Abstract
THE first number of the new Dutch periodical Physica (December 1933, pp. 96, published by Martinus Nijhoff, The Hague, 25 guilders yearly) contains a number of interesting papers. The paper by de Haas and his GO-workers on the attainment of very low temperatures by adiabatic magnetic changes is referred to in our Research Items (p. 181). Druyvesteyn describes experiments on the low-voltage arc in sodium vapour. The absorption of the D lines was measured in the arc and the reversal of the D lines against a continuous source at variable-temperature was observed. The results show that the number of excited sodium atoms is about 12 per cent of the number of the normal atoms, and that the number of Na+ions is several times the number of normal atoms. The theory of light emission in gaseous discharges is discussed by W. De Groot. Van Heel describes a quartz-fluorite combination lens which is achromatic and spherically connected. It is intended for focusing light on a thermocouple with unit magnification. P. Cohen Henriquez describes a micro-apparatus for determining the dipole moment of organic solutes. The apparatus may be used with a few milligrams of material. The ratio of the lithium isotopes has been determined by intensity measurements of the fine structure of the Li resonance line by Ornstein, Vreeswijk and Wolfsohn. Van Kreveld describes an empirical summation law for a photographic plate exposed to light of two or more colours, and Van der Pol and Weyers describe the approximations known as Tchebycheff polynomials. The papers are in English or German, and in some cases German papers are provided with an abstract in English.
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Physica . Nature 133, 170–171 (1934). https://doi.org/10.1038/133170e0
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DOI: https://doi.org/10.1038/133170e0