, 1889-11-01
eno1oeRAPHINe coLoss
1t Can be Done. but Is not Generally
Understood. as 1t Has no Great Value

Understood. as 1t Has no Great value
Capt W. de w. Abney in a paper
on the effect of light on matter read
before the British association, said:
The question is often asked when pho
Biography in natural colors will be dis
covered. Photography in natural
colors not only has been discovered,
but pictures in natural colors have
been produced / am not alluding to
the pictures produced by manual
work, and which have from time to
time been foisted on a credulous pub
lie as being produced by the action of
light itself, much to the damage OF
photography and usually 10 the so
called inventors. Roughly speaking,
the method of producing the spectrum
in its natural colors is to chlorinize a
silver plate, expose it to white light
TIL it assumes a violet color, heat till
it becomes rather rudy, and expose
1t 10 a bright spectrum. The spectrum
colors are then impressed in their nat
ural tints. Experiment has shown
hat these colors are due to an oxidized
product being formed al the red end of
the spectrum and a reduced product at
the violet end. Photography in natu-
raj colors, however, is only interest
ing from a scientific point of view,
and, so far as / a see, can never have
a commercial value.
A process 10 be useful must be one
by which reproductions are strictly
made; in other words, ii must be a de
veloping and not a printing process,
and 1t 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 be con-
ceived that in a substance which abb
serbs all the visible spectrum, the mol
ecules 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 it is almost-I might
say quite-impossible TO believe that
when this sitting has only been com
menced, as ii would be in the short ex-
posure to which n camera picture is
submitted, the substance deposited to
build up the image by purely chemi-
cal means would be so obliging as to
deposit in that the particular size of par
tcle which should give to the image
the color of the nucleus on which il
was depositing. / am aware hat in
the early days of photography we
AOsAAh N kOOu dttl dDOuL CURIOUS re-
suits that had been obtained in mega
tives, where red brick houses were
shown as red and the blue sky as blu
ish. The cause of these condolences
Is not hard to explain, and would be
exactly the same as when the red
brick houses were shown as blush and
tie sky as red in n negative. The
records of the production of the latter
nARafar~au aV.a t,af.,. IL - ,,.N ,l,rl...
since they would not attract much at
tention. | may repeat then that pho
Biography in natural colors by a print
ing out process-by which i mean by
the action of light alone-is not only
possible, but has been done; that
the production of a negative in natu-
raj colors might be produced appears,
in the present state OF our knowledge.
TO be impossible. Surprising it were
not impracticable, it would be unsatis-
factory, as the light with which the
picture was impressed would be very
different from that in which it would
be viewed.
Artists are fully aware of this diff
Guilty in painting, and take their pre-
cautions against it. The nearest APP
proach TO success in producing pie
lures by light alone is the method Of
taking three negatives of the same
subject through different coiored
glasses, complementary TO the three
color sensations which together give
TO 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 a device could
be adopted whereby only those three
parts c' the spectrum could be sever
ally used which form the color sensa-
tons, the method would be more per-
feet than it is at present. Even then
perfection could not be attained, ow-
ing TO a defect which is inherent in
photography and which cannot be
eliminated. This defect is the imperfect
representation of graduation of tone.
Forinstance, if we have a strip gradu-
ated from what we call black to white
Dit must be recollected that no tone
can scientifically be called black and
none white) and photograph it, we
find that in a print from the negative
the darkness which is supposed to rep
resent a gray of equal mixtures Of
black and white by no means does SO
unless the black is not as black nor the
white as white IS the original.