40 2 Dr priesi ley’s Experiments refuting to PbJogifion , 
Before this firft experiment was concluded, I perceived, that 
if the phlogifton in inflammable air had any bafe, it muft be 
very inconliderable : for the procefs went on till there was 
no more room to operate without endangering the receiver; and 
examining, with much anxiety, the air that remained, I found 
that it could not be diftinguilhed from that in which 1 began 
the experiment, which was air extracted from iron by oil of 
vitriol. I was therefore pretty well fatisfied that this inflam- 
mable air could not contain any thing befides phlogifton ; for 
at that time I reduced about 45 ounce meafures of the air to 
five. 
In order to afcertain a fact of lo much importance with the 
g reate ft care, I afterwards carefully expelled from a quantity of 
minium all the phlogifton, and every thing elfe that could 
have a (fumed the form of air, by giving it a red heat when 
mixed with fpirit of nitre; and immediately uflng it in the 
manner mentioned above, I reduced 101 ounce meafures of 
inflammable air to two. To judge of its degree of inflamma- 
bility, I prefen ted the flame of a fmall candle to the mouth of 
a phial filled with it, and obferved, that it made thirteen fepa- 
rate explofions, though weak ones (flopping the mouth of the 
phial with my finger after each explofion), when frefh made 
inflammable air, in the fame circumftances, made only four- 
teen explofions, though flronger ones. 
After this experiment I could not hefitate to conclude, that 
this inflammable air went totally, and without decompofition, 
into the lead which I formed at that time ; and if the necefiary 
circumftances of the experiment be confidered, it will be thought 
extraordinary that, even admitting this, the refult fhould be fo 
decilively clear in favour of it : for, in the firfl place, the 
greateft care muft be ufed to expel all air from the minium, 
3 and 
