56 



Composition of the Atmosphere 



Using identically the same apparatus, Oettel in Hempel's labora- 

 tory determined each day the carbon dioxide and oxygen of Dresden air 

 from October 12, 1884, to December 24, 1884. Oettel's results are ex- 

 pressed in the form of a curve not easily reproduced, but table 40 shows 

 his results from November 8 to 18. The duplicate analyses permit an 

 estimate of the accuracy of the method he used. The figures also show 

 the general extent of the variations he observed in the oxygen and carbon- 

 dioxide content of the atmosphere. 



Table 40. Determinations of oxygen in Dresden air, made by Oettel. 



A few months later Hempel, in defending the use of potassium pyrogal- 

 late from the criticism raised by Kreusler, 1 published further experiments 

 on air. 2 In one sample of air he reports, as the result of four determina- 

 tions in which carbon dioxide and oxygen were collectively absorbed, 

 20.936, 20.938, 20.938, and 20.938 per cent, respectively an agreement 

 that is striking. 



Table 41. Determinations of oxygen in atmospheric air, made by Hempel. 



Date. 



1885. 



Feb. 3 

 Feb. 6 

 Feb. 7 

 Feb. 8 

 Feb. 9 

 Feb. 10 



Date. 



Oxygen and c b 

 carbon r. .r 



dioxide. I dloxlde " 



18*5. 



Feb. 11 

 Feb. 12 

 Feb. 13 

 Feb. 14 

 Feb. 15 



p. ct. 



\ 20.950 

 "/ 20.944 

 \ 20.965 

 ') 20.968 

 \ 20.958 

 1 20.974 

 \ 20.932 

 , 20.946 

 \ 20.975 

 ( 20.971 



p. ct. 



0.037 

 .035 

 .036 

 .034 

 .035 



Average 

 oxygen. 



p. ct. 



20.910 

 20.932 

 20.930 

 20.905 

 20.938 



Beginning with February 3, 1885, Hempel made duplicate analyses of 

 air nearly every day until March 28. The results for the first half of 



1 Kreusler, loc. cit. 



2 Hempel, Berichte der deutschen chemischen Gesellschaft, 1885, 18, p. 1800. 



