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The temperature dependence of the electrical resistance of polycrystalline and epitaxially grown silver and gold films, deposited on freshly cleaved NaCl substrates, was measured between 295°K and 4.2°K. The polycrystalline layers were obtained by condensing on glass substrates and also on non-freshly cleaved NaCl substrates. A pressure lower than 5 × 10−7 torr was obtained during evaporation using a diffusion pump of the Venema-type1). The thickness of the films ranged between 450 and 1050 A; it was determined by the Tolansky-method. A comparison of the results with those reported by Chopra2) for films condensed on mica is given. The influence of alpha irradiation on the structural properties as well as on the electrical resistance of the silver and gold films was also studied. The latter are less sensitive on alpha irradiation than the former. The structure of the films was determined using an electron microscope as well as by electron diffraction.

Measurements were made on the absorption of sound between room temperature and about 90°C, first on pure CO2 gas, and then on CO2 gas to which small quantities of H2O or D2O-vapour were added. From these measurements the relaxation times were computed. It was found that β C 2 OD 2 O β CO 2 H 2 O is equal to about 1,5 and that this ratio is nearly independent of the temperature. Measurements were also made on CO2 gas to which a small quantity of Ne gas was added. A small excitation of CO2 by Ne was observed. Finally, measurements were made on the absorption of sound in oxygen gas between 50°C and 150°C. From these data obtained the relaxation times were computed.