30 8 Papers  relative  to  an  Accident 
Every  charge,  from  the  nature  of  the  fluid  which  pro- 
duces it,  muft,  while  fuch  charge  remains,  continually 
aft  upon  the  air  furrounding  it;  and  of  confequence 
upon  the  fluid  alfo,  which  Hands  diffufed  therein,  and  in 
the  intervals  between  its  parts  by  its  repulfive  principle. 
This  appears  to  be  true,  not  only  from  theory  but  expe- 
riment. 
The  ftate  of  the  fluid  in  the  air  neareft  to  the  cylinder 
that  is  charged,  muft  therefore  be  in  an  oppofite  ftate  to 
that  which  is  in  the  cylinder ; that  is,  in  the  one  cafe  it 
will  be  condenfed,  and  in  the  other  ratified. 
Now,  becaufe  the  power  arifing  from  the  charge 
within  the  cylinder,  which  caufed  the  rarefaction  beyond 
its  outward  furface,  is  limited;  the  diftance  to  which 
that  rarefaction  extends, muft  be  limited  alfo : and  beyond 
that  diftance  the  fluid  muft  be  condenfed  more  or  lefs, 
according  to  the  power  of  the  charge  which  caufed  the 
rarefaction. 
Whenever  therefore  we  are  difpofed  to  open  a door  to. 
let  the  charge  out  of  the  cylinder,  the  rarified  fluid  near 
the  outficle  of  the  cylinder  muft  neceflarily  promote  the 
difcharge  at  that  inftant. 
As  to  the  diftance  to  which  this  rarefaction  extends,  it 
will  always  depend  upon  the  ftrength  of  the  charge,  and 
the 
