Evening star. [volume] (Washington, D.C.) 1854-1972, 1893-11-25

HM OIL investigators in
| NA/ } the mysterious and
~ sAN>r~S seductive field of op-
| sa,ES tics Today the most
eminent experts in
this line all over the world are trying to
solve it. That the object aimed at will be
accomplished before very long there can be
no reasonable doubt
In fact, the thing has been done already,
only that the processes require perfecting
monographs of the solar spectrum show
ing all the brilliant hues of the rainbow.
have been made, possessing the long sought
quality Of permarencA. This is accomplish
Gu III way devised by member of the
National Academy of France From a
| scientific point of view his process is the
most interesting ever invented He laws
upon sheet of glass a very delicate, trans
lucent film of chloride of silver and against
the MIN he places vessel containing mer-
curry, SO that the latter is in contact with
| the film.
Inc glass sheet and mercury thus arrang-
ed are placed in the camera like an ordina-
ry sensitive plate. Exposure being made
the image or the object to be photographed
is projected upon the glass. The light con-
Veylng the image passes through the glass,
| on through the translucent film, and is re-
| Hected back by the mercury behind The
| action of the light splits the silver in the
him into thin layers which break up the
light rays into their component colors.
! 1t is we'll known that the play of colors
| in an opal are due 10 the fact that this
| gem is composed of layers of quartz super
POSED one upon anothe-. These layers
| break up the light into various hues The
| same effect is accomplished by the layers of
| silver In the film, which through the opera
ton of curious law reproduce the tints of
/ the object photographed. In this way the
brilliant coloration of gorgeous parrots has
been copied by the camera, and sun pictures
made in this way are permanent
In sense this process may be said to
/ have solved the problem referred to; but it
! Is defective in that long exposure of the
/ plate is reQured-that is to say from five
minutes to half an hour. But, in order TO
/ overcome this difficulty, it is merely neceS-
sary that the film shall be rendered more
sensitive to light. The same trouble for a
long time interfered with the usefulness of
/ the dague-reotype method, fifty years ago,
which could not be utilized for portraits,
| because an exposure of several hours was
necessary, and nobody could keep still 50
/ long.
! Results of Previous Efforts.
Photography in colors is no new thing
In the early days of that art daguerreo-
|
though it was wholly accidental. The man.
| I er in which this was accomplished long
remained a mystery, but it is now supposed
| that the phenomenon was due to contamina-
ton of the silver surface of the copper plate
! by the copper beneath 1t has been found
| that chloride of silver with chloride of cop
per will reproduce colo-s to some extent.
/ But the coiors in these old pictures quickly
| faded.
About the year 1854, Becquerel and Niepce
| St. Victor produced photographs in colors,
using ordinary daguerreOtype plates, which
/ they subjected to elaborate treatment for
the purpose. incidentally baking them for
a long time in an oven. But the tints re-
/ fused to stay, and no process could be dis
covered for rendering them permanent.
They would fade and disappear in few
minutes on being exposed to daylight The
plates which they prepared exhibited one
popularity quite remarkable from a techni-
/ cal standpoint. They would reproduce
white lights as we'll as colors, whereas,
dinarily speaking, plates that are sensitive
to colored lights are not sensitive to white
lights. After prolonged and laborious eX~
perlments, Messrs St. Victor and Becquerel
abandoned their effort as hopeless.
Nevertheless, there can be no doubt that
first rate portraits in colors will eventually
be made, suTers eding perhaps the work of
/ the portrait painter. Such hkeaesseS will
be very different from the dead things in
]
artists of the camera produce today. They
will reproduce the tintS of the complexion,
/ the brightness of the eye, and all those de-
tails of varied hues which are of life itself.
One difficulty to be yet overcome in this
matter will relate to the intensifcation of
color effected in photographing a human
face down to what is called cabinet size.
/ You can See what this means by looking
! through camera at a person sitting for
his or her portrait. This would be particu-
larly objectionable from the point of view
of an individual afflicted with a red nose.
! Eventually great paintings will be copied
/ impershably with the camera. Though
time must destroy the originals, the photo
graphic replicas will remain through CEN
turtles, being susceptible of indefinite null
tiplication. Perchance they will take the
place Of the ''chromoS" of today, and doubt
less the same methods will be utilized for
making the sun himself do landscapes in
/ the twnkling of an eye, with all the tintS
=, of nature duly guaranteed correct by
the celestial artist, himself the author of
all color effects.
In the rainbow photographed by the
French academician referred to, black
bands at either end stand for what are
now known the ultra red and "infra
violet" These are really bands of colors-
hues unknown to and indistinguishable by
| the human eye. Yet Prof. Langley says
that to them are largely due the exquisite
beauty of the rose and other flowers.
! BY rainbow here Is meant the image
of the solar spectrum produced by passing
a suns ray through a prism The ultra
red is to the left of the red end, while the
mira violet is to the right of the violet end,
the length of the spectrum being thus adj
ded to in both directions. BY an instrument
of his own invention Prof. Langley has
! traced this rainbow for more than twice
its visible length. Not one-half of 1T, as
his experiments show, is perceptible to the
eye. His contrivance-a thin film of iron
through which current of electricity is
passed-is moved along over the spectrum,
the interruption of the current register
ing the heat of the hidden rays and thus
declaring their existence.
Photography in COlOrs.
Applica ton has been recently entered
at Washington for a patent on a process
for printing sun pictures in colors-the in
vention of New York photographer. BY
means of a camera, it reproduces water
color paintings with such perfection that
/ the counterfeits can hardly be distinguished
from the originals. The method employed
involved the use of tinted glass screens,
ana three negatives are required for each
picture.
The negatives are made on glass in the