25 o Analyfis of the Air. 
faft, and confequently the veficles will fall 
flat, notwithftanding the endeavours of the 
extending Thorax to dilate them as ufual ; 
whereby the motion of the blood through 
the lungs being flopped, inftant! death en~ 
fues. 
Which fudden and fatal effeft of thefe 
noxious vapours, has hitherto been fuppofed 
to be wholly owing to the lofs and wafte of 
the vivifying Jpirit of air $ but may not 
unreafonably be alfo attributed to the lofs 
of a confiderable part of the air’s elafticity, 
and the groffnefs and denfity of the vapours, 
which the air is charged with; for mutu- 
ally attra£ling particles, when floating in fo 
thin a medium as the air, will readily coa- 
lefce into grofier combinations : "Which ef- 
fect of thefe vapours, having not been duly 
obferved before, it was concluded, that 
they did not affeft the airs elafticityj 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 dccreafes faft in its elafticity, 
I was affured by the Experiment I made on 
ipy felf, in Exper. 19 3 . for when toward^ 
the 
