examined the finest variety of Gamboge, 
and concluded that it is composed of eighty 
per cent. resin, and twenty per cent. gum ; 
that the gum is acid in its re-action on ve- 
getable colours, and allied in nature to 
plum-tree gum; that the resin possesses 
the colour of the crude drug, is converted 
into an orange or cherry-red soap with 
potassa, yields a little oxalic and malic 
acids and a larger quantity of a bitter prin- 
ciple on being treated with nitric acid, and 
when subjected in fine powder to a stream 
of chlorine, forms a colourless compound 
with that gas, which is permanent, except 
under the influence of destructive distilla- 
tion, concentrated acids, and other power- 
ful decomposing agents. In 1813, John 
of Berlin, apparently unacquainted with 
the prior investigations of Braconnot, also 
examined this substance, and obtained the 
sme principles, but in very different pro- 
portions, the resin amounting in his ana- 
lyses to eighty-nine or ninety per cent., 
and the gum to nine and a half or ten and 
a half only? It may be added, that he 
was led by this analysis to throw doubts, 
as others indeed had done before him, over 
the belief, at that time general, in the ex- 
Istence of a gummy-resinous principle as 
à simple proximate constituent of vegeta- 
Substances. For in regard to Gamboge, 
m to be one of the most characteristic 
xamples of such a principle, he proved 
not merely that it may be resolved into 
* otiam true resin, but likewise that 
.. ^y be re-produced by simply triturat- 
ing the resinous part with a due proportion 
Bum-arabic, 
P inquiries of John and Braconnot 
ving been confined to a single variety of 
NS sins at least three principal 
is d ra in emmerce; 1t occur- 
icit at it might be desirable to as- 
Meu ceo of each—first, in 
Wille end e cause of their respective 
of the preference given to 
1 
ru ent po Gommes-résines, Annales 
* Chemische Voip es 
suchun 
tabilischer 
1513, 
s gen, mineralischer, vege- 
» und animalischer substanzen, iii. 190.— 
ON THE SOURCES AND COMPOSITION OF GAMBOGE. 
237 
one particular kind for the art of painting 
as well as in medicine—and secondly, in 
the hope that their respective analysis 
might throw some light on the question of 
their botanical origin. 
The specimens of Pipe and Cake Gam- 
boge of Siam, which were used in the fol- 
lowing analysis, were chosen for me by 
Mr. Duncan, an intelligent druggist of 
this city, as characteristic examples of the 
two varieties; and the specimens of Pipe 
Gamboge, which is the most important of 
the whole, were declared by an eminent 
professional colourist to be as fine as he had 
ever seen. The specimens of Coarse Gam- 
boge were obtained for me by an experi- 
enced wholesale druggist in London. Of 
Ceylon Gamboge I have been fortunate 
enough to obtain several authentic and 
characteristic examples. One was left in 
the museum of my predecessor, Dr. Dun- 
can, junior, to whom it was sent about se- 
ven years ago by Mr. David Anderson 
Blair from Colombo, as a specimen of the 
ordinary Gamboge of Ceylon. Another was 
lately transmitted by Mrs. Colonel Walker, 
also from Colombo, to my colleague, Dr. 
Graham, as a specimen of the exuded juice 
simply as collected from the tree and dried 
in moulds for preservation. A third is a 
beautiful and undoubted specimen of the 
exuded juice concreted on the bark of the 
tree which yields it. This was also sent 
by Mr. Anderson Blair to the late Dr. 
Duncan. 
1. Pipe Gamboge is so termed in the 
nomenclature of the drug-market, from 
its peculiar form. It occurs chiefly in cy- 
lindrical masses, from three-quarters of an 
inch to nearly three inches in diameter, 
commonly hollow, and often doubled upon 
themselves, and cohering. Not unfre- 
quently several of these pipes or cylinders 
are firmly accreted into irregularly-shaped 
cakes or balls, two or three pounds in 
weight; in which, however, the remains 
of the cavities may be traced, though much 
flattened. The surface of the unaccreted 
cylinders is dirty greenish-yellow, and stri- 
ated—evidently from the impression of the 
reed-moulds into which it is run when soft. 
