1899 paper distinguishes between two types of radioactivity, which he labels alpha and beta. This paper is at the ChemTeam site. This paper is at the ChemTeam site. The paper is worth reading for the careful marshalling of one last conclusive piece of evidence about the nature of the particles Rutherford and his co-workers had been studying for a decade. This paper is at the ChemTeam site.
Rutherford concludes the nitrogen atoms are disintegrated in the process.
So atoms are not indestructable after all, and the alchemists' dreams of transmutation are realized.