Abstract
LONDON. Royal Society, January 26.—Sir Charles Sherrington, president, in the chair.—W. A. Bone, A. R. Pearson, E. Sinkinson, and W. E. Stockings: Researches on the chemistry of coal. Pt. 2: The resinic constituents and coking propensities of coals. Prolonged extraction of eight selected coals by typical resin-solvents in a Soxhlet apparatus has no appreciable effect upon their coking propensities, which therefore cannot be ascribed to the presence of free resins. A resin isolated by a new method from two typical bituminous coals has a molecular weight of about 450, agreeing with the empirical formula C31H32O3; its properties correspond with those of a resene in Tschirch's classification of resins. The usual pyridine-chloroform method of extracting coals does not effect a complete separation between the resinous constituents and the degradation products of the cellulose of which coal is conglomerated. It yields an admixture of resins with a predominance of non-resinous substances of cellulosic origin, provisionally designated “humic” bodies. These substances may amount to 4 per cent, of the coal substance. The strong coking propensities of some coals are principally due to the presence, or formation in them by heat, of such non-resinous “humic” substances of cellulosic origin the fusion temperatures of which are below those at which they undergo rapid decomposition; the more complex substances of cellulosic origin, which form the main portion of the coal substance and decompose without fusion, have little or no influence upon the coking, properties.—J. A. Crowther and B. J. Schonland: The scattering of β-rays. The scattering of a homogeneous beam of β-rays has been measured for various elements, and at various angles with the beam. The results obtained are compared with the, nuclear theory of scattering of Sir Ernest Rutherford, a correction being applied to allow for the variation of the mass of the β-particle with velocity. Scattering is due to single encounters between the β-particle and the deflecting particles as postulated by the theory until the thickness of the scattering material reduces the radiation to half value. The scattering by gold is iff numerical agreement with the theory when measured at very small angles with the primary beam. It increases rapidly as the angle is increased, and finally attains a value approximately four times that given by the theory. This high value is given by the lighter elements at all the angles investigated. Present theories of scattering require modification when the collisions between the β-particle and the deflecting nucleus are closer than a certain critical distance which is of the order of 10-10 cm. in the case of gold.—Ann C. Davies: The minimum electron energies associated with the excitation of the spectra of helium. The lines of the orthohelium and parhelium series are simultaneously excited when ionisation of the helium atom has occurred. The limiting voltages for excitation are 20.4 and 25.2, according to whether ionisation bv multiple impacts can occur or not. The corresponding voltages in the case of the enhanced line λ4686 are 54.2 and 80.0 respectively. This line can also be excited from the helium positive ion without further ionisation of the atom at 50.8 volts, the value deduced from Bohr's theory. The minimum voltage for the appearance of the helium band spectrum is 20.4, and the conditions indicate that it is emitted by He, molecules. Orthohelium and parhelium lines and the band spectrum are maintained as the voltage is backed down to 13 volts at high pressures.—C. N. Hinshelwood, H. Hartley, and B. Topley: The influence of temperature on two alternative modes of decomposition of formic acid. Formic-acid vapour in contact with glass surfaces between 200° and 300° C. decomposes mainly in the following ways:—
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Societies and Academies. Nature 109, 156–159 (1922). https://doi.org/10.1038/109156b0
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DOI: https://doi.org/10.1038/109156b0