﻿Richards 
  and 
  Trowbridge 
  — 
  Conductivity, 
  etc. 
  391 
  

  

  Aet. 
  XXXVIII. 
  — 
  The 
  Effect 
  of 
  Great 
  Current 
  Strength 
  on 
  

   the 
  Conductivity 
  of 
  Electrolytes 
  ; 
  by 
  Theodore 
  William 
  

   Kichards 
  and 
  John 
  Trowbridge. 
  

  

  In 
  a 
  recent 
  paper 
  on 
  the 
  temperature 
  and 
  ohmic 
  resistance 
  

   of 
  gases 
  during 
  the 
  oscillatory 
  electric 
  discharge,* 
  we 
  have 
  

   described 
  a 
  method 
  of 
  determining 
  resistance 
  by 
  measuring 
  its 
  

   damping 
  effect 
  upon 
  electric 
  oscillations. 
  The 
  method 
  is 
  ob- 
  

   viously 
  one 
  which 
  will 
  apply 
  to 
  electrolytes 
  also, 
  provided 
  that 
  

   the 
  resistance 
  to 
  be 
  measured 
  is 
  less 
  than 
  twenty 
  ohms 
  ; 
  and 
  it 
  

   seemed 
  to 
  be 
  very 
  well 
  worth 
  while 
  to 
  determine 
  if 
  the 
  intense 
  

   current 
  involved 
  in 
  the 
  discharge 
  of 
  a 
  large 
  condenser 
  is 
  capa- 
  

   ble 
  of 
  causing 
  any 
  change 
  in 
  the 
  condition 
  of 
  an 
  electrolyte. 
  

  

  In 
  our 
  first 
  experiment, 
  two 
  copper 
  plates 
  of 
  sixteen 
  square 
  

   centimeters 
  area 
  were 
  clamped 
  at 
  a 
  distance 
  of 
  three 
  centime- 
  

   ters 
  apart 
  by 
  means 
  of 
  vulcanite. 
  Upon 
  being 
  immersed 
  in 
  a 
  

   saturated 
  solution 
  of 
  pure 
  Cupric 
  sulphate 
  at 
  15° 
  C, 
  the 
  plates 
  

   allowed 
  about 
  ten 
  oscillations 
  from 
  one 
  of 
  our 
  large 
  Leyden 
  jars, 
  

   nine 
  from 
  two 
  jars, 
  and 
  eight 
  from 
  three 
  jars, 
  to 
  pass 
  through 
  

   it. 
  According 
  to 
  the 
  scale 
  of 
  standards, 
  reprinted 
  from 
  our 
  

   last 
  paper,* 
  each 
  of 
  these 
  results 
  corresponds 
  to 
  a 
  little 
  less 
  

   than 
  four 
  ohms 
  resistance. 
  By 
  means 
  of 
  Kohlrausch's 
  method, 
  

   using 
  a 
  very 
  small 
  inductorium, 
  this 
  cell 
  gave 
  an 
  extremely 
  poor 
  

   minimum 
  at 
  a 
  point 
  corresponding 
  to 
  a 
  resistance 
  of 
  about 
  ten 
  

   ohms. 
  The 
  plates, 
  which 
  had 
  purposely 
  been 
  left 
  very 
  dirty, 
  

   in 
  order 
  to 
  test 
  the 
  efficiency 
  of 
  the 
  method, 
  were 
  now 
  scrupu- 
  

   lously 
  cleaned 
  with 
  alkali 
  and 
  acid, 
  and 
  were 
  then 
  both 
  care- 
  

   fully 
  plated 
  with 
  pure 
  copper. 
  With 
  Kohlrausch's 
  method, 
  

   the 
  cell 
  now 
  gave 
  an 
  excellent 
  minimum 
  at 
  exactly 
  four 
  ohms 
  

   resistance, 
  and 
  further 
  cleaning 
  and 
  plating 
  caused 
  no 
  further 
  

   change. 
  New 
  photographs 
  of 
  the 
  sparks 
  from 
  the 
  two 
  jars 
  

   sent 
  through 
  the 
  cell 
  showed 
  again 
  about 
  nine 
  half 
  oscillations, 
  

   corresponding 
  to 
  about 
  3*8 
  ohms. 
  It 
  is 
  evident, 
  then, 
  that 
  the 
  

   resistance 
  of 
  concentrated 
  cupric 
  sulphate 
  is 
  not 
  essentially 
  

   altered 
  by 
  great 
  alterations 
  in 
  the 
  strength 
  of 
  the 
  current. 
  

  

  Experiments 
  with 
  zincic 
  sulphate 
  gave 
  similar 
  results, 
  and 
  a 
  

   solution 
  of 
  cadmic 
  sulphate 
  between 
  cadmium 
  electrodes 
  which 
  

   possessed 
  a 
  resistance 
  of 
  4'7 
  ohms 
  according 
  to 
  Kohlrausch's 
  

   method, 
  gave 
  nine, 
  seven, 
  and 
  six 
  half 
  oscillations 
  with 
  one, 
  

   two, 
  and 
  three 
  jars 
  respectively, 
  corresponding 
  to 
  about 
  5 
  ohms 
  

   in 
  each 
  case. 
  

  

  Undoubtedly 
  the 
  reason 
  why 
  the 
  strong 
  instantaneous 
  cur- 
  

   rent, 
  which 
  alters 
  so 
  much 
  the 
  resistance 
  of 
  gases, 
  has 
  so 
  little 
  

   effect 
  upon 
  solutions, 
  is 
  because 
  of 
  the 
  great 
  mass 
  and 
  specific 
  

  

  * 
  This 
  Journal, 
  vol. 
  iii, 
  p. 
  327. 
  

  

  Am 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  Ill, 
  No. 
  It.— 
  May, 
  1897. 
  

  

  27 
  

  

  