ESSAY ON SCAMMONr. 
13 
The constituent of which the greater part of this is made, 
is soluble and insoluble gum, which I presume to be gum 
tragacanth from its behaviour with water. It slightly effer- 
vesces with muriatic acid, and is changed to a brown with 
a slight tinge of blue by iodine. This specimen was ob- 
tained from Boston. Considerable quantities are in the 
market. 
Another specimen in similar sized and shaped masses, 
presents a rough earthy surface ; it is lighter coloured in- 
ternally than the preceding, and breaks with a horny rough 
fracture. It has a decided odour, is mucilaginous and 
bitter to the taste, somewhat gritty to the teeth, and forms 
with moisture on the finger a viscid clear mucilage. With 
water it dissolves, becoming a gruel-like viscid substance. 
It contains — Resin, 6.00. The remainder as above. 
This article is offered as prime scammony, and I have seen 
it in several forms and in quantity in the market. 
Black Gummy Scammony. 
The specimens I have examined of this kind had the form 
of the preceding; externally they arc of a plumbago colour, 
internally iron grey. They are heavy, hard, difficult to reduce 
to powder, which is dark. Odour slight, and taste viscid and 
gritty. From one of the specimens I obtained ten per cent, 
of resin. The residue seemed to be made up of tragacanth 
and bone black, the latter substance existing in patches un- 
mixed in a second specimen. This scammony is in the 
market in large quantities. y 
Factitious Smyrna Scammony. 
Two specimens of this I have met with. It corresponds 
to the description given of it by Pereira, " It is blackish 
and has externally a slaty appearance. It breaks with 
difficulty, its fracture is dull and black. Its sp. gr. 1.412. 
Moistened and rubbed it evolves the smell of guaiacum. 
Boiled with water it yields a turbid liquor, (which is not 
rendered blue by iodine,) and deposits a black powder; the 
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