Although the problem of transmuting chemical elements into each other is much older than a satisfactory definition of the very concept of chemical element, it is well known that the first and most important step towards its solution was made only nineteen years ago by the late Lord Rutherford, who started the method of the nuclear bombardments.
Nobel Lecture (physics) December 12, 1938, Artificial Radioactivity Produced by Neutron Bombardment, (p. 414)