It has been assumed that in the simplest case every atom that hits a crystal surface of the same material condenses. The corresponding speed of sublimation had been calculated theoretically. The formula for the equilibrium pressure is changed in the case of atoms, if the electron weight in the gaseous state is different from the solid state. The influence of this fact on the speed of sublimation is discussed in the first part of the paper and it is shown that for true metals the speed of sublimation is probably increased, while for non‐metals a reflection coefficient exists. For molecules the equilibrium pressure is higher than for atoms because in sublimation there is a transition from a limited oscillation of the axes to free rotation. It is made plausible that this results in an increased speed of sublimation but a finite reflection coefficient might also occur.

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O. K.
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853
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H.
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3
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107
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1935
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2.
K. F. Herzfeld, Kinetische Theorie der Wärme, Braunschweig, 1925, p. 223.
3.
I.
Langmuir
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8
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149
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4.
This is in agreement with experiments on Hg, Cd, Zn by
M.
Knudsen
,
Ann. d. Physik
50
,
472
(
1916
);
and
R. W.
Wood
,
Phil. Mag.
30
,
300
(
1915
);
R. W.
Wood
,
32
,
364
(
1916
).,
Philos. Mag.
5.
The formula for k0 which results from (4) has been deduced from kinetical considerations directly on p. 232 of book cited, footnote 2; see also
R.
Becker
,
Zeits. f. Physik
28
,
256
(
1924
).
6.
L.
Nordheim
,
Zeits. f. Physik
46
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833
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L.
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Proc. Roy. Soc.
A121
,
626
(
1928
).
7.
J. C.
Slater
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Rev. Mod. Phys.
6
,
209
(
1934
).
8.
M.
Knudsen
,
Ann. d. Physik
50
,
472
(
1916
).
9.
A distinction analogous to that between (b′) and (b″) is also made by J. H. Van Vleck, The Theory of Electric and Magnetic Susceptibilities, Oxford, 1932, p. 283, cases e, f.
10.
D. H.
Andrews
,
Proc. Amst. Acad.
29
,
744
(
1926
);
see also
A.
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16
,
364
(
1920
);
A.
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and
E.
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Zeits. f. Physik. Chemie
112
,
479
(
1924
);
A.
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and
F.
Fried
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Zeits. f. Physik
32
,
151
(
1925
);
F.
Simon
,
Zeits. f. Physik
31
,
225
(
1925
).
11.
M.
Volmer
and
I.
Estermann
,
Zeits. f. Physik
7
,
1
(
1921
).
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