Radio Activity
RADIUM THERAPY—Radium possesses more than any other substance the properties known as radioactivity; libera¬tion of light and heat, the power of ionization (dissociation into ions), and the production of rays having power to pass through opaque bodies, affect photographic plates with impressions and cause various biological changes. Other radio-active minerals, possessing less of these properties, are uranium, polonium, actinium, and thorium. It was while in¬vestigating the phosphorescence of uranium salts that Profes¬sor Henry Becquerel, of Paris, discovered in 1896 the property of radioactivity. Radium itself was discovered in 1898 by Madame Curie, of Paris, and immediately became a source of hectic inquiry and controversy.