CINCHONA. 
285 
' The Red Peruvian bark comes to us generally in much larger, 
thicker, and flatter pieces than either of the former; it is sometimes 
found also in the form of quills. It is heavy, lirra, sound, and dry ; 
friable between the teeth, does not separate into fibres, but breaks 
short, close, and smooth. It has three layers, the outer of which is 
thin, rugged, of a reddish brown colour, and, like the Loxa bark, 
frequently covered with moss or lichen ; the middle layer is thicker, 
more compact, darker coloured, very resinous, brittle, and is the 
first to yield to the pestle ; the inner layer is more woody, fibrous, 
and of a brighter red ; when powdered, its colour resembles that of 
the Armenian bole. 
The yellow Peruvian bark has only been introduced into European 
practice since 1790, when it was sent from Santa Fe by Mutis. It 
consists of pieces about six inches in length, thicker, and less rolled 
up than the red or pale bark ; its inner surface is of a deeper red ; the 
epidermis, which is as thick as the bark itself, is sometimes wanting.* 
It is lighter, and more friable than the pale bark ; its fracture is fibrous, 
and when reduced to powder it is of a paler colour. Its taste is 
much more bitter, astringent, and stronger, but its smell weaker. 
Its decoction when hot is redder, but when cold paler ; and its solu- 
tion strikes a deeper colour with the sulphate of iron. According 
to the opinion formerly entertained, it contained more of the active 
constituents, than either the pale or the red bark ; was a more 
powerful medicine, and indeed, according to Mutis, was the only one 
which was directly febrifuge. The fallacy of these opinions are now 
evident. 
Peruvian bark yields its virtues to both cold and boiling water; 
but the decoction is thicker, gives out its taste more readily, and 
forms an ink with a chalybeate, more suddenly than the fresh cold 
infusion ; f the latter however contains as much extractive matter, 
but more in a state of solution, and its colour, on standing with the 
chalybeate, becomes darker, while that of the decoction becomes 
fainter : after some time, the addition of a chalybeate renders them 
green, when they are found to be in a state of fermentation. J Mild 
* The epidermis, when present, should always be removed before powdering. 
+ We have always considered the cold infusion one of the most elegant preparations 
of bark, particularly as a tonic, and for a weak stomach. The recent chemical prepa- 
rations of this medicine will however shortly set aside all the extemporaneous prepara- 
tions which have hitherto been in use. 
J Dr. Duncan says, that " in all cases where an excess of the chalybeate is used, a 
green colour is produced." These effects were ascribed to the presence of tannin, but 
Dr. Maton found that Cinchona contained very little tannin. 
