Anahfis of the Air. 247 
Which fudden and fatal efFeft of thcfe 
noxious vapours, has hitherto been fuppofed 
to be wholly owing to the lofs and wafte of 
the 'vivifying fprit of air ; but may not 
unreafonably be alfo attributed to the lofs 
of a confiderable part of the air’s elafticity, 
and the groflnefs and denfity of the vapours, 
which the air is charged with ; for mutu- 
ally attrafting particles, when floating in fo 
thin a medium as the air, will readily coa- 
lefce into grofler combinations : Which 
efFcifl: of thefe vapours, having not been duly 
obferved before , it was concluded, that 
they did not afFcfl: the airs elafticity 5 and 
that confequently, the lungs muft needs be 
as much dilated in infpiration by this, as 
by a clear air. 
But that the lungs will not rife, and di- 
late as ufual, when they draw in fuch noxi- 
ous air, which decrcafes faft in its elafticity, 
I was aftured by the Experiment I made on 
my felf in Exper. 107. for when towards 
the latter end of the minute, the fufFocating 
quality of the air in the bladder was grea« 
feft, it was with much difficulty that I 
could dilate my lungs a very little. 
R 4 
Fron;i 
