Abstract
LONDON Royal Society, Feb. 16.—P. M. S. BLACKETT and G. OCCHIALINI: Some results of the photography of the tracks of penetrating radiation. About 500 photographs have been taken of these tracks, using an automatic method by which the passage of the particles through two counters causes the expansion to occur. The most striking feature of the results is the extraordinary variety and complexity of the multiple tracks, some of which show more than twenty separate tracks. An analysis of the nature of the particles producing these tracks leads to the conclusion, already put forward tentatively by Anderson (Science, Sept. 9, 1932), that some of the tracks are due to particles with a positive charge, but with a mass comparable with that of an electron rather than with that of a proton. These ‘positive electrons’ seem to be produced during the nuclear collision processes giving rise to the showers. W. E. Garner and H. R. Hailes: Thermal decomposition and detonation of mercury fulminate. Single crystals of mercury fulminate have been heated in vacuum at temperatures between 100° and 150° C. and a detailed examination made of the decomposition which ensues. In vacuum the thermal decomposition passes into detonation at 105°-115° C. The conditions which govern the inception of detonation have been investigated. The thermal decomposition occurring below the ignition temperature occurs in three stages: (1) a quiescent period during which there is a slight browning of the crystal, the decomposition being mainly superficial; (2) a period of acceleration of the rate of reaction; and (3) a region where the equation of the first order applies. These results have been interpreted as due to the commencement of thermal decomposition in the Smekal cracks of the fulminate crystal and the spread of the reaction to crystallites isolated by the destruction of the cementing material. The critical increment of the thermal? reaction is approximately 30 k. cal. C. R. Bailey and A. B. D. Cassie: Investigations in the infra-red region of the spectrum. (8) The grating spectrometer previously described has been applied to certain bands in the infra-red spectra of sulphur dioxide, carbon disulphide, and ozone. The upper limit of resolution at which the spectrometer has been used corresponds to a slit width containing some 2 cm.-1. As a consequence, a previously unsuspected Q branch has been revealed in one of the sulphur dioxide bands, which makes it certain that this molecule is an isosceles triangle with a vertical angle of 120°. The structure of ozone is briefly discussed, but sufficient evidence is not available for a definite conclusion.
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Societies and Academies. Nature 131, 286–288 (1933). https://doi.org/10.1038/131286a0
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DOI: https://doi.org/10.1038/131286a0