The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1880-05-01
PHOSPHORESCENT LIGHT.


civilized man. He has always found the
hours of daylight too few for his pur-
poses. and has been compelled to supply
artificial illuminatorS in ord to curtail
his hours of darkness. For ages he has
been content to perform his indispensa-
BILE night-work by the light emitted from
the flame of some one of the many hydro
carbons. but at present another method
of obtaining light appears to be coming
into general use. Instead of using the
direct rays of a burning hydro-cafbon,
its heat is employed to create electricity,
which is made to give off light by the
Scintillation of conductor. Instead OF
taking its light from original combus-
tion, the world is preparing to take it at
second hand from an agent which that
combustion sets in motion. There is to
be no more burning of lamps, candles, OF
gases. These little fires are to be BAN
ished from streets and buildings. and the
light is to be drawn from the large fires
under the boilers. The subtitle agent
which is so plenty, and about which so
little is known, is to be sent coursing
along wires from central generators. and
made to pause and glow at the bidding
of whOmsoever may need its illumina-
ton. Instead of catching the light as it
is given off by burning illuminator. the
heat given off in the burning is to be
used to store up the light, to be drawn
on at will. In other words. it is the
power evolved by the burning hydro-car-
bon. and not the light. which is to fur
nish light III the future. The possibility
Of furnishing light economically in this
way depends upon whether it is cheaper
to burn crude hydro-carbon for its
power or to purify it so that it can be
burnt to give light-that is to say wheth-
IT it is cheaper to manufacture electricity
than gas. from coal. The economical
question is already partially solved. and
the electric light appears to be steadily
Gaining ground. For lighting very large
spaces it is found to be cheaper than any
other illuminator and it may be consid-
cred certain that eventually the difficulty
nf subdividing it into small lights will be
overcome.
But while the electric light is claiming
so large share of public attention, an
other method of generating, or rather
storing. light has been brought into no
tice. 1t is an automatic illumination.
which does its work by the sun S storing
up its own light. to be given off after its
departure. Il is well known that GER
tain substances are phosphorescent. Ger
rain bodies. after exposure to light, have
the property ofemitting light when placed
i'll darkness. The cause of this particu-
lar kind of phosphorescence-for there
are several other kinds-it is not neces-
sirv to explain: but the phenomenon it
self is closely allied to fluorescence. The
phosphorescent substances seem to in
crease the wave-lengths of the spectrum.
and retain motion capable of producing
the sensation Of light fora sensible period
after the melting light is removed. For
it must be remembered that the ewes is
an imperfect visual apparatus. To use
an apparent paradox. there is good deal
of light which the eye can not see. Be-
yond the red end of the spectrum there
are light waves too long to make any
impression on the visual organs, and be-
yond the violet end there are waves too
short to produce any effect on them.
If substance could be discovered
which, by exposure to sunlight during the
day, would remain actively phosphores-
cent for sufficient time to make its
light available, it is manifest that very
cheap source of light would be found.
1t would be practically simple prolonga-
ton of sunlight. A few years since al
English chemist claimed to have discov-
cred such substance, and took out :,
patent for it. He has since died. and the
present owners of the patent are again
bringing his discovery into notice in the
form of luminous paint. The sub
stance is compound Of lime and sui
phur. and on being mixed with oil and
other paint, renders them luminous. 1t
is claimed that it can be manufactured
more cheaply than white lead, and from
the cheapness of the ingredients the
claim does not appear to be unreasona-
BILE. Exposed to the ordinary light of
day. this paint remains phosphOrescent
all night. and has been experimentally
applied to variety Of uses. Clock faces
painted with it show the time all night,
and watch boxes are constructed which
illuminate the dials of watches. The
ends of match boxes are painted with it,
and some singular effects have been pro-
duccd by painting statuary and grotto
work in gardens. Recently it was ap-
piled to the dress of diver, and gave
light enough in - feet of not very clear
water to enable him to distinguish bolt
heads on the bottom of a vessel. The
roof of a railroad car coated with it was
run through tunnel and proved an
agreeable dispeller of the darkness
usually attending underground travelling.
Names of streets and signs painted with
it remain visible all night, and it has
been successfully tried in mines where
safety is of more Importance than bril-
liancy. Its illuminating power is not
very great, and it is not claimed that its
use will supersede that of more brilliant
illuminatorS, but it is expected that its
general employment will obviate the ne
cessity for additional light in many in
stances. The fronts of houses painted
with luminous paint would shed a mild
radiance on the street, which would sell
dom require reinforcement from the
more concentrated light of street lamps.
Indeed, if it were applied to all the
houses of Il city, the only necessity for
additional light would be at those places
where no buildings have been erected
Such thing as total darkness would
then be unknown. Door knobs coated
and key holes encircled with it will prove
of valuable assistance to suoh as some
times seek entrance to their homes under
difficulties of y peculiarly distressing
nature. Phnsphorescence rs an illumi-
nator is, however, in it's early infancy,
and it would be rash to say, that it can
never uSnrn the Mace of others which at