474 On phlogiston. 



Repeating the experiment with fixteen ounce meafures 

 of azotic gas, fifty-lix of oxygenous gas from red precipi- 

 tate, and twenty-four of hydrogenous gas, from malleable 

 iron and the diluted fulphuric acid, the greateft quantity 

 of nitric acid was produced. 



The acid obtained in any of thefe experiments, was not 

 equal to three grains of concentrated nitric acid, confe- 

 quently the theory of Dr. Prieftley muft be wrong, for it 

 is not probable, that fifty-fix ounce meafures of oxygen- 

 ous gas, enter into the compofition of three grains of ni- 

 tric acid. 



The Dodor is certainly right when he fays, if phlogi- 

 rticated air be purpofely introduced into the mixture of 

 dephlogifticated and inflammable air, it will not be affeded 

 by the procefs. It is neceffary however, to have regard to 

 the quality and proportion of the oxygenous and hydro- 

 genous gafes ; when thefe airs are pure, and contain no 

 azotic gas, which is fcarcely ever the cafe, water only will 

 be formed. When azotic air is mixed with them, which 

 it almoft always is, that part of the oxygen, which does 

 not unite to the hydrogen gas and form wrater, joins with 

 the azotic gas and forms the nitric acid. 



When carbonated hydrogen gas is ufed, carbonic Jwid, 

 water and nitric acid will be generated. 



That inflammable air does not enter into the compofition 

 of nitric acid is evident, for none of it, nor any thing into 

 which it enters, as a conftituent part, can be procured from 

 the nitric acid, nor any combination of this acid with al- 

 kalies, earths or metals. 



On the other hand, nitric acid may be feparated into its 

 elementary parts, oxygenous and azotic gas ; and if the 

 acid was compofed of pure and inflammable air, it could 

 be made by heating red precipitate in inflammable air. 



Mr. Keir who analyfed the liquor obtained by Dr. 

 Prieftley, from the explofion of pure and inflammable air^ 



fuppofed 



