Early Dewlopement of the Theory of Comhuftion. 499 



eacK of thefe bodies are, I fhall not here examine, intending it in another place, but Qiall 

 rather add, that this hypothefis does fo cxa6lly agree with all phenomena of fire, and fo 

 genuinely explicate each particular circumftance that I have hitherto obferved, that it is 

 more than probable that this caufe which I have affigned is the true, adequate, real, and 

 only caufe of thefe phenomena; and therefore I fhall proceed a little further to fliew the 

 nature and ufe of the air. 



Tenthly, therefore the dilTolvIng parts of the air are but few that is, it fecms, of the nature 

 of thokfaliiie meiijlruums or fplrits that have very much phlegm mixed with the fpirits, and 

 therefore a ftaall parcel of it is quickly glutted, and will diflblve no more, and therefore 

 unlefs fome frefh part of this menftruum be applied to the body to be diflblved, the a£lion 

 ceafes, and the body leaves to be diflblved and to fhine, which is the indication of it, though 

 placed or kept in the greateft heat ; whcrezs falipeire is a meiijirutim, when melted and red hot, 

 that abounds more with thofe diflblvent particles, and therefore as a fmall quantity of it will 

 diflblve a great fulphureous body, fo will the difl"olution be very quick and violent. 



Therefore, in the eleventh place, it is obfervable that, as in other folutions, if a copious 

 and quick fupply of frefli menftruum, though but weak, be poured on, and applied to the 

 diflbluble body, it quickly confumes it ; fo this menjlrimtn of the air if by bellows, or any 

 other fuch contrivance, it be copioufly applied to the fliining body, is found to diflTolve it as 

 foon and as violently as the more ftrong menftruum of melted nitre. 



Therefore, twelfthly, it fcems reafonable to think that there is no fuch thing as an ele- 

 ment of fire that Ihould attradl or draw up the flame, or towards which the flame fhould 

 endeavour to afcend out of a defire or appetite of uniting with that as its homogeneal primi- 

 tive, and generating element ; but that the {hining tranfient body which we call flame it 

 nothing elfe but a mixture of air and volatile fulphureous parts of diflbluble or combuftiblc 

 bodies, which are ading upon each other whilft they afcend, that is, flame feems to be a 

 mixture of air and the combuftiblc volatile parts of any body, which parts the encompafling. 

 air does diflblve or work upon, which aftion, as it does intend the heat of the aerial parts 

 of the difi"olvent, fo does it thereby further rarify thofe parts that are afting, or that are very 

 near them, whereby they growing much lighter than the heavy parts of that menftruum . 

 that arc more remote, arc thereby protruded and driven upwards ; and this may be 

 eafily obferved alfo in diflblutions made by any other menfruum, efpecially fuch as either 

 create heat or bubbles. Now this adlion of the menjlruum or air on the diflbluble parts is 

 made with fuch violence, or is fuch that it imparts fuch a motion or pulfe to the diaphanous 

 parts of the air, as I have elfewhere fliewn is requifite to produce light. 



This hypothefis I have endeavoured to raife from an infinite of obfervations and ex- 

 periments, the proccfs of which would be much too long to be here inferted, and will per- 

 haps another time afibrd matter copious enough for a much larger difcourfe ; the air being 

 a fubjeft which (though all the world has hitherto lived and breathed in, and been uncon- 

 verfant about) has yet been fo little truly examined or explained, that a diligent enquirer 

 will be able to find but very little information from what has been (till of latej written of 

 it} but being once well underftood, it will, I doubt not, enable a man to render an 

 4 intelligible, 



