ORPIMENT (auripigmentum)  , arsenic trisulphide, As2S3, or yellow realgar (q.v.), occurring in small quantities as a mineral crystallizing in the rhombic system and of a brilliant golden-yellow colour in Bohemia, Peru, &c . For industrial purposes an artificial orpiment is manufactured by subliming one part of sulphur with two of arsenic trioxide . The sublimate varies in colour from yellow to red, according to the intimacy of the combination of the ingredients; and by varying the relative quantities used many intermediate tones may be obtained . These artificial preparations are highly poisonous . Formerly, under the name of " king's yellow," a preparation of orpiment was in considerable use as a pigment, but now it has been largely superseded by chrome-yellow . It was also at one time used in dyeing and calico-printing, and for the unhairing of skins, &c.; but safer and equally efficient substitutes have been found .