﻿The 
  Failure 
  of 
  German- 
  Silver 
  and 
  Platinoid 
  Wires, 
  157 
  

  

  coefficients, 
  are 
  so, 
  rigorously, 
  only 
  at 
  infinite 
  dilution 
  ; 
  and 
  

   (2) 
  the 
  value 
  of 
  the 
  specific 
  molecular 
  conductivity 
  at 
  

   infinite 
  dilution 
  for 
  an 
  electrolyte 
  in 
  a 
  mixture 
  may 
  be 
  

   taken 
  to 
  be 
  the 
  same 
  as 
  the 
  value 
  determined 
  by 
  experi- 
  

   ments 
  on 
  a 
  simple 
  solution, 
  only 
  at 
  infinite 
  dilution. 
  It 
  was 
  

   to 
  be 
  expected 
  also 
  that, 
  except 
  for 
  the 
  accumulation 
  of 
  acci- 
  

   dental 
  errors, 
  the 
  differences 
  in 
  the 
  case 
  of 
  the 
  stronger 
  solu- 
  

   tions 
  would 
  have 
  the 
  same 
  sign 
  ; 
  for 
  the 
  errors 
  in 
  the 
  values 
  

   of 
  the 
  a's 
  and 
  the 
  /x«'s 
  would 
  have 
  the 
  same 
  signs 
  for 
  different 
  

   solutions. 
  When 
  we 
  consider 
  the 
  large 
  number 
  of 
  sources 
  of 
  

   error 
  involved 
  in 
  the 
  determination 
  of 
  the 
  constituent 
  solu- 
  

   tions, 
  the 
  preparation 
  of 
  the 
  mixtures, 
  and 
  the 
  finding 
  of 
  their 
  

   conductivity, 
  the 
  agreement 
  between 
  the 
  observed 
  and 
  the 
  

   calculated 
  values 
  in 
  the 
  case 
  of 
  the 
  weaker 
  solutions 
  must 
  be 
  

   regarded 
  as 
  quite 
  satisfactory, 
  and 
  as 
  warranting 
  the 
  conclu- 
  

   sion 
  that 
  it 
  is 
  possible 
  by 
  the 
  aid 
  of 
  the 
  dissociation 
  theory 
  to 
  

   calculate 
  the 
  conductivity 
  of 
  dilute 
  aqueous 
  solutions 
  contain- 
  

   ing 
  sodium 
  chloride 
  and 
  potassium 
  sulphate, 
  and 
  therefore 
  

   also 
  sodium 
  sulphate 
  and 
  potassium 
  chloride, 
  within 
  the 
  limit 
  

   of 
  observational 
  error. 
  

  

  XV. 
  The 
  Failure 
  of 
  German 
  Silver 
  and 
  Platinoid 
  Wires. 
  

   By 
  Rollo 
  Appleyard 
  *. 
  

  

  THE 
  object 
  of 
  the 
  present 
  paper 
  is 
  to 
  direct 
  attention 
  to 
  

   the 
  serious 
  mechanical 
  defectiveness 
  of 
  certain 
  alloys 
  

   used 
  for 
  electrical 
  wires. 
  The 
  question 
  is 
  the 
  more 
  important 
  

   because 
  mechanical 
  weakness 
  implies 
  electrical 
  instability. 
  In 
  

   what 
  follows 
  I 
  endeavour 
  to 
  bring 
  together 
  facts 
  enough 
  to 
  

   indicate 
  the 
  general 
  behaviour 
  of 
  german-silver 
  and 
  platinoid, 
  

   and 
  especially 
  to 
  settle 
  the 
  case 
  as 
  regards 
  the 
  conditions 
  

   external 
  to 
  the 
  wires. 
  

  

  It 
  is 
  necessary 
  to 
  remember 
  that 
  great 
  differences 
  exist 
  

   between 
  different 
  samples 
  of 
  the 
  same 
  nominal 
  quality 
  of 
  

   alloy; 
  so 
  that, 
  of 
  a 
  hundred 
  pounds' 
  weight 
  of 
  wire, 
  ninety-nine 
  

   may 
  be 
  proof 
  against 
  all 
  ordinary 
  climates 
  and 
  conditions 
  to 
  

   all 
  time, 
  while 
  the 
  remaining 
  pound 
  may 
  become 
  fragile 
  

   under 
  the 
  same 
  treatment 
  in 
  a 
  few 
  weeks. 
  

  

  Many 
  suggestions 
  have 
  been 
  made 
  to 
  me, 
  and 
  are 
  yet 
  

   current, 
  as 
  to 
  the 
  cause 
  of 
  the 
  failure 
  of 
  these 
  wires. 
  A 
  well- 
  

   known 
  expert 
  in 
  electrical 
  matters 
  attributes 
  it 
  to 
  sulphur 
  in 
  

   the 
  ebonite 
  of 
  the 
  electrical 
  apparatus. 
  It 
  will, 
  however, 
  he 
  

   shown 
  that 
  failure 
  occurs 
  apart 
  from 
  all 
  ebonite 
  and 
  sulphur. 
  

   Paraffin-wax 
  has 
  been 
  mentioned 
  by 
  another 
  authority 
  as 
  the 
  

   probable 
  cause 
  of 
  these 
  defects. 
  Instances 
  will 
  be 
  given 
  to 
  

  

  * 
  Communicated 
  by 
  the 
  Physical 
  Society 
  : 
  read 
  Nov. 
  26, 
  1897. 
  

   Phil. 
  Mag. 
  S. 
  5. 
  Vol. 
  45. 
  No. 
  273. 
  Feb. 
  1898. 
  N 
  

  

  