Light and Colour Theories, and their relation to light and colour standardization

by Joseph W. Lovibond

Complex Name.			High value. Lower.
To develop a	Red-Orange	insert a	Red and Yellow.
"	Yellow-Orange	"	Yellow and Red.
"	Yellow-Green	"	Yellow and Blue.
"	Blue-Green	"	Blue and Yellow.
"	Blue-Violet	"	Blue and Red.
"	Red-Violet	"	Red and Blue.

A reference to the circles, 7, 8, and 9, on the cards supplied with the apparatus will show that all complex colours are members of the same triad group, and experiments have shown that the six combinations above are the only ones distinguishable in Nature, subject, however, to unlimited variations in brightness or dullness. It remains to be shown how these variations are effected.

Variations in brightness are produced by inserting with the two glasses forming a complex colour the third spectrum colour, always bearing in mind that it must be less in value than either of the other two. The addition of the third colour has a dulling or saddening effect, the degree of which is determined by the numerical value of the third colour. The colour produced by the addition of the third colour may be termed a saddened or dingy colour, the appearance being that of a brighter colour seen in shadow.

Reviewing the foregoing, it is demonstrated that primary or dominant colours are transmitted by a single coloured standard glass; the secondary or subordinate colours are transmitted by two equal standard glasses of different colours; the complex colours by two unequal standard glasses of different colours. Saddened pure colours are developed either by one coloured standard glass combined with two equal standard glasses of different colours and lesser value or by two equal standard glasses of different colours and a third of lesser value. Saddened complex colours by three unequal standard glasses of different colours. Greys, which are steps towards blackness, are produced by three equal standard glasses of different colours.

It is well known that Colour Blindness is a defect in the vision often involving the confusion of such utterly distinct colour sensations as Red and Green, Orange and Violet, and many others as widely different. In the cases of Red and Green the confusions are specially disastrous should the subject be a railwayman or a sailor. It is not, however, so well known that many cases of so-called Colour Blindness are in reality cases of Colour Ignorance, and the capacity for distinguishing between colours and shades is often latent, and only waiting to be developed by Education.

When a child persistently misnames colours after having received an amount of instruction sufficient to remove colour ignorance in a normal case, the errors are probably due to some form of colour blindness.

Such cases should be registered for further examination, taking note of the miscalled colours. It would be an additional precaution to change the position of the colours in the windows of the apparatus, in order to prevent the association of colours with their positions as first given in the instructions.

Note.—The paints which most nearly correspond to the colour standards in the Colour Educator are tabulated below, the third column containing their measured colour proportions when they are washed thickly on white paper (Whatman’s).

Spectrum Names.	Artists’ Names.	Colour Composition in Standard Units.
		Red.	Orange.	Yellow.	Green.	Blue.	Violet.
Dominants:
Red	Crimson Lake	18·0	0·4	—	—	—	—
Yellow	Lemon Yellow	—	—	6·6	—	—	—
Blue	Cobalt	—	—	—	—	9·0	—
Subordinates:
Orange	Chrome Orange	—	7·2	1·6	—	—	—
Green	Emerald Green	—	—	0·40	5·4	—	—
Violet	Mauve	3·3	—	—	—	—	8·2

In mixing two dominant colours (artists’ primaries) to develop subordinates (artists’ secondaries), their relative colour depth must be taken into account; for instance, Crimson Lake has a natural colour depth nearly three times that of Lemon Yellow; therefore, in order to develop a normal Orange nearly three times the quantity of Yellow must be used, presuming that they were originally ground to an equal degree of fineness.