﻿402 
  

  

  J. 
  H. 
  Pratt 
  — 
  Double 
  Halides 
  of 
  Coesi 
  

  

  um. 
  

  

  added 
  to 
  a 
  very 
  concentrated 
  solution 
  of 
  50 
  g. 
  of 
  rubidium 
  

   bromide. 
  It 
  crystallizes 
  in 
  beautiful 
  golden 
  yellow 
  crystals, 
  

   which 
  are 
  very 
  soluble 
  in 
  water, 
  giving 
  the 
  1 
  : 
  1 
  salt 
  on 
  recrys- 
  

   tallizing. 
  Careful 
  efforts 
  were 
  made 
  to 
  obtain 
  a 
  2 
  : 
  1 
  and 
  3 
  : 
  2 
  

   rubidium 
  thallic 
  bromide, 
  but 
  without 
  success. 
  Several 
  sepa- 
  

   rate 
  products, 
  made 
  under 
  very 
  different 
  conditions, 
  were 
  an- 
  

   alyzed 
  with 
  the 
  results 
  which 
  follow 
  : 
  

  

  

  Rubidium. 
  

  

  Thallium. 
  

  

  Bromine. 
  

  

  Water 
  

  

  A 
  

  

  28'57 
  

  

  

  49-29 
  

  

  2-49 
  

  

  B 
  

  

  

  20-39 
  

  

  49-66 
  

  

  

  C____ 
  _.. 
  

  

  28-18 
  

  

  20-59 
  

  

  

  

  D 
  

  

  28'03 
  

  

  20-16 
  

  

  49-42 
  

  

  

  E 
  

  

  27-70 
  

  

  20-33 
  

  

  50-28 
  

  

  

  F 
  

  

  

  20-64 
  

  

  

  

  G 
  .._ 
  _ 
  

  

  26-56 
  

  

  21-17 
  

  

  50-49 
  

  

  

  Calculated 
  for 
  

   Kb 
  TIBr 
  . 
  HO 
  

  

  i 
  26-76 
  

  

  21-28 
  

  

  50-08 
  

  

  1-88 
  

  

  The 
  somewhat 
  high 
  percentage 
  of 
  rubidium 
  and 
  the 
  low 
  

   percentage 
  of 
  thallium 
  found 
  in 
  the 
  first 
  four 
  analyses 
  is 
  prob- 
  

   ably 
  due 
  to 
  the 
  large 
  excess 
  of 
  rubidium 
  bro- 
  

   mide 
  in 
  the 
  concentrated 
  solutions 
  from 
  which 
  

   the 
  crystals 
  were 
  obtained. 
  As 
  more 
  thallic 
  

   bromide 
  was 
  added, 
  better 
  crystals 
  were 
  obtained 
  

   in 
  more 
  dilute 
  solutions, 
  which 
  give 
  percentages 
  

   agreeing 
  very 
  well 
  with 
  the 
  calculated. 
  

  

  The 
  crystallization 
  of 
  this 
  salt 
  is 
  tetragonal. 
  

   Doubly 
  terminated 
  crystals 
  were 
  obtained 
  up 
  to 
  

   a 
  length 
  of 
  6 
  mm 
  . 
  

  

  The 
  forms 
  observed 
  are 
  : 
  

  

  P 
  

  

  M 
  

  

  ^ 
  

  

  a, 
  100 
  m, 
  

  

  110 
  p, 
  111 
  

  

  

  <V 
  001 
  e, 
  

  

  101 
  

  

  habit 
  is 
  shown 
  in 
  fig. 
  3. 
  

  

  

  Axis 
  6= 
  0-80728; 
  001^101 
  

  

  = 
  38° 
  54' 
  45" 
  

  

  

  Measured. 
  

  

  Calculated. 
  

  

  e 
  ^ 
  e 
  t 
  101 
  ^101 
  

  

  *77° 
  49£' 
  

  

  

  a 
  /\ 
  e, 
  100/slOl 
  

  

  51° 
  6'; 
  51° 
  2' 
  

  

  , 
  51° 
  Si' 
  51° 
  Si 
  

  

  a 
  /yp, 
  100 
  /sill 
  

  

  57 
  52; 
  57 
  54 
  

  

  57 
  53 
  57 
  52 
  

  

  e 
  A.p, 
  101^111 
  

  

  32° 
  5'; 
  32 
  6 
  12' 
  32 
  8 
  

  

  o 
  ^p, 
  001 
  xs 
  111 
  

  

  48 
  51; 
  48 
  

  

  55 
  48 
  46 
  

  

  m/^p, 
  110/\ill 
  

  

  41 
  7; 
  41 
  

  

  4 
  41 
  13 
  

  

  The 
  crystals 
  show 
  a 
  weak 
  negative 
  double 
  refraction. 
  

  

  3:2 
  OcBsium 
  Thallic 
  Bromide, 
  Gs 
  z 
  Tl^Br 
  v 
  — 
  This 
  salt 
  was 
  

   observed, 
  as 
  yellowish 
  red 
  crystals, 
  when 
  1 
  to 
  15 
  g. 
  of 
  thallic 
  

   bromide 
  were 
  added 
  to 
  a 
  solution 
  of 
  50 
  g. 
  of 
  csesium 
  bromide. 
  

   It 
  was 
  always 
  obtained 
  in 
  small 
  striated 
  crystals, 
  which 
  were 
  

  

  