Circles 4, 5, and 6 illustrate the development of Orange, Green and Violet from the triad groups, by intercepting the light with two glass colours.
Circle 4, Red on Yellow, develops Orange by absorbing Yellow, Green, Blue, Violet and Red.
Circle 5, Yellow on Blue, develops Green by absorbing Blue, Violet, Red, Orange and Yellow.
Circle 6, Blue on Red, develops Violet by absorbing Red, Orange, Yellow, Green and Blue.
By this method of demonstration the six colours fall naturally into two groups. The first group includes Red, Yellow, and Blue, whilst the second group includes Orange, Green, and Violet. The colours of the second group, Orange, Green, and Violet, are true monochromes, each being isolated from the light, by the absorption of the five other rays.
These illustrations deal with light and colour of 20 units intensity;[2] as the intensity of the light here is exactly equal to the absorptive power of the standards, no free light remains; where the absorptive power of the colour standards is less than the light, associated white light remains; for instance, if only one unit of colour was developed, 19 units associated white light would remain.
PLATE III
To face page 13. [Lovibond, Colour Theories.