ON CINCHONA. 
257 
appearance externally, owing to the adherent crustaceous 
litchens. 
Section 1, — True Cinchona barks, having naturally a 
brown epidermis. 
To this section belong the pale, yellow and red barks of 
commerce. The following are the characters of each of these 
sub-sections: — 
(a.) Pale barks (Cinchona pallida.) — These always occur 
in quills, never in flat pieces. Their powder is more or less 
pale, grayish, fawn color, and their taste astringent and bitter. 
They contain probably both alkalies, cinchonia and quinia, but 
the first predominates. An infusion of this bark does not 
affect very obviously a solution of the sulphate of soda, in con- 
sequence of containing a very small quantity only of lime in 
solution. In English commerce three kinds of pale barks are 
known, namely — 
1. Crown, or Loxa bark. 
2. Silver, gray, or Huanuco bark. 
3. Ash bark. 
(b.) Yellow barks (Cinchona flava.) — I use the term yellow 
bark in the sense in which it is employed in English and 
French commerce: by the Germans and Spaniards, however, 
the designation of yellow (flava) is given to certain barks 
which have a white epidermis, (namely, the Carthagena barks 
of English commerce,) and which, therefore, will be noticed 
presently. The yellow barks of English commerce occur in 
quills or flat pieces, the quills being, on the average, larger 
and much rougher than the largest quills of pale barks. The 
texture of yellow barks is much more fibrous than the pale; 
the taste is more bitter, and less astringent; the powder is 
orange or fawn yellow. The principal kind of yellow bark 
namely, the regia or Calisaya, contains both quinia and cin- 
chonia, but the first in by far the largest quantity. An infu- 
sion of this kind of bark precipitates a solution of the sulphate 
of soda, in consequence of the large quantity of lime in the 
solution. The only yellow bark which I shall notice, is — 
vol. v. — no. in. 33 
