A crucible is a vessel or melting pot made of extremely refractory materials, such as clay, graphite, clay, quartz, or harder to melt metal iron. The Crucible is a bowl-like container with a ceramic deep bottom. When solids are heated by fire, crucibles must be used. Because it can withstand the heat more than glassware.
When used, the crucible is usually inclined to the crucible to prevent the heat from jumping out and allowing the air to enter and exit freely for possible oxidation reactions. Because the bottom of the crucible is very small, it can be heated directly by fire in the mud triangle. The Crucible in the iron tripod on the use of positive or oblique, depending on the needs of the experiment can be placed on its own. The crucible is heated and not immediately placed on a cold metal table to prevent it from bursting due to a sharp cooling.