The Dallas daily herald. [volume] (Dallas, Tex.) 1873-1887, 1877-02-07
Color Ghosts.

Some years age book was pub
lished in this country-we canno
recall its exact title-the purpose
of which was the production o
ghosts. On it's pages were various
representations of spectral shapes
printed in extremely brilliant colors
on a white ground. Directions
were to fix the eyes intently Oh
these for some moments, aud then
turn them suddenly to white wal
or screen, when the "ghoSts" would
appear in the form depicted in the
book, but OF an entirely different
color. If the picture was red, the
spectre on the wall would be green;
if the former was yellow, the latter
would be blue; and so on.
A similar illusion may be pro-
duced by any of our readers in II
much simpler way. Cut small
disk out Of white paper and lay it
on black surface. Look at it
steadily for quarter Of Il minute
or so, and then direct the eye to u
white, or, better, to gray surface,
as . sheet Of gray paper, and you
will sea Il dark image Of the shape
and size of The white disk. If II col
oIcd disk il used, the after-image,
as it is called, will be colored, but of
the hue complementary to thai Of
the disk; that is, if the one is green
the other will be purple, if the one
is yellow or orange tho other will
ne of "a darker or lighter blue, etc.
Complementary cOors, as most OF
our readers probably know, are
those which, if linked, will produce
white.
If the surface is of the same color
as the disk, the afterimage will be
faint and whitish; fit is Of the color
complementary to that of the disk,
the mage will appear of the same
color intensified. Thus, if the disk
is blush green, end the gaze is turn
ed from it to u red ground we shall
see "ghosL' of n deeper and
more brilliant red. If we look up
on a colored surface Of any other
than the complementary hue, tho
color of the afterimage will blend
with that Of the surface. For in
stance, if the object is green and the
surface blue, the image will be
violet.
These phenomena admit of avery
simple explanation. When the
rctiu Of the eye has been exposed to
a continued impression of one color,
it is wcared and becomes less sem
sitivc to the color, If now it is ex-
posed to the impression of white
light, it will respond more readily
to the other colors that make up
white, that is, to those which pro-
duce the complementary nue.
Quite litely some Of our readers VINO
have occasion to use red ink have
observed that if, after writing win
it some minutes, they change dir,
ectly to black ink, the latter VIII
at first appear of distinct green
color, Some eyes are more SEN
sitiye than others to these deIaslve
Impressions, but any person can see
the complementary color it he has
looked at the other long enough to
tire the eye.
DR.. Behold, in his "Theory OF
CoIors," among many other curious
things connected with this subject
illustrates the fact that, while II II
black object be seen againsta color,
ed ground Gas black print on req
paper, the black, when viewed IN
tently, will show slight ting of the
complementary color, the effect IS
greatly heightened by laying thin
white tissue paper over the surface,
showing that ian admixturc OF
white light is favorable to the pro
singular fact that the various coIors
which may be given to the ground
differ greatly in their capabillty OF
calling forth The contrasting coIors
"Green, blue, and volet-in fact, al!
the so.cuIIed cold colors-wlll orig
mate very vivid contrasting coIors
while this is the case to q muc'l
lower degree with red, yellow. and
yellowish green" The coIorcd plates
In DR.. Bezold's illustrated book TINS
very wildly, but the reader car
produce u similar effect by putting a
disk or figure cut out of black paper
Or cloth on u bright colored surface
red, yellow, green, blue or purple
and spreading tho white tissue
paper over the whole. The variety
oil hues which the black assumes Is
very striking, and tends decidedly
10 shake ones faith in the popular
Proverb that "seeing is believing
We know that black is black, ou
We cannot see it as black, however
earnestly We may cndeavor to reason
our selves out of the illusion.