﻿852 
  Prof. 
  A. 
  Riglii 
  : 
  New 
  Experiments 
  on 
  the 
  

  

  of 
  measurements 
  with 
  the 
  aim 
  of 
  determining 
  in 
  different 
  

   circumstances 
  the 
  position 
  occupied 
  by 
  the 
  virtual 
  anode, 
  

   namely 
  its 
  distance 
  from 
  the 
  cathode. 
  

  

  Such 
  determinations, 
  made 
  by 
  increasing 
  the 
  distance 
  of 
  

   the 
  exploring 
  coil 
  as 
  long 
  as 
  the 
  secondary 
  column 
  in 
  front 
  

   of 
  it 
  remains 
  in 
  the 
  axis 
  of 
  the 
  tube, 
  or 
  is 
  divided 
  into 
  

   two 
  branches 
  symmetrical 
  with 
  respect 
  to 
  the 
  axis, 
  cannot 
  of 
  

   course 
  be 
  very 
  precise 
  for 
  evident 
  reasons, 
  among 
  which 
  is 
  

   this, 
  that 
  the 
  virtual 
  anode 
  seems 
  to 
  be 
  often 
  constituted 
  by 
  

   a 
  large 
  cloud 
  of 
  positive 
  ions. 
  By 
  repeated 
  experiments, 
  

   however, 
  one 
  can 
  obtain 
  sufficiently 
  clear 
  results 
  (especially 
  

   by 
  using 
  a 
  tube 
  not 
  less 
  than 
  one 
  metre 
  and 
  a 
  half 
  in 
  length) 
  

   in 
  order 
  to 
  construct 
  a 
  curve 
  having 
  as 
  abscissae 
  the 
  distances 
  

   of 
  the 
  virtual 
  anode 
  from 
  the 
  cathode, 
  and 
  as 
  ordinates 
  the 
  

   intensity 
  of 
  the 
  magnetic 
  field. 
  

  

  It 
  is 
  easy 
  to 
  imagine 
  the 
  shape 
  of 
  these 
  curves, 
  as 
  it 
  is 
  

   already 
  known 
  that, 
  the 
  other 
  conditions 
  being 
  the 
  same, 
  

   the 
  distance 
  of 
  the 
  virtual 
  anode 
  fiom 
  the 
  cathode 
  increases 
  

   (to 
  a 
  certain 
  extent 
  which 
  generally 
  is 
  not 
  reached 
  if 
  the 
  

   rarefaction 
  is 
  sufficient) 
  wilh 
  the 
  increasing 
  of 
  the 
  field. 
  

   They 
  slightly 
  differ 
  from 
  straight 
  lines 
  inclined 
  upwards 
  in 
  

   the 
  direction 
  of 
  the 
  increasing 
  abscissae 
  ; 
  in 
  reality 
  they 
  often 
  

   show, 
  towards 
  this 
  axis, 
  especially 
  with 
  certain 
  gases, 
  a 
  certain 
  

   convexity. 
  With 
  the 
  same 
  gas 
  the 
  curves 
  corresponding 
  

   to 
  the 
  ditferent 
  pressures 
  are 
  found 
  one 
  above 
  the 
  other 
  and 
  

   approaching 
  the 
  axis 
  of 
  abscissae 
  as 
  rarefaction 
  is 
  increased. 
  

   It 
  was 
  already 
  known, 
  in 
  fact, 
  that 
  the 
  positive 
  ions 
  go 
  to 
  

   make 
  up 
  the 
  virtual 
  anode 
  in 
  a 
  place 
  which 
  is 
  further 
  away 
  

   from 
  the 
  cathode 
  (with 
  parity 
  of 
  the 
  magnetic 
  field) 
  as 
  the 
  

   molecules 
  which 
  may 
  stop 
  them 
  are 
  rarer, 
  and 
  therefore 
  as 
  

   rarefaction 
  is 
  greater. 
  

  

  The 
  comparison 
  between 
  the 
  curves 
  obtained 
  with 
  the 
  

   different 
  gases 
  has 
  given 
  an 
  interesting 
  result. 
  

  

  The 
  place 
  where 
  the 
  positive 
  ions, 
  resulting 
  from 
  the 
  scission 
  

   of 
  the 
  doublets 
  ion-electron, 
  arrive, 
  depends, 
  of 
  course, 
  on 
  the 
  

   speed 
  impressed 
  on 
  the 
  doublets 
  by 
  the 
  magnetic 
  force, 
  and 
  

   consequently 
  it 
  depends 
  : 
  — 
  (1) 
  on 
  the 
  area 
  enclosed 
  by 
  the 
  

   orbits 
  of 
  the 
  electron 
  satellite 
  ; 
  (2) 
  on 
  the 
  speed 
  with 
  which 
  

   it 
  is 
  moving 
  in 
  this 
  orbit 
  ; 
  (3) 
  on 
  the 
  mass 
  of 
  the 
  positive 
  

   ion. 
  Not 
  having 
  precise 
  data 
  it 
  is 
  difficult 
  to 
  foresee 
  how 
  

   with 
  equal 
  conditions 
  the 
  position 
  of 
  the 
  virtual 
  anode 
  changes 
  

   with 
  the 
  gas. 
  Nevertheless 
  it 
  seems 
  likely, 
  that 
  to 
  a 
  great 
  

   variation 
  of 
  the 
  mass 
  of 
  the 
  positive 
  ions 
  should 
  correspond 
  

   a 
  variation 
  in 
  an 
  opposite 
  sense 
  of 
  the 
  speed 
  impressed 
  by 
  

   the 
  magnetic 
  field 
  on 
  the 
  pair 
  ion 
  -electron 
  and 
  therefore 
  of 
  

   the 
  distance 
  from 
  the 
  cathode 
  at 
  which 
  the 
  virtual 
  anode 
  is 
  

  

  