CHAPTER  VI

HIGH-POTENTIAL    CURRENTS    WITH   VACUUM   TUBES

Vacuum  tubes  employed  in  connection  with  high-poten-
tial currents  were  first  constructed  of  the  Geissler  type,
having  a  wire  passed  from  without  to  the  interior  of  the
tube.  A  later  type  which  serves  the  same  purpose  is  the
plain  vacuum  tube  without  any  metallic  connection  with
the  interior.  Both  types  of  tubes  are  made  in  various
forms  suited  to  the  treatment  of  special  conditions,  and
also  having  various  degrees  of  vacuum.  They  may  be
employed  with  any  high-potential  apparatus  provided
with  an  interrupter,  and  do  not  necessarily  require  that
the  discharges  be  of  high  frequency.  The  term  so  often
employed  of  '^  high-frequency  vacuum  tubes  "  is  there-
fore technically  a  misnomer.  While  it  is  necessary  that
there  be  interruptions  somewhere  in  the  circuit  of  a
current  of  high  potential  to  produce  these  effects,  high
frequency  is  not  essential.  The  term  which  should  be
employed  in  therapeutics  with  reference  to  these  tubes
should  therefore  be  high-potential  vacuum  tithes  if  re-
ferred to  therapeutics,  or  vacuum  tubes  for  use  in  con-
nection with  high-potential  currents.  The  tendency  for
terms  to  creep  into  medical  literature  which  are  unau-
thorized and  unscientific,  and  which  call  for  corrections
and  establishment  later  of  a  different  nomenclature,  has
led  to  much  confusion  in  the  past.
