Sublimation

'Sublimation is the chemical process in which a pure chemical element or a chemical compound is converted from a solid state to a gaseous state without first passing through a liquid phase. The example most likely to be observed by non-chemists is the conversion of dry ice into carbon dioxide gas. In chemistry labs, sublimation, when possible, serves as a very convenient method of chemical purification. The halogens bromine and iodine are often purified in laboratories by sublimation.