104 



Composition of the Atmosphere 



For the best proof of the accuracy and sensitiveness of the apparatus 

 we must again turn to our analyses of cylinder air. These were made in 

 parallel with the analyses of outdoor air and continued from April 15 to 

 June 7, 1911. The results are given in table 62. 



Table 62. Analyses made at the Nutrition Laboratory of air confined in a steel cylinder. 



Series 4. 



Inasmuch as the analyses indicated that the air had remained ap- 

 proximately constant throughout several months, it was believed that 

 the conditions inside the cylinder were not such as to cause any material 

 oxidation. When the air-analyses were resumed in the fall, after a sum- 

 mer of unprecedented heat in Boston, the oxygen percentage was found 

 to have materially decreased. Excluding a few analyses made between 

 September 15 and September 25, we have the results given in table 63. 



