or p^obuetiott of f frtitetft 5 



ons, though it may it felf be made up 

 of two, three, or more particles of a 

 Gmpler nature, is confidered here per 

 modum Vnius^ or as one intire cor- 

 pufcle. And this is one Qualification 

 conducive to the Fixtnefs of a bo- 

 dy. 



The next is the ponder oufnefs or 

 folidity of the corpufcles it is made up 

 of. For if thefe be very folid, and 

 £ which folid and compaft bodies 

 ufuallyare) of a confiderable fpeci- 

 fi c K g rav ky* 'hey will be too heavy 

 to be carried up by the effluvia or 

 the a&ion of the fire, and their pon- 

 deroufneft will make them as unwiel- 

 dy, and indifpofed to be elevated by 

 fuch Agents, as the groflhefs of their 

 bulk would make bigger corpufcles, 

 but of a proportionably inferiour 

 fpecifick weight. On which account 

 the calces of fome metals and mine- 

 rals, as Gold, Silver, &c. though, by 

 the operation of Solvents, or of the 

 fire, or of both, reduced to powders 

 exceedingly fubtile, will refill: fuch 

 vehement fires, as will eafily drive 

 A 3 up 



