SUBLIMATION, a chemical operation effected by the application of heat to ccrtaiu bodies; it is essentially similar to distillation in principle, but differs from it in the nature of the substances to which it is applied. In distillation liquids are converted iuto vapour, and condensed into the same form by the cooling agency of water ; whereas in sublimation solid bodies are vaporised, aud afterwards reassume the solid state, in general merely by the cooling power of the air, without the assistance of cold water.
Sublimation is usually conducted in one vessel, the product being deposited in the upper part of it in a solid state, while the impurity remains in the lower. In small experimental researches a Florence flask answers perfectly well, and a good exemplification of the process is that produced by heating iodine in it : a purple vapour rises, which almost immediately condenses in small brilliant dark-coloured crystals in the upper part of the flask, the impurity remaining in the lower.
Sublimation is extensively employed, and for two different purposes; the simplest case is that of using it for purifying a substance, camphor for example, in which the pure camphor is vaporised, and condenses in the upper part of the vessel, while the impurities remain in the lower part.
In preparing corrosive sublimate and calomel, these substances are formed and sublimed by the same operation : in general large green glass vessels, called boltheads, arc used for calomel and corrosive subli K mate ; while for camphor very thin flInt.gtital kuIsseli Ara tido& %Odell are called tombola', from the Italian tombola s in both cases a vessel is broken after each operation, to obtain the product. Among other substances procured by Is benzoic acid, formerly called )(ewers of besjentie. This acid is sublimed in much larger and not usually made of glass ; while the vapour of sulphur is condensed iu a large chamber, or sulphur-hottse, and adheres to the walls in the form of a fine powder, known by the name of Sublimed Sulphur, or Amer' of sulphur. (Ditertt.LATIos.]