V 
The P R E F A C E. 
Where it appears by many chymioftaticafc 
Experiments, that there is diffufed thro* all 
natural, mutually attracting bodies, a large 
proportion of particles, which, as the firft 
great Author of this important difcovery , 
Sir Ifaac Newton, obferves, are capable of 
being thrown off from denfe bodies by heat 
or fermentation into a vigor oufty elaflick and 
permanently repelling ft ate : And alfo of re- 
turning by fermentation, and fometimes with- 
out it, into denfe bodies : It is by this amphi- 
bious property of the air, that the main and 
principal operations of Nature are carried 
on 5 for a mafs of mutually attracting par- 
ticles, without being blended with a due 
proportion of elaftick repelling ones, would in 
many cafes foon coale fee into a ftuggifh lump . 
It is by thefe properties of the particles of 
matter that he folves the principal 'Pheno- 
mena of Nature . And Dr. Freind has from 
the fame principles given a very ingenious 
Rationale of the chief operations in Chy - 
miftry . It is therefore of importance to have 
thefe very operative properties of natural bo- 
dies further afeertained by more Experiments 
and Obfervations : And it is with fat isf ac- 
tion that we fee them more and more confirm- 
ed to us, by every farther enquiry we make , 
