Vital Air In the Atmofpherc, i^f 



In examining vital air, fuch as that which iffues from 

 plants cxpofed to the fun^ it fometimcs happens that the 

 eudiometric proof muft be performed with a fmall quantity : 

 if the air colle^led occupies only the fpace of 25 lines, 

 inftead of a hundred, it is evident that a hundredth inftcad of 

 a line will corrcfpond to a fourth part of one ; but in por- 

 tions of air dill Icfs, as the divifions would be infenfible, a tube 

 of a lefs diameter muft be employed. With this precaution, 

 and that of not forgetting to fliake the fulphuret before with 

 mephitic air, in order to faturate it fully, and of employing 

 flafks proportionally lefs, thofe who have acquired the prac- 

 tice and addrefs neceffary for fuch experiments will never find 

 the dilfercnce of a hundredth part. 



I repeated them fo many times with atmofpheric air, and 

 on fo great a number of days, that the uniformity in my 

 rcfuits demonflrates not only the exaftnefs of this method, 

 but it feems to refult from my obfervations made on the 

 fouthern coaft of this province : 



ift, That the wind never canfed the variation of a hun- 

 dredth part in the refpcftive quantities of vital air and azotic 

 gas which compofe the elaftic fluid of our atmofpherc, fince 

 I have always found that a hundred parts contained 79 of 

 the latter and ai of the former, without ever reaching at 22. 



2d, That neither the moifture nor drynefs of the atmo- 

 fpherc, nor the ftate of the latter in being tndre or lefs 

 charged with exhalations, nor ferene or rainy weather, occa- 

 fioncd any difference. It cannot be denied that, in an equal 

 ipace of the atmofpherc, as the aeriform fluid contains a 

 greater portion of water difl'olvcd, and more impregnated 

 with other heterocreneous bodie?, there cannot be found the 

 fame ([uantity of air free from foreign matters; but the 

 number 2 r of the vital part, found fo many times in the two 

 cafes, fliows that the elements which conftitute its elaflic 

 portion, ib valuable andfc)abundant,are refpe-dlively invariable. 



3d, That the proportion of the quantities of the two fam0 

 principles was equally conftant during the days that Reau- 

 mur's thermometer flood at the freezing point, as well as 

 during thofe when it indicated 24 degrees of heat. 



4th, That I did not obferve any variation in the air thus 

 Vol. IX. K k taken 



