﻿748 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  Specific 
  

  

  corresponded 
  to 
  a 
  forward 
  displacement 
  of 
  the 
  rod 
  of 
  

   •0635 
  cm. 
  It 
  is 
  to 
  be 
  understood 
  that 
  fig. 
  2 
  is 
  purely 
  

   diagrammatic 
  and 
  does 
  not 
  represent 
  the 
  proportionate 
  size 
  

   of 
  the 
  different 
  pieces 
  of 
  apparatus 
  indicated. 
  

  

  The 
  current 
  used 
  to 
  heat 
  the 
  strip 
  was 
  admitted 
  by 
  the 
  

   stout 
  platinum 
  wires 
  PP' 
  fused 
  into 
  the 
  tube 
  Q 
  x 
  . 
  These 
  

   dipped 
  into 
  mercury 
  cups 
  connected 
  to 
  the 
  leads 
  gg 
  previously 
  

   described. 
  The 
  current 
  was 
  supplied 
  by 
  the 
  storage-battery 
  

   L, 
  regulated 
  by 
  the 
  sliding 
  rheostat 
  M, 
  and 
  measured 
  by 
  the 
  

   ammeter 
  N. 
  The 
  whole 
  circuit 
  was 
  insulated 
  and 
  could 
  be 
  

   maintained 
  at 
  any 
  desired 
  static 
  potential 
  by 
  connecting 
  the 
  

   circuit 
  to 
  a 
  battery 
  not 
  shown, 
  the 
  other 
  terminal 
  of 
  which 
  was 
  

   connected 
  with 
  Q 
  2 
  . 
  The 
  potential 
  of 
  the 
  strip 
  and 
  plates 
  was 
  

   measured 
  by 
  a 
  voltmeter, 
  also 
  not 
  shown. 
  One 
  terminal 
  of 
  

   this 
  was 
  connected 
  to 
  Q 
  2 
  , 
  and 
  the 
  other 
  could 
  be 
  switched 
  

   either 
  on 
  to 
  P 
  or 
  P'. 
  The 
  mean 
  of 
  the 
  two 
  readings 
  was 
  

   taken 
  as 
  the 
  average 
  potential 
  of 
  the 
  strip 
  and 
  plates. 
  

  

  The 
  nuts 
  k 
  and 
  I 
  connected 
  respectively 
  with 
  the 
  plates 
  cc 
  } 
  

   and 
  the 
  electrode 
  i 
  (fig. 
  1) 
  were 
  each 
  soldered 
  to 
  a 
  narrow 
  

   spiral 
  of 
  thin 
  copper 
  wire, 
  which 
  in 
  turn 
  was 
  soldered 
  to 
  

   thin 
  straight 
  platinum 
  wires. 
  These 
  were 
  fused 
  into 
  the 
  

   drawn-out 
  glass 
  tubes 
  AB, 
  and 
  thence 
  led 
  to 
  the 
  mercury 
  

   cups 
  C 
  and 
  D. 
  This 
  arrangement 
  was 
  sufficiently 
  flexible 
  

   to 
  admit 
  of 
  the 
  upward 
  and 
  downward 
  motion 
  of 
  the 
  carriage 
  

   to 
  which 
  k 
  and 
  I 
  were 
  rigidly 
  attached. 
  Wires 
  passed 
  from 
  

   the 
  mercury 
  cups 
  E 
  and 
  F 
  to 
  the 
  condenser 
  Gr 
  and 
  one 
  pair 
  

   of 
  quadrants 
  of 
  the 
  electrometer 
  respectively. 
  The 
  other 
  

   pair 
  were 
  connected 
  to 
  earth 
  and 
  the 
  shielding 
  arrangement 
  

   indicated. 
  The 
  three 
  mercury 
  cups 
  J 
  were 
  connected 
  to 
  the 
  

   earth, 
  the 
  electrometer, 
  and 
  the 
  condenser 
  respectively. 
  All 
  

   the 
  connexions 
  and 
  keys 
  between 
  k 
  and 
  Z 
  and 
  the 
  electrometer 
  

   and 
  condenser 
  were 
  surrounded 
  by 
  earthed 
  metal 
  shields, 
  

   not 
  all 
  of 
  which 
  are 
  shown. 
  Before 
  taking 
  a 
  reading 
  the 
  

   mercury 
  cups 
  J 
  were 
  connected 
  together 
  by 
  the 
  plug 
  K 
  3 
  , 
  

   and 
  the 
  plug 
  K 
  : 
  was 
  placed 
  in 
  the 
  key 
  C 
  D 
  E 
  F. 
  Thus 
  

   k 
  I 
  Gr 
  and 
  H 
  were 
  all 
  connected 
  to 
  earth. 
  At 
  the 
  beginning 
  

   of 
  an 
  observation 
  K 
  3 
  was 
  taken 
  out, 
  leaving 
  k 
  connected 
  

   with 
  G 
  and 
  I 
  connected 
  with 
  H. 
  Thus 
  the 
  current 
  to 
  the 
  

   plates 
  all 
  flowed 
  into 
  the 
  condenser, 
  whilst 
  that 
  passing- 
  

   through 
  the 
  slit 
  flowed 
  into 
  the 
  electrometer. 
  After 
  a 
  

   certain 
  interval 
  of 
  time, 
  depending 
  on 
  the 
  temperature 
  of 
  the 
  

   strip, 
  the 
  plug 
  K 
  x 
  was 
  removed, 
  both 
  currents 
  being 
  thus 
  

   interrupted 
  simultaneously. 
  The 
  steady 
  deflexion 
  of 
  the 
  

   electrometer 
  was 
  then 
  read 
  ; 
  this 
  measures 
  the 
  number 
  of 
  ions 
  

   which 
  pass 
  through 
  the 
  slit. 
  E 
  and 
  F 
  were 
  then 
  connected 
  

   together 
  by 
  inserting 
  the 
  plug 
  K 
  2 
  and 
  the 
  charge 
  in 
  the 
  

  

  