f &44 
Stomack, does not ordinarily arife between the Ali- 
ment and the Saliva, but between the feveral Parts of 
the Saliva it felf. And indeed, if the Saliva did notcon- 
fift of two Juices, whofc Nature is infuch a manner dif- 
ferent, as to render them apt to ferment upon their Mix- ' 
ture, it would be very hard to conceive how it ftiould 
fo readily and indifferently fervc for the Digeftion of all 
Eatables ; how it fliould ferment with, and diffolve fo 
great a Variety of things, not only of a different, but 
of a contrary Nature how it jhould ferment with 
Acids as well as Alkalies, digeft things that are cold as 
well as hot or temperate ; Ibme things that are fait, o- 
thers that are infipid, bitter, and (weet, mucilaginous, 
oily, &c. But if we fuppofe, that the Fermentation, 
which ftrves for the Digeftion of the Food, arifes from 
a peculiar DifTerence in the nature of two Juices, which 
conftitute the Saliva, it will be eafie to give a rational 
Account of our Concodion of innumerable things of a 
different Nature. And this feems to be as eflediual, and 
a more certain way to attenuate and difFoIve the grofler 
X Parts of our Food, than if the Fermentation were made 
only between the Saliva and the Aliment : Befides, the 
Saliva feems to difcover a Fermentation upon the Mix- 
ture of its conft it uent Juices, even at thofe times when 
W€ do not actually eat,* for it is always attended with 
Bubbles, and a Froth, when it has not been at all agi- 
tated in the Mouth, and many of thofe Bubbles will 
remain for fome confiderable time after we have fpit it 
out. 
Nature therefore having appointed the Saliva for the 
Digeflion of the Food, has taken care that it fhall be 
thrown in upon the Aliment on every fide. Thus the 
Clandula t^ficiiam, and the Parotides fijpply their Juices 
to that part of the Food, which lies on the outfide of 
the Gums, between the Gheeks and the Teeth, and the 
Glandule 
