58 



Composition of the Atmosphere 



results obtained from the Tromso samples were for oxygen plus carbon 

 dioxide and not for oxygen alone. 



Table 42. Comparative study of the oxygen content of air, made by Kreusler, Hempel, 



and Morley. 



The Dresden samples showed very slight variations, the results for 

 the same day usually being very close, and commonly exactly alike. In 

 one instance only was there a difference of 0.02 per cent. The average 

 for different days ranged from 20.96 per cent down to 20.88 per cent; the 

 maximum and minimum did not coincide with those for Tromso. 



For the Para samples the agreement for individual days was likewise 

 very close, although in all not so many samples were analyzed. The 

 agreement was within 0.01 or 0.02 per cent, the difference in no instance 

 being more than 0.02 per cent. The average for the day showed fluctu- 

 ations from 20.99 to 20.86 per cent. 



The analyses made in Tromso, Dresden, and Para, therefore, since 

 they all represent the content of oxygen plus carbon dioxide, are directly 

 comparable with one another, the averages being respectively: For Trom- 

 so, 20.946 per cent; for Dresden, 20.928 per cent; and for Para, 20.923 

 per cent. On the supposition that the carbon-dioxide content remained 

 on the average 0.03 per cent, and assuming that it was somewhat higher 

 in the day period than in the night, Hempel computed the average oxygen 

 content by deducting 0.03 per cent, and found for Tromso, 20.92 per cent; 



