(106) 
from rigid become flexile,and confequently loofe their Spring. 
Here he takes occafion to deliver his thoughts again of the 
Nature of F/>^, which fecms to him to be nothing elfe, than a 
Congeries of very minute fparks copioufly ftruck out of the Ae- 
rial parts by the allifion of the fulphureous ones 5 efteeming the 
Aerial parts folid and rigid enough, to have fire ftruck out of 
them. 
This done,he further declaresjthat the Nicro-aerial particles, 
from which,/« his opinion^ the Spring of the Air proceeds, are 
lodged in the very parts of the Air, and carried away from it 
by the Burning of a Candle ,or the Refpiration of Animals, fo 
that, tohim^ thofc Nitro-aerialand Elaftique parts, that come 
to fail,arc not the Air it felf,but the fubtileft and the mod: afiive 
part thereof, which being expelled by burning or refpiration, 
the Air becomes effete,and deftitute of its Spring. 
Moreover, he confiders,How the Air, when deprived of its 
Nitro-aerial parts,is afrefh fupplied with them ? Likewife, he 
takes occafion to declare his opinion, firft,of the nature of the 
Sun^ viz. That it feems to be nothing elfe than a vafl: Chm of 
Nitro-aerial corpufcles, wheeled about by a perpetual and ve- 
ry fwifc rotation 5 fecondly, of the Nature of Cold^ that it is 
fomcthingP^»/Jir/x'f,confifl:ing in this,tbat the Nitro-aerial parts, 
which being vehemently mov'd conftitute the Body of the Sun, 
do, when removed from the Sun into the Midle region of the 
Air,ceafe from that motion of Circumgiration, and either total- 
ly ceafe,or move on funStim like fo many briftles or darts. 
Further,he obferves,that fince the parts of the Air being de- 
prived of the Nitro-aerial Spirit are raifed upward, and being 
there impregnated afrefii,return thence downward again^there- 
fore the Air, being the Blood as 'twere of the ^acmofm, is 
in a continual Circulation,and doth it felf,forafmuch as in cir- 
culating it takes in the Nitro-aerial Spirit, exercifea kind of 
Refpiration. 
Hereupon he proceeds to explainjn what manner theNitro- 
aerial Spirit is breathed in by Animals^ and how it comes to 
loofe in them its Elaftique power ; and of what ufe it is being 
infpired : where he teachctb, that thofe Nitro-aerial partsare 
in Animals as well as in Vegetables the principal Inftrument of 
