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PRODUCTION  OF  LOCAL  ANAESTHESIA,  ETC. 
tube,  and  which  has  been  so  extensively  applied  as  a  parlor 
curiosity  for  perfuming  the  atmosphere.  This  consists  of  two 
glass  tubes  with  capillary  extremities,  so  connected  together 
that  one  is  vertical  and  the  other  horizontal,  their  orifices  being 
so  arranged  in  position  that  a  current  of  air  blown  through  the 
horizontal  tube  passes  across  the  extremity  of  the  vertical  tube, 
and  causes  an  upward  current  by  suction.  If  now  the  inferior 
end  of  the  vertical  tube  be  placed  in  a  vial  containing  an  odor- 
ous fluid,  and  a  strong  current  of  air  be  blown  through  the 
horizontal  tube,  the  air  is  drawn  out  of  the  former,  which  causes 
the  fluid  to  rise  to  the  orifice  and,  under  the  influence  of  the 
current  of  air,  to  be  converted  into  an  exceedingly  fine  spray  or 
mist,  which  readily  mingles  with  the  air  and  odorizes  it.  Various 
other  forms  of  apparatus,  involving  the  principal  of  the  Bergson 
tube,  have  been  suggested,  among  which  is  that  of  Dr.  Siegle,  in 
which  a  current  of  steam,  at  a  regulated  temperature  and  pres- 
sure, takes  the  place  of  air  ;  and  that  of  Dr.  Andrew  Clark,  of 
London,  who  uses  a  gum-elastic  tube,  attached  to  the  horizontal 
tube  of  Bergson's  apparatus,  and  containing  two  hollow  gum- 
elastic  balls,  one  of  which  acts  as  a  reservoir  for  air,  and  is  sur- 
rounded by  netting  to  prevent  its  expansion  beyond  a  certain 
degree ;  the  other  ball  is  constructed  like  the  ordinary  gum 
syringe  ball,  with  two  valves,  so  that  simple  compression  and 
release  will  force  a  current  of  air  into  the  upper  ball,  from  which 
it  gradually  escapes  with  a  force  proportioned  to  the  condensa- 
tion of  the  air.  By  means  of  these  instruments  a  current  of 
spray  or  "  pulverized  fluid  "  may  be  directed  against  any  part  of 
the  body  requiring  this  form  of  medication,  with  the  greatest 
ease,  especially  to  the  eyes,  ears,  gums,  etc.  It  has  long  been 
well  known  that  rapid  evaporation  produces  a  reduction  of  tem- 
perature, and  the  cold  produced  by  the  action  of  the  Bergson 
tube  was  soon  observed.  Dr.  Richardson,  in  searching  for  a 
means  of  applying  cold,  saw  the  applicability  of  this  principle 
to  his  purposes,  and  devised  the  following  arrangement,  whereby 
ether  and  other  volatile  fluids  may  be  rapidly  vaporized  and 
directed  to  any  desirable  point.  It  consists  of  a  graduated  bottle 
for  holding  the  ether;  in  the  mouth  of  this,and  passing  through 
a  good  cork,  is  a  double  glass  tube,  so  arranged  that  the  inner 
