AKALTSIS OJ" GUM AMMONIACUM. ^9 



<J. Oxalate of ammonia throws down from the solution a 

 precipitate of oxalate of lime, but I do not know by what 

 acid the lime is neutralized in the gums*. 



7. Decoction of galls detects nothing in it. 



8. This gum, treated with the nitric acid of the shops, 

 yielded nearly the same products as that of olibanum; that 

 is, a large quantity of mucous acid, some oxalic acid, and 

 a very little malic acid. 



i). The alcoholic solution (J) being evaporated to dry-Resiiu 

 ness, yielded 17'5 gram. [270 grs.] of a resin, which ex- 

 hibited the following characters. 



1. It was of a reddish yellow, transparent, brittle as Its properdet, 

 wax at a low temperature, having a wavy and shining 

 fracture, receiving a slight impression from the nail, and 



readily growing soft in the mouth or between the fingers. 

 It had no sensible taste : its smell was the same as that of 

 ammoniaeum itself. Friction did not render it electric. 



2. This resin, like wax, melts at 43^ [129^ F.]. At a 

 higher temperature it swells up considerably, emits a pecu- 

 liar smell, and leaves a light, spongy, bulky coal. 



3. This resin easily combines wlthalkalis, even cold; and 

 the results are saponaceoils compounds of considerable 

 bitterness +. 



4. Sulphuric acid readily dissolves the resin of ammonia- 

 eum, particularly with a gentle heat. AVater decomposes 

 this solution. If it be heated more, the result is a hidro- 

 guretted coal ; which, after being washed, dissolves ia 

 nitric acid, and yields by evaporation an astringent sub- 

 stance, which gives a brown precipitate with isinglass. 



5. Nitric acid heated on the resin at first produced only Treated with 

 some white vapours : but at length the red fumes appeared "'"^*^ ^^^ 

 on a sudden with great vehemence. The product was a 



* Mr. Vauquelin, who has made known the existence of phos- ' 

 phate of lime in the ashes of gum arable and gum tragacanth, 

 supposes the lime in these gums is saturated in great part by the 

 acetic acid. 



t Tlie soap or saponule of common resin has likewise a decidedly . 

 bitter taste, which seems to me to indicate in these resinous com- 

 pounds efficacious properties, that deserve the attention of th« 

 ©^serving physician, 



yellov 



