Dodgeville chronicle. [volume] (Dodgeville, Wis.) 1862-current, 1866-06-14
LIGHT.

after speaking OF the natural HgnL OF Inc
sun, the modes Of producing artificial lights
were discussed at length. All these are
various plans of heating some solid body to
very high temperature. Gases, however
highly heated, emit very little light. When
any substance is burned, if the product is
wholly and Immediately gaseous, little light
is produced; while if the product Of COM
bustion is solid, the burning is accompanied
by great production of light. To illus
trate this, some sulphur was burned in
jar Of pure oxygen gas; the product OF
combustion in this case is a gas-sulphurous
acid-and the flame was very dull. = coil
of iron wire was then heated at the end and
plunged into jar of oxygen, when it
burned with scintilations so brilliant that
they were painful tothe eyes. The lecturer
explained that the product of combustion
was a solid-the oxide of iron-and he
called attention to the fact that the jar was
Redeemed by the fumes. The bottom Of the
Jar contained bed of sand, covered by
water to depth of five or six inches, and
as the white-hot pellets of the oxide of iron
dropped into the water they continued red
hot until they reached the bottom. In ex-
PLANTATION it was stated that each pellet on
entering the water Immediately became sur
rounded by an atmosphere of steam, which
preserved it from contact with the liquid.
OUR COMMON LIGHTS.
All our light in ordinary use comes from
intensely heated carbon--generallyb by burn
ing carbon in connection with hydrogen.
Illuminated gas is carbureted hydrogen, and
the products Of its combustion are steam
and carbonic acid. AS both of these are
gases, how is it that great light is produced
light being emitted in any considerable
quantity only from solids? We may burn
gas so that the flame will be very dull it is
necessary only to mingle it, before burning,
thoroughly with air, SO that combustion will
take place throughout the volume. When
it is burned from a jet in the usual way, the
combustion goes on only on the outside
of the issuing stream, and the hydrogen is
burned first, thus decomposing the
gas, and leaving the carbon momentarily in
the solid state. This solid carbon is highly
heated by the flame, and from it, while in
this condition, is emitted nearly all the light
of the Jet. So soon as the hot carbon
passes outward from the body Of the flame
and comes in contact with the air, it also is
burned, combining with the oxygen of the
atmosphere to form carbonic acid.
THE CALCIUM LIGHT.
nu6u hydrogen anu oxygen RdBSS are
burned together, Though the heat is not the
most intense of any that man can produce
with the single exception of the electric
current, the product Of the combustion be-
ing water, in the gaseous form Of steam, the
light emitted is very feeble, but if into the
flame we introduce any solid which will re-
main solid at the intense heat of the flame,
it CLOVIS with a dazzling light. Nearly all
solid substances are either fused or evapo-
rated by the oxy-hydrogen fame, but there
are few that will resist even it's intense
heat, and the most convenient of these is
lime. As lime is the oxyde of the metal,
calcium, the light thus produced is called
the calcium light.
Two calcium lights, prepared by DIR.
Grant of New York, man who makes q
business of exhibiting them, were then
lighted, and the parabolic refectors were
slowly turned around, so as to throw the
parallel beam into different parts of the
house. 1t was curioua to see the universal
dropping of heads, or raising of hats and
handkerchiefs to shield the eyes from the
intolerable brilliancy of the shining bits of
lime.
TPE ELECTRIC LIGHT.
If piece of zinc and piece of platinum
be partially immersed in a vessel of diluted
sulphuric acid, and their outer ends be con-
nected by metallic rod or other conductor
of electricity, the zinc is gradually oxidiz-
ed, and at the same time current Of cleo
tricity starts from the zinc plate, passes
through the fluid to the copper, and thence
flows around through the metallic rod to the
zinc again. This was discovered by DR..
Volta, an Italian physicist, and is therefore
called voltaic circle.
If the metallic rod be of sufficient size to
freely conduct all the electricity generated,
no cheat or light is emitted; but if one
portion of the rod be made so small that
the whole current cannot pass, then this
small portion is heated, and if it be made
sufficiently hot, light is produced. If the
heated rod be of a metal which at high
temperature has strong affinity for oxy-
gen, 1t will of course, be rapidly consumed,
but platinum wire may thus be kept
glowing for many hours
Upon the front of the stage was an APP
par"tus having point of carbon connect
ed with one pole of powerful voltaic bat
terry, while with the opposite pole was
connected a wheel with radiatirg spokes.
the several spokes being armed with differ
ent kinds of metal. This wheel was turned
so as to bring the copper spoke in connec-
tion with the carbon point, and was then
slightly withdrawn so as to make short
break in the circuit between the carbon and
copper. Both were quickly heated to a
high temperature, and the copper was
burned with dazzling green fame. Iron,
zinc, AMI other metals were consumed in the
same way.
Finally, The spoke of the wheel bearing a
carbon point was iyrned in contact with It's
fellow carbon Of the opposite pole, and then
slightly Withdrawn, when the space between
the two was instantly spanned by the arch
of the electric light; before the unequaled
brillial ey of its glow, the gas jets of the
Academy became of yellow, sickly hue,
and the two calcium lights ''paled their
Intellectual fires"
ThE ELECTRIC LIGHT UNDER WATER.
70 show that the light was produced, not
oy the combustion of the carbon, but By its
being intensely heated, the light was exhib-
lted IN vacuum. The points were so ar
ranged that they could be covered by bell
glass, the air was then exhausted by an air
pump, and when the connection was made,
the same brilliant effects followed
Inc points were also connected in a Jar
Of water, but this had the effect somewhat
TO dim the light.
The lecturer explained that the light
comes mainly from intensely heated parti-
Giles OF carbon, which are carried over by
the current from the positive to the mega
i've misunderstanding away the power of
the former and increasing the size of the
latter.
MoNoC HRoMATIC LIGHT.
The large, shallow, leaden tank in front