﻿the 
  Electrical 
  Resistances 
  of 
  Pure 
  Metcds. 
  

  

  525 
  

  

  For 
  magnesium 
  ft 
  appears 
  to 
  be 
  abnormally 
  high. 
  Thus, 
  

   according 
  to 
  Fizeau, 
  the 
  value 
  of 
  a. 
  at 
  40° 
  is 
  '00002694, 
  and 
  

   •00002762 
  at 
  50°, 
  so 
  that 
  £ 
  = 
  '00281. 
  We 
  must 
  therefore 
  

   conclude, 
  either 
  that 
  magnesium 
  does 
  not 
  conform 
  with 
  the 
  

   relation 
  for 
  7, 
  or 
  that 
  Fizeau's 
  value 
  for 
  /3 
  is 
  not 
  charac- 
  

   teristic 
  of 
  the 
  metal 
  itself, 
  but 
  of 
  a 
  particular 
  specimen 
  only. 
  

   For 
  the 
  remaining 
  metals, 
  with 
  the 
  exception 
  of 
  . 
  those 
  after- 
  

   wards 
  to 
  be 
  mentioned, 
  data 
  cannot 
  be 
  obtained 
  respecting* 
  

   8 
  and 
  j3. 
  a 
  

  

  According 
  to 
  the 
  temperature 
  relation 
  — 
  = 
  1. 
  + 
  [e-f-^(/3' 
  — 
  

  

  °"° 
  

   8')t] 
  A-\e{&' 
  — 
  8')t 
  2 
  , 
  since 
  in 
  the 
  case 
  of 
  the 
  metals 
  tabulated 
  

  

  above 
  8' 
  is 
  less 
  than 
  /3', 
  the 
  locus 
  of 
  u 
  or 
  — 
  must 
  be 
  concave 
  

  

  clu 
  . 
  cr 
  ° 
  

  

  upwards, 
  and 
  the 
  value 
  of 
  — 
  must 
  increase 
  as 
  the 
  temper- 
  

   ature 
  rises. 
  This 
  is 
  in 
  accord 
  with 
  the 
  results 
  of 
  observation, 
  

   as 
  the 
  following 
  table 
  will 
  show, 
  where 
  -y 
  and 
  its 
  mean 
  value 
  

  

  between 
  0° 
  and 
  100° 
  are 
  tabulated. 
  For 
  comparison, 
  the 
  

   values 
  deduced 
  from 
  Fleming 
  and 
  Dewar's 
  observations, 
  

  

  Tin 
  

  

  Copper 
  

  

  Cadmium 
  . 
  

  

  Lead 
  

  

  Zine 
  

  

  Silver 
  .... 
  

  

  Aluminium 
  

  

  00440 
  + 
  

   00425 
  -t- 
  

   00403 
  + 
  

  

  00413 
  4- 
  

   00412 
  + 
  

   00412 
  + 
  

  

  00410 
  4- 
  

   00405 
  -f 
  

  

  00402 
  + 
  

  

  00390 
  + 
  

   00399 
  + 
  

   00395 
  4- 
  

  

  00388 
  + 
  

   00395 
  + 
  

  

  00391 
  + 
  

   00391 
  + 
  

   00397 
  + 
  

  

  00403 
  + 
  

   00408 
  + 
  

   00388 
  4- 
  

  

  0000054 
  t 
  

   0000040 
  t 
  

   0000117 
  t 
  

  

  0000033 
  t 
  

   0000033 
  t 
  

   0000060 
  t 
  

  

  0000032 
  t 
  

   0000028 
  t 
  

   0000018 
  t 
  

  

  0000017 
  t 
  

   0000024 
  t 
  

   0000028 
  t 
  

  

  0000016 
  t 
  

   0000020 
  t 
  

  

  0000018 
  t 
  

   0000018 
  t 
  

   0000014 
  t 
  

  

  0000027 
  t 
  

   0000030- 
  * 
  

   0000026 
  t 
  

  

  Mean. 
  

  

  00467 
  

   00445 
  

   00461 
  

  

  00429 
  

   00428 
  

   00442 
  

  

  00425 
  

   00419 
  

   00412 
  

  

  00399 
  

   00411 
  

   00409 
  

  

  00396 
  

   00405 
  

  

  00400 
  

   00400 
  

   00404 
  

  

  00416 
  

   00423 
  

   •00401 
  i 
  

  

  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  3. 
  No. 
  17. 
  May 
  1902. 
  

  

  2N 
  

  

  