108 



Composition of the Atmosphere 



The wisdom of taking samples dry is seen from these results, since in 

 all dry samples the percentage of carbon dioxide was found to be always 

 normal. The oxygen percentages again show a striking uniformity and 

 constancy, irrespective of geographical location, weather conditions, etc. 



ANALYSES OF AIR FROM PIKE'S PEAK. 

 The interesting expedition to the top of Pike's Peak made by Haldane, 

 Yandell Henderson, Douglas, and Schneider, in the summer of 1911, was 

 utilized in that these gentlemen kindly consented to collect samples of 

 air for this research. The apparent constancy in composition of the 

 cylinder air during the early half of 1911 led to the belief that air samples 

 stored in steel cylinders would not undergo a material loss of oxygen; and 

 obviously samples collected in this way would give opportunity for in- 

 numerable analyses. Consequently three small steel cylinders, fitted 

 with proper valves, and a strong bicycle pump were sent to Professors 

 Haldane and Henderson. Both these gentlemen questioned seriously 

 the advisability of using this method of sampling, and fortunately insisted 

 upon having the usual glass samplers sent to them, in which they collected 

 additional samples. The analysis of the air from Pike's Peak was not taken 

 up until the fall of 1911. At this time it was found that during the sum- 

 mer the oxygen percentage of the air in the control cylinder had changed 

 from 20.918 to 20.880, this not inconsiderable change possibly resulting 

 from the extreme heat of the summer, which had been abnormal for this 

 section. Since there had been a change in the oxygen content of this air, 

 it was seen that no reliance could be placed upon the constancy in compo- 

 sition of air stored in steel cylinders, so that any results which might be 

 obtained with air collected in this way on Pike's Peak would be vitiated. 

 Furthermore, it could not even be assumed that cylinders filled on the 

 same day and under the same conditions would be equal in oxidation ; hence 

 any variations from the normal oxygen content found at sea-level could not 

 reasonably be ascribed to a persistent regular oxidation in the cylinders. 

 Table 66. Analyses at Nutrition Laboratory of air from summit of Pike's Peak. 



[Air collected and stored in steel cylinders.] 



Data. 



Collected Aug. 6, 1911, 5 p.m. 

 Wind, moderate N.W. : 

 Weather clear. 



Data. 



Collected Aug. 8, 1911,5 p.m. 

 Wind, moderate N.W. 

 Weather clear. 



Carbon 

 dioxide. 



p. ct. 



0.031 

 .032 

 .032 

 .035 

 .033 

 .032 



Oxygen. 



p. ct. 



20.881 

 20.883 

 20.880 

 20.886 

 20.887 

 20.889 



The samples of air collected in the steel cylinders were analyzed be- 

 tween September 20 and October 5. While the results have but little 

 value, they are given in table 66 as a further demonstration of the inade- 

 quacy of this method of preserving air samples. The very .large differences 

 in the oxygen content of the two cylinders bears out the belief that the 



