110 



Composition of the Atmosphere 



safely asserted that this apparatus was sufficiently sensitive to show even 

 the slight contamination produced by the congestion of population in a 

 narrow city street. It is also remarkable that under these conditions 

 the carbon-dioxide increment and oxygen deficiency were not very much 

 greater. Observations such as these tend to demonstrate the extent of 

 the diffusion of gases and the establishment of equilibrium by air-currents. 



Table 68. Analyses made at the Nutrition Laboratory of air collected on a crowded 



business street in Boston. 



ANALYSES OF SUBWAY AIR. 

 Although foreign to the major question here studied, namely, the 

 composition of uncontaminated air, it was also of interest to find out to 

 what extent the air was vitiated in the modern "tube" or "subway" so 

 extensively used for suburban passenger traffic. Two samples taken si- 

 multaneously at the Park Street station in the Boston subway gave the 

 results presented in table 69. 



Table 69. Analyses made at the Nutrition Laboratory of air collected 

 at the Park Street station of the Boston subway. 



The samples were taken immediatedly after the "rush hours" were 

 ended and when the oxygen content of the air in the subway might be ex- 

 pected to be at a minimum. The fall of approximately 0.03 per cent in 

 oxygen is accompanied by a rise of 0.032 per cent in the carbon dioxide. 

 Here again one is divided between appreciation of the extraordinary sen- 

 sitiveness of the Sonden apparatus and surprise that the circulation of 

 air in the subways can be so good and the diffusive power of air so ex- 

 tended that the increases in carbon dioxide and decreases in oxygen are of 

 such slight amount. 



Thanks to the kindness of Dr. E. F. DuBois and Dr. Warren T. Cole- 

 man, two specimens of air were collected from the subway in New York 

 City. The results, which are given in table 70, differ in no wise from 

 those found in the Boston subway and show an increase in carbon dioxide 

 and decrease in oxygen infinitely less than one would normally have ex- 

 pected. 



