An improved apparatus was designed to prepare large organic crystals by the Bridgman method. The improved furnace, in which the whole process could be observed, was constructed from two concentric tube of Pyrex glass. A heating wire of nickel-chrome alloy was wound around the inner tube. Three sensors were used for the temperature control ranging from 0 to 100℃. Single crystals of naphthalene and durene were grown from melts of zone-purified material in the furnace. Details of the apparatus and the procedure are shown. Factors exerting influences on the preparations and crystalline properties are discussed.
