ANALYSIS OF AIR TAKEN BY A BALLOON. 209 



contrary opinion. He believed that the oxygen 

 and nitrogen of the air were always in the pro- 

 portions just stated in the lower regions; but 

 that as we ascended higher and higher, in con- 

 sequence of the superior heaviness or density 

 of oxygen over nitrogen, the proportion of it 

 became smaller; the oxygen being supposed to 

 gravitate more towards the earth than its com- 

 panion nitrogen. The analysis of air from these 

 regions would therefore indicate, if this sup- 

 position be correct, the presence of less oxygen 

 and more nitrogen, in a certain amount of air. 

 This subject is one of great interest. Some 

 curious and inexplicable phenomena connected 

 with the variable quantities of these gases, 

 appear to countenance it. Dr. Dalton also con- 

 ceived that he had actually proved the fact, by 

 analysing a portion of air from the summit of 

 Snowdon, which certainly contained less oxygen 

 than a similar quantity taken from the neigh- 

 bourhood of Manchester. 



But when all the facts are inquired into, it 

 seems almost certain that such is not the 

 case. Gay Lussac, by means of the balloon, 

 brought down air in a vessel from the height of 

 between three and four miles. On being analysed 

 it was found to be in no respect different from 

 the air of the lower strata of the atmosphere. 

 A distinguished French chemist also spent a 



