V O L U M E 5 , D O C U M E N T 3 4 9 b 1 9
[1]Dated on the assumption that the letter was written before Richard Swinne informed Einstein
that experiments performed before the conception of Einstein 1911a had shown that a quotient with
v instead of
v2/3
is to be preferred (see Richard Swinne to Einstein, 1 February 1912 [Vol. 5, Doc. 350]).
[2]In Einstein 1911a (Vol. 3, Doc. 12) the relation is derived. Here is
the surface tension, k a constant, the molar heat of evaporation, and the volume. From the
approximate linear dependence of on the temperature T, it follows that the right-hand side is con-
stant, which, for ideal gases, corresponds to the relation mentioned in this letter. If, on the other hand,
in Einstein’s equation should be replaced by v, as suggested by Swinne (see note 1), the relation
of this letter is no longer compatible with Einstein’s theory.
Vol. 5, 349b. To Robert Heller[1]
Prag 1. II. 12
Lieber Herr Heller!
Ihr Kärtchen hat mich sehr gefreut. Im Sommer schon werde ich wieder freie
Luft von Zürich schnappen! Ich freue mich riesig & werde nie vergessen, dass ich
dies allein meinem lieben Freund Zangger
verdanke.[2]
Was ihn nur bedrückt? Ich
merke aus seinen Briefen, dass er deprimiert
ist.[3]
Wie könnte man ihm wohl eine
kleine Freude machen? Gewiss ist er sehr isoliert und wird viel geärgert. Man wird
ihn nicht eher auch Verdienst schätzen, als wenn er Zürich einmal den Rücken ge-
kehrt
hat.[4]
Ich freue mich, dass wir bald unsere früheren gemütlichen Beziehungen wieder
aufnehmen
können.[5]
Einstweilen die besten Grüsse von Ihrem
Einstein
Beste Grüsse von meiner Frau.
Herzliche Grüsse an Herrn Zangger.
ALS (SzZ, Nachl. H. Zangger, box 1d). [86 566].
[1]Heller (1876–1930) was working on his dissertation, with Heinrich Zangger as adviser (see
Vol. 5, Doc. 361, note 2).
[2]Apparently Heller had congratulated him upon the approval of Einstein’s appointment as
professor at the Swiss Federal Institute of Technology. The decree of the Swiss Federal Council was
issued the day before; Einstein was officially informed of it on 7 February 1912 (Vol. 5, Doc. 355).
On Zangger’s role as the intermediary between the Swiss authorities and Einstein on the question of
the appointment, see Heinrich Zangger to Ludwig Forrer, 9 October 1911 (Vol. 5, Doc. 291), notes 2
and 10.
[3]See Heinrich Zangger to Einstein, 30 January 1912 (Vol. 5, Doc. 347).
[4]A year earlier, Zangger was considering taking up employment in Paris (see Einstein to Heinrich
Zangger, 13–16 December 1911 [Vol. 5, Doc. 325]).
[5]Heller kept in contact with Einstein even in Prague, where he visited him at least on two occa-
sions (see Einstein to Heinrich Zangger, 24 August 1911 [Vol. 5, Doc. 279]).
T
d
dT
------ –
k Ds RTs –
vs 2 /3
----------------------------- =
Ds vs
vs 2 /3