818 CURRENT TOPICS. [J. F. I. Use of Cirrus Clouds in Forecasting the Weather. G. REBOUL and L. DU~'0YER.. (Comptes Rendus, March 22, I92O.)--The appearance of cirrus clouds has for a long time been known to be connected with the shifting of barometric pressures. The authors have subjected certain phases of this relation to the test of com- parison over considerable lengths of time. In 93 per cent. of the cases it was true that the appearance of this type of cqoud indicated a barometric depression in the neighborhood. In 82 per cent. of the cases the direction in which these clouds moved was toward the depression. The agreement in France was, however, much bet- ter for a motion from the west than in the opposite direction. In about 63 per cent. of the cases the cirrus clouds moved in the same general direction as the depression. Seventy per cent. of the times a great velocity in these clouds means a great velocity in the motion of the depression. The development of cirrus clouds in quantity means either that the depression is close at hand or that it is quite considerable in amount. G. F. S. Acid $olutions.--The relationship between the total acidity, the concentration of the hydrogen, and the taste of acid solutions has been investigated by R. B. HARVEY (Journal of the American . Chemical Society, 192o, xlii, 712-714). Total acidity is the total amount of free acid present in the solution, and includes both that in the molecular state and that dissociated into its ions. Concentra- tion of the hydrogen ion represents the hydrogen ions, and therefore measures the dissociated free acid present in the solution. Harvey's results indicate that the sour or acid taste of an acid solution depends on both the total acidity and the hydrogen ion concentration. It is therefore desirable that both these values be determined in the case of acid foods. The addition of sugar alters the taste, but does not change either the total acidity or the hydrogen ion concentration. J. S.H. The Constitution of Atmospheric Neon. F.W. ASTON. (Phil. Mag., April, I92O.)--By the use of the Positive Ray Spectrograph it has been proved that neon contains two isotopes of atomic weights, 20.00 and 22.oo respectively. Their ratio by volume is 9: I. There is some indication of the existence of a third isotope. G. F. S. ¢ PRESS OF J. B. LIPPINCOTT COMPANY PI{ ILADELPHIA

Use of cirrus clouds in forecasting the weather

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Page 1: Use of cirrus clouds in forecasting the weather

818 CURRENT TOPICS. [J. F. I.

Use of Cirrus Clouds in Forecas t ing the Weather . G. REBOUL and L. DU~'0YER.. (Comptes Rendus, March 22, I92O.)--The appearance of cirrus clouds has for a long time been known to be connected with the shif t ing of barometr ic pressures. Th e authors have subjected certain phases of this relat ion to the test of com- parison over considerable lengths of time. In 93 per cent. of the cases it was true that the appearance of this type of cqoud indicated a barometric depression in the neighborhood. In 82 per cent. of the cases the direction in which these clouds moved was toward the depression. The agreement in France was, however , much bet- ter for a motion from the west than in the opposite direction. In about 63 per cent. of the cases the cirrus clouds moved in the same general direction as the depression. Seventy per cent. of the times a grea t veloci ty in these clouds means a great veloci ty in the motion of the depression. The development of cirrus clouds in quant i ty means ei ther that the depression is close at hand or tha t it is quite considerable in amount .

G. F. S.

Acid $o lu t i ons . - -The relat ionship between the total acidity, the concentration of the hydrogen, and the taste of acid solutions has been investigated by R. B. HARVEY (Journal of the American . Chemical Society, 192o, xlii, 712-714). Total acidity is the total amount of free acid present in the solution, and includes both that in the molecular state and that dissociated into its ions. Concentra- tion of the hydrogen ion represents the hydrogen ions, and therefore measures the dissociated free acid present in the solution. H a r v e y ' s results indicate tha t the sour or acid taste of an acid solution depends on both the total acidity and the hydrogen ion concentrat ion. I t is therefore desirable tha t both these values be de termined in the case of acid foods. The addition of sugar al ters the taste, but does not change ei ther the total acidity or the hydrogen ion concentrat ion.

J. S . H .

T h e Const i tu t ion of Atmospher ic Neon. F . W . ASTON. (Phil. Mag., April, I92O.)--By the use of the Positive Ray Spectrograph it has been proved that neon contains two isotopes of atomic weights, 20.00 and 22.oo respectively. Their ratio by volume is 9: I. There is some indication of the existence of a third isotope.

G. F. S.

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