﻿248 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OE 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  10 
  

  

  INORGANIC 
  CHEMISTRY.— 
  7/^£? 
  crystal 
  structures 
  of 
  the 
  alkali 
  

   halides} 
  II. 
  Eugen 
  Posnjak 
  and 
  Ralph 
  W. 
  G. 
  Wyckoff, 
  

   Geophysical 
  Laboratory, 
  Carnegie 
  Institution 
  of 
  Washington. 
  

  

  These 
  determinations 
  of 
  the 
  crystal 
  structures 
  of 
  the 
  halides 
  of 
  

   lithium 
  and 
  the 
  fluorides 
  of 
  the 
  alkali 
  metals 
  have 
  been 
  carried 
  out 
  by 
  

   the 
  same 
  procedure 
  and 
  with 
  the 
  same 
  apparatus 
  used 
  for 
  part 
  I 
  of 
  

   this 
  paper. 
  ^ 
  Except 
  for 
  RbF 
  and 
  CsF, 
  determinations 
  of 
  density 
  

   were 
  at 
  hand 
  for 
  use 
  in 
  finding 
  the 
  number 
  of 
  molecules 
  to 
  be 
  asso- 
  

   ciated 
  with 
  the 
  unit 
  cube. 
  In 
  all 
  cases 
  data 
  will 
  be 
  given 
  for 
  only 
  

   enough 
  lines 
  to 
  assure 
  the 
  correctness 
  of 
  the 
  chosen 
  structure. 
  In 
  

   every 
  instance 
  the 
  other 
  lines 
  that 
  appeared 
  gave 
  satisfactory 
  agree- 
  

   ment. 
  

  

  LITHIUM 
  FLUORIDE 
  

  

  This 
  salt 
  has 
  already 
  been 
  determined^ 
  to 
  have 
  the 
  "sodium 
  chlor- 
  

   ide' 
  ' 
  structure 
  (fig. 
  1 
  , 
  part 
  I) 
  . 
  According 
  to 
  this 
  previous 
  measurement 
  

   thelengthof 
  thesideof 
  theunitcubeis4.14 
  A. 
  U. 
  (or 
  4.14 
  X10~^cm.). 
  

  

  LITHIUM 
  CHLORIDE 
  

  

  Bstimated 
  Calculated 
  intensity 
  

  

  hkl 
  intensity 
  NaCl 
  grouping 
  ZnS 
  grouping 
  

  

  111 
  (1) 
  10 
  6,900 
  10,500 
  

  

  100 
  (2) 
  10 
  7,530 
  3,700 
  

  

  110 
  (2) 
  6 
  6,640 
  6,640 
  

  

  113 
  (1) 
  4 
  4,480 
  6,800 
  

  

  Calculated 
  density 
  = 
  2.02. 
  

   Spacing: 
  dioo 
  = 
  5.17 
  ± 
  0.02A. 
  U. 
  

   Structure: 
  NaCl 
  grouping 
  (fig. 
  1, 
  part 
  I). 
  

  

  LITHIUM 
  BROMIDE 
  

  

  Calculated 
  density 
  = 
  3.46. 
  

   Spacing: 
  dioo 
  = 
  5.48 
  =t 
  0.02 
  A. 
  U. 
  

   Structure; 
  NaCl 
  grouping. 
  

  

  1 
  Received 
  April 
  20, 
  1922. 
  

  

  2 
  Ralph 
  W. 
  G. 
  Wyckoff. 
  This 
  Journal 
  11: 
  429. 
  1921. 
  

  

  3 
  P. 
  Debye 
  and 
  P. 
  vScherrer. 
  Phys. 
  Z. 
  17: 
  277. 
  1916. 
  

  

  