Societies and Academies

Abstract

LONDON. Royal Society, Apiil 28.—Sir Archibald Geikie, K.C.B., president, in the chair.—R. B. Sangster: The rotatory character of some terrestrial magnetic disturbances at Greenwich and on their diurnal distribution. The paper commences with an investigation of the changes in direction of the line of total magnetic force at Greenwich on 1903 October 12d. 18h. to 23h., when a considerable magnetic disturbance was in evidence. Measurements of the published registers of all three force components were made at equivalent time intervals of about five minutes, whence is obtained a diagram showing the variation of the force component perpendicular to the line of total force. The diagram shows there was an almost wholly rotatory motion of the transverse disturbance vector, the trace consisting of six distinct convolutions varying greatly in size, but consistent in anticlockwise progression. Several other disturbances during epoch 1900–7 are examined in detail, and it is shown that a right- or left-handed rotatory character in the motion of the disturbance vector was of fairly frequent occurrence, while change from left to right not uncommonly occurred about midnight. It was also found that the same direction of rotation often persisted for several hours, and tables of the diurnal distribution of right- and left-hand rotatory disturbance are furnished to show that those of right-hand character were entirely absent during the hours 4 p.m. to 9 p.m., while, meantime, the left-handed rotations were very prevalent, and reached a notable maximum at 8 p.m. Other points in the diurnal distribution are noted, including the more decided effect resulting from a seasonal grouping of the seventy disturbed days dealt with.—D. Orson Wood: The liberation of helium from minerals by the action of heat. Experiments were made to determine how the volume of helium liberated from radio-active minerals by the action of heat depends on the temperature, and on the time for which that temperature is maintained, in particular with the view of the future use of heat to release all the helium contained in minerals not easily treated by chemical methods. The minerals experimented on were monazite and thorianite, the one comparatively poor and the other very rich in helium. The ground minerals were heated, in vacua, in tubes of Jena glass or quartz, by an electric heater consisting of a single coil of nickel wire, to temperatures up to 1200° C., which were measured by a Pt resistance thermometer or a Pt Pt-Rh thermocouple. The gas released was purified by drawing it through KOH and P2O5 tubes, and finally by Na —K electrodes. The volume was measured in a modified McLeod gauge (described by Prof. Strutt, Proceedings, vol. Ixxx.) specially constructed for the measurement of volumes over a large range—i c.c. to i c.mm. Curves are given to show the volume of helium liberated with time at constant temperatures (250°–1000° C.), and also the percentage of the total content obtainable after prolonged heating at the different temperatures. The way in which the gas must be supposed to be retained within the mineral to accord with the results obtained is discussed, and it is concluded (1) that heat may be used for the complete liberation of the gas if a sufficiently high temperature (about 900° C.) is reached, and (2) that the results are in agreement with the supposition that a small proportion of the gas is diffused through the mineral and that the remainder is concentrated in very minute cavities within it.—Prof. Swale Vincent: The chromophil tissues and the adrenal medulla. The author gives an account of the gross anatomy and histology of the chromophil tissues in mammals, and especially in the dog. Descriptions and drawings of the groups of cells in the sympathetic ganglia and of the chromophil bodies in other regions are furnished, and comparisons are made between their structure and that of the adrenal medulla. An extract of the abdominal chromophil body of the dog has precisely the same powerful effect upon the blood pressure as an extract made from the medulla of the adrenal. There seems no reason why one cannot admit the hypothesis that all the chromophil cells have an internal secretion, though this process is more completely elaborated in the larger chromophil bodies and in the adrenal medulla.