472 On PHLOGJS'rON. 



One ounce of thefe borings, difTolved in lulphurlc acid 

 and water, left a refiduum of thirty-four grains, eighteen 

 of which were coal and fixteen filicious earth. 



The carbonic acid gas obtained in thcfe experiments, 

 evidently proceeded from the coal, contained in the call 

 iron. 



The Doctor alfo obtained carbonic acid, by heating the 

 charcoal of copper in dephlogifticated air. This charcoal 

 of copper is made by paffing the fteam of alkohol over 

 red hot copper, and as it confifts principally of carbon, 

 which is one of the component parts of alkohol, no ar- 

 gument can be adduced from it, in fupport of his hypo- 

 thefis. 



He alfo fuppofes that the fixed air, procured in animal 

 reipi ration, is formed without charcoal, but as we feed up- 

 on vegetable fubflances, which contain coal, the carbonic 

 acid, thrown out from the lungs, muft be formed of this 

 coal, uniting to the pure air taken into this vifcus in in- 

 fpiration. 



SECTION V. 



Of the Witric Acid. 



It is unneceffary to refer Dr. Prieftley, to the experi- 

 ments of various chemifts, to prove that the nitric acid is 

 compofed of oxygen and azote, as he muft be well ac- 

 quainted with every thing that has been done upon this 

 lubjea. 



As the Do£lor obtains this acid at pleafure, by decom- 

 poling by the ele£lric fpark, a mixture of oxygenous and 

 hydrogenous gafes, in the proportion of a little more than 

 one meafure of the former to two of the latter, he fup- 

 pofes the acid is formed of thefe airs. But let us attend 

 ilriftly, to what takes place in experiments of this kind. 



Thirty- 



