460 RESINS 



the chief constituent being succino-abietinolic acid together with 

 succoxyabietic acid, succino-silvic acid and succino-abietol) 

 associated with a little bornyl succino-abietate. The part insoluble 

 in alcohol, succinin, is a compound of succinic acid, with a resin- 

 alcohol, succino-resinol. Succinite contains in addition traces of 

 sulphur and of inorganic substances. By destructive distillation it 

 yields a dark tarry oil accompanied by water ; the former, separated 

 from the watery fluid and redistilled, forms the genuine yellow oil of 

 amber of commerce, which may be distinguished from a common 

 substitute made from colophony by its higher specific gravity (0-926 

 to 0-930) and optical rotation (+ 23 to + 26). 



GUAIACUM RESIN 



(Resina Guaiaci) 



Source, &C. Guaiacum resin is the resin obtained from the stem 

 of Guaiacum officinale, Linne, or Guaiacum sanctum, Linne (N.O. 

 Zygophyllece) . The bulk of the resin of commerce is produced in the 

 following rather crude way from the trunk of the tree, the heartwood 

 of which, as already stated (see 'Guaiacum Wood'), contains from 

 20 to 25 per cent, of resin : A log of the wood is supported in a 

 horizontal position above the ground by two upright bars. Each 

 end of the log is then set on fire, and, a large incision having been 

 previously made in the middle, the melted resin runs out therefrom 

 in considerable abundance (' Pharmacographia ') ; or one end of a log 

 of wood is raised, and fire applied to it, when the melted resin will 

 run out of a groove cut in the other end, and may be received in 

 potsherds (block resin). 



It is said that the resin may also be obtained in the form of tears 

 by incisions made into the trunk, but it is more than doubtful whether 

 the tear resin of commerce is so produced. 



Description. Guaiacum resin is usually seen in large masses of dark 

 colour, often more or less covered with a greenish powder. The resin 

 breaks easily with a clean, glassy fracture, thin splinters viewed by 

 transmitted light being transparent, and varying in colour from 

 yellowish green to reddish brown. The powder is greyish, but 

 becomes green by exposure to light and air. It has a slightly acrid 

 taste, and, especially when warmed, a somewhat balsamic odour. It 

 is freely soluble in alcohol, chloroform, and solution of caustic potash, 

 incompletely in ether, but only slightly soluble in petroleum spirit, 

 carbon disulphide, or benzene. 



The resin in tears forms rounded masses, attaining 2 to 3 cm. in 

 diameter, usually covered with a greenish powder, and exhibiting the 

 characters already detailed. 



