3So Vfe of Oxygen Gas in Reftlration. [Book V. 



in the lungs. It is therefore the great attraction which 

 exifts between the matter of coal and the bails of pure 

 air which renders this fluid fo proper for breathing. 

 The pure air which we breathe performs two functions 

 equally necefritry to our prefervation ; it carries off 

 from the blood that matter of coal, the fuperabundancc 

 of which would be pernicious, and the heat which this 

 combination depofits in the lungs repairs the continual 

 lofs of heat which we experience from the attraction 

 of furrounding bodies. According to Dr. Prieftley 

 and others, the bafis of oxygen gas is alfo abforbed by 

 the blood. 



Since, therefore, a great quantity of heat is difen- 

 gaged from pure air in refpiration, it follows, that this 

 fluid muft be very pernicious to animals who breathe 

 this air alone for a confiderable time; and this is con- 

 fonant with the obfervations of phyficians, who have 

 attempted to cure pthifis by the refpiration of vital 

 air. 



The bafis of this empyreal or pure air, or oxygen, 

 as the French chemifts term it, is one of the confti- 

 tuent parts of water. It has been mentioned, that it- 

 is alfo the matter which gives the acid character ta. 

 all the acids ; fulphur, for inftance, is a very innoxious, 

 infipid body, till by burning, that is by abforbing oxy- 

 gen, it becomes vitriolic acid. "Whether the bafis of 

 this empyreal air is a fimple or compound fubftance, 

 we are unable to determine j in the prefent ftate, 

 however, of philofophical knowledge, we are juftifiecl 

 in tonfidering it as a fimple elementary body, for it 

 has never yet been decompofed. 



If the limits of this work permitted, or if the re- 



fearches of philofophers had furniihed us with fufficient 



materials, it would be a mofl pleafing fpeculation to 



trace the wifdom of Providence in the very ample 



8 meajis 



