OZONE IN THE UPPER ATMOSPHERE 467 



through the vessel during an ascent and descent was made from 

 the following data. From the calibration made above, it was 

 seen that the exposure of the vessel to a horizontal flow of 

 air of one mile caused the passage of 5-12 litres. Expressing 

 in centimetres, this gives for a displacement of 1 cm. 



5"I2 X IO 3 



r6x io : ' 



c.c. = 0*032 c.c. 



since 1 mile = i'6 x io 5 cm. 



On the assumption that the volume circulated is proportional 

 to the displacement through the air, it follows that during an 

 ascent and descent, the mass of air passed through in grams 

 is given by 2 (p — p,) x 13-6 x 0-032, or 0-87 (p — p,), where p is 

 the atmospheric pressure in cm. of mercury at ground level, 

 Pi that at the highest level reached, and 13-6 the density of 

 mercury. The volume circulated in litres (measured at N.T.P.) 

 is therefore 0*675 (p — p,). 



The values for the pressures at different altitudes have been 

 taken from meteorological tables as reproduced below : 



At a height of about 6,000 metres the temperature is always 

 below the freezing point of the reagent (— 24°), so that reaction 

 must then take place with the solid. It was seen above that 

 under these conditions the method applied did not enable a 

 distinction between ozone and oxides of nitrogen. However, in 

 all measurements made up to 3,600 metres, it was found that 

 neither this gas nor hydrogen peroxide were present in any 

 appreciable quantity. Nitrogen peroxide is of course quite 

 stable at ordinary temperatures, and until dissolved by atmo- 

 spheric water as nitric acid, any gas formed at high altitudes 

 would remain undecomposed. 



The reagent placed in the vessel in these atmospheric tests 

 consisted of 5 to 7 cc. of the 50 per cent, potassium iodide 

 solution as used in all the other measurements. After being 

 returned by the finder through the post, the amount of solution 

 remaining usually amounted to about 2 cc. The values given in 

 the tables are calculated on the initial quantity of reagent. 



