294 
OBSERVATIONS ON COPAIBA. 
When mixed with one-sixteenth of magnesia and allowed 
to stand five days, no combination ensued; it was then heat- 
ed, with no increase of solidity, except what might be at- 
tributed to loss of oil ; in other words, though thick and 
resinous, it is not solidifiable, because it contains no copaivic 
acid. 
The following table exhibits these results at one view. 
Stoltze 
Gerbers 
fresh co- 
paiba 
Gerbers 
old co- 
paiba 
Durand 
Gui- 
bourt 
Volatile oil. 
38. 
41. 
31.7 
50 
45. 
Ccpaivic acid. 
52.75 
51.38 
53.68 
53.9 
^50. 
Soft resin. 
1 66 
2.18 
11.15 
1.1 
Water & loss. 
7.59 
5.44 
4.10 
Wip. 
pie 
80 
^20 
By a comparison of these results, we are first struck with 
the great variation in the proportion of volatile oil, which 
varies from 31 to 80 per cent. Second : in the three first 
and the fifth analyses, the ratio of copaivic acid is nearly 
equal, while the soft resin varies from 1.66 to 11.15 per 
cent., being greatest in the oldest. Third : that only three 
specimens, containing from 50 to 60 per cent, of resin will 
solidify. Fourth: that the resin in the specimen a differs from 
all the rest both in color, consistence, and want of acidity, 
the copaiba being apparently immature; and lastly that in 
the spontaneous oxidation of copaiba and its volatile oil, it 
is the soft resin only that is formed. 
3d. The causes modifying the proximate constitution of 
copaiba, existing and acting before and after the extrac- 
tion of the juice, are several. 
It is an ascertained fact that the ascending juices of plants, 
particularly of trees, are much more simple than those 
which descend, after having passed the circulation of the 
leaves; and the principles deposited by the downward cur- 
rent contain more carbon and less oxygen, than those con- 
tained in the ascer.ding current. This arises from the chemi- 
cal changes going on in the leaves during the action of 
light on them, by which oxygen is evolved from the carbonic 
acid and other constituents of the juices. "Their green 
