32 



Composition of the Atmosphere 



later some 50-liter samples, which were taken in Paris and analyzed 

 with the very greatest care, showed variations equally as great; thus, 

 on September 20 the percentage was 20.875, while on September 22 it 

 was 20.709. 



Brunner's method was used successfully by Verver 1 in Groningen in 

 May and August 1838. As a result of 45 analyses, he found the average 

 oxygen content of carbon-dioxide and water-free air to be 20.864 per cent. 

 The oxygen percentages obtained by Verver are given in table 10. 



Table 10. Percentages of oxygen in air analyzed by Verver. 



Dumas and Boussingault were at first inclined to believe that since 

 their results, those of Berger, Gay-Lussac, and von Humboldt, the earlier 

 results of Boussingault, and the results of Brunner, all agreed so remark- 

 ably, the composition of the atmosphere was uniform. Subsequent ex- 

 periments made in combination with Brunner on the air from the Faul- 

 horn, Paris, and Berne showed that there were also differences; they ac- 

 cordingly modified their conception and said that although on the whole 

 the composition of the air was constant, nevertheless there must be cer- 

 tain variations which might occur. 



The demonstrated accuracy of the method of Dumas and Boussingault 

 led to its extensive use by other observers. In 1841 and 1842 Lewy made 

 analyses of air from the North Sea, the court of the Polytechnic School, 

 Copenhagen, and the coast at Elsinore. 2 In November and December of 

 1841, five analyses of air in Copenhagen were made, giving 20.82, 20.83, 

 20.78, 20.81, and 20.84 per cent of oxygen, respectively, with an average 

 of 20.816 per cent. The author points out that these results agreed per- 

 fectly with those obtained by Dumas and Boussingault in their analyses 

 of the air collected in Paris and on the Faulhorn, as well as with those 

 obtained by Stas in Brussels, Marignac in Geneva, Brunner in Berne, and 

 Verver in Groningen. 



1 Verver, Bulletin des Sciences Physiques et Naturelles en N6erlande, 1840, p. 191. 



2 Lewy, Annales de Chimie et de Physique, 1843, ser. 3, 8, p. 425. 



