In August 1940, Paul Langevin, then director of the Municipal School of Physics and Industrial Chemistry, desperately waited with his friend Henri Wallon (1879-1962) for a visa to return to Toulouse, but postal communications with the Free Zone were cut off. .

"I had previously spent six weeks in Toulouse where, on the night of June 10 to 11, I had sent research and teaching equipment" which he is now trying to recover; he laments the difficulties: “Restarting a house like this is not easy in the conditions of complete separation between the two areas where we are now”. He evokes the material difficulties he has to face in Toulouse, for him and the forty of his collaborators. He gives news of his relatives. “Wallon is fine and waiting like me. I had two letters from Jean-Richard [Bloch] who is in Poitiers, who works there and whom I encouraged to stay there as long as possible. I had the unexpected good fortune to see all my children arrive in Toulouse in succession […]. Material life is not too difficult at least for now. But the winter will certainly be harsh. The moral state is that of prisoners doing their best to ignore the presence of their guards. The atmosphere is calm but heavy and the horizon very opaque. There was in this school, at the beginning of the Occupation, a withdrawal of boxes that we had not been able to fold up. And the presence of a detachment from the health service, which left a fortnight ago without leaving any appreciable traces of its passage. My apartment and my office have not received any visitors so far. Hope it lasts! […]”.

Langevin will be arrested a month later, on October 30, 1940, by the police in Paris.