402 DOCUMENTS 351, 352 FEBRUARY 1912 oration. An alternative method, based on molecular physics, of calculating these two quanti- ties, led to the conflicting result that their quotient is proportional to v~s1/3. [3]paul Walden (1863-1957) Walden 1909c. In his paper Walden concludes that the first of the two quotients is a constant for a wide range of substances, in contrast to the second one, which is only approximately a constant. See also Walden and Swinne 1912, p. 750, footnote, where Einstein's apparent ignorance of Walden 1909c is noted. [4]M is the molar weight and a2 is the specific cohesion, which is related to the surface ten- sion through the relation a2 = 2y/ (gp), with g the acceleration of gravity and p the density (see, e.g., Walden 1909b). [5]Walden 1909a, 1909b. [6]Paul Dutoit (1873-1944) and Pierre Mojoi'u Dutoit and Mojoi'u 1909. [7]See note 2 for the difficulties discussed on p. 167 of Einstein's paper. As Swinne points out, the discrepancy could be resolved by taking the molar internal energy of evaporation pro- portional to vs instead of v2s/3 as Einstein had done. [8]Walden 1911. [9]Gustav Tammann Tammann 1911. 351. To Ludwig Forrer Prag. 2. II. 1912. Hochgeachteter Herr Bundespräsident! Ich danke Ihnen von Herzen für die rasche Ernennung ans Polytechni- kum.[1] Es ist mir eine grosse Freude, so bald wieder in der Schweiz als Lehrer wirken zu dürfen. Um meine Entlassung aus dem österreichischen Staats- dienst habe ich bereits nachgesucht.[2] Mit aller Hochachtung Ihr ganz ergebener A. Einstein. ALS (SzZ, Autographensammlung-Albert Einstein). [70 179]. [1]The Swiss Federal Council, of which Forrer was President, approved Einstein's appoint- ment three days earlier, news of which Einstein had probably received in a telegram from Heinrich Zangger (see Doc. 347). On 1 February, the federal councillor responsible for edu- cation transmitted the decree of Einstein's appointment to the office of the President of the ETH (see Marc Ruchet to Präsidium des schweizer. Schulrates, 1 February 1912, SzZE Schul- ratsarchiv 1912, Akten, no. 120). [2]Einstein petitioned for release from his position at the German University a day later (see Geschäfts-Protokollbuch 1911/12, CzPCU, 3 February 1912, no. 912). 352. To Alfred and Clara Stern Prag. 2. II 12. Verehrter Herr Professor und verehrte Frau Professor Stern! Vor zwei Tagen wurde ich (haleluia!) an das Polytechnikum in Zürich be- rufen[1] und habe hier schon meinen k. k. Abschied angemeldet.[2] Darob bei