12 DR. R. ANGUS SMITH ON THE 



a sample collected near the surface at the same time, with 

 the following results : — 



Air 18,000 Air near 

 feet high. the earth. 

 Percentage of oxygen 2o"88 zo'gz 



Dr. Frank] and ^ found at — 



Oxygen. Carbonic acid. 



Grands Mulets 20*802 o"iii 



Summit of Mont Blanc 20*963 o*o6i 



Chamounix 20'894 0063 



He thinks it probable that the carbonic acid is generally, 

 but not invariably, greater in the higher regions of the 

 atmosphere. Messrs. H. and A. Schlagintweit found the 

 carbonic acid to increase up to the height of 1 1,000 feet. 



If the carbonic acid of the higher regions be really greater 

 than in the best air below, and the oxygen less, it will pro- 

 bably be in part owing to the oxidation having been com- 

 pleted more fally. De Saussure considered it to be owing 

 to the action of vegetation decomposing the acid and giving 

 out oxygen at the surface. The organic matter wUl pro- 

 bably be entirely removed by thorough oxidation in great 

 oceans of air. The process which converts oxygen into 

 ozone would seem very well fitted for removing all organic 

 matter. This, then, might lead to the existence of a 

 smaller amount of oxygen in the air above, and the riddle 

 would be solved. The diminution of the oxygen is pro- 

 bably a disadvantage — although to such a small extent is it 

 so, that there is abundant compensation in the purification 

 consequent on the removal of organic substances. We 

 shall have, then, a distinct variety of air on mountains 

 differing from that of the plains. In the one there would 

 be more carbonic acid and less oxygen, with no organic 

 matter — constituting mountain air; whilst the air of the 

 plains would have more oxygen, less carbonic acid, and 

 more or less organic matter. 

 * " On the air of Mont Blanc," Journal of the Chemical Society, for 1861. 



