Un manoscritto inedito in francese di Ettore Majorana

We report on the retrieval of the last missing papers of the "Senatore folder", given by Majorana to one student of his in Naples in 1938, just before his disappearance. The mentioned manuscript is conserved at the Domus Galilaeana in Pisa (Italy), and was written in French, probably for a conference in Leningrad (or in Kharkov) in 1933 (or in 1934). Majorana was invited to attend to such a conference but, actually, he did not tke part to it. The retrieved text deals with quantum electrodynamics by using the formalism of field quantization. It is here reported, for the first time, in translation. An accurate historical and scientific account is given as well.