ABSTRACT
In the early experiments which led to the discovery of the artificial disintegration of nitrogen, Rutherford observed by the scintillation method, that the passage of alpha-particles from radium C through nitrogen and oxygen gave rise to some swift particles which had an equivalent range in air of about 9 cm. Beyond the range of the alpha-particles from radium C, the scintillations due to these particles are generally brighter than those due to hydrogen nuclei. The authors focused on the groups of long-range particles from radium C, since the active sources used in experiments on artificial disintegration usually consist of this material. They examined carefully the number and range of the particles, and obtained convincing evidence that the long-range particles from radium C of 9.3 and 11.2 cm range are alpha-particles of mass 4 which have their origin in the source itself.
