Light produced by Inflammation . '507 
the inflammation takes place, appears from obferving 
the bottom and lower part of the flame of a candle, 
where the inflammation is; the light produced is blue. 
Or take a candle which has burnt for fome time, extin- 
guifh it by applying tallow to the wick, and let it ftand 
to cool; afterwards fet it on fire by the flame of another 
candle : at firft, no more vapour will arife than can be 
a&ed upon by the air at once ; inflammation, therefore, 
will go on m the whole fmall flame, and it will be blue. 
It may be neceflary to obferve here, that, when a candle 
burns, the following procefs happens. The tallow boils 
in the wick, and is converted into empyreumatic oil, riling 
from it in the form of vapour. As it rifes from every part 
of the wick, the volume is increafed till it comes to the 
top, and gives to the lower part of the flame the form of 
a fruflum of an inverted cone. The air is applied to the 
outer furface of the column of vapour, and, there de- 
compofing the empyreumatic oil, produces heat and blue 
light; the Jlratum of vapour, within the outer burning 
furface, is heated white-hot; the heat diminifhes towards 
the center, which, if the flame be large, is fcarcely red-hot ; 
as the column riles, decompolition taking place conftantly 
on its furface, it neceflarily diminifhes, and the upoer 
part of the flame is conical. That the tallow boils in the 
wick can be feen ; that it is converted into empyreumatic 
oil is proved by drawing the vapour, riling in the middle 
°f tbe flame, where it does not burn, into a glafs tube; 
the empyreumatic oil condenies. This alfo fhews, that 
the flame does not burn in the middle. That the heat is 
Vol. LXVJ. X x x produced 
