EINSTEIN'S
DISSERTATION
ON THE DETERMINATION OF
MOLECULAR DIMENSIONS
I
Einstein
submitted
a
dissertation to the
University
of
Zurich in
1901,
about
a
year
after
graduation
from the
ETH,
but withdrew it
early
in 1902.[1]
In
a
successful
second
attempt
three
years later,
he combined the
techniques
of
classical
hydrodynamics
with
those of
the
theory
of diffusion to create
a new
method for the determination
of molecular
sizes and
of
Avogadro's
number, a
method he
applied
to solute
sugar
molecules.[2] The
dissertation
was
completed on
30
April
1905 and submitted to the
University
of
Zurich
on
20
July.[3]
On 19
August
1905, shortly
after the thesis
was accepted,
the Annalen
der
Physik
received
a
slightly
different version for
publication.[4]
Einstein 1906c
(Doc. 33), published
half
a year
later
as a supplement
to
Einstein
1906a,
utilizes
experimental
data not
previously
available to recalculate the size
of
sugar
mole-
cules. In
1911,
after
Jacques
Bancelin found
a discrepancy
between the results
of
his
experiments
and
Einstein's
predictions, a
calculational
error
in
Einstein
1905j (Doc.
15)
was
discovered. Traces
of
an
unsuccessful
attempt by
Einstein to locate the
error,
pre-
served
as marginalia
and interlineations in
an offprint
of
the
paper, are
discussed
in the
annotations to Doc. 15.
A
correction
of
the
error,
which
was
found
by
Ludwig
Hopf,
then
a
collaborator of
Einstein, is
published
in Einstein 1911d. The
correction
was
reiterated
in
Einstein
1920 and
integrated
into the
republication
of Einstein's
dissertation in
Einstein
1922.
[5]
II
By
1905 several methods
for
the
experimental
determination
of molecular dimensions
were
available.[6]
Although
estimates
of
upper
bounds for the sizes
of
microscopic
con-
stituents
of
matter
had been discussed for
a long
time,
the first reliable methods for deter-
mining
molecular sizes
were developed
in the second
half
of
the
nineteenth
century,
based
[1]
For evidence
of Einstein's
submission
of
the dissertation,
see
the
Receipt
for the Return
of
Doctoral
Fees,
1
February
1902
(Vol. 1,
Doc.
132).
[2]
See
Einstein
1905j (Doc. 15).
For
a study
of Einstein's
dissertation, see
Pais
1982,
chap.
2,
§5.
[3]
See Einstein
to
Rudolf
Martin,
20
July
1905.
[4]
The thesis
was
unanimously accepted
by
the
Mathematics and
Physics Faculty on
27
July
1905
(see
Protokollbuch der
Konferenz,
Abtei-
lung
VI A, SzZE Bibliothek,
Hs
1079:2).
For
the
changes
that Einstein made in the Annalen
version,
Einstein
1906a,
see
the notes
to
Ein-
stein
1905j (Doc.
15).
[5]
For
an English
translation of Einstein
1922,
see
Einstein
1926. For the
history
of
Einstein
1922,
edited
by
Reinhold Fürth,
see
the editorial
note,
"Einstein
on
Brownian Motion,"
§
I,
p.
206. Some
of Fürth's
annotations
for the
1922
edition
(see
Fürth
1922)
have been utilized in
these editorial notes.
[6]
For
a survey
of
the
development
of
meth-
ods
for
the determination of molecular dimen-
sions,
see
Brush
1976,
pp.
75-78.
For
a
contem-
porary
survey,
see
Meyer,
O. E.
1899,
chap.
10.