37 2 Different Namts ajpgned to this Fluid. "[Book V. 



by Dr. Prieflley from fuppofing it free from phlogifton 

 or inflammable matter ; when it was found effential to 

 animal life, it obtained the name of pure or vital air ; 

 and when it was found to contribute efientially to ig- 

 nition, and the other phenomena of fire, it was termed 

 empyreal air ; but the French chemifts, having difco- 

 vered that it is the fubftance which imparts the acid 

 character to all the mineral and vegetable acids, have 

 cliftinguifhed it by the name of oxygen * gas. 



Oxygen, or the bafis of oxygen gas, is naturally or 

 artificially combined with a great variety of fubftances. 

 From fome of theie it may be detached by the fimple 

 application of heat, fince it has a remarkable attrac- 

 tion for the matter of fire, with which, when it unites, 

 -it becomes expanded, and aflumes the form of gas 

 or air. 



The fubflances from which it may be moft eafily 

 f xtracted, by means of heat, are red lead, calcined 

 mercury, nitre, and manganefe. Dr. Prieftley ex- 

 .pofed a quantity of red lead in the focus of a burning 

 glafs twelve inches in diameter. A quantity of fixed 

 air, or carbonic acid gas, as it is now called, was al- 

 ways produced at firft ; but after that was fcparated, 

 the remainder was found to fupport flame, and to fuf- 

 tain animal life much more vigoroufly than common 

 air, and to have all the characters of dephlogifticated 

 air, or oxygen gas. 



By fucceeding experiments of Dr. Prieftley and 

 others it however appears, that dephlogifticated or 

 oxygen air, may be obtained not only by means of 

 heat, but alto by the action of the vitriolic and nitrous 



* From o|v; (oxus) " fharp or acid," and yt\i'.py.\ (ginomai) 

 " to beget or produce." Oxygen is then literally tke principk 

 'r fubftance producing acids. 



acids 



