﻿228 
  A. 
  P. 
  lioness 
  — 
  Etching 
  Figures 
  of 
  Beryl. 
  

  

  by 
  «, 
  b, 
  c 
  and 
  d 
  of 
  fig. 
  5. 
  All 
  of 
  the 
  figures 
  are 
  symmetrical 
  

   to 
  two 
  planes, 
  and 
  reveal 
  very 
  clearly 
  the 
  symmetry 
  of 
  the 
  

   unit 
  prism. 
  

  

  Base. 
  — 
  Immersion 
  in 
  the 
  fused 
  potassium 
  hydroxide 
  for 
  

   approximately 
  one 
  minute, 
  etched 
  the 
  base 
  very 
  successfully. 
  

   The 
  figures 
  as 
  they 
  first 
  became 
  visible 
  were 
  circular, 
  identical 
  

   with 
  those 
  produced 
  by 
  the 
  sodium 
  hydroxide, 
  and 
  very 
  shal- 
  

   low. 
  As 
  they 
  became 
  larger, 
  through 
  repeated 
  immersions 
  in 
  

   the 
  solvent, 
  small 
  faces 
  began 
  to 
  appear 
  ; 
  a 
  few 
  pits 
  became 
  

   dihexagonal, 
  others 
  appeared 
  to 
  possess 
  twenty-four 
  faces, 
  and 
  

   still 
  others 
  appeared 
  to 
  be 
  bounded 
  by 
  a 
  large 
  number 
  

   of 
  very 
  small 
  planes. 
  As 
  solution 
  continued, 
  this 
  series 
  of 
  

   small 
  faces 
  gave 
  rise 
  to 
  six 
  well-formed 
  planes, 
  forming 
  perfect 
  

   hexagonal 
  pits, 
  similar 
  to 
  those 
  produced 
  by 
  sodium 
  hydroxide, 
  

   but 
  differently 
  oriented 
  (iig. 
  3). 
  Instead 
  of_occupying 
  a 
  posi- 
  

   tion 
  with 
  their 
  edges 
  parallel 
  to 
  the 
  edge 
  1010/0001, 
  they 
  are 
  

   turned 
  through 
  a 
  revolution 
  of 
  thirty 
  degrees, 
  about 
  a 
  vertical 
  

   axis, 
  thus 
  the 
  one 
  hundred 
  and 
  twenty 
  degree 
  angles 
  of 
  the 
  

   figures 
  are 
  symmetrically 
  turned 
  toward 
  the 
  edges 
  of 
  the 
  face. 
  

   This 
  is 
  not 
  the 
  result 
  obtained 
  by 
  Traube* 
  in 
  his 
  investigation 
  

   of 
  the 
  etchings 
  on 
  beryl. 
  

  

  Pyramids. 
  — 
  The 
  first-order 
  pyramid 
  etched 
  with 
  consider- 
  

   able 
  difficulty, 
  in 
  fact, 
  only 
  after 
  repeated 
  immersions 
  in 
  the 
  po- 
  

   tassium 
  fusion 
  for 
  five 
  minutes 
  could 
  distinct 
  forms 
  be 
  observed 
  

   and 
  these 
  were 
  exceedingly 
  rare, 
  possibly 
  four 
  or 
  five 
  figures 
  

   scattered 
  over 
  a 
  considerable 
  surface. 
  After 
  only 
  a 
  brief 
  im- 
  

   mersion 
  in 
  the 
  fusion, 
  the 
  entire 
  face 
  assumed 
  a 
  fused, 
  glassy 
  

   appearance, 
  which 
  did 
  not 
  seem 
  to 
  change 
  as 
  the 
  figures 
  

   developed 
  ; 
  the 
  other 
  forms, 
  especially 
  the 
  base, 
  0001, 
  and 
  first- 
  

   order 
  prism, 
  1010, 
  became 
  beautifully 
  etched, 
  and 
  due 
  to 
  con- 
  

   tinued 
  immersion, 
  consequently 
  corroded 
  (fig. 
  6). 
  The 
  solu- 
  

   tion, 
  eating 
  into 
  the 
  first-order 
  pyramid 
  on 
  all 
  sides, 
  caused 
  the 
  

   edges 
  to 
  appear 
  rough 
  and 
  deeply 
  notched, 
  while 
  the 
  surface 
  

   maintained 
  that 
  fused, 
  glassy 
  appearance 
  (fig. 
  4), 
  and 
  even 
  the 
  

   figures 
  themselves 
  had 
  rounded, 
  glassy 
  -looking 
  margins. 
  

   Nevertheless, 
  the 
  etchings 
  are 
  distinct 
  and 
  bounded 
  by 
  three 
  

   faces, 
  the 
  intersections 
  of 
  which 
  with 
  the 
  crystal 
  face 
  are 
  

   curved. 
  The 
  figures 
  appear 
  as 
  fiattened 
  isosceles 
  triangles, 
  hav- 
  

   ing 
  but 
  little 
  depth, 
  with 
  the 
  apex 
  turned 
  upward, 
  the 
  longer 
  

   side 
  extending 
  parallel 
  to 
  the 
  edge 
  1011/1010 
  and 
  the 
  larger 
  

   plane 
  of 
  the 
  figure 
  lying 
  in 
  this 
  zone. 
  (See 
  diagram 
  E, 
  fig. 
  15.) 
  

   The 
  angle 
  at 
  the 
  apex 
  measures 
  approximately 
  one 
  hundred 
  

   sixteen 
  degrees. 
  These 
  figures 
  are 
  quite 
  similar 
  to 
  those 
  

   described 
  by 
  Traube,fand 
  although 
  his 
  figures 
  possess 
  a 
  fourth 
  

   plane, 
  extending 
  from 
  the 
  deeper 
  part 
  of 
  the 
  pit 
  to 
  the 
  apex, 
  

  

  *L. 
  c. 
  -fL. 
  c. 
  

  

  