94 



Composition of the Atmosphere 



Technology for the purpose of making control analyses of the air in the 

 cylinder. The steel cylinder employed, which had formerly been used 

 for compressed oxygen, was repeatedly exhausted by a vacuum-pump and 

 outdoor air admitted. It was assumed that the inner walls of the cylin- 

 der would not absorb oxygen from the air rapidly. It was furthermore 

 assumed that air stored in the large compressed-air chamber of the In- 

 stitute of Technology would be thoroughly mixed and have a fairly con- 

 stant composition. Employing precisely the same technical routine, 

 samples of the cylinder air were frequently analyzed as a control on the 

 analyses of the outdoor air. The results of these analyses made between 

 December 3, 1910, and February 9, 1911, are given in table 54. 



As the simultaneous analyses of outdoor air and cylinder air pro- 

 gressed, it soon became apparent that there was some intimate relation 

 between the fluctuations in oxygen content of the outdoor air and the 

 fluctuations observed in the oxygen content of the cylinder air. Further- 

 more, while a steady slight decrease in the oxygen percentage of cylinder 

 air might have been expected, as a matter of fact the fluctuations were 

 such as to indicate at times apparent increases. This was conclusive 

 evidence that in spite of all precautions and delicacy of manipulation, 

 the observed fluctuations in the oxygen content of outdoor air might well 

 be due to errors in technique. 



THIRD ROUTINE, AND RESULTS OBTAINED. 



The fluctuations in the oxygen content of the cylinder air led to the 

 belief than an error was introduced by the distillation of water from the 

 measuring pipette over into the strong alkali. A series of test experiments, 

 which occupied several weeks, almost to the exclusion of regular air- 

 analyses, finally resulted in an alteration in the routine on February 15, 



