. eolour. In fine specimens of this Gamboge 
[have always found the flocculent resi- 
. duum to be composed entirely of gum, 
presenting. the leading. characters of the 
prototype of the gummy principle named 
Arabin, from its forming almost the entire 
. mass of gum-arabic. It is entirely and 
easily soluble in cold water, forming a pale 
yellowish solution, which, when concentrat- 
ed, becomes viscous, and when dried, forms 
a transparent, reddish substance, of a mu- 
cilaginous taste without acridity. Bracon- 
not thought the gum analogous to that of 
the plum-tree; which, however, contains 
a considerable proportion of the insoluble 
variety of gum named Cerasin, a variety 
entirely absent in Pipe Gamboge. 
The proportions of the two principles 
vary somewhat, as will appear from the 
following results of trials made with one 
hundred grains of two distinct specimens 
apparently of the same quality. 
Resin heated at 400°, till š hs Pme 
it ceased to lose seigut 42 718 
Arabin, or soluble gum, 
heated at 212», till ps 24.0 
"rwn to lose weight . 
oisture discharged by a 
ime 7| 48 Mn 
ov dus e trace trace 
Total....100.8 100.4 
In another analysis so much as 27. 3 per 
cent, of gum was obtained. But as the 
a Was not carefully determined, and 
“ere was therefore no check on the analy- 
“ts, the accuracy of that result cannot be 
positively relied on. 
_It follows that Pipe Gamboge consists 
ias and gum, without any volatile oil, 
à very common ingredient of other 
summy-resinous exudations. The large 
aue of gum accounts well for its 
y miscibility with water, by which, on 
oedema its suitableness for the pur- 
a the painter is judged of, and 
. Ch, on the other hand, renders it in me- 
En des convertible into a smooth 
Perlect emulsion, without any of the 
ON THE SOURCES AND COMPOSITION OF GAMBOGE. 
239 
additions usually resorted to for that 
e 
a 
Qs 
I have nowhere met with any allusion 
to the question, in what principle the ac- 
tive properties of Pipe Gamboge reside. 
Since it consists of nothing else but gum 
and resin, the natural inference must be, 
that as gum is always bland and simply 
demulcent when pure, the acridity will be 
found to reside in the resin. This I have 
accordingly ascertained to be the case. 
The resin of Gamboge, heated to 260° to 
drive away most of the ether, was adminis- 
tered as a purgative to several individuals 
alternately with Gamboge itself; and both 
were found to occasion identically the same 
effects in kind—the resin, like the crude 
drug,occasioning profuse watery discharges, 
without pain or other uneasiness, in the 
dose of five grains. But its operation was 
certainly different in degree, the effect be- 
ing always less in the dose of five or five 
and a half grains, than from the equivalent 
dose of seven grains of Gamboge, although 
care was taken to administer both to the 
same individuals, and in identically the 
same circumstances, so far as this condi- 
tion could be secured. I was at first in- 
clined to imagine that the diminution of 
effect might be owing to a partial change 
produced by the heat to which the resin 
had been exposed. But this idea was ne- 
cessarily abandoned on subsequent proof 
being obtained that a higher heat of 400°, 
which is little short of that required to 
produce chemical disorganization of the 
resin, has no further deteriorating influence. 
But it may be asked, whether the acrid- 
ity of Gamboge is a property of the resin 
itself, or of some principle united with 
pure resin, and concentrating in itself the 
whole active qualities of the drug. On 
this point chemical analysis has not yet 
thrown any light; nor have I been able to 
add any thing to what is already known. 
Certainly no decomposing agent hitherto. 
applied has detached a peculiar active: 
principle from the resin; and it further 
appears probable 
ponification, which 
detach an active principle, if it really were 
