or p^otmcttort of tftjttnefe* 19 



of fuch parts is a proper means to 

 make the aggregate of thofe that re- 

 main more fixt, I prefume you will 

 not put me folicitoufly to prove 5 

 and we have a manifeft inftance of it 

 in Sooty where.; though many aftive 

 parts were by the violence of the 

 fire and current of the air carried up 

 together by the more volatile parts 5 

 yet, when Soot is well diftilled in a 

 Retort, a competent time being gi- 

 ven for the extricating and avolation 

 of the other parts, there will at the 

 bottom remain a fubltancq that will 

 not now fly away, as it formerly did* 

 And here let me oblerve) that the 

 recefTe of the fugitive corpufcles may 

 contribute to the fixation of a body 9 

 not barely becaufe the remaining 

 matter is freed from fo many unfixt^ 

 if.not alfo volatilizing, parts 5 but 9 as 

 it may often happen, that upon their 

 receffe the pores or intervals, they 

 left behind them, are filled up with 

 more folid or heavy matter, and the 

 body becomes D as more homogeneous^ 

 fd more clofe and compaft. And 

 B 2 where- 



