D O C U M E N T 2 6 6 A P R I L 1 9 2 6 2 7 9 the diminished volume × the square of the molecule’s radius, by [using] the ¢best² usual indicators for the polymerization, one then obtains (less exactly) approxi- mately the same series of whole numbers. An empirically found correction with the ratio of the sums of the atomic weights to the sum of atomic numbers improves the result, which then seems suitable for establishing the polymerization conditions for doubtful cases. (Polymerization is, of course, of some importance, also in a crystal lattice.) Upon applying this method, the coordination compounds (complex salts, etc.) are also clearly distinguished. In order of magnitude, the inner atomic electron velocities result corresponding to RT.[2] This surely is an amusing thing I was surprised that you didn’t write me any- thing about it. Here, too, reality is once again simpler than the theoretical concep- tions would lead one to expect. —Most recently I was in Italy. My sister[3] is going through a critical period it gives me much to think about. We have moved: Trechselstrasse 9, in the immediate vicinity of your former apartment on Aegerten Street.[4] — Peter Winteler is coming to Bern.[5] And when are you coming? Warm regards from us all! Your Michele 266. From Georg Joos[1] Jena, Kaiser Wilhelmstr. 7a, 25 April 1926 Dear Professor, After thinking about the suggestion for an experiment on the emission process that you communicated in Naturwiss[enschaften],[2] I came upon the enclosed chains of reasoning, whose publication in Naturwiss[enschaften] could perhaps of- fer some inspiration for further experiments.[3] According to these considerations concerning the Zeemann effect, the outcome of such experiments would seem to be that everything does function “quite classically.” Your opinion on these thoughts would be of utmost value to me. At the same time, I would like to inform you that, with the assistance of Zeiss and the Jungfrau railway company, a repetition of Michelson’s experiment has been secured for a mine shaft inside the Jungfraujoch.[4] Its execution will probably be deferred to 1927. The interferometer is being built at the present time a few pre- liminary trials are being performed on the best kind of mounting before the large apparatus is erected. I want to do the job in a vacuum and record everything under