﻿Frequency 
  and 
  Molecular 
  JS 
  umber. 
  451 
  

  

  Group 
  II. 
  

  

  On 
  the 
  whole 
  the 
  results 
  tor 
  compounds 
  containing 
  

   elements 
  belonging 
  to 
  the 
  second 
  group 
  are 
  less 
  reliable 
  

   than 
  those 
  already 
  considered. 
  This 
  arises 
  partly 
  from 
  the 
  

   fact 
  that 
  in 
  many 
  cases 
  there 
  is 
  uncertainty 
  as 
  to 
  the 
  true 
  

   value 
  of 
  the 
  melting-point, 
  no 
  values 
  later 
  than 
  those 
  of 
  

   Carnelley 
  being 
  recorded 
  for 
  several 
  compounds*; 
  further, 
  

   the 
  product 
  Ni/ 
  is 
  in 
  general 
  greater 
  for 
  these 
  compounds 
  

   than 
  it 
  is 
  for 
  the 
  corresponding 
  compounds 
  containing 
  

   elements 
  of 
  the 
  first 
  group, 
  so 
  that 
  larger 
  frequency 
  numbers 
  

   are 
  required. 
  Consequently 
  the 
  frequency 
  numbers 
  given 
  in 
  

   the 
  following 
  Tables 
  are 
  not 
  to 
  be 
  regarded 
  in 
  all 
  cases 
  as 
  

   final; 
  some 
  of 
  them 
  — 
  especially 
  amongst 
  the 
  larger 
  numbers 
  

   — 
  may 
  require 
  revision 
  when 
  more 
  exact 
  data 
  have 
  been 
  

   obtained. 
  

  

  In 
  spite 
  of 
  such 
  uncertainties 
  a 
  comparison 
  between 
  the 
  

   compounds 
  in 
  these 
  Tables, 
  and 
  also 
  between 
  these 
  and 
  the 
  

   corresponding 
  compounds 
  for 
  the 
  first 
  group, 
  will 
  show 
  

   many 
  suggestive 
  relationships. 
  

  

  Group 
  II. 
  

  

  Beryllium 
  Compounds 
  (N 
  = 
  4). 
  

  

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

   Beryllium 
  

  

  fluoride 
  BeF 
  a 
  22 
  5-213 
  5^x20*9 
  

  

  iodide 
  Bel 
  2 
  110 
  1*339 
  7"x21*0 
  

  

  Magnesium 
  Compounds 
  (N 
  = 
  12). 
  

   Magnesium 
  

  

  chloride 
  C 
  MgCl 
  2 
  46 
  2-807 
  6x21-5 
  

  

  fluoride 
  C 
  MgF 
  2 
  30 
  5*446 
  8x20-4 
  

  

  Calcium 
  Compounds 
  (N 
  = 
  20). 
  

   Calcium 
  

  

  aluminate 
  CaAl 
  2 
  4 
  78 
  3-011 
  ll|x20'4 
  

  

  bromide 
  CaBr 
  2 
  90 
  1*783 
  8x20-1 
  

  

  chloride 
  CaCl 
  2 
  54 
  2-302 
  6 
  X20*7 
  

  

  fluoride 
  CaF 
  2 
  38 
  4757 
  9 
  x20\L 
  

  

  iodide 
  Cal 
  2 
  126 
  1-464 
  9x20"5 
  

  

  nitrate 
  (a) 
  C 
  Ca(K0 
  3 
  ) 
  2 
  82 
  1-715 
  7x20-1 
  

  

  nitride 
  Ca 
  3 
  N 
  2 
  74 
  2*532 
  9 
  X20-8 
  

  

  oxide 
  CaO 
  28 
  7-696 
  10^x20-5 
  

  

  silicate 
  CaSiOs 
  58 
  3-531 
  l(fx20-5 
  

  

  sulphate 
  CaS0 
  4 
  68 
  2-979 
  10 
  X203 
  

  

  (a) 
  Highest 
  density 
  recorded, 
  2*472 
  (Lnndolt-Bornstein). 
  

  

  * 
  These 
  cases 
  are 
  indicated 
  in 
  the 
  tables 
  by 
  the 
  letter 
  C 
  following 
  the 
  

   name 
  of 
  the 
  compound. 
  

  

  