Arialyfis of the Air. 273 
them : And therefore the Candle and Matches 
ceafing to burn, foon after they are confined 
in a fmalf quantity of air, feems not to be 
owing to their having rendred that air effete^ 
by having confumed its vivifying ffiriti but 
fliould rather be owing to the great quantity 
of acid fuliginous vapours, with which that 
air is charged, which deftroy a good deal of 
its elafticity, and very much clog and retard 
the elaftick motion of the remainder. 
And the effed the half exhaufting of a 
receiver has upon the elafticity of the re- 
maining half of the air, feems to be the rea- 
fon why the flame of a Candle does not 
continue burning, till it has filled the recei- 
ver it ftands in with fumes, but goes out 
the quicker, the fooner the air is drawn out 
to that degree j which feems therefore to be 
owing to this, that an air rarified to double 
its fpace, will not expand fo briskly with 
the warmth of flame, as a more condenfed 
air will do : And confequently adion and 
re-adion being reciprocal, will not give fo 
brisk a motion to the flame, which fubfifts 
fj by a conftant fucceflSon of frefli air, to fup- 
j ply the place of the either abforbed, or much 
1 dilated air, which is continually flying off. 
