﻿Deposit 
  upon 
  the 
  Poles 
  of 
  Metallic 
  Arcs. 
  335 
  

  

  great 
  variety, 
  each 
  growth 
  glistening 
  with 
  numerous 
  metallic 
  

   globules 
  which 
  it 
  had 
  caught 
  from 
  the 
  disintegration 
  of 
  the 
  

   metal 
  poles. 
  

  

  A 
  marked 
  feature 
  of 
  these 
  structures 
  was 
  the 
  increase 
  in 
  

   their 
  rate 
  of 
  growth 
  as 
  they 
  approached 
  the 
  positive 
  pole 
  ; 
  

   in 
  some 
  instances 
  the 
  gap 
  appeared 
  to 
  be 
  instantaneously 
  

   bridged, 
  and 
  great 
  difficulty 
  was 
  experienced 
  in 
  determining 
  

   how 
  the 
  poles 
  were 
  finally 
  spanned, 
  frequently 
  it 
  seemed 
  

   that 
  a 
  molten 
  drop 
  leaped 
  from 
  the 
  apex 
  of 
  the 
  deposit 
  to 
  

   the 
  positive 
  pole, 
  leaving 
  in 
  its 
  trail 
  a 
  fine 
  thread 
  which 
  was 
  

   so 
  quickly 
  formed 
  that 
  it 
  was 
  free 
  from 
  lateral 
  branches. 
  

   The 
  most 
  rapid 
  changes 
  occurred 
  when 
  the 
  arc 
  gave 
  rise 
  to 
  

   a 
  sudden 
  outburst 
  of 
  vapour, 
  this 
  it 
  occasionally 
  did 
  with 
  

   almost 
  explosive 
  violence, 
  instantly 
  destroying 
  the 
  numerous 
  

   growths 
  in 
  its 
  vicinity, 
  but 
  these 
  were 
  quickly 
  replaced 
  by 
  a 
  

   new 
  forest 
  of 
  growths 
  completely 
  formed 
  and 
  as 
  profuse 
  as 
  

   they 
  had 
  been 
  before 
  the 
  outburst. 
  Their 
  production 
  seemed 
  

   to 
  be 
  almost 
  instantaneous 
  and 
  as 
  though 
  they 
  were 
  suddenly 
  

   crystallized 
  in 
  their 
  final 
  form. 
  

  

  Not 
  infrequently 
  the 
  growth 
  completed 
  its 
  effort 
  to 
  reach 
  

   the 
  positive 
  pole 
  by 
  stretching 
  out 
  towards 
  it 
  as 
  a 
  whole 
  as 
  

   though 
  it 
  were 
  viscous, 
  the 
  thinnest 
  parts 
  stretching 
  most. 
  

   Such 
  a 
  growth 
  was 
  in 
  tension, 
  and 
  when 
  it 
  broke 
  the 
  two 
  

   ends 
  were 
  often 
  thrown 
  with 
  some 
  force 
  upon 
  their 
  respective 
  

   poles. 
  

  

  When 
  cold 
  the 
  growth 
  was 
  brittle 
  and 
  frequently 
  dropped 
  

   off 
  the 
  electrodes. 
  If 
  the 
  negative 
  pole 
  to 
  which 
  the 
  growths 
  

   were 
  attached 
  remained 
  connected 
  to 
  the 
  terminal 
  of 
  the 
  

   battery 
  after 
  the 
  arc 
  was 
  stopped, 
  the 
  growths 
  more 
  or 
  less 
  

   retained 
  their 
  form, 
  but 
  if 
  disconnected 
  the 
  laterals 
  collapsed 
  

   upon 
  the 
  stem 
  and 
  the 
  stem 
  upon 
  the 
  pole, 
  clearly 
  demon- 
  

   strating 
  that 
  their 
  formation 
  is 
  largelv 
  conditioned 
  by 
  

   electrostatic 
  repulsion. 
  Incidentally 
  it 
  involves 
  the 
  material 
  

   of 
  which 
  they 
  are 
  composed 
  being 
  conducting. 
  

  

  To 
  test 
  whether 
  under 
  any 
  circumstances 
  the 
  growths 
  can 
  

   be 
  cultivated 
  upon 
  a 
  positive 
  pole, 
  a 
  copper 
  wire 
  was 
  intro- 
  

   duced 
  above 
  a 
  horizontal 
  arc 
  produced 
  by 
  a 
  storage 
  battery 
  

   supplying 
  100 
  volts 
  with 
  suitable 
  resistances 
  in 
  circuit. 
  The 
  

   negative 
  pole 
  was 
  earthed 
  and 
  so 
  was 
  one 
  terminal 
  of 
  a 
  

   battery 
  consisting 
  of 
  a 
  large 
  number 
  of 
  small 
  secondaries 
  

   whose 
  other 
  terminal 
  was 
  connected 
  with 
  the 
  exploring 
  

   electrode. 
  The 
  potential 
  difference 
  at 
  the 
  terminals 
  of 
  the 
  

   arc 
  was 
  about 
  30 
  volts 
  ; 
  when 
  a 
  positive 
  potential 
  of 
  100 
  volts 
  

   was 
  applied 
  to 
  the 
  third 
  pole 
  placed 
  about 
  2 
  mm. 
  above 
  the 
  

   gap, 
  the 
  tree-like 
  structures 
  sprang 
  almost 
  instantly 
  into 
  

   existence 
  and 
  grew 
  with 
  vigour. 
  The 
  growth 
  became 
  still 
  

  

  