i $4 A Treatifi of B O D I E S. Cfap. 1 7. 



of thernfelvcs fet on fire : and the like vv'ill happen to coach- 

 wheels in the iiimmer if they be overheated with motion. 

 2. To conclude our difcourfe of rarcht&ion,we may look a little 



or therrat into the power and erficacity of ic, which is no where to be teen 

 faction? **''*' * c ^ ear ^y as m ^ re - And as fire is the generall caufe of rarefa- 

 clion, fo is it of all bodies that which is moft ratified. Ami 

 therefore it is no marvail if its effects be the greateft thac are in 

 nau:ic, feeing it is the proper operation of the moil ailive Ele- 

 ment. The wonderful! force of it we dayly fee in thunder, in 

 guns, in granado's, and in mines; of which, continuall experi- 

 ence, as.well as feverail hirtorics witnefleth little lefle then mi- 

 racles. Leaving them ro the remarks of curious perfons, \ve will 

 onely loo'< inco the way by which lo main effects do proceed 

 from caufes that appear fo (lender. 



It is evident that fire (as we have faid before ) dilatcth ic 

 fclf fphcrically; as nature fhewcth us manifefily in bubbles of 

 boyliog water, and of milk, and generally of inch fubttances as 

 are of a vifcuous compofition; for thole bubbles being rounci,do 

 aflure us that the ciule which made them, did equally dilate 

 them from the center unto all parts. Now then rcmembring the 

 infinite multiplication which is in fire, we may conceive that 

 when a grain of gun-powder is turned thereinto, there Ire fo 

 many little bubbles of a vifcuous fubftance one backing ano- 

 ther with great celerity , as there arc parts of fire more then 

 there uere of gun-powder. And if we make a computation of 

 the number and of the celerity of thele bubbles, we fliall find 

 that although every one of them (ingle do fccm to be of an in- 

 conficierable force, yet the whole number of them together, will 

 exceed the refinance of the body moved or broken by them: e* 

 fpccially* if vve note, that when hard fubttances have not time 

 allowed them to yickhthcy break the fboner. And then we lliall 

 not fo much admire the extremities we fccadrcd by thcfc meins. 

 Thus hating looked into the nature of rarefaction, and traced 

 The firitman. ^ 1C prcgrcffc of it from the motion -of the fun & fiicjin the next 

 nerofconien- place we arc to examine t!;c nature of condcnfacion. And we 

 ' fliall ofcentiir.es find it likcvvifean effeclofthe iiinccauie other- 

 wife working: for there being two different vvaycs to dry any 

 \\ctthinp; the one, by taking away that juyce which makcrh a 

 body liquid; the ether,. by putting more drought to the wet bo- 

 dy, 



