Why is the crucible burned and then black, oxidized, chemically?
If you are using candles, candles contain carbon, incomplete combustion of carbon black (black carbon pen usually in composition) attached to the crucible surface, so the look is black, a hand is not gone.
The burning of incomplete carbon is attached, I think. Candles, for example, often do.
If the crucible is heated by an alcohol lamp, the black substance, which is the main component of the black substance after the fire has been burned, is one of the carbon elements, chemically called C., which is produced by incomplete combustion of alcohol
