M. Giesel has made a preparation of barium-radium platinocyanide.

The changed barium platinocyanide is partially regenerated by the action of light.

Suddenly he noticed a flicker on a barium platinocyanide screen.

When this salt is newly crystallised, it has the appearance of ordinary barium platinocyanide and is very luminous.

The man noticed that in a dark room, the tube in which the transmission took place (covered with barium platinocyanide) caused a fluorescent effect.

M. Curie and myself first discovered this phenomenon when causing polonium to act upon a layer of barium platinocyanide through aluminium foil.

The rays emitted by the components of polonium and radium make barium platinocyanide fluorescent; their action in this regard is analogous to that of the R�ntgen rays, but considerably weaker.