Ghap. 1.] [ 371 ] 



CHAP. II. 



OF OXYGEN GAS, OR PURE, VITAL, EM- 

 PYREAL, OR DEPHLOGISTICATED AIR. 



Explanation of Terms. Reafons for the different Names ajfigned to 

 this Fluid. Ho-w procured. From Calces of Metals, By Pege- 

 iation.-. From Water. Properties of Oxygen Gas. A powerful 

 Agent in the Syjlem of Nature. - Ho-iv ejfential to Flame and Life.- 

 Various Modes provided by Nature for furnijbing a Supply of thit 

 Fluid. 



IT has been already intimated that&r, fignifying 

 fpirit or ebullition, was a term employed by Van 

 Helmont, and other Dutch and German chemifts, to 

 clefcribe thofe elaftic fluids, which appeared in their 

 nature different from common or atmofpheric air. 

 From the preceding hiftory of fire or caloric, the 

 reader will be at ho lofs to underftand, that every 

 aeriform fluid confifls of a bafts, or matter peculiar to 

 itfelf combined with the matter of heat, which is in- 

 deed the real efficient caufe of all fluidity whatever. 

 The word gas has therefore been employed by the 

 French chemifts to denote an aeriform Auid compofed 

 of a certain bafis, which gives it its peculiar character, 

 combined with the matter of heat or fire. It will be 

 alfo proper to remember, that of thofe fluids which 

 are termed elaftic, fome are permanently elaftic, as the 

 aeriform fluids, others, fuch as common vapour from 

 water, are condenfible by coldj and that it is only 

 of the former kind that we have now to treat. 



The fluid under our immediate confidcration was 



originally termed dephlogifticated air, a name given it 



Bb 2 by 



