94 ^ Treatise 
tue to a few Grains of an Alkali, which are in- 
volved and loaded with an acid Sulphur and Earth, 
Some in Oppofition alledge the Bitternefs of 
the Bark, fuppofing all bitter Subftances to be 
of the alkaline Tribe. But herein they are 
miftaken. For, by the Help of Chymiftry, they 
may learn that Bitters are not to be ranked among 
Alkalies *, becaufe, in a Refolution of them into 
their Principles, a large Quantity either of an acid 
or neutral Salt is obtained : And thofe artificial 
Compounds which are indued with the moft in- 
tenfe Bitternefs, fuch as the Cryjials of Silver and 
the bitter cathartick Salt , contain no Portion of an 
Alkali, but are conftituted of the ftronger Acids. 
To attribute, therefore, the Caufe of an intermit- 
ting Fever and its Symptoms to an acid Juice, and 
the Virtue of curing it in the Bark to an alkaline 
Salt, is manifeftly erroneous. 
The Author who bell has handled this Subjedt is 
Richard Morton , a learned Englijh Phyfician, and a 
careful Obferver of Nature, in his Treatife on Fe- 
vers. He judges the Caufe of Fevers to be fome 
venomous or deleterious Particles contrary to the 
Principle of Life or animal Spirits, which, de- 
ftroying their expanfive Faculty, necefiarily ex- 
tinguifh the vital Flame ; and that the Peruvian 
Bark, after the Manner of Antidotes, fubdues this 
febrile Virulency, and obliterates the deleterious 
Character which is imprefifed upon the Spirits. But 
this Hypothecs fuppoies the Exiftence of animal 
Spirits, which many Anatomifts, and even fome 
of the moft fkilful, have called in queftion. Be- 
jfides, he no where explains the Manner in which 
the Febrifuge adts upon the Nerves, imagining 
fuch an Inquiry entirely ufelefs ; fince it would be 
impofiible, in his Opinion, to determine any 
Thing certain in a Matter fo obfcure. Neverthe- 
i lefs. 
