Societies and Academies

Abstract

LONDON. Royal Society, May 25.—Sir Charles Sherrington, president, in the chair. —C. H. Lees: The thermal stresses in solid and in hollow circular cylinders concentrically heated. The method of calculation is similar to that used in dealing with spheres. Two cases of practical importance are worked out-that of a furnace with the temperature throughout the wall steady, and that of a pillar supporting the floor above a room in which a fire occurs. Curves are given for the thermal stresses produced.—B. F. J. Schonland: On the scattering of 3 -particles.— N. K. Adam: The properties and molecular structure of thin films. Pt. II. Condensed films. Pt. III. Expanded films. Saturated and unsaturated fatty acids of the long straight chain series, and their derivatives, including esters, substituted ureas, an alcohol, amide, and nitrite have been studied. Below a certain temperature determined by the conditions, the molecules appeared to be closely packed or “condensed.” Above this temperature greater areas on the surface were occupied, such films being called “expanded films.” Two general types of condensed film were found: one in which the hydrocarbon chains are close packed, while in the other probably only the polar groups touch. In the temperature interval (about 25° C.) between fully condensed and fully expanded states, pressure-area curves resemble isothermals of a vapour near critical temperature. Probably expanded films resemble vapours in two dimensions. Increase in length of hydrocarbon chains raises the temperature of expansion regularly. The lateral attraction which tends to keep the molecules close packed therefore depends on the length of these chains. Probably the greater attraction between longer chains diminishes the area of the expanded films. The area actually filled by molecules both of saturated and unsaturated acids is probably nearly the same in expanded and in condensed films; therefore it is unlikely that the unsaturated linkage in oleic acid approaches the water closely, as was previously thought.—E. Wilson: On the susceptibility of feebly magnetic bodies as affected by compression. Rock specimens were examined and the compressive stress was necessarily limited to about 120,0 kgm. per sq. cm. Some feebly magnetic alloys have also been tested. All the specimens are in the form of short bars about 4 cm. in length, with a cross-section either i cm. square or i cm. in diameter, and the compressive stress has been applied in the direction of the length of the bar. The susceptibility has been measured (a) in the direction of the stress and (b) at right-angles to it.— S. F. Grace: Free motion of a sphere in a rotating liquid parallel to the axis of rotation. The motion is a small disturbance from one of uniform rotation, like a rigid body due to a projection, parallel to the axis of rotation, of a sphere of density equal to that of the liquid and originally at rest relative to it. The path of the centre of the sphere is a straight line, and the motion is symmetrical about it. The sphere oscillates about a point with amplitudes which diminish rapidly, being less than 0-02 of the velocity of projection, after one revolution of the liquid. The velocity of the liquid in this line is oscillatory. The disturbance over the plane through the centre of the sphere perpendicular to the axis is oscillatory, and confined to the immediate neighbourhood of the sphere. The components of verticity contain terms proportional to the time, so that the assumptions of small motion are ultimately violated.