48 &t t$e .tfecfiam'cat ©itatne 



tion of Air, purpofely left in the Vef- 

 fels, may more than compenfate the 

 greater fpace that is to be afccnded 

 by the vapours or exhalations of the 

 matter that is to be diftilled or fubli- 

 med. And .if, inclofe Veffels, the 

 prefence of the Air may promote the 

 afcention of bodies, it may well be 

 expe&ed, that the elevation ofdi* 

 vers -of them may be furthered by 

 being attempted in open Veflels, to 

 which the Air has free acccfs. And 

 if we may give any credit to the pro- 

 bable Relations of fome Chymifts, 

 the Air does much contribute to the 

 volatilization of fome bodies that are 

 barely, though indeed for no ihort 

 time, expofedtoit* But the account 

 on which the Air by its bare pretence 

 or peculiar operations conduces to 

 the Volatilization of fome bodies, is 

 a thing very difficult to be determi- 

 ned, without having recourfe to fome 

 Notions about Gravity and Levity^ 

 and of the Conftitution of the cor- 

 pufciesthat compofe the Air 5 which 

 I take to be both very numerous and 



