249 
sent to him by Mr. Anderson Blair, is cer- 
tainly not so emulsive as Siam Gamboge. 
But the ordinary Cingalese article, also 
sent by the same gentleman, is much more 
perfectly so. And the specimens sent by 
Mrs. Colonel Walker to Dr. Graham, as 
well as others subsequently sent to myself, 
comprising a splendid specimen of it ad- 
hering to the bark of the tree, seem to me 
to form with great ease an emulsion nowise 
inferior in smoothness, and very little, if 
at all, in liveliness of tint, to that of the 
very best Pipe Gamboge of Siam. On 
this point I have taken the precaution of 
consulting an experienced professional co- 
lourist; and he reports that Mr. Anderson 
Blair’s specimens present many fragments 
quite equal to the Pipe-Gamboge as a 
pigment, but that it does not mix well with 
some other colours, such as Prussian blue, 
and shows a tendency to curdle with them 
—an objection, however, from which I 
have since been told the finest varieties of 
Gamboge are not quite exempt. To this 
testimony may be annexed that of Mrs. 
Walker herself, who is a skilful colourist, 
and who both states in her communication 
to Dr. Graham, that she finds Ceylon Gam 
boge quite equal to that of Siam, and has 
since added, in a very interesting letter to 
myself, that all the additions sometimes 
made to it by the Cingalese artists, such 
as lime-juice, the gum of the Feronia ele- 
phantum, or lime-powder, are not only 
unnecessary, but have likewise appeared 
to her even to injure its tint. 
The inference, that good Ceylon Gam- 
boge may be easily put to use in the art of 
painting, is borne out by its chemical com- 
position. As in the instance of Cake Gam- 
boge, so here, sulphuric ether and cold 
water do not effect a complete solution, 
but leave about five per cent. of insoluble 
tirely away with a good deal of flame and 
& smell of burning wood, and has a dark 
ON THE SOURCES AND COMPOSITION OF GAMBOGE, 
brownish-black colour. The ashes of this 
residuum, amounting to three per cent. 
it, consist of carbonate of lime, with a 
trace of oxide of iron, 
different in purity. The quantity used was 
one hundred grains. g 
First. Second. 
Resin, heated at 400° 68.8 
Arabin, dried at 240°. 20.7 
Fibre of wood = 6.8 
bark, at 212° 
Moisture ..; eee: 
4.6 
‘Total... 100 M 
in some specimens of fine Pipe Gamboge. 
Having arrived at this result, it appear 
ed to me an object of interest to examine 
the late Dr. Duncan’s specimen of concrete 
boge. I could spare only about four a - 
dd grains [4.329], without injuring — 
the specimen ; but by proceeding c xe 
the following results were obtained :— p 
Grains. Per cent. 
3.970 75.5 
Resin, heated at 400° . . 0.793) 
Arabin, dried at 212° .. 
Insoluble residue, pro- 
bably Cerasin, because 
soluble in boiling wa- 
ter, yet not then acted 
on by iodine 
Probable moisture, 
as in Siam Gambo 
Total.... 4-300 
ue is 
From this analysis it seems pe? : 
the present specimen is generica" y | 
.029 
wi 48 
ge. 
POR 
that 
