Foreign Vegetables. 93 
Then feparate the Tindture by Expreffion, and 
pour upon the Refiduum Ifeiv. of drong Wine, 
and diged in a Sand-Heat for twenty four 
Hours. Strain again by Exprefiion, and eva- 
porate both Tindtures together in a Sand- 
Heat to the Confidence of Honey. To this 
add giij. of the Syrup of Kermes, and mix- 
ing them well, evaporate to the Confidence 
of a folid Extradk 
As to the Manner in which this Bark exerts its 
Adtion, the common Opinion is, that the Caufe of 
an intermitting Fever is a coagulating acid Salt, 
which dimulating the nervous Membranes gives 
Rife to all the febrile Symptoms ; and that the Pe- 
ruvian Bark, abounding with an alkaline Salt, ab- 
forbs this Acid, and dedroys its bad Effedts, by 
diffolving the infpilfated and coagulated Humours. 
But this Hypothecs is altogether repugnant to Ex- 
perience. For, if the Fever were owing to an 
Acid, it would thence follow that Alkalies, whether 
fixt or volatile, faline or terredrial, would be 
much better and more efficacious Abforbents of 
that Acid ; and that Acids, on the other Hand, 
would increafe the Fever. But the clear contrary 
falls out : For Alkalies are vadly inferior to Acids 
in the Cure of Fevers. Nay, even the dronger 
Alkalies, fuch as Salt of Tartar or the volatile Salt 
of Hartfhorn, or the terredrial ones, as Crabs Eyes, 
&c. feldom abate the Fever ; whereas it is very 
frequently appeafed by a few Drops of the Spirit 
of Vitriol, Sulphur or Nitre, or by the acid 
Juices of Sorrel, Lemons, £s?r. Befides, the Pe- 
ruvian Bark contains but a very fmall Portion of 
alkaline Salt, either fixt or volatile, but, on the 
contrary, a large Quantity of acid Salt and Oil. 
So that it feems fomewhat abfurd to afcribe its Vir- 
tue 
