12 Dr. Priestley’s Experiments 
procefs, found it to be far more deciiively conclufive in favour 
of my opinion than I had imagined. In the former experiment I 
had attended only to the drop of water which was found in the 
veflel in which the procefs was made ; and finding that it 
turned the juice of turnfole red, I concluded, that it contained 
nitrous acid : but I now examined the air that remained in the 
veflel, and found that a confiderable proportion of it was fixed 
air ; fo that I am now fatisfied this was the acid with which it 
was impregnated, and not the nitrous. Still, however, fome 
acid is the conftant refult of the union of the two kinds of 
air, and not water only. A quantity of the fame precipitate 
per Je yielded no fixed air by heat* 
Comparing this experiment with that in which iron is ignited 
in dephlogifticated air, this general conclufion may be drawn, 
viz. that when either inflammable or dephlogifticated air is 
extracted from any fubftance in contact with the other kind of 
air, fo that one of them is made to unite with the other in 
what may be called its nafcent Jlaie , the refult will be fixed air ; 
but that if both of them be completely formed before their 
union, the refult will be nitrous acid .. 
It has been faid, that the fixed air produced in both thefe 
experiments may come from the plumbago in the iron from 
which the inflammable air is obtained. But fince we afcertain. 
the quantity of plumbago contained in iron by what remains after 
Its folution in acids, it is in the higheft degree improbable, that 
whatever plumbago there may be in iron, any part of it fhould 
enter into the inflammable air procured from it. Befides, ac- 
cording to the antiphlogiftic hypothefis, aU inflammable air 
comes from water only. 
As it cannot be faid, that any real fixed air is fouud in in- 
flammable air from iron (fince it is not difcoverable by lime- 
h water) 
