Radiation and the Disintegration and Aggregation of Atoms.

Professor R. A. Millikan' has recently found evidence for the existence of very penetrating radiation which originates from sources outside of the earth. The mass-absorption coefficient of these rays is but 0.0018 per gram of water, which is far below the absorption coefficient of the hardest gamma rays. These Millikan rays are so short that their total mass-absorption coefficient isequal to the mass-scattering coefficient, the true absorption coefficient being negligible. A. H. Compton2 gives