In 1895, Wilhelm Roentgen accidentally discovered that a cathode-ray tube could make a sheet of paper coated with barium platinocyanide glow, even when the tube and the paper were in separate rooms.

1895年，·琴偶然发现阴极射线管能使涂有一层氰亚酸盐钡的薄发光，甚至当阴极射线管和别放在不同的房间时也能发光。