Comparative Analysis of the Gum Resins. 355 
with that which [ have designated by the name of resino- 
bitter, but it differs from it in the stability and proportion 
of its elements. 
ANALYSIS OF GUM AMMONIA. 
§ I. No traveller fias ever described the plant which pro- 
duces gum ammonia; but from the inspection of the seeds 
which are always found in the leaves of ammonia, it is at 
least very probable that it flows in a milky form from one 
of the umbelliferze, particularly when we recollect that other 
gummo-resins also flow from the juice of several feru- 
laceous plants. In fact, the seeds which we meet with in 
the gum ammonia are oval, compressed, relieved on each 
side by three longitudinal’ strize, and composed of two el- 
liptical seeds laid against each ‘other ; these characters be- 
long, as we may be satisfied, 'to' the’ #enus: Perula: ‘Hence it 
seems to me to result that’ a spetied OF this @entis furnishes 
the gum ammonia which is brought from the deserts of 
Africa, and from’ Libya ‘to’ Alexandria, from whence it 
reaches us as an article of commerce, j 
The gum ammonia which J, made use. of,.in,,my experi- 
ments was in irregular masses, yellowish externally, slightly 
transparent on the edges when they are thin, presenting a 
shell-like fracture, shining, white, sometimes slightly mar- 
bled, and having the aspect of certain resiniform silices, par- 
ticularly the variety known by the name of cacholong. It 
has little smell, at least if it be not pulverized. Its taste 1s 
slightly aerid, bitter, and nauseous, “It is easily diluted in 
water, producing a very white milky liquor." 
It should seem that the ancients have rather ventured 
upon conjectures ‘as'‘to the nature of the:substance in ques- 
tion, than made any, real experiments: thus they say, that 
boiling water dissolves it almost entirely, which made Car- 
theuser suspect that the ‘extractive’ part is more abundant 
in it than the resinous part; but we shall see that this as- 
sertion is unfounded, 
§ If. Gum ammonia when exposed to a heat incapable 
of decomposing it easily becomes soft, and loses --8,, of its 
weight in humidity. 
Twenty-five grammes of this substance furnished on be- 
ing distilled ou the open fire twelve grammes of liquid, the 
greater part of which was a brown empyreumatic oil: this 
produet when mixed with lime set free a smell of volatile 
alkali. There remained in the retort a charcoal weighing 
7°5 grammes, which furnished after its incineration 3°2 
grammes of ashes mixed with gravel, which Fareiaenen $9, 
Z2 
