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i 



VI. 



Of nitrous Air. 



Ever mice I firfif read Dr. Hales's moft excellent 

 Statical EiTays, I was particularly ft rnck with that 

 experiment of his, of which an account is given, 

 Vol. L- p. 224, and Vol. II. p. 280 ; in which 

 common air, and air generated from the Walton 

 pyrites, by fpirit of nitre, made a turfud red mix- 

 ture, and in which part of the common air was. ab- 

 forbed ; but I never expected, to have the fatisfacYion 

 of feeing this remarkable appearance, ...fuppofing it to, 

 "be peculiar to that particular minerah Happening 

 to mention this, fubjecl: to the Hon* Mr. Cavendifh, 

 when I was in London, in the fpring of the year 

 1772, he faid that he did not imagine but that 

 other kinds of pyrites might anfwer as well as that 

 which Dr. Hales made ufe of, and that probably 

 the red appearance of the mixture depended upon 

 the fpirit of nitre only. This encouraged me to 

 attend to the fubject ; and having no pyrites, I be- 

 gan with the folution of the different metals in fpirit 

 of nitre, and catching the air which was generated in 

 the folution, I prefently found what I wanted, and 

 a good deal more. 



Beginning with the folution of brafs, on the 4th of 

 June 1772, I firft found this remarkable fpecies of 

 air; one efFecl: of which, though it was cafually ob- 

 ferved by Dr. Hales, .he. gave but little attention to ; 

 and which, as far as I know, has paflTed altogether 

 unnoticed fince his time, infomueh that no name has 

 been given to it. I therefore found myfelf, contrary 



to. 



