Abstract
LONDON. Royal Society, December 3.—W. A. Bone and G. W. Andrew: Studies in catalytic combustion. Pt. ii. The union of carbon monoxide and oxygen in contact with nickel, copper, and other oxides. With nickel gauze at 365° C., the formation of a highly reactive Ni-CO (or possibly O-Ni-CO) complex in the surface layer may become a prime factor in the catalytic combustion. The action of the metal may really be of a dual character, involving (a) the “activation” by the metal of the two gases marked by a comparatively low rate of carbon dioxide formation, and (b) the intermediate formation of still more reactive CO-Ni-O complexes. With copper gauze at 135° and 250° C., for the real “catalytic” reaction, no prior formation of either copper oxide or any Cu-CO complex was required, but only the “occlusion” of the respective gases. With granular nickel oxide at 150° C., and granular copper oxide at 165° to 175° C., respectively, the catalytic action depends upon the formation at the surface of an “activated” oxygen film probably of more than monomolecular thickness. The real catalytic com bination of carbon monoxide and oxygen over all these surfaces is independent of either the oxida tion of a primarily formed “carbonyl” film or the reduction of a metallic oxide.—F. H. Constable: Immobile groups of atoms with strong specific external fields as the cause of catalytic activity. Copper surfaces made by electrolytic deposition, reduction of alkaline copper solutions, and by hammering and polishing, have an activity probably less than 1/9000th that of the reduced metal. When the surface was produced by sudden cooling of the vapour, or by thermal decomposition of copper salts of organic acids, or by reduction of copper oxides, a markedly active product was obtained. The passage of ammonia gas over the metal at 820° C. produced some activation. The physical appearance of the surfaces varied from a metallic colour, through dull yellow to red-brown. Generally the surface activity and the temperature coefficient of activity were nearly the same. A new method of comparing surface activities of preparations has been devised, depending on the behaviour of copper on alternate oxidation and reduction. The catalytic action is considered to be due to fixing groups of atoms in such a state of strain that strong specific external fields are main tained.—S. C. Roy: On the law and mechanism of monomolecular reaction.—F. A. Williams: The effect of temperature on the viscosity of air. The co efficient of viscosity of dry air free from, carbon dioxide has been studied by a comparative trans piration method, with a silica spiral, from 15° C. to 1002° C. The results show that Sutherland's formula for the temperature coefficient of viscosity holds with great accuracy between 250° and 1000°, the value of C, the Sutherland constant, in this range being 172.6. Below 250°, Sutherland's law is no longer true, and the value of C falls off as the temperature decreases.—R. W. Kenning: Gaseous combustion at medium pressures. Pts. i. and ii. Pressure - time records of the explosion of a complete combustion, carbon monoxide-air mixture with additions of (a) hydrogen-air and (6) water vapour, give records identical with those produced by (i) carbon monoxide-air plus I -2 per cent, of water vapour, (2) carbon monoxide-air plus 2.1 per cent, of hydrogen-air (nearly dry). Closed-vessel explosions of methane-air mixtures were also in vestigated, the initial temperatures ranging from 24° C. to 400° C., and the initial pressures from 30 Ib. to 171 Ib. per square inch. For a mixture containing 9.9 per cent, of methane, the explosion-time was increased by (i) increasing the charge density, (z) reducing the initial temperature, and (3) adding a diluent such as combustion products or water vapour.:—R. K. Schofield and E. K. Rideal: The kinetic theory of surface films. Pt. ii. In Pt. i. it was shown in the case of dilute aqueous solutions of the fatty acids C4-C6, that the ratio FA/RT (where A = i/r is the area.occupied by a gram molecule of fatty acid in the film) is not unity, but varies with F in a manner completely analogous to the variation of pv/KT with p for real gases. FA/RT, F curves for surface films of the sparingly soluble fatty acids C8, C10, and C12 on dilute hydrochloric acid have been constructed from the surface tension-concentration data of Frumkin. At high-surface pressures the curves are straight, and thus (like those for the lower acids) conform to the two-dimensional Amagat equation F(A -B) = #RT. At low-surface pressures the curves, though essentially similar, do not corre spond exactly with those of fluids. This is attributed partly to the molecules in the film having two distinct parts with different cohesions, and partly to the elongated shape of the molecules, which become inclined to the plane of the interface when in the act of separating from one another, thus causing the critical area to increase with the length of the hydro carbon chain.