400 On the Conftttuent Parts, &c. 



nation. It is for this reafon that the two bafes of a fped/fe 

 gravity fo different, that of azot and that of oxygen, do not 

 entirely feparate from each other, though the high regions 

 are moft charged with azot. Hence azot retains fo ftronglr 

 the laft portion of the oxygen, which phofphorus, the ful- 

 phure of pqtafh, and other acidifiable bafes ought to take 

 from it; and I have for tliis reafon feen that the nitrous gas 

 a£ls in proportions very different in decomposing the natural 

 atniofpheric air, or a compound of 27 of oxygen and 73 of 

 azot. But how could Morozzo think to imitate the atmo^ 

 fphere by mixing the carbonic acid and oxygen ? He has. 

 confounded azot with the carbonic acid gas. But he aflures 

 us that his atmofphcric air with a carbonic acid bafe, gave 

 the fame fpecific weight as atniofpheric air. Here is a 

 rery ftriking experiment : one cubic inch of azot weighing 

 0,46624 grains, while the fame cubic inch of carbonic 

 acid weighed 0,67500 grains ! Morozzo tells us that a 

 candle burnt in his artificial mixture with a very brilliant 

 flame {con jiamma lucni'ijjima) . By combining 0,25 of the 

 carbonic acid with 0,75 of oxygen, I have feen a wax taper 

 extinguished. The fame tiling took place when in com- 

 pany with Taffeart in Vauquelin's laboratory, I mixed two- 

 parts of the carbonic acid gas with ten parts of atmofpherie 

 air. There is then formed a new chemical combination : 

 the carbonic acid lays hold fo ftrongly of the oxygen of the 

 atmofphere, that the affinity pre'fented by the lighted wax 

 taper is not powerful enough to take it away. In my 

 work on the analyfis of the mephitie vapour of mines, 

 which is about to be translated into French, it will be feen 

 that there exifts airs not unfit for refpiration, which are com- 

 pofed of 0,27 of oxygen, 0,70 of azot, and 0,03 of carbonic 

 acid gas. It ie the flate of the combination, and not always the 

 quantity of oxygen, which venders ait more or lefs capable to 

 deftroy animal life, or to extinguish flame. 



XVIII. Cur- 



