Foreign Vegetables. 97 
Speed and Safety. And this Virtue is owing, partly 
to its ftyptick Bitternefs, and partly to the acid 
Salts which it contains. 
Acid Medicines frequently remove Fevers, by 
obtunding the Caufticity of the alkaline or febrile 
Venom. But the Difeafe fometimes returns, be- 
caufe the due Excretions being not perfedtly re- 
ftored, the fame remote Caufe is ftill fubfifting. 
Bitter Medicines alfo fometimes fubdue Fevers ; 
though not fo much by breaking the cauftick 
Salt of the febrile Humour, as by removing the 
Caufe of the Fever. We have faid, that the in- 
ternal antecedent Caufe of the Fever is a Sup- 
preflion of fome wonted Excretion,, which arifes 
from a Laxnefs and Flaccidity of the nervous Fibres 
compofing the Emundtories appointed for this Eva- 
cuation. Now, bitter Remedies, by their Styp- 
ticity, reftringe the too lax Fibres, and fo re-efta- 
blifh the Excretions, which were either fuppredfed 
or diminifhed. 
In the Peruvian Bark the Virtues of both thefe 
Kinds of Medicines are united : That is to fay, 
by Means of the acid Salt wherewith it abounds, 
it blunts the acrid, cauftick Salts of the febrile 
Venom ; and thus it conquers the Symptoms in a 
fhort Time. Afterwards, by a longer Ufe of it, all 
the Juices of the Body are imbued with its ftyp- 
tick Bitternefs, whereby it conftringes and ftrength- 
ens the Fibres, which a moift Intemperies of the 
Air, or fome other Caufe had relaxed ; and fo it 
removes the antecedent Caufe However, it is not 
furprizing that the Fever fhould often return upon 
omitting the Ufe of the Bark too foon, efpecially 
in a cold and moift Conftitution of the Air, where- 
in the Fibres are again relaxed by the external 
Contadt of the Air adting continually upon them. 
If the Ufe of the Febrifuge be continued for a fuf- 
H ficient 
