COMPOSITION OP GAMBOGE. 
141 
insoluble matter remains, which in cold water subsides com- 
monly in two layers — the uppermost white, and very finely 
pulverulent; the lower one grayish, and rather flocculent. 
The former proved to be fecula, entirely soluble in boiling 
water, and then giving an abundant blue precipitate with 
tincture of iodine — the latter quite insoluble in boiling water 
with even six hours of ebullition, burning entirely away, with 
the flame and odour of burning wood, and with a mere trace 
of earthy residue, and therefore apparently woody fibre or 
lignin. The analysis of two samples gave results nearly 
concordant, as follows: — One hundred grains were used, and 
all visible fragments of wood were excluded. 
First. 
Second. 
Resin, dried in oil bath at 400°, 
64.3 
65.0 
Arabin, dried at 260°, 
20.7 
19.7 
Fecula, dried at 212°, 
6.2 
5.0 
Lignin, dried at 212°, 
4.4 
6.2 
Moisture, 
4.0 
4.2 
99.6 
100.1 
" The proportion between the gum and the resin is here 
identically the average proportion already mentioned as ex- 
isting in Pipe Gamboge; so that, on simply abstracting the 
fecula and woody fibre, an article is constituted of precisely 
the same chemical composition. This circumstance, coupled 
with the presence of the particular principle fecula and the 
vesicular structure of the cakes, renders it extremely probable, 
if not certain, that Cake Gamboge is not simply a natural pro- 
duction, but rather a manufactured substance — an adulteration. 
For in the first place, it is the pure exudation plus so much 
impurity; secondly, fecula, is not known to be produced from 
the trunks, branches, or leaves of plants belonging to that 
part of the botanical system in which the true Gamboge tree 
undoubtedly will be found to be properly placed, and it is 
therefore almost impossible that its presence depends on 
