﻿W. 
  P. 
  White 
  — 
  Silicate 
  Specific 
  Heats. 
  37 
  

  

  the 
  effect 
  is 
  clearly 
  not 
  due 
  to 
  sluggishness. 
  (3a) 
  In 
  

   sulphur 
  the 
  change 
  in 
  melting 
  point 
  is 
  due 
  to 
  the 
  presence 
  

   of 
  S/a, 
  a 
  metameric 
  form 
  which 
  can 
  be 
  separated 
  out 
  and 
  

   recognized. 
  Since 
  the 
  amount 
  of 
  S/x 
  changes 
  as 
  the 
  sul- 
  

   phur 
  melts, 
  the 
  phenomena 
  in 
  that 
  respect 
  are 
  of 
  the 
  

   same 
  character 
  as 
  with 
  the 
  organic 
  liquids 
  of 
  fig. 
  3, 
  with 
  

   the 
  additional 
  feature 
  that 
  it 
  is 
  now 
  the 
  solid 
  state 
  in 
  

   which 
  formation 
  of 
  a 
  dissolved 
  metamer 
  occurs. 
  But 
  

   though 
  the 
  solid 
  inversion 
  temperature 
  is 
  also 
  affected 
  by 
  

   the 
  amount 
  of 
  S/* 
  present, 
  the 
  S/* 
  may 
  then 
  be 
  considered 
  

   to 
  affect 
  this 
  temperature 
  as 
  any 
  other 
  impurity 
  might, 
  

   since 
  the 
  S/* 
  is 
  not 
  supposed 
  to 
  be 
  one 
  of 
  the 
  metamers 
  

   A 
  or 
  B, 
  which 
  are 
  essential 
  to 
  the 
  inversion. 
  These 
  

   metamers 
  are 
  as 
  hypothetical 
  in 
  this 
  case 
  as 
  in 
  others. 
  

   (3b) 
  In 
  mercuric 
  iodide 
  it 
  has 
  been 
  claimed 
  by 
  Smits 
  46 
  

   that 
  an 
  inversion 
  actually 
  occurs 
  sooner 
  when 
  approached 
  

   rapidly. 
  This 
  is 
  the 
  inversion 
  from 
  the 
  yellow 
  to 
  the 
  red 
  

   form 
  on 
  cooling. 
  The 
  explanation 
  is 
  as 
  follows 
  : 
  The 
  

   line 
  VW, 
  ~$ig. 
  4, 
  is 
  supposed 
  to 
  run 
  up 
  toward 
  the 
  right, 
  

   On 
  sudden 
  cooling 
  the 
  chemical 
  equilibrium 
  retains 
  for 
  

   a 
  few 
  seconds 
  its 
  high 
  temperature 
  value, 
  and 
  a 
  composi- 
  

   tion 
  represented 
  by 
  the 
  point 
  V 
  ± 
  is 
  cooled 
  below 
  the 
  solu- 
  

   bility 
  line 
  NP, 
  and 
  inverts 
  at 
  W', 
  although 
  still 
  above 
  the 
  

   regular 
  inversion 
  temperature 
  of 
  W. 
  The 
  chemical 
  

   equilibrium 
  might 
  afterward 
  be 
  expected 
  to 
  change 
  and 
  

   the 
  red 
  form 
  revert 
  again 
  to 
  the 
  yellow 
  which 
  is 
  normal 
  

   at 
  that 
  temperature, 
  and 
  this 
  is 
  said 
  to 
  actually 
  hap- 
  

   pen 
  in 
  a 
  few 
  seconds. 
  Tammann 
  47 
  disparages 
  Smits' 
  

   experimental 
  result 
  on 
  mercuric 
  iodide, 
  though 
  without 
  

   attempting 
  to 
  test 
  it 
  — 
  a 
  somewhat 
  remarkable 
  proceed- 
  

   ing 
  for 
  so 
  simple 
  an 
  experiment. 
  In 
  collaboration 
  with 
  

   Dr. 
  H. 
  E. 
  Merwin, 
  of 
  this 
  laboratory, 
  I 
  have 
  attempted 
  

   to 
  repeat 
  the 
  observations. 
  "We 
  worked 
  in 
  front 
  of 
  a 
  

   large 
  window, 
  on 
  a 
  bright 
  day, 
  with 
  considerable 
  varia- 
  

   tion 
  of 
  conditions, 
  and 
  with 
  care 
  as 
  to 
  the 
  calibration 
  of 
  

   our 
  thermometers. 
  The 
  material 
  was 
  from 
  a 
  C.P. 
  lot, 
  

   but 
  was 
  not 
  specially 
  analyzed. 
  It 
  was 
  used 
  both 
  as 
  fine 
  

   powder 
  and 
  as 
  small 
  lumps 
  formed 
  by 
  fusing 
  that 
  in 
  the 
  

   tubes. 
  The 
  external 
  diameter 
  of 
  the 
  tubes 
  was 
  from 
  1 
  

   to 
  3 
  mm. 
  We 
  found 
  no 
  sign 
  of 
  the 
  premature 
  inversion 
  

  

  48 
  Both 
  articles 
  cited 
  ; 
  also 
  ' 
  ' 
  A 
  new 
  theory 
  of 
  the 
  phenomenon 
  allotropy, 
  ' 
  ' 
  

   K. 
  Akad. 
  Wetenschappen, 
  Amsterdam, 
  1910, 
  768; 
  and 
  "On 
  the 
  system 
  

   mercury-iodide, 
  ' 
  ' 
  ibid., 
  19, 
  703, 
  1916. 
  

  

  47 
  Zs. 
  phys. 
  Chem., 
  83, 
  733, 
  op. 
  cit. 
  

  

  