following series of colours:—
Yellow-red.
Yellow.
Green.
Blue.
Blue-red.
215.
If we place a black band, or stripe, on white paper,26 the violet border will spread till it meets the yellow-red edge. In this case the intermediate black is effaced (as the intermediate white was in the last experiment), and in its stead a splendid pure red will appear.27 The series of colours will now