_The Law of Simultaneous Contrast of Colours demonstrated by the
Juxtaposition of a certain Number of Coloured Bodies._
20. Let us now apply the above formula to the seventeen observations
of Chapter I., and we shall see that the modifications of contiguous
colours are precisely those which would result from the addition to
each of them of the complementary of the contiguous colour (18). The
rank these colours occupy in Chapter I. may be readily noted, as I have
attached to each the number applied to it in that chapter. And for the
complementary of each colour see (6). (See Plate II.)
_Orange and Green_, 7.
21. Orange, the complementary of Blue, being added to Green,
makes it Bluer or less Yellow.
Green the complementary of Red being added to Orange
makes it Redder less Yellow.
_Orange and Indigo_, 8.
22. Orange, the complementary of Blue, being added to Indigo,
makes it Bluer or less Red.
Green the complementary of Red being added to Orange
makes it Redder less Yellow.
_Orange and Violet_, 9.
23. Orange, the complementary of Blue, being added to Violet,
makes it Blue or less Red.
Violet the complementary of Orange-yellow being added to
Orange makes it Yellower less Red.
_Green and Indigo_, 13.
24. Green, the complementary of Red, being added to Indigo,
makes it Redder or more Violet.
Indigo the complementary of Orange-yellow being added
to Green makes it Yellow.
_Green and Violet_, 14.
25. Green, the complementary of Red, being added to Violet,
makes it Redder.
Violet the complementary of Green-yellow being added to
Green makes it Yellower.
_Orange and Red_, 1.
26. Orange, the complementary of Blue, being added to Red,
makes it Violet or Crimson.
Red the complementary of Green being added to Orange
makes it Yellower.
_Violet and Red_, 5.
27. Violet, the complementary of Green-yellow, being added
to Red, makes it Orange-yellow.
Red the complementary of Green being added to Violet
makes it Indigo.
_Indigo and Red_, 4.
28. Indigo, the complementary of Orange-yellow, being added
to Red, makes it Orange.
Red the complementary of Green being added to Indigo
makes it Blue.
_Orange and Yellow_, 6.
29. Orange, the complementary of Blue, being added to Yellow,
makes it Greener.
Yellow the complementary of Indigo being added to Orange
makes it Redder.
_Green and Yellow_, 10.
30. Green, the complementary of Red, being added to Yellow,
makes it Orange.
Yellow the complementary of Indigo-violet being added
to Green makes it Blue.
_Green and Blue_, 12.
31. Green, the complementary of Red, being added to Blue,
makes it Indigo.
Blue the complementary of Orange being added to Green
makes it Yellower.
_Violet and Blue_, 16.
32. Violet, the complementary of Greenish-yellow, being added
to Blue, makes it Greenish.
Blue the complementary of Orange being added to Violet
makes it Redder.
_Indigo and Blue_, 15.
33. Indigo, the complementary of Orange-yellow, being added
to Blue, makes it Green.
Blue the complementary of Orange being added to Indigo
makes it Violet.
_Red and Yellow_, 2.
34. Red, the complementary of Green, being added to Yellow,
makes it Green.
Yellow the complementary of Indigo-violet being added
to Red makes it Violet.
_Red and Blue_, 3.
35. Red, the complementary of Green, being added to Blue,
makes it Green.
Blue the complementary of Orange being added to Red
makes it Orange.
_Yellow and Blue_, 11.
36. Orange-yellow, the complementary of Indigo-violet,
being added to Blue, makes it Indigo.
Blue the complementary of Orange being added to Yellow
makes it Orange.
_Indigo and Violet_, 17.
37. Indigo, the complementary of Orange-yellow, being added
to Violet, makes it Red.
Violet the complementary of Greenish-yellow being added
to Indigo makes it Bluer.
