The residue left after distilling off the volatile oil from turpentine, U.S.P.

Characters. - Translucent, yellowish, brittle, pulverisable; fracture shining.

Composition. - Resin is the portion of turpentine fixed by oxidation. The greater part of it consists of abietic anhydride (C44H62O4), this being formed by the dehydrating of abietic acid (C44H64O5), during the distillation of the oil. It is again transformed into abietic acid by treating it with alcohol. A small proportion of pimaric acid is obtained from resin.

Preparations.

B.P

Charta Epispastica. Emplastrum Calefaciens.

„ Cantharidis.

„ Opii.

,, Picis.

„ Resinae.

,, Saponis.

Unguentum Resinae.

„ Terebinthinae.

U.S.P

Ceratum Resinae. Emplastrum Resinae.

Use. - Resin is only used externally as a stimulant application, in the form of ointment or plaster.