Abstract
American Journal of Science, November.—On the wavelength of the D3 helium line, by A. De Forest Palmer, jim. The definition and intensity of this line varied greatly from day to day. The best combination of intensity and definition was obtained by avoiding prominences and working only on very clear days. The average for seventeen series of measurements was 5875˙939±˙006.—Some additional notes on argon and helium, by Edwin A. Hill. The. conclusion that argon is monatomic depends upon the correctness of three assumptions, viz., that a gas, with little or no rotational energy, must be monatomic; that the ratio of the two specific heats of 1˙67 proves the gas to have no rotational energy; and that the ratio of the two specific heats is correctly determined. In choosing between the two alternatives of a diatomic gas without rotational energy or a free atom devoid of chemical affinity, the presumption is strongly raised that it is not a monatomic gas, but diatomic and chemically inert because the two.atoms of the molecule are very strongly bound together. There is not much doubt that helium is a mixture, and if anything can be argued from the analogies betvveen argon and helium, argon is a mixture likewise.—Recent progress in optics, by W. Leconte Stevens. Part II. This concluding portion of the presidential address deals with colour photography, with recent researches on the spectrum and on polarised light, and with colour sensation.—Effect of the mutual replacement of manganese and iron on the optical properties of lithiophilite and triphylite, by S. L. Penfield and J. H. Pratt. The transition from LiMnPO4 to LiFePO4 is marked by a considerable change in the optical characters of these isomorphous minerals. With an increase in iron there is an increase in the indices of refraction, and also the divergence of the optical axes changes rapidly.—The reduction of selenic acid by hydrochloric acid, by F. A. Gooch and P. S. Evans, jun. A solution of selenic acid is boiled in hydrochloric acid, and if the solution is not too dilute the reduction is obtained in a few moments. The hydrochloric acid must form at least 30 per cent, of the entire solution. The solution should be boiled until all the chlorine is expelled, but must not be allowed to fall below two-thirds of its original volume.—Reduction of selenic acid by potassium bromide in acid solution, by F. A. Gooch and W. S. Scoville. When intermixed with sulphuric acid and potassium bromide, selenic acid liberates bromine in proportion to the excess of acid, the bromide, and the elevation of the temperature. On boiling, the bromine is evolved and may be collected in potassium iodide, and the iodine thus set. free may be determined by standard sodium thiosulphate and taken as the measure of the bromine distilled.—Restoration of some European Dinosaurs, with suggestions as to their place among the Reptilia, by O. C. Marsh. The geological positions of Compsognathus and Scelidosaurus are fully determined, but that of Hypsilophodon and Iguanodon is not so clear. The latter are found in the Wealden, which is usually considered to be Cretaceous, but might as well be classified as Upper Jurassic.
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Scientific Serials. Nature 53, 190 (1895). https://doi.org/10.1038/053190a0
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DOI: https://doi.org/10.1038/053190a0