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XIX Obfervatwns on different Kinds of 

 Air. By Jofeph Prieftley, LL. Z>. 

 r, K. u. 



Read March 5, r |""*HE following obiervations on the 

 12,19,26, 1772. J^ properties of feveral different kinds 

 of air, I am feniible, are very imperfe<5t, and fome of 

 the courfes of experiments are incomplete ; but a 

 confiderable number of fads, which appear to me 

 to be new and important, are furliciently afcertained ; 

 and I am willing to hope, that when philofophers 

 in general are apprized of them, fome perfons may 

 be able to purfue them to more advantage than rriy- 

 felf. I therefore think it my duty to give this So- 

 ciety an account of the progrels I have been able to 

 make ; and I mall not fail to communicate any far- 

 ther lights that may occur to me, whenever I refume 

 thefe inquiries. 



Jn writing upon this fubjecl, I find myfelf at a 

 lofs for proper terms, by which to diftinguifh the 

 different kinds of air. Thofe which have hitherto 

 obtained are by no means fufficiently characteriftic, 

 or diftincl:. The terms in common ufeare, fixed air, 

 mephitic, and inflammable. The laft, indeed, fuffi- 

 ciently characterizes and diftinguifhes that kind of 

 air which takes fire, and explodes on the approach 

 of flame; but it might have been termed fixed wifii 



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