﻿452 
  Hohbs 
  — 
  Crystal 
  Form 
  of 
  Borneol 
  and 
  Isoborneol. 
  

  

  prism 
  m, 
  oo 
  P 
  (1010). 
  Quite 
  frequently 
  the 
  former 
  appears 
  

   forming 
  two 
  opposite 
  sides 
  of 
  the 
  rhomboid, 
  the 
  other 
  two 
  sides 
  

   being 
  formed 
  by 
  the 
  prism 
  alone 
  (see 
  figure 
  3). 
  The 
  form 
  x 
  

   may 
  be 
  the 
  one 
  from 
  which 
  Traube 
  determined 
  the 
  axial 
  ratio 
  

  

  of 
  this 
  substance. 
  Determined 
  from 
  the 
  writer's 
  measurements 
  

   of 
  the 
  position 
  of 
  this 
  plane 
  the 
  axial 
  ratio 
  would 
  be 
  (consider- 
  

   ing 
  it 
  the 
  fundamental 
  rhombohedron) 
  c 
  = 
  1*589, 
  Traube's 
  

   value 
  being 
  c 
  = 
  141. 
  The 
  observed 
  forms 
  comprising 
  _this 
  

   combination 
  are 
  : 
  c, 
  oP 
  (0001) 
  ; 
  x, 
  |K 
  (5053) 
  ; 
  m, 
  oo 
  P(1010) 
  ; 
  

   t, 
  f 
  K 
  (2023) 
  ; 
  a, 
  5K- 
  (5051) 
  ; 
  and 
  e, 
  -4R 
  (4041). 
  The 
  forms 
  y, 
  

   ^R 
  and 
  r, 
  R 
  (or 
  yf-B.) 
  were 
  also 
  observed 
  on 
  one 
  crystal 
  but 
  

   their 
  sign 
  was 
  not 
  determined. 
  The 
  above 
  forms 
  were 
  identi- 
  

   fied 
  by 
  means 
  of 
  the 
  following 
  measurements 
  : 
  

  

  Average. 
  Calculated. 
  

  

  89° 
  59' 
  90° 
  0' 
  

  

  

  Measured. 
  

  

  caw, 
  

  

  89° 
  58' 
  

  

  

  89 
  59 
  

  

  C 
  /\ 
  t)u 
  } 
  

  

  62 
  31 
  

  

  

  60 
  17 
  

  

  

  61 
  26 
  

  

  e^e, 
  

  

  76 
  44 
  

  

  c~y> 
  

  

  10 
  30 
  

  

  

  10 
  43 
  

  

  c^z, 
  

  

  79 
  31 
  

  

  c^t, 
  

  

  36 
  54 
  

  

  c^r, 
  

  

  49 
  31 
  

  

  61 
  

  

  25 
  

  

  76 
  

  

  44 
  

  

  10 
  

  

  36 
  

  

  79 
  

  

  31 
  

  

  36 
  

  

  54 
  

  

  49 
  

  

  31 
  

  

  (R, 
  

  

  60 
  

  

  49 
  

  

  76 
  

  

  54 
  

  

  10 
  

  

  9 
  

  

  79 
  

  

  27 
  

  

  35 
  

  

  37 
  

  

  47 
  

  

  3 
  

  

  49 
  

  

  32 
  

  

  As 
  regards 
  color, 
  enclosures, 
  and 
  cleavage, 
  isoborneol 
  seems 
  

   to 
  differ 
  but 
  little 
  from 
  borneol. 
  The 
  great 
  difference 
  between 
  

   the 
  two 
  substances 
  is 
  seen 
  when 
  they 
  are 
  examined 
  in 
  prismatic 
  

   sections 
  in 
  parallel 
  polarized 
  light. 
  A 
  section 
  of 
  borneol 
  in 
  

   which 
  double 
  refraction 
  is 
  not 
  perceptible, 
  would 
  if 
  prepared 
  

   from 
  isoborneol 
  yield 
  yellow 
  of 
  the 
  first 
  order. 
  Sections 
  of 
  

   isoborneol 
  2 
  mm 
  . 
  in 
  thickness 
  yield, 
  when 
  the 
  interference 
  of 
  the 
  

   crystal 
  is 
  added 
  to 
  that 
  of 
  the 
  quarter 
  undulation 
  mica 
  plate, 
  

   violet 
  of 
  the 
  second 
  order, 
  whereas 
  similar 
  sections 
  of 
  borneol 
  

   yield 
  under 
  the 
  same 
  conditions 
  yellow 
  of 
  the 
  first 
  order. 
  The 
  

   optical 
  character 
  has 
  been 
  tested 
  on 
  a 
  considerable 
  number 
  of 
  

   crystals 
  and 
  found 
  to 
  be 
  always 
  negative. 
  The 
  substance 
  ex- 
  

   amined 
  by 
  Traube 
  is 
  reported 
  to 
  be 
  positive. 
  

  

  In 
  conclusion 
  I 
  would 
  express 
  my 
  thanks 
  to 
  Professor 
  

   Edward 
  Kremers 
  and 
  Mr. 
  Carl 
  G-. 
  Hunkel 
  of 
  the 
  Department 
  

   of 
  Pharmacy, 
  University 
  of 
  Wisconsin, 
  for 
  supplying 
  me 
  with 
  

   the 
  material 
  studied. 
  

  

  Mineralogical 
  Petrographical 
  Laboratory, 
  University 
  of 
  Wisconsin. 
  

  

  