398 General Properties [Book V. 



this kind of air extinguishes flame, it may, by certain 

 procefies, be brought to fuch a ftate. that a candle will 

 burn in it with an enlarged flame, and it then becomes 

 \vhat Dr. Prieftley calls drpblogifticated nitrous air. Its 

 fupporting flame in this inftance evidently depends on 

 the large quantity of oxygen which enters into its com- 

 pofition. 



id. When oxygen or empyreal air is added to ni- 

 trous air, it hnparts to it the acid character, and it be- 

 comes true nitrous acid. Mr. Cavendifh impregnated 

 fifty ounces of diftilled water with fifty-two ounce mea- 

 fures of nitrous air, mixed with as much common air 

 as was neceffary to decompound it. The water thus 

 impregnated was fenfibly acid, and being diftilled, the 

 firft runnings were very acid, and fraelt pungent: what 

 came next had no tafte or fmell > but the laft runnings 

 were very weak nitrous acid *. 



3d. Of all the different fpecies of air, this feems the 

 moft noxious to animal life. Infects, which can bear 

 azotic and inflammable air, will die immediately upon 

 their being immerfed in this. Even fiihes will not 

 live in water impregnated with it. 



It may fccm extraordinary that nitrous gas, which is 

 of fo deleterious a nature, and fo oppofite in its qualified 

 to common air, fhould yet fubftantially confift of the 

 fame principles, differing, however, in the proportions. 

 To remove the difficulty, it will be necefiary to recol- 

 lect what has been more than once intimated concern- 

 ing the difference between mixtxre and combination. In 

 fimple mixture the two bodies dill retain their own- 

 diftinct properties > but in chemical combination a third 

 fubftance is formed from the two, entirely different 

 from both in its nature and properties. Thus, from 



Phil. Tranf. for 1784* 



marine 



