﻿F. 
  W. 
  Glarhe 
  — 
  Constitution 
  of 
  Tourmaline. 
  

  

  117 
  

  

  The 
  reduced 
  analyses 
  and 
  tlieir 
  comparison 
  with 
  the 
  calcu- 
  

   lated 
  composition 
  is 
  as 
  follows 
  : 
  

  

  SiO,-. 
  

  

  BA- 
  

  

  AlA- 
  

   FeO.. 
  

  

  CaO_. 
  

  

  Na,0. 
  

  

  H,0.. 
  

  

  Found. 
  

   Stony 
  Pt. 
  

  

  34-10 
  

  

  9-98 
  

  

  32-37 
  

  

  17-33 
  

  

  •52 
  

  

  2-22 
  

  

  3-48 
  

  

  Found. 
  

   Brazil. 
  

  

  34-26 
  

  

  9-54 
  

  

  32-54 
  

  

  17-45 
  

  

  •33 
  

  

  2-40 
  

  

  3-48 
  

  

  Calc. 
  

   A13B2C9. 
  

  

  34-27 
  

  

  9-99 
  

  

  32-36 
  

  

  17-14 
  

  

  -45 
  

  

  2-22 
  

  

  3-57 
  

  

  Found. 
  

   Auburn. 
  

  

  34-75 
  

  

  9-56 
  

  

  33-73 
  

  

  15-99 
  

  

  •15 
  

  

  2-23 
  

  

  3-59 
  

  

  Calc. 
  

  

  A36B2C2- 
  

  

  34-48 
  

  

  10-06 
  

  

  33-28 
  

  

  15-95 
  

  

  -17 
  

  

  2-50 
  

  

  3-56 
  

  

  Found. 
  

   Paris. 
  

  

  34^70 
  

  

  8-94 
  

  

  34^82 
  

  

  15^30 
  

  

  •25 
  

  

  2-33 
  

  

  3-66 
  

  

  Calc. 
  

   A10B1C9 
  

  

  34-62 
  

   10-10 
  

   33-60 
  

   15^23 
  

  

  •27 
  

   2^67 
  

   3-51 
  

  

  100-00 
  100-00 
  100-00 
  100-00 
  100-00 
  100-00 
  100-00 
  

  

  Here 
  again 
  the 
  agreements 
  between 
  analysis 
  and 
  theory 
  are 
  

   as 
  close 
  as 
  could 
  be 
  reasonably 
  expected. 
  The 
  same 
  thing 
  is 
  

   true 
  of 
  the 
  black 
  tourmalines 
  from 
  Haddam, 
  Conn., 
  and 
  I^antic 
  

  

  Gulf. 
  Using 
  letters 
  to 
  represent 
  the 
  several 
  molecules, 
  as 
  

   above, 
  the 
  Haddam 
  mineral 
  is 
  sharply 
  represented 
  by 
  A^B^I).,, 
  

   and 
  that 
  from 
  Nantic 
  Gulf 
  by 
  AgB^CgE^. 
  Here 
  is 
  the 
  com- 
  

   parison 
  : 
  

  

  Haddam. 
  Nantic 
  Gulf. 
  

  

  Found. 
  Reduced. 
  

  

  SiO, 
  34 
  

  

  BA---- 
  9 
  

  

  TiO, 
  

  

  AlA 
  ---- 
  31 
  

   FeA 
  -- 
  

  

  FeO 
  11 
  

  

  MnO 
  

  

  MgO 
  4 
  

  

  CaO 
  ., 
  

  

  Na,0 
  ..._ 
  2 
  

  

  K,0 
  

  

  HO 
  3 
  

  

  -95 
  

   •92 
  

   •57 
  

   •11 
  

  

  •50 
  

   •87 
  

   •09 
  

   •45 
  

   •81 
  

   •22 
  

   •24 
  

   •62 
  

  

  33-78 
  

   9-60 
  

  

  30-74 
  

  

  19-31 
  

  

  •78 
  

   2^30 
  

  

  3-49 
  

  

  Calc. 
  

   33-67 
  

  

  9-82 
  

  

  30-67 
  

   19-24 
  

  

  •75 
  

  

  2-48 
  

  

  3-37 
  

  

  100-35 
  100-00 
  100-00 
  

  

  Found. 
  

   35-34 
  

   10-45 
  

   -40 
  

   30-49 
  

  

  8-22 
  

   trace 
  

   7^76 
  

   2-32 
  

   1-76 
  

   •15 
  

   3^60 
  

  

  100^49 
  

  

  Reduced. 
  

   33^34 
  

  

  9-86 
  

  

  29^01 
  

   20-46 
  

  

  2-19 
  

   1-74 
  

  

  3-40 
  

  

  Calc. 
  

   33-60 
  

   9-80 
  

  

  28-84 
  

  

  20-55 
  

  

  2-15 
  

   1-70 
  

  

  3-36 
  

  

  100-00 
  100-00 
  

  

  To 
  the 
  lithia 
  tourmalines, 
  as 
  analyzed 
  by 
  Riggs, 
  a 
  similar 
  set 
  

   of 
  formulse 
  apply, 
  although 
  the 
  comparison 
  between 
  fact 
  and 
  

   theory 
  is 
  not 
  quite 
  so 
  close 
  as 
  in 
  the 
  preceding 
  cases. 
  The 
  red 
  

   tourmalines 
  from 
  Brazil 
  and 
  from 
  Rumford, 
  Maine, 
  are 
  very 
  

   nearly 
  represented 
  by 
  the 
  expression 
  

  

  Al,(SiO.).(BOJ, 
  . 
  B03R'H 
  . 
  Al.R'H, 
  ; 
  

  

  with 
  Li:Na 
  approximately 
  as 
  5:4. 
  The 
  slight 
  deficiency 
  in 
  

   the 
  alkalies 
  is 
  made 
  up 
  by 
  the 
  presence 
  of 
  small 
  amounts 
  of 
  

   calcium, 
  iron 
  and 
  manganese 
  ; 
  but 
  the 
  ratio 
  Alg 
  : 
  Sig 
  is 
  very 
  

  

  