METEOROLOGY 357 



collected some trustworthy information about the " eye " of 

 the storm. He finds that the maximum wind speed occurs 

 very close to this area, and that the whole inner region (the 

 " eye " and the violent winds immediately adjoining it) is 

 roughly symmetrical about the centre. 



The central " calm " is not always complete ; within it 

 the barometer not infrequently falls towards the centre, but 

 sometimes varies irregularly. A rise of temperature and fall 

 of relative humidity has often been observed on land during 

 the passage of the " eye," but not at sea. 



With regard to the height of a cyclone, observations by 

 Dallas of the crossing of storms from the Bay of Bengal to the 

 Arabian Sea over the Western Ghats suggest that these whirls 

 considerably exceed 3,000 feet in height. Most writers agree 

 in believing that the whole phenomenon takes place below the 

 level of Cirrus and Alto-stratus clouds. There is observational 

 evidence furnished by cloud movement of an outward flow of 

 air from the centre, but the height of such clouds being unknown, 

 it is not possible to say exactly at what level this takes place. 



The rain which accompanies the passage of a cyclone not 

 infrequently amounts to 20 or 30 inches and is often accom- 

 panied by thunder and lightning. 



PHYSICAL CHEMISTRT. By W. E. Garner, University College, 

 London. 



Chemical Reactivity. — ^During the last year, several papers 

 have appeared which illustrate some of the fundamental 

 problems of chemical reactivity, and, in a number of cases, 

 the phenomena described are not readily explained by current 

 chemical theory. The positive catalysis of chemical reactions 

 by minute concentrations of water vapour has long been 

 known, and was explained by Dixon in the case of the reaction 

 between CO and Oj as due to the formation of an intermediate 

 substance, nascent hydrogen. H. B. Baker [Trans. Chem. 

 Soc.y 1922, 121, 568) has succeeded in showing that traces of 

 water vapour not only influence chemical reactivity, but also 

 play a part in the normal processes of evaporation and melting 

 of organic and inorganic substances. In 191 2 he found that 

 the boiling points of the tri- and the tetroxides of nitrogen are 

 raised b^'- 44° C. and 47° C. respectively when dried over 

 phosphoric oxides, and he has recently extended his investiga- 

 tions to a number of other liquids — benzene, hexane, ether, 

 bromine, etc. — and, after several years' drying, finds that the 

 boiling points are raised by from 30°-4o° C. Benzene, for 

 example, was found to boil at 106° C. instead of the normal 

 value, 80° C. There is no abnormality in the boiling, and it 