—H. B. Dixon and G. Greenwood: On the velocity of sound in mixtures of gases. The method adopted was by comparing the dust-figures produced in a standard gas and those in the mixture by the resonance set up in two similar tubes. The results obtained (i.) in mixtures of gases of different density, (ii.) in mixtures of gases of the same density, are in close accord with the theoretical values calcu lated from the density of the mixtures and the specific heats of their constituents.—A. Page and L. F. G. Simmons: An investigation of the air flow pattern in the wake of an aerofoil of finite span. The vorticity is distributed over an area forming a band roughly parallel to the plane and ending in regions approximately opposite the tips, where the intensity is high. Farther behind the aerofoil, the band disappears from the central part, and at about 13 chords away the vortex system resolves itself into two localised areas. In front of the aerofoil, and beyond each wing tip, the flow is irrotational. Over each of the planes of exploration behind the aerofoil, the velocity is sensibly uniform.—W. L. Webster: Magneto-striction in iron crystals. For the (i, o, o) axis there is an increase in length for all values of the magnetisation; for the (i, i, o) axis there is an initial increase in length, followed by a contraction as magnetic saturation is approached; for the (i, i, i) axis there is a continual contraction. A combination of these effects seems to explain the results for soft iron, which are similar to those for the (i, i, o) axis. The effect of stress on magnetisation in the same rods is measured, and the results applied to a thermo-dynamically obtained, reciprocal relation between magneto-striction and the effect of stress on magnetisa tion. The agreement is satisfactory.—R. W. James and W. A. Wood: The crystal structure of barytes, celestine and anglesite. The structures of the iso-morphous sulphates of barium, strontium and lead are all very similar. The structure is based on a simple orthorhombic lattice having four molecules to the unit cell, and the space group is V,16. The positions of the atoms have been determined by a study of intensities. In calculating the structure factors, the figures for the diffracting power of ions at different angles calculated by Hartree have been employed with slight modifications. The absolute intensity of reflection observed is lower than, although of the same order of magnitude as, that calculated on the classical theory.—O. Maass and J. H. Mennie: Aberrations from the ideal gas laws in systems of one and two components.—R. G. Lunnon: Fluid resistance to moving spheres. A large number of measurements of the times of fall of spheres, differing in size and density, through distances varying from 3 to 538 metres, in coal-mine shafts and other places, have been made. The resistance of air is calculated, and the way in which resistance depends upon velocity and acceleration for any sphere in linear motion is deduced. The range of velocity is such that the values of the Reynolds number are in the critical region (104<R105), in which the resistance to uniform motion is proportional first to a power higher than the second, and later to a lower power. The effect of acceleration is to accentuate the rapid! change in the resistant coefficient (F/pVW). An application of the theory of dimensions suggests that the fluid resistance may depend not only upon velocity and acceleration, but also upon the rate of change of the acceleration.—W. G. Palmer: The adsorptive equilibria of binary gaseous mixtures. The method of the “coherer” is now applied to the determination of the composition of films containing two gases in adsorptive equilibrium with mixtures of the gases. The present application leads to a purely empirical method. The hypothesis that gaseous films are commonly only one molecule thick is corroborated. Examples of the following cases are given: (i) each gas competes equally for all the spaces on the surface; (z) a complex containing both gaseous molecules is formed, and acts as a single unit on the surface; (3) one gas is adsorbed only on specific areas of the surface. The method is rapid and should form a useful adjunct to investigations of catalytic actions upon solid surfaces.—I. Sandeman: The secondary spectrum of hydrogen at higher pressures, (ii.) A P and an R series have been selected, fitting along with Richardson and Tanaka's 83(3 into a P, Q, and R combination, and closely conforming with the com bination principle. This band is one of four bands the null lines of which are given by the Rydberg formula:
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Societies and Academies. Nature 116, 885–887 (1925). https://doi.org/10.1038/116885b0
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DOI: https://doi.org/10.1038/116885b0