Volume 9, Issue 8, 01 August 1938
Index of content:
9(1938); http://dx.doi.org/10.1063/1.1710445View Description Hide Description
9(1938); http://dx.doi.org/10.1063/1.1710450View Description Hide Description
Two new methods for measuring the reflection coefficient of mercury atoms from a mercurysurface are described. In the first, a micromanometer gives both the change in pressure on the surface, and the subsequent rate of evaporation, when a mercury pool is exposed to an opposing liquid air cooled condensing target. From these, reflection coefficients from 0.93 to over 0.99 are obtained. In the second, from measurement of the vapor density between evaporating and condensing surfaces by an ionization gauge, the reflection coefficient can be calculated. With careful purification of the mercury, quite small reflection coefficients result, a mean of 0.2, and a minimum of 0.07 being found. Exposure of the mercurysurface to the atmosphere for half an hour brings the reflection up to 0.8, while after 10 days' exposure the reflection coefficient becomes 0.92.
Studies in Lubrication II. Experimental Friction Coefficients for Thick Film Lubrication of Complete Journal Bearings9(1938); http://dx.doi.org/10.1063/1.1710451View Description Hide Description
A straight line which, when extended, passes through the origin of coordinates is obtained when the coefficient of friction for a full journal bearing operating in the thick film region is plotted against μN/P, where μ is the lubricant viscosity,N the journal speed, and P the bearing load per unit of projected area. At higher speeds, when the film temperature around the bearing is not reasonably uniform, large deviations from this line are found. An increase of friction, which qualitatively confirms the theory developed in part I of this series, is observed when the strength of the source of lubricant is increased.
9(1938); http://dx.doi.org/10.1063/1.1710452View Description Hide Description
X‐ray studies of samples made of sucrose, glucose, and acetylsalicylic acid were made to determine if the latter is in solid solution with the sugars. The main constituent of the samples was sucrose and the amounts of acetylsalicylic acid varied from one and a half to twenty per cent. The samples were prepared by melting and heating the sugar combinations to 160°C, removing essentially all the water and allowing to cool. The acetylsalicylic acid was then incorporated in one set of samples at 140°C and in another at a temperature between 110–115°C, that is, both above and below the melting point (133–5°C) of the compound. The former samples were far more hygroscopic than the latter, but in neither case did the acetylsalicylic acid seem to form a solid solution with the rest of the constituents.