﻿51 
  8 
  Mr. 
  W. 
  Williams 
  on 
  the 
  Temperature 
  Variation 
  of 
  

  

  On 
  account 
  of 
  the 
  irregularities 
  of 
  the 
  metal, 
  the 
  result 
  in 
  

  

  the 
  case 
  of 
  arsenic 
  cannot 
  be 
  taken 
  as 
  definite 
  *. 
  

  

  Now, 
  the 
  groups 
  that 
  are 
  thus 
  characterized 
  by 
  different 
  

  

  values 
  for 
  c 
  are 
  also 
  characterized 
  by 
  corresponding 
  

  

  values 
  for 
  K. 
  Thus, 
  where 
  c 
  = 
  '045, 
  K 
  is 
  1*72 
  x 
  10 
  2 
  . 
  

  

  Where 
  c 
  is 
  approximately 
  (-^x'045), 
  K 
  is 
  approximately 
  

  

  2 
  x 
  1*72 
  x 
  10 
  2 
  , 
  and 
  where 
  c 
  is 
  approximately 
  (2 
  X 
  '045), 
  K 
  is 
  

  

  approximately 
  (J 
  x 
  1*72 
  x 
  10 
  2 
  ). 
  This 
  suggests 
  that 
  the 
  

  

  relation 
  for 
  a 
  can 
  be 
  rendered 
  more 
  comprehensive 
  if 
  written 
  

  

  A 
  mVd 
  

   o- 
  == 
  -^~- 
  m 
  — 
  p=- 
  ? 
  where 
  A 
  is 
  a 
  constant. 
  Thus 
  modified, 
  the 
  

  

  relation 
  gives 
  the 
  following: 
  values 
  for 
  cr 
  : 
  — 
  

  

  Silver 
  

  

  Copper 
  .... 
  

   Magnesium 
  

   Sodium 
  .... 
  

  

  Zinc 
  

  

  Cadmium 
  . 
  

   Potassium 
  . 
  

   Thallium 
  . 
  

  

  Lead 
  

  

  Arsenic 
  .... 
  

   Antimony 
  . 
  

   Bismuth.... 
  

  

  Observed. 
  Calculated. 
  

  

  1-6 
  

  

  1-5 
  

  

  1-7 
  

  

  2-0 
  

  

  4-1 
  

  

  3-4 
  

  

  5-1 
  

  

  71 
  

  

  5-8 
  

  

  5-36 
  

  

  7-5 
  

  

  795 
  

  

  8-4 
  

  

  11-5 
  

  

  17-6 
  

  

  17*7 
  

  

  200 
  

  

  21-7 
  

  

  35-1 
  

  

  34-3 
  

  

  43-1 
  

  

  50-2 
  

  

  108-0 
  

  

  80-1 
  

  

  Except 
  in 
  the 
  case 
  of 
  sodium, 
  the 
  order 
  in 
  which 
  the 
  

   metals 
  stand 
  is 
  the 
  same 
  as 
  regards 
  the 
  observed 
  and 
  cal- 
  

   culated 
  values 
  of 
  a 
  ; 
  and 
  although 
  the 
  differences 
  are 
  great 
  in 
  

   the 
  case 
  of 
  some 
  of 
  the 
  metals, 
  the 
  values 
  are 
  throughout 
  of 
  

   the 
  proper 
  order 
  of 
  magnitude. 
  The 
  modified 
  relation 
  fails 
  

   to 
  hold, 
  however, 
  for 
  gold, 
  indium, 
  tin, 
  and 
  aluminium, 
  so 
  

   that 
  these 
  metals, 
  as 
  before, 
  are 
  exceptional. 
  Whether 
  it 
  

   holds 
  for 
  calcium 
  and 
  mercury 
  cannot 
  be 
  ascertained 
  until 
  

   the 
  value 
  of 
  e 
  can 
  be 
  obtained 
  for 
  those 
  metals. 
  If 
  they 
  

   follow 
  Pictet's 
  law, 
  so 
  that 
  c 
  lies 
  between 
  *04 
  and 
  '05, 
  they 
  

   will 
  conform 
  with 
  the 
  relation 
  in 
  its 
  modified 
  form 
  to 
  the 
  

   same 
  degree 
  of 
  approximation 
  as 
  they 
  do 
  in 
  the 
  case 
  of 
  the 
  

   original 
  one. 
  

  

  If 
  ra, 
  in 
  the 
  relation 
  for 
  <r, 
  is 
  to 
  be 
  the 
  maximum 
  valency 
  

   according 
  to 
  the 
  Periodic 
  Law, 
  the 
  relation 
  will 
  approximately 
  

   hold 
  for 
  platinum 
  and 
  palladium. 
  Thus 
  : 
  

  

  V. 
  m. 
  T. 
  c. 
  a. 
  a'. 
  Diff. 
  

  

  Palladium 
  9'2 
  8 
  1775 
  -0411 
  8-44 
  10-2 
  17 
  p. 
  cent. 
  

  

  Platinum 
  9-1 
  8 
  2050 
  "0379 
  7*82 
  9'0 
  13 
  „ 
  

  

  * 
  The 
  metal 
  sublimes 
  when 
  heated 
  and 
  has 
  a 
  definite 
  melting-point 
  

   only 
  under 
  pressure. 
  

  

  