296 
OBSERVATIONS ON COPAIBA. 
this is true, and there appears no reason to doubt it, the " so- 
lidifiable balsam" is the least valuable as a medicine, and it 
becomes an important question whether the practice of extract- 
ing the juice from the older trees is the most eligible? It is 
for therapeutists to ascertain whether such copaiba as (a) is 
or is not better than such as (e.) 
Tt is apparent from the analyses above detailed, that copaivic 
acid is a natural product formed in the juice of the plant, and 
not after its extraction, by exposure to the air. The exami- 
nation of old copaiba by Gerber, and of the specimen (jf) of 
old oil of copaiba by the writer, especially show this; hence if 
any given specimens of the drug be not naturally possessed of 
about 50 per cent, of copaivic acid, no subsequent oxidation 
will render it solidifiable. 
The soft resin formed by oxidation of the oil appears to give 
more consistence to the drug weight for weight, than thecopaivic 
acid, probably from being less soluble, and hence old copaiba 
is not only thicker in consistence from loss of volatile oil, by 
evaporation, but from the formation of the soft resin. It is 
highly probable that specimens of copaiba may be met with, 
which, originally immature, and slightly resinous, have be- 
come thick and resinous from exposure. Such copaiba will 
not solidify, for the causes mentioned. The remarks by Joseph 
Laidley at page 121 of this volume, tend to corroborate some 
of the statements in this paper, whilst these explain the diffi- 
culties met with by that writer. 
