40 



Composition of the Atmosphere 



The analyses of the atmospheric air collected on the Atlantic Ocean 

 and the Caribbean Sea are reported in table 21, the results giving an 

 average of 0.046 per cent for carbon dioxide and 21.03 per cent for oxy- 

 gen. On examining his figures, Lewy found that the composition of the 

 air collected during the day differed from that collected during the night, 

 the air of the day being richer in carbon dioxide and oxygen. He accord- 

 ingly averaged his results for both the day and the night, obtaining the 

 following values: for the day, carbon dioxide 0.053 per cent, oxygen 21.06 

 per cent; for the night, carbon dioxide 0.0346 per cent, oxygen 20.97 

 per cent. 



Table 21. Analyses of air collected on the Atlantic Ocean and the Caribbean Sea. 



Lewy concludes that the difference between the oxygen and carbon 

 dioxide in the atmospheric air on the ocean and in normal air becomes 

 more noticeable the farther away one goes from the land. He further 

 says that it is impossible to attribute this difference to errors in analysis, 

 as he maintains that two analyses of air do not differ by more than 1 part 

 in 10,000. According to his interpretation of the results, this difference is 

 caused by the fact that the water of the ocean gives off carbon dioxide and 

 oxygen. During the day the surface of the sea becomes warmed by the 

 sun's rays and a part of these gases is dissolved; during the night, on the 

 contrary, this influence is not felt. 



Results of analyses of air samples collected in New Granada on a trip 

 from Santa Marta to Montserrat are given in table 22, while the results 

 obtained from air collected in 1850 in Bogota, at a height of 2645 meters, 

 with an average barometer of 565 mm., are reported in table 23. The 

 high values for carbon dioxide are attributed to the presence of volcanoes 

 3 or 4 hours distant from Bogota. 



In a general resume of the subject, the author concludes that by ex- 

 amining these results (tables 21 to 23), one sees that the composition of the 

 air up to a height of about 3000 meters is nearly the same in the New 



