Radium and Radioactivity

a-rays acid Actinium actually amount of radium apparatus argon atomic weight B-rays barium Becquerel bismuth bulb calculated calorie capillary tube carbon dioxide carried cent centimetres Cloth boards coloured copper cubic centimetre cubic millimetre definite disintegration earth effect electric charge electrons electroscope element emanation emit a-particles equilibrium experiments figure fraction gases gives rise glass gram gram of radium half-life period heat helium hydrochloric acid hydrogen and oxygen ionisation ions lithium Madame Curie material matter measured mercury mesothorium metal method milligram molecules niton nitrogen numerous illustrations observed obtained ordinary oxide particles penetrating phosphorescence photographic plate pitchblende polonium present pressure produced Professor properties pump quantity of radium radiations radioactive radiothorium radium chloride radium salt Ramsay rate of decay rubidium Rutherford shown similar sodium solution spectrum ẞ-rays sulphate surface temperature thorium tion trace uranium minerals velocity vessel volume X-rays y-rays