The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1896-09-25
LIGHT MINUS HEAT.
Science Slowly Solving The Mystery
of PhosphOrescence.

The Progress Of Investigation, Experiment
and Discovery as They Have Been Made
Down to the Recognition of the Roent-
gen Ray.
Bit by bit the old mystery which sur
rounds the subject Of the emission of light
by phosphorescent substances is being I'M
raveled Uncanny stories of corpse lights
and will o. the wisps may continue to fur
nish food for the folklorist, and the tabled
lamp of Aladdin will flourish forever in
story. Science, when she dissipates a nsys-
terry, always ends by leaving the heart of
the fable untouched. Nevertheless she does
explore the facts that lie at the base of ro-
nance, and sometimes deals cruelty with
them.
OF the out of the way corners of science
none has been more tempting than that
which is concerned with the strange prop
erty of giving out light without heat To
the alchelnists are due the beginnings Of
real discovery. Did not Kraft evolve from
hideous brew of organic matter the ma
terial afterward isolated as the chemical
element, phosphorus? Its slow oxidation
miliar to every schoolboy as belonging to
lucifer matches. Did not an obscure shoe
maker of Bologna discover that by heat
ing in furnace, mixed with little flour
meal. certain powdered spar from Monte
Palermo, there was yielded chalky pow
der having the property of shining in the
dark after having been exposed TO SUM-
lghtf
Here was prime mystery. No combus-
ton, no waste of substance-in short, a
mere bottling up of daylight to emit it
again with feeble night long CLEAN when
all around was dark. To the famous phos-
phorus Of Bologna succeeded the more
brilliant phosphorus of John Canton, con-
cocted of oyster shells calcined with char
coal or meal in closed crucibie. And the
phosphorus Of Canton is in our day super
seeded by luminous paint, used for clock
faces and matchbox tops, that need to be
visible in the blackness of night. Science
tells us that, after all. these are only sui
phides Of the alkaline earths, but, be that
so, those that shine best are never pure
sulphides.
Closely akin to phosphorescence Is the
property of fuorescenoe, the nature of
which, though some of the facts were
known to Goethe, to Brewster and to
Herschel, was first explained by Sir George
Stokes. A chip of horse chestnut bark, a
crystal of uuinine or a grain of the dye
stuff eosin is dropped into water-acidu-
lated, 1t may be, to hasten solution-and,
behold, the liquid exhibits on the surface
exposed to light most beautiful ooloring,
green. blue or orange. as the case NAV be.
That liquid should possess surface
color where the light first strikes it, and
that color be quite differept from the color
of the LIQUID itself. as seen by transmitted
light, is a fact that fascinates by its para
doxical nature. Why should the green
LIQUID made by maceratfng young green
leaves in alcohol shine with q deep red
color on it's surface? Fluorspar, the ssblue-
john Of the miners, exhibits q similar
possession, for its surface color is differ
emit from the tint of the mineral.
Stokes showed that this surface tint is
due to the property of the liquid in trans
forming into Visible colored light some Of
the invisible waves which are ALWAYS pres.
| emit in daylight, and from their position in
| the spectrum are called ultra violet waves
| being waves of shorter length and higher
| frequency of vibration than the shortest Of
| visible waves-namely, the violet This
| transmission of visible into invisible
| Stokes named fuorescenoa
Then followed the discovery that these
waves, which excite fiuorescence, as above
| described, and which are the very waves
| that are most active photographioally, are
also the waves that are most active in pro-
ducing phosphorescence In the luminous
paints. Here was afforded very broad
| hint that both fuorescence and phosphor
escence might be, like Photographic ac
tions, chemical phenomena in their es
sence.
Then the patient Becquerel, using In
strumental methods for observing sub
stances in the dark after they had been ex
posed to light, and especially to ultra VIC
let waves for a brief fraction OF second
showed that phosphorescence, so far from
being rare property, is possessed by in
| Vulnerable kinds of stuffs. Chalk, poece
lain, glass of various sorts and rubies
shine for twentieth Of a second or So
| Some artificial chemical crystals, notably
the green compounds of uranium, shine