﻿814 
  Prof. 
  E. 
  Rutherford 
  and 
  Mr. 
  T. 
  Royds 
  on 
  the 
  

  

  and 
  of 
  diameter 
  1 
  mm., 
  provided 
  with 
  thin 
  platinum 
  electrodes. 
  

   A 
  tube 
  H 
  containing 
  a 
  small 
  quantity 
  of 
  coconut 
  charcoal 
  

   was 
  attached 
  to 
  the 
  side 
  tube 
  through 
  a 
  stopcock 
  L. 
  Before 
  

   the 
  experiment 
  the 
  charcoal 
  tube 
  was 
  thoroughly 
  heated 
  and 
  

  

  TO 
  PUMP 
  

  

  exhausted. 
  On 
  surrounding 
  the 
  tube 
  H 
  by 
  liquid 
  air, 
  all 
  the 
  

   gases 
  present 
  in 
  the 
  air 
  except 
  neon 
  and 
  helium 
  were 
  absorbed. 
  

   The 
  stopcock 
  L 
  was 
  then 
  closed, 
  and 
  by 
  raising 
  the 
  mercury 
  

   reservoir 
  the 
  gases 
  remaining 
  in 
  E 
  were 
  compressed 
  into 
  the 
  

   vacuum-tube. 
  On 
  passing 
  a 
  discharge, 
  the 
  hydrogen 
  and 
  

   mercury 
  lines 
  were 
  usually 
  prominent, 
  the 
  former 
  probably 
  

   due 
  to 
  a 
  trace 
  of 
  water 
  vapour 
  present. 
  A 
  pad 
  of 
  cotton- 
  

   wool 
  was 
  then 
  wrapped 
  round 
  the 
  spectrum-tube 
  just^ 
  above 
  

   the 
  level 
  of 
  the 
  mercury 
  and 
  was 
  soaked 
  with 
  liquid 
  air. 
  

  

  