9 6 D O C U M E N T 7 8 M A R C H 1 9 2 2 I would suggest to you: 29 April. If that is too late for you, then 22 or 24 April. 2.° Onnes recently established: Contact area between supercond[ucting] tin and supercond. lead yields no detectable resistance. I.e.: : He will write to you about it. 3.° Please forgive me for still not having corresponded with Prof. Kochert[haler] (Madrid). Permit me to wait with this until you are here because too much is unclear to me. E.g., I don’t know whether I should send him the preparation as I have it here or directly in must first convert it chemically into a form that he can use directly, which would naturally require a recalculation of the molecular weights. – In case you don’t want me to wait for you about this, do tell me whether I should first convert it chemically or not and whether he should cite it in his book solely under your name or also with mine added (forgive this immodest question—for I naturally know very well that the entire merit goes to you). Best regards to your d[ear] wife and Ilmargotse. 78. From Heinrich Zangger [after 11 March 1922] Dear friend Einstein, Are you already in Japan? When you arrive in Tokyo, do have the very interest- ing physico-chem[ical] experiment by Prof. Hashida shown to you (physiol. insti- tute). He takes continuous measurem[ents] of potential fluctuations that are physic[ally] very interesting. He was also here in Zurich for some years. You know that Besso is a grandfather that is surely the best cure against pessimism. The enclosure was written long ago. But what use is mailing, when the mind is in Japan? This winter I audited Debye’s entire course on the structure of matter—very good, just too short, but many connections in all directions and brilliant dimen- lead tin lead current current No potential difference detectable.