Abstract
LONDON. Royal Society, January 24.—Sir J. J. Thomson, president, in the chair.—Prof. A. N. Whitehead: Graphical solution-for high-angle fire.—Spencer Pickering:Flocculation. The subsidence of suspended matter on the addition of a flocculant to a mixture of kaolin and water is accompanied by an increase of 100 to 200 per cent, in the specific volume of the sediment deposited. This increase, as well as the disappearance of Brownian motion, proves that flocculation is due to an increase in the size of the particles. With acids as flocculants, definite combination between them and the kaolin occurs, the acid being almost completely removed from the solution up to the point when fiocculation is complete, beyond which no more is removed. The acids being in a highly hydrated condition accounts for the increase in volume of the kaolin particles on uniting with them. With alkalis the phenomena are the same, but combination is complete only in the presence of excess of alkali; hence the concentration at which fiocculation occurs is much higher. In very weak alkaline solutions where there is but little actual combination, the subsidence of the particles is retarded by the attraction of the alkali present.—Dr. J. Aitken: Revolving fluid in the atmosphere. The paper deals with the objections to the cyclonic theory of circulation recently advanced by Sir Napier Shaw. These objections are founded on the fact that the charts of isobars and winds of the weather maps nowhere show a circulation such as would be given by a combination of the motions of rotation and translation. It is pointed out that these objections are based on suppositions which do not find support in Nature. If the cyclone were a closed system, the winds would be such as Sir Napier says they ought to be, but as the cyclone is an open one and draws in air at its lower end, and as this incoming air is only on its way to become part of the system, it cannot be treated as having the revolution and translation of the cyclone. If the combination of these two motions is to be found anywhere, it will probably be in the higher winds, and even there they will be affected by the general circulation in the system.—Hon. R. J. Strutt: Ultra-violet transparency of the lower atmosphere and its relative poverty in ozone. (1) The lower atmosphere is found to be comparatively transparent to ultra-violet light. The A 2536 can be detected on the spectrum of a mercury lamp four miles distant. (2) The solar spectrum, even when observed from high altitudes when the equivalent thickness of air overhead (reduced to N.T.P.) is less than four miles, is limited by atmospheric absorption to A 2922. Air near the ground-level is therefore much more transparent to ultra-violet light than the upper air. (3) Since the limitation of the solar spectrum is almost certainly due to ozone, it follows that there must be much more ozone in the upper air than in the lower. (4) Scattering by small particles acts in the same way as ozone to absorb ultra-violet radiation from a distant source, and this action makes quantitative estimation difficult. Even if the observed enfeeblement of A 2536 were entirely due to ozone, 0-27 mm. of pure ozone in four miles of air would suffice to produce it. Taking scattering into account, the quantity is probably much less, and there is no evidence from this investigation that any ozone is present in the lower air.—Prof. A. Fowler: The presence in the solar spectrum of the water-vapour band A 3064. The band at A 3064, which is usually attributed to water-vapour, is quite strongly represented in the solar spectrum, and accounts for at least 1.50 lines which were previously unidentified.—Prof. A. Fowler and C. C. L. Gregory:—The ultra-violet band of ammonia and its occurrence in the solar spectrum. The ammonia band having its greatest intensity at A 3360 has been photographed with high resolving power, and the positions of 260 component lines have been determined. In the principal maximum, and in a secondary maximum at A 3371, the band lines are verv closely crowded and form series of the usual tvpe. On the less refrangible side the principal lines form three series which coalesce and fade out at A 345° and there is a similar set of three series on the more refrangible side which coalesce and disappear at A 3287. These two groups, however, are not symmetrical, and they differ considerably from the more usual type of series. It is shown that the ammonia band lines are consistently represented in the solar spectrum and account for about 140 faint lines which were previously unidentified. The remaining band lines are either too weak to appear in the sun or are obscured by lines of metallic origin. The brightest part of the ammonia band accounts for the greater part of Group P of the solar spectrum.
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Societies and Academies . Nature 100, 457–460 (1918). https://doi.org/10.1038/100457a0
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DOI: https://doi.org/10.1038/100457a0