Foreign Vegetables. 9^ 
lefs, if we attend to the evident Caufes of inter- 
mitting, or continual Fevers, and their Symptoms, 
and likewife to what happens to the Patient after 
taking the Bark, we fhall be enabled to attain 
fome Notions, both of the Nature of the Fevers, 
and of the Manner in which the Medicine operates : 
And though thefe Notions as yet may be conjec- 
tural, they feem, however, to come very near the 
Truth. 
The efficient or proximate Caufe then of in- 
termitting Fevers is an excrementitious Juice of- 
fenfive to the Nerves, wherewith the Blood is 
overftocked by Reafon of the Suppreffion of fome 
fenfible or infenfible Evacuation, which has been 
occafioned by an Abufe or Depravation of the fix 
Non-naturals ; and among thefe a cold and moift 
Intemperies of the Air may be reckoned in the 
firft Place, being more generally the external or 
remote Caufe of fuch Fevers. The Nature of this 
Juice feems to approach very near to that of an 
alkaline urinous Salt, fi nee almoft all excrementi- 
tious Humours abound with a Salt of that Kind. 
Wherefore when this Juice is redundant, a large 
and fuperfluous Quantity of that Salt muft be 
colle&ed in the Blood. And indeed a chymical 
Analyfisof the Blood ofPerfons in Fevers, evinces 
the Truth of what we have here advanced ; for 
a larger Quantity of an alkaline urinous Salt is 
obtained thence, than from the Blood of Perfons 
in Health. However, the noxious Energy of this 
Humour is not to be imputed to the Quantity of 
acrid Salts alone, but likewife to certain bilious or 
aduft fulphureous Particles, which increafe or weak- 
en it in Proportion to their Mixture with the Salts. 
Now, to difeover the Force of this falino-oleous 
Humour, the only apparent Method is from the 
Effects it produces in the Body. For inftance, 
being 
