spectrum
grew dim and disappeared As iodine was added 20 the
solution spectrum and more invaded, and
was finally cut of altogether. No visible ray passed
through -
By means Of the iodine solution employed IN this man
ner we may intercept all the luminous rays OF the spec
trum ana then the calOrihc rays alone now
place piece paper where the focus Of Light and
as you observe, it Instantly ianites
tThe papefwas placed in the position and though there
we're no traces OF light visible there the paper was
burnt by the action Of the heat which alone had
been transmitted The experiment was repeated zinc
being substituted for paper. Silver and platinum were
made 90 glow intensely
will now employ sheet OF platinum, coated with pla-
black instead OF the paper used in the first eXper-
nent Platinum with its surface thus prepared acts in
quinne paper did TO the invisible light rays visible
image carbon points appears the surface OF tue
platinum. The temperature Of tine air surrounding the
glowing PLATINUM has nothing 70 do with this circun-
stance VI heating. The air at the focus may be or a
frosty temperature heat Is communicated 10 IL
from the mirror. The heat raises the platinum to a
white heat while a citing the air This, of course
is owing the fact that while the air cannon absorb the
heat rays the platinum eau and does su keeping the
solution Of iodine IN bsupmde or carbon IN IRON, OF the
camera and thus cutting of ali The luminous rays, Will
proceed burn ~ the perfectly dark focus paper
/ and several Of the metals
Paper, zinc, and magnesium were placed in the dark
focus where the heat sufficient to cause their gni-
\ ton. Tie zinc burned with an intense hght.l
WHY Red HEAT PREcEDEs WHITE HEAT
I What agent produces these effects Let heat a
platinum wire by Of the yoltac current The wire
soon reddens and finally CLOVIS with white heat DR.
Draper to whom glad to pay a tribute Of respect
has shown by prismatic analysis OF the light emitted by
the glowing wire that the light at first pure red AS
the glow augments the red becomes more brilliant bal
at time orange rays added to tbs emission
Augmenng the temperature stili further yellow rays
appear beside the orange after the yelow green Is
are emitted ana ater tue green come ~ succession
blue indigo and violet rays To display all these coiOrs
at the same tame the platinum wire must be w1e.lot
the impression being IN TACT produced 0y the imutane
\ Gus action OF all these cOors ON the optic nerve.
THE expcriment'of heating platinum wire by means
OF yoItaic current was here well shown. The wire en-
poyed was about feet In lengthand the change In
color was distinctly visible in all parts of the hall
Ietu reason backward from this experiment OF DR..
Draper At the beginning and even before the electric
current had uced al all upon the wire, 10 emitted nyisi
bic rays. vibrations waves causing these were
too Ion and too slow 10 excite vision. What becomes Of
wayes They are not destroyed put Lnsr nensl
RES IRE augmented the shorter introduced IL IS
tine wave amplitude and not the wave length when de-
termines the intensity Of heat well as 0f hsht ana
also of gound The rule ia that the square or the
velocity OF the wave determines It's intensity All these
waves listed simultaneously, without such provision
the could be no sun There be rays without dark
also beiug found This, Hersches great discovery
mas shown. How shall We discover these dark rays
The human eye Is delicate regards the visual rays
Rnt when we come other rays not capable Of exciting
visual IMPRESSIONS rho eye viii not suffice, anu We must
employ an instrument 0f greater nicely
DELICATE DETERMINATION or HAT
Ipotice ia the poetry OF Emerson many illusions and
exnreselons which find their application. For instance
he speas at one place Of the discomfort felt by the
human mind for what may call the sateal CONDITION.
Like an organic grow Is the growth or SCIENCE some
thing seems an end but when that end Is reached the
process does not stop the bud expands and opens ana
fruit Is born aud In science, an lnvcsigituH Vi
certain subject discovers facts which a ais own dnu
others hands rpen IntO yet great ones Tor gieteI
means IN 1871 Seebec II Berlin discovered tht meat
applied junction of TWO metals Oi uheluaI Aoa'
conducting power sOldered together 40 one end thr oe
extremlIies OF the bars being connected WIN y"
yan0neer would gave rise W electric cnrfe&sS' VoiSV"'