﻿Inversion 
  Temperature 
  of 
  Kelvin 
  Effect 
  in 
  Hydrogen. 
  537 
  

  

  where 
  a. 
  and 
  /3, 
  calculated 
  from 
  the 
  experimental 
  data 
  of 
  Joule 
  

   and 
  Kelvin, 
  amounted 
  to 
  64*1 
  and 
  0*331 
  respectively 
  for 
  

   hydrogen. 
  Assuming 
  that 
  there 
  is 
  no 
  cooling, 
  we 
  obviously 
  

   get 
  by 
  means 
  of 
  the 
  above 
  formula 
  the 
  temperature 
  of 
  

   inversion, 
  which 
  in 
  this 
  case 
  amounts 
  to 
  193°* 
  7 
  on 
  the 
  absolute 
  

   scale, 
  i.e. 
  to- 
  79°-3 
  0. 
  

  

  In 
  view 
  of 
  the 
  considerable 
  difference 
  between 
  the 
  values 
  

   obtained 
  by 
  the 
  above 
  two 
  methods, 
  an 
  experimental 
  deter- 
  

   mination 
  of 
  this 
  temperature 
  appeared 
  desirable. 
  

  

  Description 
  of 
  the 
  Apparatus. 
  

  

  The 
  hydrogen 
  used 
  in 
  these 
  experiments 
  was 
  prepared 
  by 
  

   acting 
  on 
  commercial 
  zinc 
  with 
  pure 
  dilute 
  sulphuric 
  acid. 
  

   In 
  order 
  to 
  purify 
  the 
  gas, 
  it 
  was 
  led 
  through 
  wash-bottles 
  

   containing 
  solutions 
  of 
  caustic 
  soda 
  and 
  potassium 
  perman- 
  

   ganate, 
  and 
  lastly 
  through 
  a 
  vessel 
  filled 
  with 
  pieces 
  of 
  

   pumice-stone 
  soaked 
  in 
  mercuric 
  chloride. 
  The 
  gas 
  was 
  

   collected 
  in 
  a 
  large 
  zinc 
  gasometer 
  of 
  1200 
  litres 
  capacity,, 
  

   and 
  finally 
  compressed, 
  by 
  means 
  of 
  a 
  Whitehead 
  compressor, 
  

   into 
  a 
  steel 
  cylinder 
  of 
  13 
  litres 
  capacity 
  under 
  a 
  pressure 
  of 
  

   about 
  180 
  atmospheres. 
  In 
  the 
  interior 
  of 
  this 
  cylinder 
  was 
  

   placed 
  a 
  long 
  tube 
  constructed 
  of 
  wire 
  netting 
  and 
  filled 
  with 
  

   sticks 
  of 
  caustic 
  potash. 
  

  

  In 
  preparing 
  and 
  compressing 
  the 
  hydrogen, 
  care 
  was 
  taken 
  

   to 
  remove 
  the 
  air 
  from 
  all 
  parts 
  of 
  the 
  apparatus. 
  The 
  

   hydrogen 
  could 
  therefore 
  be 
  regarded 
  as 
  pure, 
  in 
  so 
  far 
  as 
  

   it 
  was 
  possible, 
  in 
  working 
  on 
  a 
  large 
  scale, 
  to 
  avoid 
  its 
  con- 
  

   tamination 
  with 
  small 
  traces 
  of 
  air. 
  

  

  The 
  essential 
  part 
  of 
  the 
  apparatus 
  is 
  shown 
  in 
  the 
  figure 
  

   (p. 
  538). 
  

  

  The 
  steel 
  cylinder 
  containing 
  the 
  hydrogen 
  under 
  high 
  

   pressure 
  is 
  connected, 
  by 
  means 
  of 
  a 
  copper 
  tube, 
  to 
  a 
  metallic 
  

   manometer, 
  and 
  also 
  to 
  the 
  copper 
  tube 
  a, 
  the 
  continuation 
  of 
  

   which 
  is 
  coiled 
  to 
  form 
  a 
  worm 
  b, 
  and 
  is 
  closed 
  by 
  a 
  valve 
  c. 
  

   This 
  valve 
  is 
  secured 
  to 
  the 
  cover 
  nnby 
  means 
  of 
  an 
  asbestos- 
  

   packed 
  stuffing-box 
  and 
  gland 
  o. 
  By 
  means 
  of 
  the 
  hand- 
  

   wheel 
  d 
  the 
  valve 
  may 
  be 
  opened, 
  when 
  the 
  hydrogen 
  escapes 
  

   into 
  the 
  box7a/>, 
  which 
  is 
  made 
  of 
  sheet 
  brass 
  and 
  stuffed 
  

   with 
  chamois 
  leather, 
  and 
  expands 
  to 
  atmospheric 
  pressure, 
  

   escaping 
  through 
  the 
  pipe 
  pi. 
  In 
  the 
  same 
  box 
  is 
  contained 
  

   a 
  resistance-thermometer 
  e, 
  a 
  full 
  description 
  of 
  which 
  is 
  given 
  

   in 
  my 
  paper 
  on 
  the 
  determination 
  of 
  the 
  critical 
  temperature 
  

   and 
  the 
  boiling-point 
  of 
  hydrogen 
  *. 
  The 
  terminals 
  / 
  and 
  g 
  

   serve 
  to 
  connect 
  the 
  thermometer 
  with 
  the 
  Wheatstone's 
  

  

  * 
  Hozpraicy 
  of 
  the 
  Cracow 
  Academy, 
  xxix. 
  p. 
  104 
  (1895) 
  ; 
  also 
  PhiL 
  

   Mag. 
  [5] 
  xl. 
  p. 
  202 
  (1895). 
  

  

  