490 OLEO-RESINS 



to preserve microscopical preparations. It has an agreeable balsamic 

 odour and a rather bitter and acrid taste. It is completely soluble 

 in chloroform, benzene, and ether, but only partially in alcohol. 



Constituents. Canada turpentine consists approximately of 16 to 

 24 per cent, of volatile oil mixed with from 70 to 80 per cent, of resin. 



The volatile oil consists chiefly of /-pinene. 



Of the resin about 20 per cent, is composed of an indifferent resene, 

 canado-resene, which is remarkable for its insolubility in alcohol. 

 A further 20 per cent, of the resin is amorphous canadinic acid. The 

 remaining 60 per cent, consists of two amorphous resin acids, a- and 

 /3-canadinolic acids, associated with 0-5 per cent, of crystalline 

 canadolic acid. 



The bitter principle, which is soluble in water, has not yet been 

 isolated. 



Uses. Canada turpentine is extensively used as a microscopic 

 mountant. For this purpose the resin, obtained by heating the 

 turpentine until the volatile oil is driven off, is dissolved in xylol, or 

 some other suitable solvent. It is also used for cementing lenses. 



Note. Oregon balsam is a similar oleo-resin obtained from Abies Menziesii, 

 Lindley, on the Pacific slope ; it is thinner than Canada balsam and yields a 

 sticky film on evaporation. 



COPAIBA 



(Copaiva, Balsam of Copaiba) 



Source, &c. Copaiba is an oleo-resin obtained from the trunk of 

 Copaifera Lansdorfii, Desfontaines (N.O. Leguminosce) , and other 

 species of Copaifera. 



The trees from which the official oleo-resin is obtained are large 

 trees attaining over 100 metres in height, indigenous to Brazil and 

 the north of South America. The drug, which was highly esteemed 

 by the natives of Brazil and had probably long been used by them as 

 a medicine, was introduced into Europe about the beginning of the 

 seventeenth century. 



The oleo-resin is contained in anastomosing, schizogenous secretion 

 ducts that form an extensive network in each zone of the secondary 

 wood of both stem and root, extending throughout the entire length 

 of the zone, resembling therefore in arrangement the laticiferous 

 tissue of the dandelion. These ducts are formed in the young wood 

 and rapidly attain their normal diameter, which is often very 

 considerable ; at the level of the insertion of the branches a number 

 of lateral ducts connect zone with zone. In addition to these 

 schizogenous ducts lysigenous cavities also appear to be formed by 

 the breaking down of the cell walls and their probable transformation 

 into resinous or oleo-resinous substances. 



