COMPOSITION OP GAMBOGE. 
145 
another is as nearly as possible the same with their proportion 
in some specimens of fine Pipe Gamboge. 
" Having arrived at this result, it appeared to me an object 
of interest to examine the late Dr. Duncan's specimen of con- 
crete juice adhering to the bark, in order to ascertain whether 
it is generically the same article with the other specimens 
whose composition has been already mentioned, and whether 
its composition throws any light on the cause of the inferior 
miscibility with water which characterizes this, in common 
with some other varieties of Gamboge. I could spare only 
about four and one-third grains (4.329,) without injuring the 
specimen; but by proceeding carefully, the following results 
were obtained: — 
Grains. Per cent. 
Resin, heated at 400°, . . . 3.270 75.5 
Arabin, dried at 212°, . . . 0.793^ 
Insoluble residue, probably Cerasin, be-^ > 19.0 
cause soluble in boiling water, yet not > 0.029 ) 
then acted on by iodine, . ) 
Probable moisture, say as in Siam Gam- } ^ . ^ 
, ' > 0.208 4.8 
boge, S 
Total 4.300 99.3 
From this analysis it seems to follow, that the present speci- 
men is generically a true Gamboge. It contains indeed 
between four and six per cent, less gum than Siam Gamboge, 
and between two and four per cent, less than the other speci- 
mens of Ceylon Gamboge which I have examined; but this 
difference can scarcely be held the less to constitute it a true 
Gamboge.* Since executing this analysis I have received 
through the great kindness of Mrs. Colonel Walker, another 
specimen similar to that of Dr. Duncan. Although I have 
* On careful comparison, it appeared that the resin of Ceylon Gam- 
boge produces, in solution, the identical tint and intensity of colour 
which have been already stated to characterize the resin of Siam Gam- 
boge. 
VOL. III. — NO. II. 19 
