﻿Resistance 
  of 
  Gases 
  fairing 
  an 
  Oscillatory 
  Discharge. 
  331 
  

  

  much 
  too 
  long 
  to 
  interfere 
  with 
  one 
  another 
  upon 
  so 
  short 
  a 
  

   circuit. 
  The 
  resistances 
  were 
  wires 
  of 
  manganin 
  0'2 
  mm 
  in 
  

   diameter, 
  stretched 
  on 
  both 
  sides 
  of 
  long 
  strips 
  of 
  thin 
  vulcan- 
  

   ite 
  plate, 
  the 
  idea 
  of 
  this 
  arrangement 
  being 
  to 
  eliminate 
  self- 
  

   induction 
  and 
  yet 
  to 
  prevent 
  the 
  short-circuiting 
  of 
  the 
  high 
  

   potential. 
  The 
  spark 
  gap 
  usually 
  consisted 
  of 
  cadmium 
  ter- 
  

   minals 
  arranged 
  in 
  the 
  focus 
  of 
  a 
  revolving 
  mirror 
  driven 
  very 
  

   rapidly 
  by 
  means 
  of 
  a 
  small 
  electric 
  motor. 
  In 
  a 
  few 
  cases 
  

   zinc 
  terminals 
  were 
  used, 
  with 
  no 
  appreciable 
  difference 
  in 
  the 
  

   results 
  (Rhigi*). 
  The 
  terminals 
  were 
  re 
  pointed 
  from 
  time 
  to 
  

   time 
  and 
  were 
  always 
  kept 
  at 
  a 
  distance 
  of 
  1'3 
  millimeters 
  

   apart. 
  With 
  this 
  apparatus 
  the 
  photographs 
  of 
  perhaps 
  five 
  

   hundred 
  sparks 
  were 
  taken 
  ; 
  and 
  the 
  results 
  are 
  recorded 
  in 
  the 
  

   following 
  table. 
  As 
  a 
  general 
  rule 
  the 
  spark 
  containing 
  the 
  

   highest 
  number 
  of 
  oscillations 
  upon 
  any 
  plate 
  was 
  taken 
  as 
  the 
  

   representative 
  one. 
  

  

  The 
  first 
  column 
  below 
  records 
  the 
  resistance 
  through 
  which 
  

   the 
  discharge 
  had 
  to 
  pass 
  before 
  reaching 
  the 
  spark 
  gap, 
  while 
  

   the 
  second, 
  third 
  and 
  fourth 
  record 
  the 
  number 
  of 
  half 
  oscilla- 
  

   tions 
  observed 
  upon 
  the 
  photographs. 
  

  

  These 
  figures 
  correspond 
  in 
  general 
  tendency 
  with 
  the 
  less 
  

   precise 
  determinations 
  made 
  by 
  Feddersen 
  ;f 
  they 
  show, 
  as 
  his 
  

   determinations 
  did, 
  that 
  the 
  larger 
  the 
  capacity, 
  the 
  fewer 
  the 
  

   number 
  of 
  oscillations. 
  This 
  tendency 
  is 
  especially 
  noticeable 
  

   between 
  two 
  and 
  ten 
  ohms, 
  the 
  part 
  of 
  each 
  curve 
  which 
  is 
  

   most 
  capable 
  of 
  accurate 
  determination. 
  While 
  not 
  perfectly 
  

   regular, 
  these 
  curves 
  manifestly 
  furnish 
  the 
  means 
  of 
  measur- 
  

   ing 
  approximately 
  any 
  small 
  resistance 
  through 
  which 
  a 
  spark, 
  

   followed 
  by 
  as 
  much 
  as 
  one-half 
  of 
  an 
  oscillation, 
  is 
  able 
  to 
  

   pass. 
  

  

  Having 
  now 
  our 
  scale 
  of 
  measurement, 
  we 
  substituted 
  for 
  

   our 
  known 
  resistances 
  a 
  Pliicker 
  tube 
  attached 
  to 
  an 
  admir- 
  

   able 
  automatic 
  Toepler 
  air-pump 
  (of 
  Kiss, 
  Budapest), 
  as 
  well 
  

   as 
  to 
  receivers 
  containing 
  pure 
  hydrogen 
  and 
  nitrogen. 
  These 
  

   gases 
  could 
  be 
  delivered 
  individually 
  into 
  the 
  tube 
  at 
  any 
  

   desired 
  pressure. 
  The 
  bulbs 
  of 
  the 
  pump, 
  aggregating 
  over 
  a 
  

   liter 
  in 
  volume, 
  were 
  always 
  in 
  communication 
  with 
  the 
  

   Pliicker 
  tube, 
  while 
  the 
  circuit 
  was 
  closed, 
  so 
  that 
  the 
  discharge 
  

   took 
  place 
  under 
  essentially 
  constant 
  pressure. 
  The 
  hydrogen 
  

   was 
  made 
  electrolytically 
  and 
  purified 
  by 
  passing 
  through 
  a 
  

   solution 
  of 
  potash, 
  and 
  over 
  fused 
  potash 
  and 
  phosphoric 
  

   anhydride 
  ; 
  the 
  nitrogen 
  was 
  made 
  by 
  passing 
  ammonia 
  over 
  

   an 
  excess 
  of 
  heated 
  cupric 
  oxide, 
  through 
  much 
  water, 
  and 
  

   over 
  the 
  same 
  two 
  driers 
  as 
  the 
  hydrogen. 
  The 
  length 
  of 
  the 
  

   spark 
  gap 
  remained 
  always 
  the 
  same, 
  excepting 
  for 
  the 
  very 
  

   lowest 
  and 
  the 
  very 
  highest 
  pressures 
  of 
  gas, 
  through 
  which 
  

  

  * 
  Nuovo 
  Cimento, 
  II, 
  xvi, 
  97 
  . 
  f 
  Pogg. 
  Ann., 
  cxiii, 
  p. 
  437. 
  

  

  