ILLUSTRATIONS OF INDIAN BOTANY. 117 
“ The best solvent for separating the resin of Pipe gamboge is sulphuric ether. When 
agitated with the powder, a lively orange-red solution is obtained, which becomes Gamboge- 
yellow by dilution, and continues to show this tint when very greatly diluted, proving the ex- 
ceeding intensity of the colour. On distilling off the greater part of the ether, and then driy- 
ing away what remains by heating the residue in an open porcelain cup, a very beautiful, brittle 
resin is obtained, which has in thin layers a deep orange-colour and complete transparency, and 
in thicker masses a cherry-red tint, so dark as to produce almost complete opacity, and which 
possesses in fine powder a lively Gamboge-yellow hue.* It is remarkable that the very volatile 
fluid, sulphuric ether, adheres with great force to this resin, insomuch as to be the source of 
much trouble, and even error in a quantitative analysis. The vapour-bath heat of 212° F. } 
found insufficient to drive off so much ether as to leave the resin firm when cold ; even at the 
~ temperature of 270°, maintained by means of a muriate of lime-bath for six hours, so large a 
quantity was retained, that the detached principles almost always weighed conjunctly three per 
cent. more than the crude subject of analysis ; nay, a heat of 400° subsequently applied for 
four hours by an oil-bath, which I considered the highest temperature to be safely applied to the 
resin, and which sent off copious bubbles of ethereal vapour, still left a slight surplus of weight 
in the separated principles when summed up. 
he ether leaves, in the case of Pipe gamboge, a flocculent matter, which, when 
thoroughly exhausted by the repeated action of the same fluid, coheres somewhat and acquires 
a very pale yellowish white colour. In fine specimens of this Gamboge I have always found 
the flocculent residuum 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 solu- 
tion, which, when concentrated, becomes viscous, and when dried forms a transparent, reddish 
substance, of a mucilaginous taste without acridity. Braconnot 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. 
‘he proportions of the two principles vary somewhat, as will appear from the following re- 
sults of trials made with one hundred grains of two distinct specimens apparently of the same 
quality. 
First. Second. 
74.2 71.6 
Resin heated at 4002, till it ceased to lose weight......... Gnbeel adaas apo ; 
Arabin, or soluble gum, heated at 212°, till it ceased to lose weight .......,.. 21.8 24.0 
Moisture discharged by a heat of 270°............ Teer Cree et ee fy 4.8 
oath Ee. maleate yp geeerers ureteec nope a tye er arene er aan poe Chee ee ee eee oon CReeR trace, 
otal,... 100.8. 100.4 
In another analysis so much as 27.3 per cent. of gum was obtained. But as the resin was 
‘Not carefully determined, and there was therefore no check on the analysis, the accuracy of that 
result cannot be positively relied on. = & aie 
_ It follows that Pipe gamboge consists of resin and gum, without any volatile oil, which is 
a very common ingredient of other gummy resinous exudations. The large proportion of gum 
accounts well for its easy miscibility with water, by which, on the one hand, its suitableness for 
the purposes of the painter is judged of, and which, on the other hand, renders it in medical 
ractice convertible into a smooth and perfect emulsion, without any of the additions usually 
resorted to for that end.” | 
hee 
r remains, which in cold water sub- 
ry finely pulverulent, the lower one 
LS 
i 
‘i 
;s 
Co) 
