﻿462 
  On 
  Electrical 
  Discharges 
  through 
  Rarefied 
  Gases. 
  [June 
  10, 
  

  

  as 
  a 
  metallic 
  conductor, 
  and 
  a 
  current 
  flowing 
  between 
  the 
  terminals 
  

   will 
  undergo 
  the 
  resistance 
  due 
  to 
  the 
  acid 
  in 
  the 
  upper 
  part 
  of 
  the 
  

   spiral. 
  

  

  Kg. 
  3. 
  

  

  Attached 
  to 
  the 
  same 
  stand 
  is 
  a 
  coarse 
  resistance-tube, 
  adapted 
  also 
  

   to 
  currents 
  of 
  high 
  tension, 
  such 
  as 
  a 
  3- 
  or 
  4-inch 
  spark 
  from 
  an 
  induc- 
  

   tion-coil. 
  It 
  consists 
  of 
  a 
  tube, 
  S, 
  of 
  about 
  4 
  millims. 
  diameter, 
  termi- 
  

   nating 
  at 
  its 
  upper 
  end 
  in 
  a 
  funnel-shaped 
  bulb, 
  J, 
  and 
  haying 
  a 
  platinum 
  

   wire 
  fused 
  into 
  its 
  lower 
  end. 
  This 
  tube 
  is 
  filled 
  to 
  E 
  with 
  a 
  mixture 
  of 
  

   glycerine 
  and 
  water, 
  in 
  the 
  proportions 
  of 
  6 
  to 
  1. 
  L 
  is 
  a 
  long 
  steel 
  rod, 
  

   extending 
  from 
  the 
  clip 
  M 
  to 
  the 
  bottom 
  of 
  the 
  tube, 
  and 
  capable 
  of 
  sliding 
  

   up 
  and 
  down 
  ; 
  its 
  lower 
  half 
  is 
  coated 
  with 
  a 
  very 
  small 
  glass 
  tube, 
  K 
  K, 
  so 
  

   that 
  its 
  extremity 
  alone 
  is 
  exposed 
  to 
  the 
  contact 
  of 
  the 
  fluid. 
  If 
  the 
  steel 
  

   rod 
  L 
  be 
  in 
  the 
  position 
  shown 
  in 
  the 
  diagram, 
  no 
  resistance 
  will 
  be 
  offered 
  

   to 
  a 
  current 
  passing 
  through 
  the 
  system 
  ; 
  but 
  if 
  it 
  be 
  raised, 
  the 
  resistance 
  

   offered 
  will 
  be 
  in 
  proportion 
  to 
  the 
  length 
  of 
  column 
  of 
  resistiDg 
  fluid 
  

   through 
  which 
  it 
  has 
  to 
  pass. 
  

  

  