She cried out as he turned yet another corner and his fading yellow light receded into darkness.
They hovered through the air, at last reaching one of the ships, where a doorway yawned open to reveal the damp yellow light and grey corridors beyond.
It was lit with warm yellow light.
Wood, when white light is transmitted through a paste made of powdered quartz and a mixture of carbon bisulphide with benzol having the same refractive index as the quartz for yellow light.
Thus red light is reduced to such an extent as to be insufficient for growth at a depth of 34 metres, yellow light at a depth of 1 7 7 metres and green light at 322 metres.