The Preface. vii 



fometimes without it, i?ito denfe bodies : 

 It is by this amphibious property of the 

 Air, that the mam and principal ope- 

 rations of Nature are carried on ; for 

 a mafs of?nutually attraBing particles, 

 without being blended with a due pro- 

 portion of elajlick repelling ones, would, 

 in many cafes, foon coalefce into a fug- 

 gifj lu?np. It is by theje properties of 

 the particles of matter, that he fo Ives 

 the principal Ph<z?w?nena of Nature. 

 And Dr. Freind has from the fame 

 principles given a very i?tgenious Ratio- 

 nale of the chief operations in Chymijlry. 

 It is therefore of importance to have 

 thefe very operative properties of -natu- 

 ral bodies further afcertaiiied by more 

 Experiments and Obfervations : And it 

 is with fatisfaSlion, that we fee them 

 more and more confrtmd to us, by every 

 far 't her inquiry we make, as the follow- 

 ing Experiments will plainly prove, by 



Jhewing 



