r ) 
Spirit refides in the Acid fpiric of Niter,he thence infers, that 
that Nitro-aerial fpiric is of a Nitro-falin narure^obtaining ra- 
ther the natureofan Acidxh^xi Fix'dSdXt ; confideringairojthat 
the EfFefts of Fire anfwer to a very fubti'e and corrofive Salt. 
Thefe things being thus by our Author prefuppos'd, he def- 
cends to the Explication of the Nature of F/Vd', and makes its 
Form and Effence principally to depend from thefaid Nitro- 
aerial fpirit put into motion; reje6ing the opinion of thore,thac 
will have Fire producible by the fubtile and briskly mov'd 
parts of ^/y' matter, and declaring on this occafion his dilTenc 
from thofe Philofophers,that deduce all EfFefls of Nature from 
the fame Uniform Matter,and the various Modifications (here- 
of which he thinks inconfiftent with 
the rh^„on>em of Fire,not at a'l, w his y^IS^/ X'^l't 
cfimon^pxoducWAQ but by a certain de- V>oy\e about the Excellency 
terminat kind of particles, fuch as he ^P^ Grounds of the Mecha- 
Cal Is A//riJ'^W^/« This he endeavors to London this pnfcnt year 
prove by divers Experiments. ^^74- 
Having done with the Aerial of the Spirit of Nicer, he 
proceeds to Its Terr ejlr ial znci Jcid part, and labors to lleiv, 
How the Spirit of Niter is produced in the Earth, For [he 
better under/landing whereof, he premifes fomething concern- 
ing the ^firit of 'Sulphur and other Aad liquors ^ teaching, that 
that Spirit does not exiftin Sulphur before deflagration or rhe 
operation of the fire 5 and affirming, that, ^the Nitro-aerial 
fpirit of theFire,by a very brisk motion and effervefcence con» 
tending with and ading upon tht Sali^7o-fulphureous particles, 
does in a very fliort time comminure and render fluid the f alin 
parts included in the Sulphureous 5 the fame Spirir,boy]irg 
up by a more remifs motion with the fam.e Salino-fulphureoiis 
parts, doth in a longer time turn the Salin parts into an Jcid li- 
quor. Where he takes occafion to difcourfe, How Liquors in 
genera! become ^ri^ by the operation of the Nicro-aerial Spi- 
rit ; asalfo,Wherein Fermentation confifts,viz. Jn the effervef- 
cence of the Nitro-aerial pariicles with the Salino-fulphureous 
ones of the liquor* 
Thisbeinf^ explain'd,he thinks ic nor difficult to underftand. 
Ho the Ac^d fpirit oi Niter is generated in the Earth ; decla- 
ring^ 
