EFFECTS OF MOUXTALX AIR, 167 



add, another but minute constituent of the earth's atmo 

 sphere IS said to vary in quantity ; for at one and the same 

 place the carbonic acid suffers continued changes ag^o 

 quantity, according to the temperature, wind, rain, and at- 

 mosphencal pressure. Thus, near Geneva, acco^diS^ to 

 Saussure, the mean quantity of this gas in 1000 parti bv 

 volume of air is at midday 5, or more accurately 4 9 • tliP 

 maxmium IS 6 2 ; mmimum, 3.7. The same excellent ob! 

 server hnds, that m Svsitzerland carbonic acid increases in 

 sjimmcr, but dtmvuskes in autunm ; further, that the quan- 

 tity of carbomc acid at midday, in December, January, and 

 Februa^ is to that in June, July, and August JhTo 

 100 He also found, that over a ivet soil the atmosphere 

 contams less carbonic acid than over a dry one ; that more 

 ..xis sill he atmosphere during the «;>/i^ than during the 

 day , that the superior strata of the atmosphere contain 

 more t^ian the i^iferior ; and, lastly, that .1 violent tTd 

 genera ly augments the quantity in the lower atmospheric 

 strata durmg the day, by the intermixture of the lower and 

 upper aerial strata, and sometimes by the wind bIowin<T 



and water, the atmosphere occasionally contains, probably 

 in some measure as accidental mixed parts, a particular 

 vegeto-an.mal matter, and salts of various descriptions' 

 Ihe preceding details show what is expected from those 

 who may undertake to make us acquainted with the chvmica' 

 naiure of the atmosphere of India,-a subject of great im- 

 portance, but hitherto neglected. 



3._ Effects of hio-hly attenuated Momitain Air —It is well 

 known that on ascending high mountains, owing to the 

 diminished pressure of the atmosphere, the animal, and 

 indeed also the vegetable, functions are more or Jess affected. 

 •Some individuals of the human species feel these chan-^es very 

 intensely, while others experience comparatively little incon- 

 venience. Thislattercircumstancehasledsomephilosophe?s 

 to imagme that these ener^•ating effects are solely owin^ to 

 fatigue, and not to the attenuated state of the air,-an 

 opinion, however, which is disproved by a fact stated by 

 Gay Lussac, who, during his aerostatic voyage, wliife calmly 

 seated ,n his balloon, experienced all those ditt^essin. svmp^ 



l?^ne r.T n' °''"''""-" '° ^'^^^"^^^ °^ ^heir accent of 

 alpme lands. Our entcrpnsing countrymen, while ex- 



