Index of content:
Volume 11, Issue 10, 01 October 1940
11(1940); http://dx.doi.org/10.1063/1.1712714View Description Hide Description
The influence of film thickness on the formation of cupric oxide in cuprous oxide films on an abraded coppersurface was studied from measurements obtained by the electrolytic reduction method. The critical thickness value for the formation of cupric oxide in the films appeared to be near 600A for a commercial copper, and the critical thickness range was found to be approximately 400 to 800A. The thicknesses resulting from heating specimens in different atmospheres, for a given time, increase with the oxygen concentration. The time required to produce films of a given thickness decreases as the oxygen concentration increases. Murison's observations concerning the conditions favorable to the formation of cupric oxide in the films at a higher temperature were extended to include the proper period of heating and film thickness as well as oxygen concentration. Dunholter and Kersten's electron diffraction analyses of copper oxide films on mirror‐like surfaces were considered to be in satisfactory agreement with the present results.
11(1940); http://dx.doi.org/10.1063/1.1712715View Description Hide Description
This paper is a report on an experimental investigation of the resistance to the uniform motion of a solid through a viscous liquid, the results of which appear to indicate that the liquid slipped on the surface of the solid. The apparatus was a straight, closed, glass tube containing a steel ball and the liquid being studied. The tube was arranged so that it could be inclined at various angles with the horizontal, and the only motion of the ball that was considered in working up the observations was one of pure rolling. The liquids employed were mixtures of glycerine and methyl alcohol. The analysis of the data is based upon Stokes' and Oseen's forms of Rayleigh's law of resistance, and the results of the investigation are interpreted in the light of theories due to A. B. Basset and to H. Brillié.
11(1940); http://dx.doi.org/10.1063/1.1712716View Description Hide Description
An electron bombardment furnace was constructed for high temperature melting. The temperature attainable is limited only by the refractoriness of the crucible; a tantalum cup (m.p. 2850°C) was melted with the expenditure of only 700 watts. Degassing of sample and surroundings causes gas discharge if the rate of heating is too rapid. Metals volatile at their melting point cannot be melted, but this applies to only a few metals such as manganese and palladium. Alloys of platinum with tungsten,molybdenum, and cobalt are now being successfully prepared for x‐ray investigation. The tendency of some metals to react with available refractory crucibles needs further study before their alloys can be prepared.
11(1940); http://dx.doi.org/10.1063/1.1712717View Description Hide Description
In view of the increasing importance of synthetic plastic materials, a method is developed to measure their vibrational damping in a wide range of temperature up to fairly high plasticity. The method and its results should be useful both from a physical and technical standpoint.
The Optical Properties of Colloidal Suspensions in Relation to the Measurement of Particle‐Size Frequency11(1940); http://dx.doi.org/10.1063/1.1712718View Description Hide Description
11(1940); http://dx.doi.org/10.1063/1.1712719View Description Hide Description
The problem of dynamics of liquid columns, particularly in Diesel engine injection systems, requires a knowledge of the velocity of propagation of compressional waves in the system. Approximate values are generally used in the solution of such problems. In an effort to correlate the physical properties of petroleum oils with the velocity of wave propagation and to relate the characteristics determined at atmospheric pressure with those at higher pressures, tests were conducted in the Physical Laboratories of the Standard Oil Company of California on thirty‐seven hydrocarbon oils at atmospheric pressure. Five hydrocarbon oils were investigated in the Mechanical Engineering Laboratories at the University of California at four temperatures ranging from 57°F to 210°F, and pressures ranging from 500 lb. per square inch to 6000 lb. per square inch. In this paper the experimental methods are described and results presented.
11(1940); http://dx.doi.org/10.1063/1.1712720View Description Hide Description
11(1940); http://dx.doi.org/10.1063/1.1712721View Description Hide Description
Three specimens of rutile were prepared and the dielectric properties studied over a range of frequency and temperature. A dielectric constant of approximately 100 was found which remained substantially constant through the highest radiofrequencies, falling off only in the infra‐red region. The dielectric losses are low, particularly at the higher frequencies. The dielectric constant decreases with increasing temperature, having an average temperature coefficient of −8.2×10−4/°C. An exponential relationship between conductivity and the reciprocal of the absolute temperature holds for rutile in the higher temperature region. Mixtures of rutile powder with other dielectric materials obey a logarithmic mixture formula. Two mechanisms which have been proposed to explain the high dielectric constant of rutile are discussed. A simple mechanism based on the Clausius‐Mosotti equation is described.