He likely writes to fellow physicist, Aimé Auguste Cotton (1869–1951) and sends regards to his wife. In full, "Dear Sir, my Colleague, I am very grateful to you for presenting my message to the Academy, and I thank you for your remarks about the book. It would seem to me that one could posit: rotational power along the optical axis of certain uni-axis crystals, near the absorption bands, subject to the action of a magnetic field normal to that axis. We can talk about this tomorrow, by the way, because I will be coming to the meeting. If you have a few moments, I will be happy to share the observations with you that I have made over the past few days and that will render the properties of this effect more precise. Please give my kindest regards to Madame Cotton. Respectfully, Jean Becquerel." www.schulsonautographs.com.
Becquerel was likely studying positive electrons during this period. In Helge Kragh’s “Concept and Controversy: Jean Becquerel and the Positive Electron” (in Centaurus, Volume 32, no 2, pages 203-240, July 1989), it is noted, “Today’s physicists believe that all elementary particles have corresponding anti-particles of opposite electrical charge. The concept of charge conjugation, which reflects this belief in charge symmetry, goes back to the early thirties, when the anti-particle of the electron, the positron, was discovered… actual discovery in 1932….”.