SOME PROPERTIES.
It does not obey the laws of absorption which govern the red of diffused daylight. When the six transparent pigmentary colours are illuminated by direct sunlight, and viewed through a sufficient number of Neutral Tint units, the colours all disappear, all appearing red alike, with only differences in luminosity.
The spectrum position of this red energy is in the A. B. region, and further interception by Neutral Tint whilst narrowing the band, intensifies the colour, until obstructed by the large number of intercepting glass surfaces.
It has no photographic action on the six sensitised papers dealt with in the photographic section.