ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 207 



The accurate determinations of Bunsen of the oxygen in the general 

 air gave a mean of 20.93 per cent. Two hundred and three analyses 

 by Beiset gave nearly the same result. Hempel found the amount at 

 Tronso to be 20.92; at Dresden, 20.90; at Paris, 20.89. These amounts 

 must be received with qualification, because in comparing one town 

 with another more depends on the position in the town than on the 

 situation of the town. 



The average proportion of oxygen in the open country or at sea 

 may be stated at about 20.95 per cent. In large, open spaces in Lon- 

 don the amount of oxygen is nearly normal; in the streets, about 

 20.885; in Manchester, in fog and frost, 20.91; in the suburbs in wet 

 weather, 20.96 to 20.98. These figures are merely approximate. 



In the air of mines an average of 20 has been observed, and in 

 extreme cases the amount was no higher than 18.6. 



In the midst of vegetation on open ground, especially in the daytime, 

 there is an excess of oxygen. 



Angus Smith and others found the following quantities of oxygen in 

 air in different situations: 



On the Atlantic (Regnault) 20. 918 



In the Andes on Pichincha, about (Regnault) 20. 949 



Tops of hills, Scotland 20. 98 



Northeast shore and open heath, Scotland 20. 999 



Stockholm (Petersson and Hogland) 20. 94 



Suburb of Manchester, wet day 20. 98 



Middle of Manchester, inclosed space 20. 652 



Manchester, fog and frost 20. 91. 



Manchester, backs of houses and closets 20. 70 



Manchester, dense fog 20. 86 



Heidelberg (Bunsen) 20. 924 



Low parts of Perth 20. 935 



( 20 9 90 

 Swampy places, France and Switzerland < „«' qt -1 



Bengal Bay, over bad water (Regnault) 20. 387 



Sitting room, rather close 20. 89 



Small room with petroleum lamp 20. 84 



Gallery of a theater, 10.30 p. m 20.86 



Pit of a theater, 11.30 p. m 20.74 



Court of Queen's Bench '. 20. 65 



Chemical Theater, Sorboune, before lecture 20. 28 



Chemical Theater, Sorbonne, after lecture 19. 86 



In cow houses 20. 75 



In sumps or pits in mines _ 20. 14 



Worst in a mine 18. 227 



Very difficult to remain in many minutes 17. 2 



Eecent experiments by Messrs. Smith and Haldane on impure air 

 contained in a leaden chamber showed that with oxygen 20.19 and 

 carbon dioxide 3.84 two men instantly got headaches on entering. 



Oxygen is the breath of life, the element without which no human 

 being could exist for a single hour. Brought into contact by every 

 inhalation of the lungs, it revivifies the loaded blood, spreads over the 



