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

by Joseph W. Lovibond

PLATE X
COMPARISON CURVES OF HEALTHY AND DISEASED BLOOD.

To face page 80. [Lovibond, Colour Theories.

Unabsorbable Colours.—In addition to the daylight colours already dealt with, there are, in direct lights, colours which do not obey the laws of absorption governing those of diffused daylight.

The work already done on these unabsorbable rays has only been incidental, where they happened to interfere with the standardization of diffused daylight colours. The sensations excited are red and violet. They blend, producing red-violet mixtures, but in unequal proportions, the red being dominant.

The red is developed in intense lights by constant interception of neutral tint absorbents. In the case of a 4-volt incandescent light, the first absorption simply reduces the light intensity without developing colour; the light is colourless up to 14 units. At 16 units the light begins to assume a reddish hue, which rapidly becomes a brilliant intense red by further interceptions of neutral tint absorbents.

Violet is developed by constant absorption by blue standards, which grows in intensity by successive additions up to about 120 units. Beyond this point the brilliancy decreases.

Preliminary experiments point to this ray as fatal to vegetation, and presumably also to lower forms of organic life.