Anatyfis of the Air. i6j 



which I made by means of thefe inftru- 

 ments, which I have here at firft defcribed, 

 to avoid the frequent repetition of a defcrip- 

 tion of 'em. It is confonant to the right 

 method of philofophifing, firft, to analize 

 the fubjeft, whofe nature and properties we 

 intend to make any refearches into, by a 

 regular and numerous feries of Experiments : 

 And then by laying the event of thofe Ex- 

 periments before us in one view, thereby to 

 fee what light their united and concurring 

 evidence will give us. How rational this 

 method is, the fequel of thefe Experiments 

 will fhew. 



The illuftrious Sir Ifaac Newton ( query 

 31ft of his Opticks) obferves, that " true 

 lc permanent Air arifes by fermentation or 

 " heat, from thofe bodies which the chy- 

 " mifts call fixed, whofe particles adhere by 

 <c a ftrong attradion, and are not therefore 

 " feparated and rarified without fermenta- 

 *< tion. Thofe particles receding from one 

 p another with the greateft repulfive force, 

 iC and being moft difficultly brought toge- 

 " ther, which upon contact were moft ftrong- 

 " ly united. And query 30. denfe bodies by 

 cc fermentation rarify into feveral forts of 

 M 3 " Air, 



