﻿Frequency 
  and 
  Molecular 
  Number. 
  453 
  

  

  Group 
  III. 
  

  

  The 
  compounds 
  met 
  with 
  in 
  connexion 
  with 
  elements 
  of 
  

   the 
  third 
  group 
  do 
  not 
  require 
  much 
  discussion. 
  The 
  

   melting-points 
  of 
  boron 
  oxide 
  and 
  boric 
  acid 
  are 
  determi- 
  

   nations 
  of 
  Carnelley 
  in 
  1878, 
  whilst 
  those 
  for 
  aluminium 
  

   bromide 
  and 
  aluminium 
  iodide 
  are 
  of 
  an 
  even 
  earlier 
  date, 
  

   for 
  these 
  latter 
  compounds 
  the 
  degree 
  of 
  molecular 
  asso- 
  

   ciation 
  is 
  uncertain 
  also. 
  

  

  The 
  results 
  for 
  the 
  compounds 
  of 
  thallium 
  form 
  a 
  fairly 
  

   consistent 
  series, 
  and 
  it 
  is 
  of 
  interest 
  to 
  compare 
  the 
  frequency 
  

   numbers 
  with 
  those 
  previously 
  given 
  for 
  the 
  compounds 
  of 
  

   the 
  alkali 
  metals. 
  The 
  mean 
  value 
  of 
  v 
  A 
  deduced 
  from 
  the 
  

   thallium 
  salts 
  is 
  21'05 
  x 
  10 
  12 
  sec. 
  _1 
  , 
  and 
  the 
  chance 
  that 
  the 
  

   agreement 
  should 
  be 
  purely 
  accidental 
  is 
  about 
  1 
  in 
  39. 
  

  

  Group 
  III. 
  

   Boron 
  Compounds 
  (N 
  = 
  5). 
  

  

  Name. 
  Formula. 
  N. 
  vXlO 
  -12 
  . 
  NvXlO 
  -12 
  . 
  

   Boron 
  

  

  oxide 
  C 
  B 
  2 
  3 
  34 
  3'185 
  5x217 
  

  

  sulphide 
  tri 
  B.,S 
  3 
  58 
  1-613 
  4|x20*8 
  

  

  penta 
  B 
  2 
  S 
  5 
  90 
  1-271 
  5|x208 
  

  

  Boric 
  

  

  acidC 
  H3BO3 
  32 
  2-387 
  3|x21-8 
  

  

  Aluminium 
  Compounds 
  (N 
  = 
  13). 
  

   Aluminium 
  

  

  bromide 
  Al.,Br 
  6 
  236 
  0-858 
  5 
  X203 
  

  

  iodide 
  A] 
  2 
  I 
  6 
  344 
  0682 
  5^x21-3 
  

  

  oxide 
  A1 
  2 
  3 
  50 
  4-949 
  12 
  X206 
  

  

  sulphide 
  A1 
  2 
  S 
  3 
  76 
  2*212 
  8 
  x20*5 
  

  

  Yttrium 
  Compound 
  (N 
  = 
  39). 
  

   Yttrium 
  

   chloride 
  YtCl 
  3 
  90 
  1-114 
  5x20-1 
  

  

  Lanthanum 
  Compound 
  (N 
  = 
  57). 
  

   Lanthanum 
  

   chloride 
  LaCl 
  3 
  108 
  1*693 
  9x20'3 
  

  

  Cerium 
  Compound 
  (N 
  = 
  58). 
  

   Cerous 
  

  

  chloride 
  CeCJ 
  3 
  109 
  1*645 
  9x20'0 
  

  

  Thallium 
  Compounds 
  (N 
  = 
  81). 
  

   Thallium 
  

  

  bromide 
  TlBr 
  2 
  116 
  1466 
  8 
  X21-3 
  

  

  carbonate 
  Tl 
  o 
  C0 
  3 
  192 
  0825 
  7|X2M 
  

  

  chloride 
  T1C1 
  98 
  1-623 
  6 
  X211 
  

  

  iodide 
  Til 
  134 
  1247 
  8 
  x20"9 
  

  

  nitrate 
  T1N0 
  3 
  112 
  M37 
  6 
  X212 
  

  

  oxide 
  (-ic) 
  T1 
  2 
  G 
  3 
  186 
  1*067 
  9^x20-9 
  

  

  perchlorate 
  T1C10 
  4 
  130 
  1*310 
  8^x21-3 
  

  

  sulphate 
  T1 
  2 
  S0 
  4 
  210 
  0-981 
  10 
  X206 
  

  

  