of their Parts are more Fixt, and some more Volatile, how far soever either of these Two may be from a pure Elementary Nature is Obvious enough, if Men would but heed it in the Burning of Wood, which the Fire Dissipates into Smoake and Ashes: For not only the latter of these is Confessedly made up of two such Differing Bodies as Earth and Salt; but the Former being condens’d into that Soot which adheres to our Chimneys, Discovers it self to Contain both Salt and Oyl, and Spirit and Earth, (and some Portion of Phlegme too) which being, all almost, Equally Volatile to that Degree of Fire which Forces them up, (the more Volatile Parts Helping perhaps, as well as the Urgency of the Fire, to carry up the more Fixt ones, as I have often Try’d in Dulcify’d Colcothar, Sublim’d by Sal Armoniack Blended with it) are carried Up together, but may afterwards be Separated by other Degrees of Fire, whose orderly Gradation allowes the Disparity of their Volatileness to Discover it self. Besides, if Differing Bodies United into one Mass be both sufficiently Fixt, the Fire finding no Parts Volatile
