D O C . 3 4 8 M A R C H 1 9 2 0 2 9 1 ciation equilibrium in a gas mixture from quantum theory (not by Boltzmann’s “sensitive domains” but rather by means of its substitute for h.) 2. It is thereby revealed that the chemical constant of rigid multiatomic mole- cules is dependent not just on the mass and moment of inertia but also on the number of the molecules’ possible axes of symmetry. (Maybe I obtain this due to an error in the combinatorial considerations but don’t think so!!) Indeed, nothing really new has come out of it but I am very glad that I now un- derstand completely clearly why I very justifiably could never understand all the various representations, apart from Stern’s. From the outset our representation treats solely the problem for the sake of which one requires the chemical constant: the problem of dissociation. And the common quantum-theoretical roots for (1) chem. const., (2) vapor pressure const., (3) Nernst’s theorem, become clearly apparent, so it is no longer necessary to build (1) upon (2) and (3). From every possible quarter I am being asked for facts about you please pass on the enclosed questions to “your secretary” with the request for a reply to me! — • — Do you know what would delight me? If you would attach your signature to the interior of the violin, as a lovely memento for my children. — • — — • — Everyone of us is expecting you with happy impatience—quite especially the children, Tanitschka among them, although she avoids letting it be noticed.– Very cordial greetings, yours, Ehrenfest. Best regards to your wife. 348. From Ludwik Silberstein London N.W.2, 4 Anson Road, 10 March 1920 Esteemed Professor, From Dr. A. Berliner’s letter (Die Naturwissenschaften), which Laue sent to me today, I gather that you are currently staying in Berlin. I therefore take the liberty of writing you a few lines to this address and convey- ing to you in the enclosed an offprint from the Phil. Mag. about the “Stokes-Planck ether.” I place no particular value on this small sketch, which was of only passing interest to me,—yet your opinion on such an “ether” as, perhaps, an open possibil- ity, would interest me very particularly.