168
DOC.
14
HEURISTIC VIEW OF LIGHT
Meyer,
O. E. 1899. For
a
discussion
of
Ein-
stein's
other methods for
determining
N, see
the
editorial
note,
"Einstein's
Dissertation
on
the
Determination of
Molecular Dimensions,"
§
IV, pp.176-179.
[22]
See Wien 1894.
[23]
See Wien
1896,
p.
667.
Wien's
formula
was originally expressed as
the
density
px
of
ra-
diation
of
wavelength
between
X
and
X
+
dX:
C
px
=
C/X5e x0
,
where
0 is
the
temperature,
C
is
a
constant, and
c
is
the
speed
of
light.
[24]
The best
contemporary experimental
tests
were reported
in Rubens
and
Kurlbaum
1901
and
Paschen
1901a. This
latter, p. 293,
states:
"For
larger
values
of
1/AT
than about 0.0003
(XT
about
3000)
the observations follow
the
Wien law within the
margin
of
error.
For
smaller
values
of
1/AT
than about
0.0003
(XT
about
3000)
deviations from the Wien law
appear
in all
curves" ("Für
grössere
Werte
von
1/XT
als
un-
gefähr
0,0003
(XT
3000
ungefähr) folgen
die
Beobachtungen
innerhalb
der
möglichen
Fehler
dem
Wien'schen
Gesetze. Für kleinere Werte
von
1/XT
als
ungefähr
0,0003
(XT
3000
unge-
fähr)
treten
in
allen Curven
Abweichungen
vom
Wien'schen
Gesetze
auf."
[25] S
refers to radiation with
frequencies
be-
tween
v
and
v
+ dv, and
E
=
pv
dv.
[26]
This
comparison
is further discussed in
§
5.
[27]
See Boltzmann 1877. The
name
"Boltz-
mannsches
Prinzip"
("Boltzmann's
princi-
ple"),
used
in
the next
section, is
Einstein's
ter-
minology.
[28]
For
a
discussion
of
Einstein's
definition
of
probability,
see
the editorial
note,
"Einstein
on
the Foundations
of Statistical
Physics,"
p.
52.
[29]
Klein
1974b,
p.
190, suggests
that the
ma-
terial Einstein
presented
in Einstein 1909b
(Doc.
56), p. 187,
is
a partial
fulfillment
of
this
prom-
ise.
[30]
See
also Einstein 1904
(Doc.
5),
pp.
355
and 359. C is
equivalent
to
Boltzmann's
con-
stant,
now
usually designated by
k.
[31]
The last term should be
multiplied
by T.
For the extension
of
the law
of
Boyle
and
Gay-
Lussac to dilute
solutions,
see
Van
't
Hoff
1887.
See also
Einstein
1905q
(Doc. 22),
§
1.
[32]
In Einstein 1906d
(Doc. 34),
p.
203,
Ein-
stein used
Planck's
equation
to
show that the
av-
erage energy
of
a
Wien oscillator
is
much
smaller than that
of
an energy quantum,
hv.
[33]
For
a contemporary
discussion
of Stokes's
rule,
see
Winkelmann
1906b,
"Fluoreszenz,"
pp.
785-798.
[34]
This conclusion
is
consistent with Knob-
lauch
1895,
p.
198,
which states that the inten-
sities
of
fluorescent and incident
light are pro-
portional,
"even
when the
intensity
of
the latter
is
varied in the ratio
1:6400"
("selbst
wenn
die
Intensität des letzteren im Verhältniss 1:6400
verändert wird").
[35]
For further discussion
of
such
exceptions,
set
Einstein
1909b
(Doc. 56),
p.
191.
[36]
For
a contemporary survey
of
the
photo-
electric effect, with
bibliography through
1904,
see
Schweidler 1904. In
1901
Einstein read Len-
ard
1900b,
which discusses the
photoelectric
ef-
fect
(see
Einstein to Mileva
Maric,
28
May
1901
[Vol. 1,
Doc.
111]).
[37]
Lenard
1902.
[38]
For
a
discussion
of the
relationship
be-
tween
the
photoelectric
effect
and the Volta ef-
fect,
see
Einstein 1906d
(Doc. 34), pp.
203-
206.
[39]
"Elektrische Masse"
("electric mass")
here refers to the
charge
of the electron.
[40]
Stark
1902, which
Einstein cites
on p.
148,
treats the ionization
of
a
neutral
gas
mole-
cule
by
ultraviolet
light as
"a
separation
of
the
negative
electron from
its
positive
remainder
atom"
("eine
Lostrennung
des
negativen
Elek-
trons
von
seinem
positiven
Restatom")
(p.
75).
Stark and
Steubing
1908,
pp.
490-491,
reports
a
"genetic"
relationship
between fluorescence
and the
photoelectric
effect. The former is
as-
sumed
to
be
a separation
of
an
electron from
a
molecule,
followed
by
the
"reattachment
of
the
electrons"
("Wiederanlagerung
der Elektro-
nen") with the emission
of
light;
the latter
is
treated
as
the
ejection
of
electrons from
a
metal.
[41] Using
the value
of
N obtained
on p.
137
and the value for the electric
charge
obtained in
Planck
1901b,
p.
566,
converted
from
esu
to
coul, the correct value
of E
is
9.6
x
104
coul.
Thus,
II
should be
multiplied by
10-7
to convert
erg/coul
to volts.
[42]
"II•
107" should be
"II•
10-7".
[43]
Lenard 1902.
Lenard's
values
ranged
be-
tween 1.5V to
3V, depending on
the material
studied. For
a
review
of Lenard's
work, see
Wheaton 1978b.
[44]
This and other
predictions
of Einstein's
equation
for IIE
were
confirmed
in
experiments
reported
in Millikan 1916a, 1916b.
Earlier tests