2?6 Analyfis of the Air. 



And the effect; the half exhaufting of a 

 receiver has upon the elafticity of the remain- 

 ing half of the air, feems to be the reafon 

 why the flame of a Candle does not con- 

 tinue burning, till it has filled the receiver 

 it ftands in with fumes s but goes out the 

 quicker,, the fooner the air is drawn out to 

 that degree ; which feems therefore to be 

 owing to this, that an air rarefied to double 

 its fpace, will not expand fo briskly with the 

 warmth of flame, as a more condenfed air 

 will do : And confequently action and re- 

 action being reciprocal, will not give fo brisk 

 a motion to the flame, which fubfifts by a 

 eonftant fucceflion of frefh air, to fupply the 

 place of the either abforbed, or much dilated 

 air, which is continually flying off. And the 

 quicker the fucceflion of this frefh air is, by 

 blowing, the more vigorously does a fire 

 burn. 



If the continuance of the burning of the 

 Candle be wholly owing to the vivifying 

 jpirit^ then fuppofmg in the cafe of a re- 

 ceiver, capacious enough for a Candle to burn 

 a minute in it, that half the vivifying fpirit 

 be drawn out with half the air, in ten feconds 

 of time j then the Candle fhould not go out 

 at ihe end of thofe ten feconds, but burn 



twenty 



