Majoiv antiapalcd by Hooh. 373 



the air, or take fire and burn; but a part alio which is fixt, 

 ierreftrial and irrarifiabie, 



« Ninthly, that as there are thefe fcveral parts that will 

 rarifie and fly, or be driven up by the heat, fo are there 

 many others, that as they are indiffoluble by the aerial men- 

 ftruum, fo are they of fuch fluggiih and grofs parts, that 

 they are not eafily rarified by heat, and therefore cannot be 

 raifed by it ; the volatility or fixtnefs of a body feeming to 

 confift only in this, that the one is of a texture, or has com- 

 ponent parts that will be eafily rarified into the form of air; 

 and the other, that it has fuch as will not, without much 

 ado, be brought to fuch a conftitution ; and this is that part 

 which remains behind in a white body called afhes, which 

 contains a fubftance, or fait, which chymifis call alkali: 

 what the particular natures of each of thefc bodies are, I 

 {hall not here examine, intending it in another place; but 

 fliall rather add, that this hypothefis docs fo exactly agree 

 with all phenomena of fire, and fo genuinely explicate each 

 particular circumftance that I have hitherto obferved, that if. 

 is more than probable, that this caufe which I have afiigncd 

 is the true, adequate, real, and only caufe of thefe phceno- 

 mena; and therefore I fliall proceed a little further, to fhew 

 the nature and ufe of the air. 



" Tcnthly, therefore the diffolving parts of the air are but 

 few, that is, it fecms of the nature of thofe°faline men- 

 ftruums or fpirits that have very much flegme mixt with 

 the fpirits, and therefore a fmall parcel of it is quickly 

 glutted, and will diffolve no more; and therefore, unlefs 

 fome frefh part of this menftruum be applied to the body to 

 be difiblved, the action ccafes, and the body leaves to be 

 diffolved and to thine, which is the indication of it, though 

 placed or kept in the grcatelt heat ; whereas faltpctcr js a 

 ineufiruum, when melted and red-hot, that abounds more 

 with thofe diflblvepl particles, and therefore, as a fmall quan- 

 tity <>f it will diflblvfi a great fwlr.hureeus body, fo will the 

 difl'olutiou be Very ^Uick and violent. 



B b 3 " There- 



