Abstract
LONDON. Royal Society, May 31.—E. Griffiths and G. W. C. Kaye: The measurement of thermal conductivity, No. i. Three types of apparatus of the “plate” type are described for the rapid precision determination of the thermal conductivities of materials at low conductivity. Energy was supplied by electrical means and temperatures were measured by thermocouples. An average time for the attainment of the “steady state” was 30 minutes or less, and the average accuracy of measurement of the conductivity was about i per cent. Among the topics discussed was the thermal resistance at the bounding faces of a material, the effect of superimposing layers of compressible material, the measurement of the thickness of compressible material, the dependence of the conductivity of timber on structure and moisture-content and the variation of the conductivity of rubber with mineral content.—G. W. C. Kaye and J. K. Roberts: The thermal conductivities of metal crystals. I.—Bismuth. A “plate” apparatus measuring thermal conductivities as high as 0.02 C.G.S. with an accuracy of about 1 per cent., using specimens 2 cms. by i cm. in area and about 1 or 2 mm. in thickness was used. The conductivities of single crystals of metallic bismuth in directions parallel and perpendicular to the trigonal axis at 18° C. are, in C.G.S. units, 0.0159 and 0.0221. The ratio of conductivities is 1.39. The mean value 0.0191 agrees well with the figure 0.0193 obtained on bars by Jaeger and Diesselhorst in 1899. Thus in the case of bismuth metal in the aggregate, the distribution of the constituent small crystals is random, and the effect on the thermal conductivity of any inter-crystalline layers is not appreciable.— C. V. Drysdale and S. Butterworth: The distribution of the magnetic field and return current round a submarine cable carrying alternating current. Pt. I. (By C. V. Drysdale.) An exact knowledge of the magnetic field distribution in the neighbourhood of a submarine cable is of great importance in connexion with leader gear and the propagation of radio signals between submerged stations. Investigations have been carried out since 1918 at the Admiralty Experimental Stations at Parkeston Quay and Shandon, with the object of determining the magnitude and phase of the magnetic field in and above the surface, and of the return current in the water, as well as the velocity of propagation and attenuation of the electro-magnetic waves in the water and the shielding effect of the cable armouring. Measurements were made with an alternating current potentiometer on horizontal and vertical search coils above and below the surface and on electrodes in the water at frequencies from 50 to 500 periods per second. Pt. II. (By S. Butterworth.) Expressions for the distribution of electric force due to a long cable carrying alternating currents and immersed in a sea of uniform depth have been obtained in the form of Fourier integrals and formulae have been developed which cover the following cases: (1) The field above the surface of the sea when the depth of the water is small; (2) the field above the sea at large distances from the cable, there being no restriction in regard to depth; (3) the field below the surface of the sea for points vertically above the cable; and (4) the field below the surface of the sea at large distances from the cable when the depth of the sea is great. The results for points above the surface of the sea have been verified by tests in which the sea is replaced by a sheet of lead. The formulæ are in substantial agreement with actual sea observations.—S. Russ: The effect of X-rays of different wavelengths upon some animal tissues. Two regions in the X-ray spectrum were selected, and it was arranged that equal doses of X-ray energy were absorbed in their passage through the tissues. In these circumstances more profound effects were produced by the longer wave-lengths (0.45–0.30 Å.U.) than by the shorter wave-lengths (about 0.168 Å.U.), both upon the normal skin of the rat and upon Jensen's rat sarcoma. The degree of this differential action is more pronounced in the case of the skin than it is for the tumour, the numerical values being 6 and 2.6 respectively. These numbers are termed “therapeutic factors.”—E. F. Armstrong and T. P. Hilditch: A study of catalytic actions at solid surfaces. Pt. XI.—The action of alumina and certain other oxides in promoting the activity of nickel catalyst. In the absence of any carrier for the nickel, the presence of a small proportion (up to 5 per cent.) of an oxide, such as that of aluminium or magnesium, increases the catalytic activity of the reduced metal. When the nickel oxide is deposited on a support, e.g. kieselguhr from which the metallic constituents have been extracted, the catalyst is inferior to that on natural kieselguhr. Its activity is restored if about 20 per cent. of alumina is precipitated with the hydroxide of the nickel. If this proportion of alumina is first deposited on the acid-extracted kieselguhr and the nickel hydroxide or carbonate then precipitated on to this preparation, the catalytic activity of the product generally exceeds that of nickel on the natural kieselguhr. It seems that the action of the non-reducible oxide is mainly mechanical and connected with increase or diminution of the surface area of the exposed nickel.—N. K. Adam: The structure of thin films. Pt. IV.—Benzene derivatives.—A condition of stability in monomolecular films. Derivatives of benzene, such as hexadecyl phenol, containing one long chain and one polar group in the para position, orient on water surfaces like fatty acids, the phenol group forming the head of the molecule in contact with the water. Compounds such as cetyl palmitate, palmitic anilide, etc., which contain one polar group placed between two chains or one chain and a ring, do not adhere to a water surface well enough to give measurable condensed films. The para sulphonic acids in hexadecyl and octadecyl benzene give soap-like solutions in water. Pt. V. Bromine in the a position, in the bromo-acids and esters, increases the cross-section of the molecules in the films. The bromine atom increases the solubility of films of the higher fatty acids. It also lowers the temperature of change from condensed to expanded films; but it does not appreciably affect the properties of the films, when expanded. The double linkage in the a ft position relative to the COOC2H5 group increases the cross-section of the molecule in the films, as it does in iso-oleic acid.—W. B. Rimmer: The spectrum of ammonia. Of the three bands which are associated with the spectrum of ammonia, the ultra-violet band has already been investigated in detail by Fowler and Gregory, and is represented in the solar spectrum. The “Schuster bands” λ 5635 and λ 5670, have given no sign of resolution under high dispersion, and it is probable that they do not occur in the solar spectrum. The “α band” of Eder and Valenta is of great complexity, consisting of about 3000 lines; there is no conclusive evidence that this band occurs either in the solar spectrum or in the spectrum of sunspots. The Schuster bands seem to have their origin in the normal ammonia molecule and the ultra-violet band is probably due to emission from a more stable combination of nitrogen and hydrogen. The α band appears to be associated with a combination of nitrogen and hydrogen of intermediate stability. The occurrence of the ultra-violet band alone in the solar spectrum indicates that only the most stable combination of nitrogen and hydrogen can exist under the conditions that obtain in the reversing layer.
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Societies and Academies. Nature 111, 793–796 (1923). https://doi.org/10.1038/111793a0
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DOI: https://doi.org/10.1038/111793a0