﻿T 
  HE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  * 
  - 
  • 
  n 
  A 
  ** 
  

  

  [FIFTH 
  SERIES.]^ 
  APRH 
  1898 
  

  

  * 
  

  

  APRIL 
  1898. 
  

  

  

  XXXIV. 
  Variations 
  in 
  the 
  Electromotive 
  Force 
  of 
  the 
  H-form 
  

   of 
  Clark 
  Cells 
  with 
  Temperature. 
  By 
  F. 
  S. 
  Spieks, 
  JB.Sc, 
  

   F. 
  Twyman, 
  and 
  W. 
  L. 
  Waters. 
  

  

  ri^HE 
  work 
  described 
  in 
  this 
  paper 
  was 
  intended 
  as 
  a 
  corn- 
  

   -*- 
  pletion 
  of 
  the 
  investigation 
  carried 
  out 
  some 
  years 
  ago 
  

   by 
  Prof. 
  Ayrton 
  and 
  Mr. 
  W. 
  R. 
  Cooper 
  t 
  on 
  the 
  effect 
  of 
  

   variations 
  of 
  temperature 
  on 
  the 
  E.M.F. 
  of 
  the 
  Board 
  of 
  Trade 
  

   form 
  of 
  Clark 
  cell. 
  Their 
  results 
  showed 
  that 
  it 
  was 
  not 
  

   possible, 
  by 
  applying 
  the 
  ordinary 
  temperature-correction, 
  to 
  

   obtain 
  the 
  true 
  value 
  of 
  the 
  E.M.F, 
  of 
  the 
  cell 
  with 
  a 
  greater 
  

   accuracy 
  than 
  0*1 
  per 
  cent. 
  It 
  was 
  thought 
  that 
  the 
  H-form 
  

   of 
  cell 
  would 
  show 
  some 
  improvement 
  over 
  the 
  ordinary 
  type 
  

   in 
  this 
  respect 
  ; 
  and 
  this 
  was 
  confirmed 
  by 
  some 
  results 
  

   published 
  recently 
  by 
  Dr. 
  Kahle 
  J. 
  The 
  experiments 
  to 
  be 
  

   described 
  in 
  this 
  paper 
  were 
  undertaken 
  with 
  the 
  object 
  of 
  

   seeing 
  how 
  far 
  this 
  was 
  correct, 
  and 
  in 
  general 
  to 
  investigate 
  

   the 
  behaviour 
  of 
  this 
  form 
  of 
  cell 
  under 
  variations 
  of 
  tempe- 
  

   rature. 
  The 
  experiments 
  were 
  carried 
  out 
  at 
  the 
  Central 
  

   Technical 
  College. 
  

  

  The 
  tests 
  were 
  made 
  on 
  four 
  cells 
  set 
  up 
  in 
  accordance 
  with 
  

   the 
  specification 
  issued 
  by 
  Dr. 
  Kahle 
  from 
  the 
  Reichsanstalt§. 
  

   The 
  cells 
  were 
  in 
  every 
  way 
  alike 
  ||, 
  and 
  were 
  mounted 
  

  

  * 
  Communicated 
  by 
  the 
  Physical 
  Society: 
  read 
  Nov. 
  12th, 
  1897. 
  

   t 
  Proc. 
  Hoy. 
  Soc. 
  December 
  1895. 
  

   | 
  Zeitschrift 
  fur 
  Instrumentenkimcle, 
  August 
  1893. 
  

   § 
  ' 
  Electrician/ 
  vol. 
  xxxi. 
  p. 
  265, 
  July 
  1893. 
  

  

  || 
  They 
  were 
  set 
  up 
  by 
  Mr. 
  Ccoper, 
  Nos. 
  1, 
  2, 
  and 
  4 
  on 
  19th 
  March, 
  

   1895, 
  and 
  No. 
  3 
  on 
  12th 
  February, 
  1896. 
  

  

  Phil. 
  Mag. 
  S. 
  5. 
  Vol. 
  45. 
  No. 
  275. 
  April 
  1898. 
  X 
  

  

  