History of Air-Analysis 



39 



air. The analysis of air collected on February 1, 1849, in the Gulf of 

 Bengal, gave 20.460 and 20.453 per cent of oxygen. The notes which 

 accompany this sample do not present anything of distinct interest. The 

 air collected on the Ganges on March 8, 1849, shows 20.390 and 20.387 per 

 cent of oxygen, and Regnault maintains that the conditions set forth in 

 the notes accompanying this sample explain this anomalous case. Four 

 other samples taken in 1852 at different points in the Pacific and South 

 Atlantic Ocean gave 21.015, 20.935, 20.950, and 20.963 per cent of oxygen, 

 respectively. Samples of air from the Arctic Ocean were also analyzed, 

 these being given in table 20. 



Table 20. Analyses of air collected on the Arctic Ocean. 



Regnault's conclusions are: (1) that the air of our atmosphere usually 

 presents variations in composition which are sensible but very small, for 

 the percentage of oxygen varies generally only from 20.9 to 21.0, although 

 in certain cases, apparently more frequent in the warm countries, the 

 proportion of oxygen may fall to 20.3 per cent; (2) that the average per- 

 centage of oxygen contained in the air of Paris during the year 1848 was 

 20.96. 



The importance of a geographical study of the composition of the 

 atmosphere was so keenly felt that the French Academy commissioned 

 Lewy 1 to make analyses of air while on a voyage to South America. 

 The analyses were made by the method of Regnault and Reiset. Pre- 

 vious to taking this journey, he made several analyses of air in France. 

 On September 6, 1847, Lewy found as a result of three analyses of air in 

 Paris, 21.018, 21.015, and 21.008 per cent, with an average of 21.014 per 

 cent. In Havre, he found on November 22, 1847, that in three analyses 

 the percentages of oxygen were 20.895, 20.880, and 20.888, with an average 

 of 20.888 per cent. 



1 Lewy, Annales de Chimie et de Physique, ser. 3, 1852, 34, p. 5. 



