Societies and Academies

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LONDON. Royal Society, March 12.—Sir William Crookes, president, in the chair.—Sir James Stirling: Note on a functional equation employed by Sir George Stokes.—Prof. J. C. McLennan and A. R. McLeod: The mercury green line λ = 5461 as resolved by glass and quartz Lummer plates and on its Zeeman components.—H. Hartley: The electrical condition of a gold surface during the absorption of gases and their catalytic combustion. At the suggestion of Prof. W. A. Bone, the author has carried out experiments on the electrical conditions of a gold surface during its absorption of hydrogen, carbon monoxide, and oxygen, respectively, at temperatures between 300° and 400°, in order to establish certain data relative to surface combustion phenomena. The results have proved (1) that the metal acquires a negative charge during the catalytic combustion of gases in contact with it (thus confirming previous unpublished observations by Bone and Makower), which effect is probably antecedent to the actual combustion, and primarily due to “occlusion” phenomena; (2) that the metal becomes negatively charged (0.5 to 1.5 volts) during the occlusion of the combustible gas (hydrogen or carbon monoxide), and positively charged (0.8 volt) during the occlusion of oxygen; and (3) that such electrical effects are probably due to occluded gas which is leaving (rather than entering) the surface. The experiments indirectly lend support to the view that the well-known electronic emission from incandescent solids is probably de pendent upon the occlusion of gas.—J. H. Mackie: The diffusion of electrons through a slit.—Dr. A. Holt: The rate of solution of hydrogen by palladium. The rate of solution of hydrogen at constant (atmospheric) pressure by palladium in the form of black, thin and thick foil has been examined. The rate curves in the case of palladium black are simple and of continuous curvature, but for the foil a more or less pronounced discontinuity of curvature is always observed. The discontinuity is accounted for by considering that the gas is dissolved in two different forms of the metal, the rate of solution being different in the two forms. Palladium black is believed to consist almost wholly of one form, and hence gives a simple rate curve, whilst the foil (which is mainly crystalline) contains both varieties of metal, and so gives two rates, the first rate passing into the second when solution in both forms becomes equally rapid.—Dr. R. A. Hoiistoim The dispersion of a light pulse by a prism. A light pulse of a form giving the Wien energy distribution is incident on a prism, and expressions are derived (1) for the disturbance in the region immediately behind the prism where the different colours overlap; and (2) for the disturbance in the focal plane of the telescope. The first expression holds only for a particular law of dispersion, but the second is for any law of dispersion. They are both in accordance with results obtained by Lord Rayleigh by considerations of stationary phase and hydrodynamical analogy, but they go further. For example, it is definitely stated how the amplitude varies in the front and rear of and throughout the train of waves given rise to by the pulse in the different parts of the spectrum.