El Paso herald. (El Paso, Tex.) 1901-1931, 1911-07-06

with an emulsion perfectly transparent.
and. exposed in the camera with the
glass side to the lens, and with the
film side banked up with mercury. In
this way the brilliant mirror of mer-
curry comes in close contact with the
film and reflects back upon itself the
light which comes from the lens. The
film must be transparent and thick
enough for one or two Of the longest
light waves to be fully formed with
in It Where the light waves collide
there will be no image: where they do
not come together an image will ap
pear. The result Of this is that when
plate has been exposed, developed.
and dried. there Is a film upon the
glass in which the image consists Of
a series OF layers OF extremely thin
deposited silver separated by equally
thin layers Of clear gelatin. When
these layers are seen in a light fall
Ing upon them at a certain angie they
show colors just as a soap bubble does.
In this way parts Of the original which
are red appear IN the same color in
the picture. and the same is true Of
other colors. though none of them is
exactly true TO nature.
The Three Negative Process.
Another process employs three diff
ferent negatives. Suitable screens are
interposed so that only those rays are
allowed to act upon the plate which
excite a particular color sensation in
the eye. They are usually made Of
dyed gelatin or collodian Theoretically
sealed between two pieces Of perfectly
two pictures at once, is used
fiat glass. In making pictures by this
process photochromoscope taking
two pictures at once, is used
The color photographers have de-
vised an instrument known as the SEN
sitometer. by the use of which they
are able TO tell exactly what sort OF
ray-flter should be used to photo
graph a given object in it's natural
color. This sensitometer consists Of
q series Of superimposed colOred
glasses. BY holding these to the light
it is possible for the practiced eye TO
select such screens as viii keep out
all rays other than the ones it is de-
sired to catch in the photograph.
Makes Positives of Negatives.
A leading French photographer has
devised a method for making posi-
tives out of negatives. It will be re-
called that in a Photographic negative
dark spots appear where light ones
are intended to appear in the finished
photograph, and that the negative is
transparent where black is 70 appear
lin the photograph. The Paris pho
tographer subjects the negative TO the
ordinary treatment, and then closes Il
into another bath, whereby the depos-
tied silver which makes up the shad-
ing of the negative is eaten away and
a film of silver salt is placed by the
same process in those parts of the
negative which formerly were par
tally or wholly transparent. In this
way he is able to convert his mega
tive into photograph, without the
interposition of Photographic paper.
BY placing the transformed negative in
certain position II makes the image
appear to the eve in the natural col
ors of the abject
Light Theories Proven.
Color Photography has proved some
things about the properties of light
which were never known before except
in theory For instance. it has been
able 70 demonstrate that there are
colors so refined that the human eve
cannot perceive them, just as there are
sounds OF such high pitch that the ear
is insensible to them. In the range of
visible colors of the spectrum, or the
rainbow, the extreme cOIOrs are red
and violet But beyond these, invis-
ible TO the human eye are other col
ers. known TO scientific as ultra violet
and fnfra-red. That these invisible
rays of light existed was proved in
theory by chemists. but If remained
for color photography to demonstrate
them usually. Photographs have been
made with these ultra light rays. the
use Of a lens excluding all but the
infra-red rays being especially success
full. In photography made with this
light, the lights and shadows of ordi-
nary sunlight as they appear to the
eye are exactly reversed. and the sun
appears to cast a deep shadow while
the shade of tree or a wall appears
as a luminous light
Tomorrow-Hawaii