and on the Sulphurets of Lime. 403 



May 25. — Analysed ; average of six experiments gave 20*59 

 oxygen per cent. 



Country air near Manchester at same time gave average 

 20*7 per cent. 



A second bottle of air from Snowdon, taken at the same 

 time, May 18, gave on an average of four experiments 20*9 

 oxygen per cent. 



Air from the town at the same time, on an average of five 

 experiments, gave 21*04« oxygen percent. 



1826, July, Air from the Summit of Helvellyn. 

 Average often experiments gave 20*63 oxygen per cent. 

 Average of the town air found at same time was 20*73 oxy- 

 gen per cent. 



Air taken in an Aerial Voyage over Cheshire. 



Mr. Grafton was so good as to procure me a bottle of air 

 taken in an aerial voyage over Cheshire with Mr. Green, June 

 26, 1827; height 9600 feet above the sea*. The air was 

 transferred into two phials. 



First Phial. 

 June 27. — Average of seven experiments of~\ 20*7 oxygen 

 balloon air gave . . . # . J per cent. 

 Average of seven experiments \ n^.o© 



on town air gave j 



July 2. — Average of eight experiments of \ o/^.o. 



balloon air gave j ' 



Average of eight experiments on 1 -^ 



town air gave j 



The second phial of balloon air was carefully preserved, 

 the phial being filled and having a ground stopper. It was 

 analysed. 



1828, May 28. — Average of three experi- \20*70 oxygen 

 ments balloon air gave j per cent. 

 Average of three experi- I oo.ftn 

 ments town air gave J ^ 

 Aug. 5. — Average of thirteen experi- ] 



ments, being the whole > 20*52 

 of the balloon air, gave J 



* Height found as under : 



Capacity of bottle 10*47 ounces. 



On drawing the cork under water there entered 2*77 ounces. 



Left 7' 7 ounces of air. 



Also height of barometer and thermometer below given. 



i The whole air in the first phial was spent in these fifteen experiments. 

 The deterioration of the air in the first phial, by being kept half full of 

 trough water for five days, is remarkable. 



2 N2 



