﻿418 
  Dr. 
  Hodgson 
  and 
  Mr. 
  Mainstone 
  on 
  Heating 
  

  

  so 
  that 
  the 
  palladium 
  wire 
  was 
  in 
  contact 
  with 
  both 
  the 
  

   space 
  of 
  the 
  vessel 
  A 
  and 
  that 
  of 
  the 
  vacuum-tube. 
  The 
  

   wire 
  was 
  surrounded 
  by 
  a 
  platinoid 
  spiral 
  that 
  could 
  be 
  

   heated 
  to 
  redness 
  by 
  means 
  of 
  an 
  electric 
  current. 
  When 
  

   the 
  palladium 
  became 
  sufficiently 
  hot, 
  pure 
  hydrogen 
  was 
  

   absorbed 
  and 
  diffused 
  through 
  the 
  wire 
  into 
  the 
  vacuum- 
  

   tube. 
  

  

  Nitrogen 
  was 
  prepared 
  by 
  heating 
  crystals 
  of 
  ammonium 
  

   dichromate 
  in 
  tubes 
  sealed 
  on 
  to 
  the 
  apparatus. 
  The 
  sub- 
  

   stance 
  breaks 
  up 
  violently 
  in 
  a 
  vacuum, 
  and 
  it 
  is 
  necessary 
  

   to 
  seal 
  on 
  many 
  tubes, 
  each 
  containing 
  a 
  small 
  piece 
  of 
  the 
  

   substance, 
  if 
  one 
  wishes 
  to 
  avoid 
  an 
  explosive 
  evolution 
  of 
  gas. 
  

   On 
  passing 
  the 
  discharge 
  gases 
  are 
  evolved 
  from 
  the 
  elec- 
  

   trodes, 
  and 
  impurities 
  so 
  introduced 
  can 
  make 
  enormous 
  

   differences 
  in 
  the 
  cathode 
  fall. 
  When 
  this 
  occurs 
  it 
  is 
  

   necessary 
  to 
  wash 
  out 
  the 
  apparatus 
  again 
  and 
  refill 
  with 
  

   pure 
  gas, 
  repeating 
  these 
  processes 
  till 
  the 
  evolution 
  of 
  gases- 
  

   ceases. 
  

  

  § 
  7. 
  Results 
  in 
  Oxygen 
  and 
  Hydrogen. 
  

   The 
  following 
  results 
  were 
  obtained 
  : 
  — 
  

  

  Metal— 
  lead. 
  

  

  Gas 
  — 
  oxygen, 
  pr 
  = 
  3*03 
  mm. 
  

  

  i 
  = 
  0-00194 
  amp. 
  

  

  V*= 
  370 
  volts. 
  

  

  6 
  = 
  cathode 
  temperature 
  = 
  63 
  0, 
  4 
  CL 
  

  

  A 
  = 
  air 
  „ 
  =15°-9C. 
  

  

  dd 
  4-67 
  ro 
  n 
  , 
  

  

  2--- 
  gj-C 
  C. 
  per 
  sec). 
  

  

  M 
  = 
  2-20. 
  

  

  M 
  ~ 
  = 
  2-20 
  x 
  ^ 
  x 
  4-18 
  x 
  10 
  7 
  ergs. 
  

   at 
  bi) 
  

  

  = 
  7-15 
  x 
  10 
  6 
  ergs. 
  

  

  iY 
  = 
  0-00194 
  x 
  370 
  (amp. 
  volts). 
  

  

  = 
  7-18 
  xlO 
  6 
  ergs. 
  

  

  et//3 
  = 
  0-995. 
  

  

  The 
  other 
  results 
  are 
  given 
  in 
  brief. 
  

  

  * 
  The 
  values 
  of 
  the 
  cathode 
  fall 
  in 
  oxygen 
  are 
  taken 
  from 
  Thomson's. 
  

   ' 
  Conduction 
  through 
  Gases,' 
  2nd 
  edition, 
  p. 
  560. 
  For 
  other 
  gases 
  the 
  

   values 
  are 
  taken 
  from 
  the 
  following 
  paper, 
  Rottgardt, 
  Ann. 
  d. 
  Phys. 
  

   xxxiii. 
  p. 
  1161 
  (1911). 
  

  

  