318 
SELECTED ARTICLES. 
Characters. — It always occurs in the form of quills, no flat 
pieces being known. These quills are larger and coarser than 
those of Crown bark: the largest even approximate to those of 
Yellow bark, from which they are distinguished by the 
greater smoothness of their external surface. The length of 
the quills is from three to fifteen inches; their diameter from 
two lines to one and a quarter, or even two inches; their 
thickness one-third of a line to five lines. We observe on the 
epidermis transverse cracks, but they do not form rings, as in 
the Loxa or Crown bark. On the thicker quills longitudinal 
furrows are observed; and in these cases the transverse cracks 
are frequently wanting. The color of the epidermis is whitish: 
in the smaller quills it is a uniform whitish gray, while in the 
large quills we observe a kind of cretaceous covering. This 
whitish appearance, from which, indeed, the terms silver and 
gray given to this bark are derived, depends on some crusta- 
ceous lichens, as I have already observed. The structure of 
the inner surface of this kind of bark is, in the small quills, 
smooth; in the larger ones, fibrous: the color is rather red- 
dish, or rusty brown, than cinnamon brown. The fracture is 
even, and resinous; the odor clayish or sweet, and which 
Bergen says is peculiar to this kind. The taste is astringent, 
aromatic, and bitter; the powder of a deep cinnamon brown. 
Botanical history. — The tree yielding this bark is un- 
known. 
Chemical history. — I am not acquainted with any analyses 
of this bark, though several chemists have examined it with 
the view of determining the nature and proportion of its 
active principles. The following are their results: 
Quantity in a pound of Bark. 
Cinchonia. Quinia. 
Von Santen from 106# to 210 grains 
Michaelis 
finest quality 50 32 grains 
another sample 74 28 
Goebel and Kirst . . . 16S 
