j6 A TREATISE ON THE CONNECTION OF 



oxygen. The other part, c lied phlogisticated air, or 

 azot, is i furious to combustion, although necessary in 

 a certain proportion, to modify the too powerful action of 



pure air, in the respiration of animals. Vital air, by 

 combining with ignited inflammable substances, pro- 

 duces certain gasses and new compounds. 



Atmospheric air contains likewise a proportion of fix- 

 able air, or carbonic acid gas, so called by the French 

 chemists, from carbonaceous matter, or charcoal, form- 

 ing one of its constituent parts. 



Atmospheric air may also contain other gasses, or airs. 

 By far the greater part of these gasses were discovered 

 by Dr. PRIESTLEY. 



By the term of gas is to be understood, a permanently 



elastic, invisible fluid: Of these there are some which 



' ~ 



may be considered as simple, and others as compounded 



The gasses are, empyreal air, vital air or oxygen gas , 

 Fixable air or carbonic acid gas ; 

 Light inflammable air or hydrogenous gas \ 



Dense 



