The Helena independent. [volume] (Helena, Mont.) 1875-1943, 1891-04-24

sensitive matter bromide or iodine Of sill
ver. etc. must bs distributed In d state ol
division, ~ II were infinite, In = transpnr-
enh support, such ns gelAtine, nlbumen or
collodion. SECOND, the sensitive coat must
DO placed against . Rejecting surface. For
this purpose II IL fixed during the exposure
in q hollow frame containing mercury.
which forms a plain mirror In contact with
the sensitive 0oating. IL 10 In this second
condition that Prof. Lippmann'H discovery
differs from those that have preceded It.
His theory Ia that the incident rays form
ing the image in the camera interfere with
the rays reflected by the mercury, so that
there results on the interior coat a series OF
fringes Of interference.
In this reflection Of the rays Of light from
Prof. Lippman's discovery. He secures
colors that are permanent and seem to
possess the necessary powers Of endurance
even when long exposed to light. IL Ia
worthy OF note, however, that tho colors
can only be seen by reflection in looking Mt
to be demonstrated however much of an
advance Prof. LipPman may have made, he
has fully solved the problem of color pho
Biography. AS yet he appears only to have
succeeded in reproducing the primary colors.
The plates that he shows are photographs
Of the solar spectrum. All the colors of the
rainbow are reproduced. including the
infra-red and the ultraviolet, which are in
visible to human eyes. He thinks that he
will be able TO reproduce composite hues,
such as are found in the human complexion
or a landscape. But this he has not yet Mt
tempted, and as this is really the ultimate
end considered when we speak OF %photogra~,
ply in natural coIors, he can at best be said to
have taken only a step toward that result.
Whether the road along which his investi-
cations are proceeding will lead to complete
success remains for the future to disclose.
Nature still holds fast locked the secret of
photography in cOlors.
by many writer's on the subject, but by none
better than by Capt. w. de w. Abney in a
paper read before the British Association
for the Advancement of Science a year "
Simply expressed for the comprehension OF
unscientitic readers, it may be said that the
method of producing the spectrum in its
natural colors is to chlorinize o silver plate,
expose it to a white light until it assume u
violet color, heat it until it becomes rather
ruddy, and expose it to a bright spectrum.
The spectrum colors are then impressed in
their natural tints, SO far the process is
colors have not yet been discovered, unless
Prof. Lippmann nay have succeeded, and
even that appears reasonably doubtful.
What has been definitely achieved in col
ored photographs has been really by some
one or other process of printing. This,
however, liz not true color photography,
must be a developing and not 4 print
ing process. The picture must be taken in
the camera, for any printing process re-
quires not only bright light but also pro-
longed exposure and is therefore not prac-
for the end aimed at. Photography
in natural colors by n printing out process
is not only possible but has been often
done. But the production of a negative in
colors from which prints in natural
colors may be Produced is quite another
thing. Even Prof: Llppmann does no.
field is still open for future Investigators.