t 382 ] tBookV, 



CHAP. III. 



AZOTIC GAS, OR PHLOGISTICATED AIR. 



Azotic Gas is the unrefplralle Part of the Atmofphere. HO--W p r +- 

 cured. Air Bladders of Fijhes filled <witb it. 'Its Properties. 

 Azote tie Ba/is of nitrous Aridt 



TH E azotic gas was at firft called by Lavoifier mo- 

 fete, and by Dr. Prieftley phlogifticated air. It 

 conftitutes about three-fourths of the atmofphere, but 

 is not refpirable by itfelf \ whence it derives the name of 

 azote, as being unfit for the fupport of animal life. 

 Philofophers have proved, that this fluid is completely 

 formed in the atmofphere, and that it may be pro- 

 cured by merely abforbing or deflroying the pure air, or 

 oxygen gas, with which it is united in atmofpheric air. 

 Azotic gas, therefore, is always found to remain 

 after a quantity of common air has undergone the re- 

 fpiration of animals, the combuftion of bodies, or pu- 

 trefaction j becaufe in alt chefe cafes the pure air is 

 abforbed or condenfed. Azotic gas is equally invifible 

 with common air, and fomething more elaftic. Mr. 

 Kirwan procured fome air, by means of a mixture of 

 iron-filings and fulphur, fo perfectly free from vital air, 

 that it was not in the leaft diminilhed by the teft of 

 nitrous air. When this kind of air is fo produced, and 

 dried by introducing dry filtering paper under the jar 



* Or '* air which takes away life," from the Greek privative 

 particle a. and fa (zoe) " life." Dr. Prieftley called it phlogiiti- 

 ated air, from fuppofing it chiefly compoietl of an imaginary fub- 

 flance, which Scheele and his followers termed phlogilton (or the 

 food of fire) ; this appellation is now found to be erroneous. 



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