Usually made from porcelain or metal, crucibles enable chemical compounds to be heated to very high temperatures. They are sometimes used in conjunction with a loose fitting lid made of a similar material. The lid is purposely loose to allow gases to escape during heating.
Crucibles are often heated within a clay pipe triangle in order to keep it stable and to allow the base to be directly heated with a Bunsen burner. Tongs, sometimes referred to as crucible tongs, are specially designed to grip the shape of crucibles so they can be moved safely when hot.
Graphite crucibles are commonly used to heat and melt metals, these type can resist temperatures of over 1600°C.