42 



Composition of the Atmosphere 



obtained with gallic acid with percentages of oxygen as follows: 20.59, 

 20.69, 20.97, 20.52, 21.35, 20.80, 20.78, and 21.19. 



This method was destined to become one of the most important meth- 

 ods for technical gas-analysis that had ever been devised. It is interesting 

 to note that at this date (1912) practically all of the exact gas-analysis 

 apparatus employ the alkaline solution of pyrogallol. Almost imme- 

 diately after the introduction of the method it was found that under 

 certain conditions the interaction of air with pyrogallic acid and potas- 

 sium hydroxide resulted in the formation of slight quantities of carbon 

 monoxide. This for a time discouraged observers from using the method. 

 Subsequently conditions were so adjusted as to minimize this apparent 

 error. 



Using a modification of the Regnault method, Frankland and Ward 1 

 published 6 analyses of air as an indication of the accuracy of the ap- 

 paratus. The results given are 20.880, 20.888, 20.883, 20.867, 20.868, 

 and 20.876 per cent, with an average of 20.877 per cent, the greatest 

 difference being only 0.021 per cent. 



Frankland in 1861, 2 reporting the results of some air samples taken by 

 himself on an excursion to the top of Mont Blanc, cites analyses of air 

 collected during a balloon ascension in August 1852, which were made by 

 Dr. Miller. At a height of 18,000 feet the oxygen percentage was found 

 to be 20.88; a sample taken at the same time at the surface of the earth 

 gave 20.92 per cent. 3 



Frankland's analyses of the air from Mont Blanc were made by ab- 

 sorbing the carbon dioxide by means of caustic potash, and determining 

 the oxygen by explosion with electrolytically prepared hydrogen. Speci- 

 mens were taken at Chamounix (altitude 3000 feet), at the Grands 

 Mulets (11,000 feet), and at the top of Mont Blanc (15,732 feet). At 

 Chamounix the percentages of oxygen found were 20.892 and 20.870, and 

 of carbon dioxide, 0.063. At the Grands Mulets, two samples showed 

 20.793 and 20.765 per cent of oxygen and 0.111 per cent of carbon dioxide. 

 At the summit of Mont Blanc, on August 21, at 8 h 45 m a.m., two samples 

 gave 20.950 and 20.951 per cent of oxygen respectively, and 0.061 per cent 

 of carbon dioxide. The averages of all the results are, therefore, as follows : 



p 



1 Frankland and Ward, Quarterly Journal of the Chemical Society, London, 1854, 6, 

 197. 



2 Frankland, Quarterly Journal of the Chemical Society, London, 1861, 13, p. 22. 



3 Julius Hann in his Lehrbuch der Meteorologie, Leipzig, 1901, p. 9, states that sam- 

 ples of air were collected in a balloon journey made by Welsh; according to the analyses 

 made by Miller, the oxvgen content on the surface of the earth was found to be 20.92 per 

 cent; at 4100 meters, 20.89; at 5500 meters, 20.75; and at 56.80 meters, 20.89 per cent. 



