56 Professor Burnett's 
But to return to the point whence this episode sprang, and 
to the path whence a favorite topic has so long seduced 
us. There are several circumstances connected with the his- 
tory of quinia and cinchonia, the proximate principles of the 
Peruvian barks, to which, might I so far presume, I could 
much wish to invite the attention of my colleagues, the learned 
professors of Materia Medica and Chemistry; for to my mind 
they require much further elucidation, and many experiments 
seem wanting to ascertain correctly the properties of these 
barks, and the principles they respectively afford. The 
quilled or pale-brown bark was a few years since so much more 
highly prized than the yellow, that it was sold for sixteen 
shillings a pound, whilst the other would scarcely fetch a 
crown; and yet quinia, now so much esteemed, and believed 
to be the potent principle of the Peruvian barks, is abundant 
in the yellow, and all but absent from the quilled. Indeed, 
I am informed by my friend, Mr. HENNELL, of Apothecaries’ 
Hall, one of the most indefatigable and intelligent pharma- 
ceutic chemists of the day, that if the specimens submitted to 
analysis be correctly sorted, (for, in commerce, they are ge- 
nerally met with mixed,) no quinia at all will be found in the 
quilled bark, but abundance of cinchonia; while, in the yellow 
bark, the quinia is abundant, and the cinchonia wanting. 
Now this is a result which could not, a priori, have been 
conceived: for it is the guinta which is now extolled for its 
extraordinary curative effects; which principle, be it noted, 
is absent, or all but absent, from the quilled bark, so lately 
prized for similar powers; while the cénchonia, which abounds 
therein, is disesteemed: and, on the other hand, as a counter- 
part to this paradox, the yellow bark, so long neglected, yields 
abundantly, almost exclusively guénia, the present fashionable 
tonic, whilst it contains none or very little of that other prin- 
ciple cinchonia, to which all the former cures of its compeer, 
the lance-leaved bark, must be attributed ; it being, as already 
stated, in an equal degree devoid of quinia. 
In the red bark both cinchonia and quinia are found, but 
in much smaller relative proportions. It is likewise a circum- 
stance worthy notice, that some of the other species of cin- 
chona, specimens of the bark of which occasionally reach us, 
are said to afford these principles more abundantly than any 
of the officinal ones; and it is also probable, as shewn by Dr. 
Hancock, that other genera may be more advantageously 
used as febrifuges than cinchona. 
Now, from these premises, we cannot avoid the conclusion 
that further experiments and investigations, both botanical, 
chemical, and medical, are much required: for if the quilled 
