PHYSICS: BRINSMADE AND KEMBLE 
425 
One difficulty arises in connection with this theory of asymmetry. 
If the faint HCl band is a true harmonic of its strong companion the 
constant a should have twice the value for the former that it does for 
the latter. According to our observations the ratio of the two values of 
the constant is about 1.5 instead of 2. However, a very slight change 
in the assumed form of the dispersion curve in the neighborhood of 3.5 
would suffice to bring the observations on the two bands into agree- 
ment. As a matter of fact the shape of the dispersion curve in this 
region is somewhat uncertain, for the points determined by Rubens are 
far apart and slightly irregular. The wavelength scale shown in figure 
5 was obtained by drawing the best possible smooth curve through the 
points given by Rubens. 
Kinetic Energy at the Absolute Zero. — Figures 4 and 5 emphasize an 
extremely important fact already evident in v. Bahr's absorption curve 
for the HCl fundamental, viz., the absence of a central band correspond- 
ing to a group of molecules having zero angular velocity. This obser- 
vation forces the conclusion that none of the molecules are without rota- 
tional energy and brings us to a combination of the first form of Planck's 
quantum theory with the zero-point energy hypothesis which has 
hitherto been associated with the second form of his theory. Additional 
evidence in favor of this view including a discussion of the specific heat 
of hydrogen will be published shortly. 
Conclusion. — The complete verification of a natural theory of the 
asymmetry of the infra-red absorption bands of diatomic gases and the 
accompanying explanation of the apparent increase in the moment of 
inertia of the molecule with increasing angular velocity clear up the 
outstanding difficulties in the theory of the structure of these bands. 
Consequently there can be no further doubt that it is correct to con- 
clude from the discontinuities in their structure that the angular veloci- 
ties are distributed among the molecules in the discontinuous manner 
predicted by the older form of the quantum theory. The proved exist- 
ence of harmonics in the infra-red spectra of the same gases is almost 
equally good evidence that the vibrational energy of these molecules is 
distributed in the same manner. 
1 Bjerrum,N., Nernst Festschrift, Halle, 1912; Berlin, Verh.D. physik. Ges., 16, 1914, (640). 
2 V. Bahr, Eva, Berlin, Verh. D. physik. Ges., 15, 1913, (1150); Phil. Mag.. London, 28, 
1914, (71). 
3 Kemble, E. C, Physic. Rev., Ithaca, N. Y., (Ser. 2), 8, 1916, (701). 
4 Gorton, A. F., Ihid., 7, 1916, (66). 
5 Landolt and Bornstein, Physikalisch-Chemische Tabellen, Berlin, 1912, p. 972. 
6 Burmeister, W., Berlin, Verh. Dh. pysik. Ges., 15, 1913, (589). 
^ Kemble, E. C, The Infra-Red Absorption Bands of Gases and the Application of the 
Quantum Theory to Molecular Rotations. New York Meeting of Amer. Phys. Society, 
Dec. 28, 1916. 
