Dr. fordyce on the 
S°6 
appear. Open the receiver, and you will find, that the 
air will have contracted, as it does from the inflamma- 
tion of a candle in van helmont’s experiment; that is, 
about a twentieth part. It is become unfit for inflam- 
mation; for if a lighted candle be immerfed in it, it 
will be extinguifhed as well as the phofpborus , and an 
animal will be fuffocated by it. The air then has buf- 
fered the fame change, as that air which has ferved for 
the inflammation of other bodies ; and the phofpborus is 
partly decompofed, the water in the receiver being im- 
pregnated with its acid, and the air faturated with its 
phlogifton. Blow frefh air into the receiver, and the 
light and fmoke will immediately re-appear. In like 
manner, it is known, that fulphur will burn and give 
light, without heat fufficient for ignition. Take a piece 
of iron heated nearly red hot, and throw a little gun- 
powder upon it. If the heat be of a proper degree, the 
fulphur will burn off with a blue flame, without heat 
fufficient for ignition; for, if fuch heat had been pro- 
duced, the gun-powder would certainly have taken lire, 
which it does not. It is the inflammation and decompo- 
fition of the fulphur, and not its evaporation, which pro- 
duces the light; for, if we lublime fulphur in dole vei- 
l'd s, made of the molt tranfparent glafs, no light will be 
vifible, except at the very beginning, when a fmall por- 
tion of it burns till the air in the veffel be faturated, and 
rendered unfit for inflammation. 
That the light, which is produced by the decompofi- 
tion in inflammation, is blue, in whatever degree of heat 
the 
