DIPTEROCARPE. 198 
between the eye of the observer and the light, but when viewed 
by reflected light it is opaque, greenish, and fluorescent. The 
lower stratum consists of a thick, dirty white magma, and is 
generally rejected, although it is said to have the same medi- 
cinal properties as the clear Balsam. The latter has a feeble 
copaiba odour, and a bitter aromatic taste; its specific gravity 
at 16°9° C. is *964; it is soluble in pure bengol, cumol, chloro- 
form, bisulphide of carbon, and essential oils, and partially so 
in methylic, ethylic, or amylic alcohol, in ether, acetic ether, 
glacial acetic acid, carbolic acid, or caustic potash dissolved in 
_ absolute alcohol ; at about 130° C., it becomes gelatinous, and 
on cooling does not recover its fluidity. 
3 Chemical composition. —The following account by Fliickiger 
_ and Hanbury is taken from the Pharmacographia. :—‘ Of the 
Balsam 6°99 grammes dissolved in benzol and kept in a water 
bath until the residue ceased to lose weight, yielded 3-80 
grammes of a dry, transparent, semi-fluid resin, correspondin 
to 54°44 per cent., and 45°56 of volatile matters expelled by 
- evaporation. 
“ By submitting larger quantities of the Balsam to the 
usual process of distillation with water in a large copper still, 
37 per cent. of volatile oil were easily obtained. The water 
passing over at the same time did not redden litmus paper ; 
a.dark viscid, liquid resin remained in the still. 
“The essential oil is of a pale straw colour, and less odorous 
than most other volatile oils; treated with chloride of caleium 
and again distilled it begins to boil at 210° C., and passes over _ 
at 260°C., acquiring a somewhat empyreumatic smell and light _ 
Bay 
- 
_ Werner, this oil has the composition C*° H3%, like that of copaiba. a 
residual resin dissolved in benzol being wholly inactive 
oil does not form a crystalline compound with dry hys 
yellowish tint. The purified oil has a sp. gr. of 0-915 to 0-914, _ 
it is but sparingly soluble in absolute alcohol or glacial acetic fe: 
acid, but mixes readily with amylic alcohol. According to 
