No abstract

Previous work on these gases has yielded values for the expansion coefficients (T/v)(dv/dT) p , -(p/v)(dv/dp)T, and for ~T(d 2 v/dT 2 ) p at temperatures between -70° and 400° or 500°C and at pressures between 25 and 1200 atmospheres. The evaluation of such derivatives renders possible the calculation of many physical properties of the substance. To those properties that have been reported previously for nitrogen, carbon monoxide and hydrogen, the authors now add the change in entropy AS= -f\ v (dv/ dT) p dp along isotherms. The integral is evaluated by graphical quadrature from the previously determined expansion coefficient (T/v)(dv/dT) p .The absolute entropy at various pressures along an isotherm is then obtained by adding AS to the entropy at one atmosphere. The calculated values of AS are shown in a table, and the absolute entropies are shown by isotherms at various temperatures between -75° and 600°C to 1200 atmospheres. With an ideal gas, the integral AS= -fiV(dv/dT) p dp would be simply -R In p along all isotherms. The authors' calculations show that AS is always greater in absolute value than R In p, the difference being more pronounced at low 109

Recent observations of the reflection and absorption of radio waves have afforded much information regarding the behavior of the ionosphere during a radio fade‐out of the type occurring at the time of conspicuous outbursts in the chromosphere of the Sun. Berkner and Wells [see 1 under “References” at end of paper], using the automatic multifrequency technique, have studied the detailed behavior of the ionized layers during a fade‐out and find that conditions in the F1‐ and F2‐regions undergo essentially no change. In the E‐region a small increase in virtual height and maximum ion‐density seems to occur. After the E‐region conditions have returned to normal, abnormal absorption of the exploring radio waves is still observed, showing that absorption occurs below the maximum of the E‐region ionization.

Absorption maxima occurring in the near infra-red spectra of phenol and seven of its halogen derivatives have been measured and interpreted as combination frequencies in which the valence vibration of the OH group combines with frequencies of the body of the molecule. Certain of these absorptions underlie some of the trans-peaks of the orthohalogen phenols causing such a trans-peak to appear of larger area than that due to the trans-peak alone. A group of the combination frequencies which lie in the range 1000–1600 cm—1 above the first overtone OH absorption have been observed as a group of an order of magnitude weaker intensity in the frequency range twice the values above the first overtone OH and also above the fundamental OH absorption, apparently involving two units of vibration in the combining frequencies. A close correspondence is found between the frequencies involved in these combination tones and the frequencies which have been observed in some of these compounds in the deep infra-red and in Raman spectra.

Molecular structures of P4O6 and As4O6 were determined from electron diffraction data. P4O6 was found to have the symmetry of the point group Td with an angle P–O–P of 128.5±1.5°, and a P–O distance of 1.67±0.03A. In this structure the phosphorus oxygen distances and the phosphorus valence angles were preserved with resulting deformation of the oxygen valence angle. The separation of the arsenic atoms in As4O6 was found to be 3.20±0.05A. Because of the predominant scattering of the arsenic atoms it was difficult to determine the oxygen valence angle, As–O–As. Values of 120°, 127.5° and 140° gave approximate agreement between the observed and calculated positions of maxima. Electron diffraction photographs obtained from P4O10 differ considerably from those found for P4O6. It was not possible to explain all of the features of the P4O10 diffraction pattern by a model having the symmetry of the point group Td and it is thought that the structure might be one of lower symmetry. Data were obtained on P4O8 which indicated that it has approximately the same electron diffraction pattern as P4O10.