f Analysis or olibanum. 345 



stance, which, being well washed with alcohol and dried, 

 weighed 9 gram. [139 grs.] 



B, This matter insoluble in alcohol was dissolved in Residuum dis- 

 boiling water, with the exception of a soft grayish sub-^°^^ mwaer, 

 stance, of a gummy appearance, and weighing when dry 



1*3 gram. [20 grs ]. This burned wi»h flame; and whed 

 treated with nitric acid, produced a greenish resiniform sub- 

 stance; which may lead us to suspect, that some resin had 

 escaped the action of the alcohol, though I took great care 

 to wash the residuum wi^h boiling spirit of wine. 



C. The aqueous soluiion (B)y after boing filtered, Gum. 

 yielded by evaporation 75 gram. [1 13*8 grs.] of a gum, of 

 which the following are the properties. 



1. This gum, which was considered as extractive matter Its properties, 

 by the older chemists, though it has by no means the ap- ^ 

 pcarance of it, has a yellowish trails parency, and a flat 



taste. 



2. It dissolves easily in water, without leaving' any resi- 

 duum. ^ 



3. Exposed to the fire it burns with but little flame, and 

 leaves white ashes, formed in great part of carbonate of 

 lime. 



4. Its aqueous solution does not redden infusion of litmus. 



5. Oxalate of potash forms a precipitate in the solution. 



6. Acetate of lead produces in it no very apparent 

 change ; but the nitrate, and more especially the subacetate 

 of lead and the nitrate of mercury occasion in it very 

 copious, thick, white precipitates, completely soluble in 



; |(istiled vinegar. 



7. The decoction of galls precipitates the solution of the 

 gum of olibanum, but not that of the gum of myrrh. 



8- Lime-water in excess does not ati'ect its transparency, 

 even after standing some time. 



9. This gum is carbonized by sulphuricacid, but does not 

 emit acetic vapours on heating the mixture. What thea 

 is it, that neutralizes the lime in this gum ? Thad. a suspi- 

 cion of benzoic acid, but this requires to be confirmed. 



10. The gum of olibanum heated with nitric heat lets fall, 

 particularly on cooling, a pretty large quantity of very . 

 white powder, granular as jif crystalline. Oa continuing 



the 



