Democratic messenger., 1889-11-16
PHoroeRAPHINo coLoRs.
q Can be Done. but II not Generall
Undcrstood. as II Has no Great Value.

e Can be Done. but II not Generally
Understood. ss II Has no Great Value.
Capt. w. de w. Abney, in a paper
on the effect cf light on matter read
before the British association. said:
The question is often asked when pho
Biography in natural colors will he dis
covered. Photography in natural
colors not ON !. has been discovered.
but pictures in natural c0lors have
been produced. lam not alluding to
the pictures produced by manual
work. and which have from time To
time been foistcd on u crcdulous pub
lie as being produced by the action Of
light itself. much To the damage Of
photography aud usually To the 80
called inventors. Roughly speaking,
the method Of producing the spectrum
in lis natural colors is 10 chlorinize
silver plate, expose il la white light
till il assumes violet color. heat till
it becomes rather ruddy. and expose
II 10 u bright spectrum. The spectrum
colors are then impressed in their nat
ural tints. Experiment haS shown
that these colors are due to an oxidizcd
product being formed at the red end Of
the spectrum and reduced product ut
the violet end. Photography in natu-
raj colorS, however, is only interest
ing from scientific point Of view,
aud, SO far rs can see, can never have
a commercial value.
\ process 10 be useful must be one
by which reproductions are strictly
made; in other words, il must be de-
veloping and not printing process,
and IL must be taken in the camera,
for any printing process requires not
only a bright light. but also a pro-
longed exposure. Now, it can he con-
ccived that in a substance which alb
serbs all the visible spectrum, the mol
eculcs can be SO shaken and sifted by
the different rays that eventually they
sort themselves into masses which re-
fleet the particular rays by which they
are shaken; but il is almost-I might
say quitc-imposSiblc 10 believe that
when this sitting has only been COM
mcnccd, MS il would be in the short ex-
posirc 10 which a camera picture is
submitted. the substance deposited To
build up the image by purely chemi-
cal means would be So obliging rs to
deposit in that the particular size OF par
ticlc which should give to the image
the color Of the nucleus on which il
was dcposiiing. am aware that in
the early days of photography We
heard good deal about curious re-
suits that lad been obtained in mega
tivcs. where red brick houses were
shown as red and the blue sky as blu
ish. The cause of these condolences
is not hard Ia explain, and would be
exactly the same MS when the red
brick houses were shown us BLUSH and
the sky as red in a negative. Tho
records of the production Of the latter
negatives are naturally not abundant,
since they would not attract much at.
tcntion. may repeat then that pho
Biography in natural colors by print.
ing out proceSs-by which mean by
the action of light alonc-is not only
possible. but has been done; that
the production of "A negative in natu-
raj colors might bc produced appears,
in the present state Of our knowledge.
Ia bc impossible. Surprising il were
not impraclicablc. il would b. unsatis-
factory, us the light with which the
picture was impressed would he very
different from that in which il would
be viewed
Artists are fully aware of this diff
Guilty in painting, and take their pre-
cautions against il. The nearest ap-
proach Ia success in producing pie
lures by light alone is the method of
taking three negatives Of the same
subject through different colorcd
glasses. complementary Ia the three
color sensations which together give
Ia the eye the sensations Of white
light. The method is opened to OBJ
lection on account of the impure color
of the glasses used. II n device could
be adopted whereby only those three
parts of the spectrum could bc sever
ally used which form the color sensa-
tions. the method would be more per.
feet than il is at present. Even then
perfection could not be attained, ow-
ing la defect which is inherent in
photography aud which cannot be
eliminated This defect is the imperfect
representation of gridatiOn of tone.
Forinstancc. il we have strip gradu.
ated from what we call black io white
(it must bc recollectcd that no tone
can scientifically be- called black and
none whitcl and photograph il, We
lind that in print from the negative
the darkness which is supposed To rep
resent gray II equal mixtures ~
black and white by no means does 50
unless the black is not rs black nor the
white nS white ms the original.