COMPOSITION OF THE ATMOSPHERE. 27 



from its summit, I was naturally led to look on the sub- 

 ject in this way, and to add this to Dr. BurdePs opinion, 

 although I confess I do not understand the part he wishes 

 the electricity to play. All I can see is, that there is a 

 difference in these hilly regions. I do not pretend to see 

 anything affecting animal life that can result from the 

 difference ; and in the Sologne there are not the moun- 

 tainous ranges to account for any such differences. 

 Experiment has led me to form the following 



Table of the Composition of the Air of pure and impure 

 places, beginning with that containing most oxygen, 

 although probably not the very richest specimen : — 



Oxygen. 



N-E. sea-sLiore and open heath (Scotland) 20*999 



Tops of hills (Scotland) 20*98 



In a suburb of Manchester in wet weather 20*98 



„ „ „ ^0-96 



In the outer circle of Manchester, not raining 20*947 



Low parts of Perth ^o'935 



Swampy places, fayourable weather 20*922 



to 2o*95 



In fog and frost in Manchester 20*91 



In a sitting-room, which felt close, but not excessively so. . . 20*89 



In a small room with petroleum-lamp, well ventilated ... 20*84 



Ditto, after six hours 20*83 



Pit of theatre, 11.30 p.m 20*74 



About backs of houses and closets 20*70 



Gallery, 10.30 p.m 20*86 



In large cavities in mines 20*77 



In currents 20*65 



Under shafts 20*424 



In sumps 20*14 



When candles go out 18*5 



The worst specimen yet examined in the mine 18*27 



Very difficult to remain in for many minutes 17*2 



It has been shown that air in places where putrefaction 

 may be supposed to be going on has been found by other ob- 

 servers to contain less oxygen than pure air. This inquiry 

 puts the subject in a somewhat clearer light than hitherto. 



