﻿the 
  Electrical 
  Resistances 
  of 
  Pure 
  Metals. 
  

  

  517 
  

  

  The 
  metals 
  of 
  the 
  alkali 
  and 
  arsenic 
  groups 
  also 
  fail. 
  

   Thus 
  :- 
  

  

  Potassium 
  

   Sodium 
  .. 
  

   Arsenic 
  .., 
  

   Antimony 
  

   Bismuth 
  

  

  454 
  

   23-7 
  

   13-2 
  

   17-9 
  

   21-1 
  

  

  T. 
  

   i 
  

  

  <r. 
  

  

  cr'. 
  

  

  335 
  

  

  23-4 
  

  

  8-4 
  

  

  369 
  

  

  11-1 
  

  

  5-1 
  

  

  773 
  

  

  14-8 
  

  

  351 
  

  

  710 
  

  

  21-7 
  

  

  43-1* 
  

  

  538 
  

  

  33-9 
  

  

  108-0 
  

  

  According 
  to 
  Pictet, 
  if 
  a 
  is 
  the 
  coefficient 
  of 
  thermal 
  

   expansibility, 
  V^zT 
  is 
  a 
  constant 
  for 
  metals. 
  Calling 
  this 
  

   constant 
  c, 
  we 
  get 
  the 
  following 
  for 
  its 
  values 
  in 
  the 
  case 
  of 
  

   the 
  metals 
  discussed 
  above 
  : 
  — 
  

  

  Silver 
  

  

  Copper 
  

  

  Gold 
  

  

  Magnesium 
  

  

  Zinc 
  

  

  Cadmium 
  .. 
  

  

  Tin 
  

  

  Thallium 
  .. 
  

   Aluminium 
  

  

  Y, 
  

  

  102 
  

   7-1 
  

   101 
  

   13-9 
  

   91 
  

   12-9 
  

   163 
  

   172 
  

   10-6 
  

  

  Indium 
  153 
  

  

  Lead 
  

  

  184 
  

  

  •0000194 
  

   •0000170 
  

   •0000147 
  

   •0000270 
  

   •0000298 
  

   •0000316 
  

   •0000230 
  

   •0000302 
  

   •0000222 
  

   •0000417 
  

   •0000290 
  

  

  T. 
  

  

  c. 
  

  

  1173 
  

  

  •0486 
  

  

  1333 
  

  

  •0436 
  

  

  1310 
  

  

  •0417 
  

  

  1023 
  

  

  •0664 
  

  

  •• 
  676 
  

  

  •0421 
  

  

  593 
  

  

  •0440 
  

  

  503 
  

  

  0293 
  

  

  561 
  

  

  •0437 
  

  

  923 
  

  

  •0450 
  

  

  449 
  

  

  •0465 
  

  

  605 
  

  

  •0461 
  

  

  Excluding 
  magnesium 
  and 
  tin, 
  the 
  probable 
  value 
  of 
  the 
  

   constant 
  is 
  '045\ 
  

  

  The 
  alkali 
  metals 
  appear 
  to 
  constitute 
  a 
  separate 
  group 
  

   having 
  a 
  different 
  value 
  for 
  c, 
  thus, 
  

  

  Sodium 
  23*7 
  

  

  Potassium 
  45"4 
  

  

  a. 
  

  

  T. 
  

  

  G. 
  

  

  OU0072 
  

  

  369 
  

  

  •0763 
  

  

  000083 
  

  

  335 
  

  

  •0992 
  

  

  The 
  mean 
  value 
  for 
  c 
  being 
  '088, 
  or 
  about 
  double 
  its 
  value 
  

   for 
  copper, 
  (tec. 
  The 
  arsenic 
  metals, 
  or 
  at 
  least 
  bismuth 
  and 
  

   antimonv, 
  also 
  appear 
  to 
  constitute 
  a 
  separate 
  group, 
  having 
  

   c 
  = 
  '0'21 
  or 
  half 
  its 
  value 
  for 
  copper, 
  &c. 
  Thus, 
  

  

  Antimony 
  179 
  

  

  Bismuth 
  211 
  

  

  •0000116 
  

  

  T. 
  

  

  710 
  

  

  c. 
  

   ■0215 
  

  

  0000137 
  

  

  538 
  

  

  •0204 
  

  

  * 
  For 
  antimony, 
  <r 
  ! 
  = 
  45-8 
  according 
  to 
  Lorenz, 
  arid 
  40-3 
  according 
  to 
  

   Berget, 
  

  

  