Crystallography is inherently a solid-state technique. However, where a material is a liquid under ambient conditions, it may be possible either to grow a crystal at low temperature and mount it using cryo-techniques or, alternatively, grow a crystal in situ on the diffractometer. In order to be successful, the material must crystallise. If this is the case it is then sealed in a capillary and mounted on the diffractometer. It is then cooled to form a microcrystalline powder which is then zone-heated to melt the smallest crystallites so that they can enlarge the biggest crystallites ultimately leading to the formation of one, large, single crystal.