  We give an accurate historical and scientific account of a previously unknown
manuscript written by Ettore Majorana in French. The retrieved text deals with
Quantum Electrodynamics by using the formalism of field quantization, and it is
here reported, for the first time, in translation. It is likely related to an
invited talk for a conference at Leningrad (or Kharkov) in 1933 (or 1934)
which, however, Majorana never attended. Probably this manuscript refers to the
last missing papers of the ``Senatore folder'', given by Majorana to one
student of his at the University of Naples in 1938, just before his
disappearance.
