Observations. 455

was presently reduced to one fifth of thewhole. Thus it continued two months,without any sensible change; after whichI found that the air that remained un-abforbed did not affect common air, nor didthe air that was emitted by the charcoal,when it was plunged in water; so that,in boththese cafes, the air seems to be intirelydeprived of its peculiar properties, and tobecome mere phlogisticated air.

§ 4. Of nitrons air being , to Appearance,converted into Inflammable Air.

I have mentioned a cafe, Vol. I. p. 217,in which nitrous air, after having beenexposed to iron, became not only partiallyinflammable, admitting a candle to burn init with an enlarged flame, but was evenfired with an explosion, like inflammableair from metals by oil of vitriol. I havesince met with a more remarkable fact ofthe kind.

At the latter end of September 1778, Ihad put a pot of iron filings and brimstoneinto a jar of nitrous air, which, in the courseG g 4 of