38. It is evident that, all other things being equal, the modifications
of contiguous colours will be so much the more marked, as the
complementary colour C or Cʹ, which is added to each of them, differs
more from them; for the complementary Cʹ which is added to the colour
O, is identical with it, as the complementary C is identical with
the colour P to which it is added; and the modifications of O and P
will simply augment the intensity of their colours. But are there yet
any two bodies known which present to the observer two pure colours
perfectly complementary to each other? Certainly not; all those which
are coloured by reflection reflect (7), besides white light, a great
number of rays of various colours. We cannot instance a _red_ body and
a _green_ body, or an _orange_ and a _blue_, or an _orange-yellow_ and
an _indigo_, or a greenish-yellow and a _violet_, which reflect pure
or mixed colours, absolutely complementary to each other. So that the
juxtaposition of these colours produces only a simple _augmentation of
their intensity_. Hence, although it is less easy to verify the law of
contrast with respect to red and green, or orange and blue, &c., than
with respect to those which are the object of the seventeen experiments
just described (15), yet, upon applying it to the former, it will be
seen that their colours acquire a most remarkable brilliancy, strength,
and purity. This result, perfectly conformable to the law, may be
easily understood: for example, an orange-coloured object reflects blue
rays, as a blue object reflects orange rays (7). Hence, when a blue
stripe is put in contact with an orange stripe, although it is admitted
that the first appears to the eye to receive blue from the orange of
the second, as this appears to receive orange from the blue of the
blue stripe; or what is the same thing, that the blue stripe appears
to destroy the effect of the blue rays of the second stripe, as these
appear to destroy the effect of the orange rays of the blue stripe—it
is evident that the two colours so contrasted must purify each other,
and become more intense. But the blue may incline to green or violet,
and the orange to yellow or red; that is to say, the modification may
not only affect the intensity of the colour, but also its physical
composition. However, if this latter effect take place, it is always
much more feeble than the first. Besides, if you look several times
at the same coloured stripes, you will see that the blue which at
first had appeared to you greenish will afterwards appear inclining to
violet; and that the orange, which had appeared at first yellowish,
will incline to red; so that the phenomena of modification, as it
affects the physical composition of colour, will not have the constancy
of those which are the subject of the preceding seventeen observations
(15). I now proceed to state the observations I have made on colours
which are most nearly complementary to each other.
_Red and Green._
39. _Red,[1] the complementary of Green, placed by
the side of Green, increases its intensity._
_Green, the complementary of Red, placed by the side
of Red, increases its intensity._
[1] In the original French Edition there is evidently a confusion of
terms in this and the two following articles (39, 40, 41, 42). The Red
is there represented as placed in juxtaposition with _red_, and green
with _green_, and so on with the other instances; orange and blue;
orange-yellow and indigo; greenish-yellow and violet; instead of being
made by contrast with their respective complementaries to intensify
each other.
Such is the theoretical result, the experimental result entirely
agrees with it. When we place a green, inclining more to yellow than
to blue, side by side with, 1st, a slightly orange-red, 2nd, a slightly
crimson-red, and 3rd, an intermediate red, and repeat our observations
several times on each of these assemblages of colour, we shall observe
different results; that is to say, in one case the red will appear more
orange and the green yellower, and in another the red will appear more
violet and the green bluer. We shall find also that the change may be
attributed as much to a difference in the intensity of the light upon
the colours as to fatigue of the eye.
When we place a green, inclining rather to blue than to yellow, side by
side with, 1st, a slightly orange-red, 2nd, a slightly crimson-red, and
3rd, an intermediate red, the results are the same as with the first
green, but with this difference,—that in the assemblage of bluish-green
and of slightly crimson-red, observed several times, the green and
the red appear almost constantly yellower than they are separately. A
result very easily understood.
_Orange and Blue._
40. _Blue, the complementary of Orange, placed by the
side of Orange, increases its intensity._
_Orange, the complementary of Blue, placed by the
side of Blue, increases its intensity._
Upon repeating these observations with a deep blue and an orange which
is not too red, the two colours appear commonly to become redder.
_Orange-Yellow and Indigo._
41. _Orange-yellow, the complementary of Indigo,
placed by the side of Indigo, increases its intensity._
_Indigo, the complementary of Orange-yellow,
placed by the side of Orange-yellow, increases its intensity._
[Illustration: PLATE III.]
_Greenish-Yellow and Violet._
42. _Greenish-yellow, the complementary of Violet,
placed by the side of Violet, increases its intensity._
_Violet, the complementary of Greenish-yellow, placed
by the side of Greenish-yellow, increases its intensity._
The result of observation is almost always in conformity with this law.
43. According to the law of the simultaneous contrast of colours, and
the insensible gradation of modification, beginning at the contiguous
edges of the colours in juxtaposition (11), we may show, by means of
coloured circular spaces, the modifications which the principal colours
induce in those which are contiguous to them.
Place wafers, circular pieces of paper, or any other convenient
material about an inch and a half in diameter, coloured red, green,
orange, blue, greenish-yellow, violet, indigo, and orange-yellow, each
separately upon a sheet of white paper; then tint the white paper
around the circle with its complementary colour, gradually softening it
off from the coloured circle, when it will be found that
The Red circle tends to colour the surrounding space
with its complementary Green.
Green ” ” Red.
Orange ” ” Blue.
Blue ” ” Orange.
Greenish-yellow ” Violet.
Violet ” ” Greenish-yellow.
Indigo ” ” Orange-yellow.
Orange-yellow ” Indigo.
These figures are designed to exhibit the effects of contrast to those
persons who, not having studied physical laws, are, notwithstanding,
desirous of understanding these effects.