The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1893-12-02
COLOR PHOTOGRAPHY.
A Difficult Problem that'May soon be
Solved.

|
New ideas from them looking in that
direction are flowing into the patent
| Office. The problem has long been. the
| ignis fatuus of Investigators in the myst-
erious and seductive field of optics. To-
| day the most eminent experts. in this line
all over the world are trying to solve 1T.
That the object aimed at will be accom-
piished before very long there can be no
reasonable doubt.
In fact the thing has been done already
only that the processes require perfecting.
Photographs of the solar spectrum, show
ing all the brilliant hues of the rain bow,
have been made possessing the long
sought quality of permanence This is
accomplished in a way devised by men,
| Der of the National Academy of France.
From scientific point of view his pro-
cess is the most interesting ever invented.
He lays upon sheet of glass very deli
cate, translucent film of chloride of sill
yer, and against the film he places YES
sci containing m ercury, SO that the
latter is in contact with the film.
The glass sheet and mercury thus
arranged are placed in the camera like
an ordinary sensitive plate Exposure
being made the image of the object to
be photographed is projected upon the
glass. The light convey ing the image
passes through the glass, on through
back by the mercury behind. The action
of the light splits the silver in the film
| into thin layers, which break up the
| light rays into their component colors.
1t is well known that the play of col
ors in an opal are due to the fact that
| this gem is composed of layers of quartz
superimposed one upon another. These
| hues. The same effect is accomplished
| by the layers of silver in the film. which
| through the operation to a curious law
reproduce the tints of the objecJ photo
graphed. In this way the brilliant colora-
tion 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 required-that is to say,
from five minutes to half an hour. But
in order to overcome this difficulty, it
is merely necessary that the film shall
be rendered more sensitive to light. The
same trou BILE for long time interfered
with the usefulness of the daguerrotype
method, fifty years ago, which could
not be utilized for portraits, because an
exposure of several hours was necessary,
and nobody could keep still so long.
Results of Previous Efforts Z
Photography in colors is no new thing.
III the early days of that art daguerreo-
types were occasionally produced in col
ors, though it was wholly accidental
The manner in which, this was accom-
plished long remained msytery, but it
is now supposed that the phenomenon
was due to contamination of the silver
surface of the copper plate by the copper
beneath. 1t has been found that chIor-
ide' of silver with chloride of copper will
reproduce colors to some extent. But
the colors 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 elabor-
ate treatment for the purpose, inciden-
tally baking them for long time in an
oven. But the tints refused TO stay, and
no process could be discovered for rem
ering them permanent. They would fade
| and disappear in few minutes on being
exposed to light. The plates which
tnSy DIGpdE0 tAulD1UCu OuG1
| quite remarkable from u technical
standpoint. They would reprouce white
| lights as welle as colors, whereas, ordi-
narily speaking, plates that are sensitive
| to colored lights are not sensitive to
white lights. After prolonged and la
! borious experiments Messrs. st. Victor
| and Becquerei abandoned their effort as
| hopeless.
Nevertheless, there can be no doubt
| that first rate portraits in colors will
eventually be made, superseding perhaps
| the work of the portrait painter. Such
| likenesses will be very different from
| the dead things in black and white
| which are the best that artists of the
| camera produce today. They will repro
duce the tints of the complexion the
brightness of the eye, and all those de-
| tails of varied hues which are of life it.
| self. One difficulty to be yet overcome
| in this matter will relate to the intensi-
fication of color effected in photograph
| ing man face down to what is called
cabinet" size. You can see what this
means by looking through camera at
person sitting for his or her portrait.
| This would be particularly Objectionable
| from the point of view of an individual
| afflictedwith red nose.
Eventually great paintings will be cop
| led imperishably with the camera
| Though time must destroy the originals,
Jne pHOtoSidpHlC felIlcdS Will remain
| through centuries, being susceptible of
| indefinite multiplication. Perchance
| they will take the place of the chromosn
of today, and doubtless the same methods
| will be utilized for making the sun him
self do landscapes in the. twinkling of an
eye, with all the tints of nature duly
guaranteed as correct by the celestial
artist, himself the author of all color
| effects.
In the rainb bow photographed by the
| French academician referred to, black
abounds at either end and for what are
now known as the ultra redr and
"infra violet" These are really bands
of colors-hues unknown to and indis-
| tinguishable 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 pass
| ing suns ray through a prism. The
| ultra red is to the left OF the red end,
while the mira violet is to the rig of
the violet end, theslength ofathe spectrum
being thus added 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-haIf of it, as his experiments show,