292 PROCEEDINGS OF SECTION B. 



The subtance was treated successively with light petroleum, 

 ether, alcohol (sp. gr. '834), Avater, soda solution (-2 per 

 cent.), and hydrochloric acid, with the following results : — 



Light petroleum dissolved 17*63 per cent, of a pale resin 

 after 8 days, together with essential oil. 



Ether, after 8 days, extracted 13-379 per cent, of a yellow 

 resin, which retained a trace of the characteristic odour 

 of the essential oil to which the odour of the gum-resin 

 is due. 



Alcohol dissolved 4*109 per cent, of a yellow resin, 



A¥ater dissolves 1*38 per cent.; the soluble matter is 

 precipitable by alcohol, and proves to be arabin. 



On treatment Avith soda solution the liquid deepens in 

 colour to a dark yellow, and 19'575 per cent, is dissolved ; 

 from this 1-642 per cent, is precijutated by alcohol, and is 

 metarabin, the remainder (17*933 per cent.) being a resin 

 soluble in the alkaline solution. 



Hydrochloric acid has but the slightest action upon the 

 residue, or in fact upon the original gum-resin. 



The residue was principally insoluble gum or mucilage, 

 together with insoluble resin, the total amount being 41*42 

 per cent. ; the percentage of ash made by direct estimation 

 Avas -469. 



These amounts give a total of 97*493 per cent., leaving (by 

 difference) 2*507 per cent, of volatile oil, and this deter- 

 mination was confirmed by estimations of oil contained in 

 two separate sixths of the light petroleum solution. 



Summary. 



Eesin soluble in light petroleum 17*63 



„ „ ether 13*379 



,, „ alcohol 4*109 



Arabin 1*380 



Resin and colouring matter soluble in soda 17 ■ 933 



Metarabin rG42 



Essential oil 2*507 



Residue (insoluble mucilage, resin, and impurities) 41*420 



100*000 



2. Examination of the soft inner portion of the 

 Gum-Resin. 



The dried external portion of the gum-resin is very 

 insoluble in all solvents, and experiments with it are not 

 entirely satisfactory, I therefore i*emoved this outer portion. 



