﻿Thermal 
  Conductivity 
  of 
  Glass. 
  

  

  603 
  

  

  Thorough 
  stirring 
  is 
  essential, 
  because 
  if 
  the 
  water 
  is 
  allowed 
  

   to 
  remain 
  at 
  rest 
  for 
  a 
  very 
  short 
  space 
  of 
  time, 
  the 
  readings 
  

   obtained 
  are 
  inconsistent. 
  

  

  The 
  couple 
  can 
  be 
  easily 
  calibrated 
  in 
  position 
  at 
  any 
  time 
  

   in 
  the 
  following 
  way. 
  The 
  water 
  in 
  the 
  tank 
  is 
  allowed 
  to 
  

   stand 
  until 
  its 
  temperature 
  is 
  equal 
  to 
  that 
  of 
  the 
  room. 
  The 
  

   cold 
  junction 
  is 
  then 
  removed 
  from 
  the 
  tank 
  and 
  placed 
  in 
  

   ice 
  or 
  in 
  cold 
  water. 
  The 
  deflexions 
  corresponding 
  to 
  these 
  

   temperature 
  differences 
  are 
  then 
  observed 
  and 
  a 
  graph 
  plotted. 
  

   The 
  graph 
  given 
  in 
  tig. 
  4 
  was 
  plotted 
  from 
  the 
  following 
  

   observations 
  : 
  — 
  

  

  1500 
  

  

  mo 
  

  

  ii-oo 
  

  

  qw 
  

  

  Too 
  

  

  5W 
  

  

  5W 
  

  

  Galvanometer 
  

  

  Deflexion. 
  

  

  mm. 
  

  

  Temperature 
  

  

  Difference. 
  

  

  °C. 
  

  

  43-4 
  

  

  3-59 
  

  

  56-7 
  

  

  4-68 
  

  

  85-2 
  

  

  7-01 
  

  

  115o 
  

  

  9-55 
  

  

  1386 
  

  

  11-46 
  

  

  183-0 
  

  

  15-10 
  

  

  Fiar. 
  4. 
  

  

  

  \ 
  

  

  

  

  

  

  < 
  '\ 
  

  

  p 
  

  

  

  

  

  

  y 
  

  

  

  

  3 
  

  

  

  

  

  

  

  

  

  * 
  

  

  

  

  / 
  

  

  

  

  

  

  

  

  

  

  Caubra 
  

  

  ION 
  Cu 
  

  

  IV 
  £ 
  

  

  - 
  

  

  

  

  

  

  \/_ 
  

  

  

  

  t 
  

   The 
  r 
  ml 
  

  

  >- 
  Coupi 
  

  

  :e 
  

  

  

  

  

  / 
  

  

  

  

  

  

  Deflec 
  

  

  T/O/V- 
  M/> 
  

  

  s. 
  

  

  40 
  do 
  80 
  

  

  The 
  mean 
  value 
  of 
  

   082° 
  C. 
  

  

  100 
  110 
  /40 
  /60 
  /SO 
  

  

  mm. 
  deflexion 
  was 
  thus 
  found 
  to 
  be 
  

  

  