,6 A TREATISE ON THE CONNECTION OF 



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

 azot, is i.^jurioas to combustion, although necessary in 

 a certain proportion, to modify the too powerful adion 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, mvisible 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 j 

 Fixable air — or — carbonic acid gas ; 

 Light inflammable air — or — hydrogenous gas ; 



Dense 



