﻿Holborn 
  dt 
  Day 
  — 
  Thermoelectricity 
  in 
  Certain 
  Metals. 
  303 
  

  

  Art. 
  XXXIY. 
  — 
  On 
  Thermoelectricity 
  in 
  Certain 
  Metals 
  ; 
  by 
  

   LuDWia 
  Holborn 
  and 
  Arthur 
  L. 
  Day. 
  

  

  [Communication 
  from 
  the 
  Physikalisch-Technlsche 
  Reichsanslalt, 
  Charlotten- 
  

   burg, 
  Germany. 
  Laid 
  before 
  the 
  Konighch 
  Preussische 
  Akadeaiie 
  der 
  Wissen- 
  

   schaften, 
  Berlin, 
  July 
  20, 
  1899.] 
  

  

  In 
  connection 
  with 
  the 
  investigation 
  of 
  the 
  gas 
  thermometer 
  

   at 
  high 
  temperatures 
  and 
  the 
  application 
  of 
  thermo-elements 
  of 
  

   the 
  platinum 
  metals 
  to 
  the 
  comparison 
  of 
  its 
  results, 
  the 
  need 
  

   of 
  a 
  law 
  which 
  should 
  accurately 
  express 
  the 
  relation 
  between 
  

   the 
  electromotive 
  force 
  developed 
  by 
  the 
  latter 
  and 
  the 
  tem- 
  

   perature 
  became 
  strongly 
  felt. 
  Theoretical 
  considerations 
  led 
  

   us 
  to 
  carry 
  the 
  research 
  further, 
  and 
  include 
  the 
  lowest 
  avail- 
  

   able 
  temperatures 
  as 
  well 
  ; 
  thus 
  the 
  range 
  of 
  the 
  investigation 
  

   became 
  so 
  broad 
  that 
  the 
  behavior 
  of 
  thermo-elements 
  was 
  

   shown 
  in 
  a 
  much 
  clearer 
  light 
  than 
  heretofore, 
  as 
  will 
  be 
  seen 
  

   from 
  the 
  following 
  brief 
  sketch 
  of 
  the 
  results. 
  

  

  Avenarius, 
  as 
  is 
  well 
  known, 
  was 
  the 
  first 
  to 
  show 
  that 
  the 
  

   electromotive 
  force 
  of 
  a 
  thermo-element, 
  expressed 
  as 
  a 
  func- 
  

   tion 
  of 
  the 
  temperature, 
  approximated 
  very 
  closely 
  to 
  a 
  para- 
  

   bola, 
  and 
  this 
  result 
  has 
  been 
  confirmed 
  for 
  various 
  temperature 
  

   ranges 
  by 
  Tait, 
  Knott 
  and 
  MacGregor, 
  and 
  Noll. 
  Up 
  to 
  the 
  

   present 
  time, 
  however, 
  the 
  agreement 
  can 
  be 
  said 
  to 
  be 
  satis- 
  

   factory 
  only 
  between 
  0° 
  and 
  300-4:00°, 
  and 
  even 
  here 
  several 
  

   metals 
  show 
  considerable 
  irregularities. 
  Attempts 
  have 
  even 
  

   been 
  made 
  recently 
  to 
  apply 
  logarithmic 
  formulae 
  where 
  the 
  

   difference 
  in 
  temperature 
  between 
  the 
  junctions 
  was 
  large. 
  

  

  The 
  thermo-elements 
  which 
  we 
  have 
  investigated 
  have 
  not, 
  

   to 
  be 
  sure, 
  followed 
  the 
  law 
  of 
  Avenarius 
  in 
  every 
  case 
  over 
  

   the 
  entire 
  measured 
  temperature 
  domain, 
  but 
  within 
  very 
  

   wide 
  limits 
  the 
  agreement 
  is 
  so 
  astonishingly 
  exact 
  that 
  the 
  

   failure 
  of 
  the 
  law 
  to 
  apply 
  further 
  can 
  only 
  be 
  regarded 
  as 
  an 
  

   evidence 
  of 
  some 
  change 
  in 
  the 
  condition 
  of 
  the 
  metal 
  investi- 
  

   gated 
  at 
  that 
  point 
  — 
  perhaps 
  due 
  to 
  the 
  absorption 
  of 
  gases. 
  

   The 
  great 
  range 
  of 
  temperature 
  to 
  be 
  covered 
  by 
  this 
  investi- 
  

   gation 
  made 
  it 
  only 
  possible 
  to 
  include 
  metals 
  which 
  remain 
  

   chemically 
  unchanged 
  at 
  high 
  temperatures, 
  i. 
  e., 
  the 
  platinum 
  

   group 
  together 
  with 
  gold 
  and 
  silver. 
  Thanks 
  to 
  the 
  kind 
  

   assistance 
  of 
  the 
  firm 
  of 
  Heraus 
  in 
  Hanau 
  and 
  the 
  chemical 
  

   laboratory 
  of 
  the 
  Reichsanstalt, 
  especially 
  Prof. 
  Mylius, 
  we 
  

   were 
  able 
  to 
  lay 
  much 
  emphasis 
  upon 
  the 
  chemical 
  purity 
  of 
  

   the 
  metals 
  investigated. 
  

  

  One 
  of 
  the 
  best 
  means 
  of 
  testing 
  the 
  purity 
  of 
  a 
  metal 
  is 
  

   often 
  the 
  measurement 
  of 
  its 
  electrical 
  resistance. 
  This 
  has 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  VIII, 
  No. 
  46. 
  — 
  October, 
  1899. 
  

   21 
  

  

  