﻿G. 
  P. 
  Merrill 
  — 
  Calcium 
  Phosphate 
  in 
  Meteoric 
  Stones. 
  323 
  

  

  visionally 
  referred 
  to 
  francolite. 
  Three 
  of 
  these 
  occurrences 
  

   in 
  a 
  single 
  slide 
  (No. 
  62-a) 
  are 
  figured 
  herewith, 
  the 
  actual 
  

   diameters 
  being 
  from 
  0*5 
  to 
  l'5 
  uim 
  . 
  The 
  mineral 
  is 
  in 
  all 
  cases 
  

   colorless, 
  without 
  crystal 
  outline 
  (its 
  form 
  being 
  controlled 
  by 
  

   that 
  of 
  the 
  interstices 
  in 
  which 
  it 
  occurs), 
  no 
  definite 
  cleavage, 
  

   a 
  complete 
  lack 
  of 
  pleochroism, 
  polarizing 
  if 
  at 
  all 
  only 
  in 
  light 
  

   and 
  dark 
  colors, 
  sometimes 
  almost 
  completely 
  isotropic, 
  and 
  

   giving 
  at 
  best 
  poor 
  interference 
  figures 
  indicative 
  of 
  its 
  biaxial 
  

   nature. 
  The 
  isotropic 
  sections 
  are 
  so 
  colorless 
  and 
  lacking 
  

   relief 
  that 
  on 
  hasty 
  inspection 
  such 
  might 
  be 
  mistaken 
  for 
  

   holes 
  in 
  the 
  slide, 
  a 
  glass, 
  or 
  even 
  

   the 
  problematic 
  maskelynite. 
  Once 
  

   seen, 
  however, 
  they 
  are 
  readily 
  

   recognizable. 
  In 
  the 
  three 
  forms 
  

   here 
  figured 
  the 
  position 
  of 
  maxi- 
  

   mum 
  extinction 
  is 
  shown 
  by 
  the 
  

   small 
  black 
  cross. 
  In 
  the 
  case 
  of 
  

   the 
  larger 
  form, 
  the 
  black 
  brushes 
  

   of 
  the 
  hyperbola 
  emanating 
  from 
  a 
  

   point 
  outside 
  the 
  field 
  of 
  view, 
  

   indicative 
  of 
  its 
  biaxial 
  character, 
  

   are 
  readily 
  obtained. 
  The 
  phos- 
  

   phatic 
  nature 
  of 
  the 
  mineral 
  has 
  

   been 
  determined 
  beyond 
  question 
  

   by 
  the 
  usual 
  microchemical 
  method. 
  

   An 
  attempt 
  at 
  a 
  quantitative 
  deter- 
  

   mination 
  was 
  made, 
  but 
  with 
  unsat- 
  

   isfactory 
  results. 
  

  

  Studies 
  of 
  thin 
  sections 
  of 
  the 
  

   Waconda, 
  Kansas, 
  stone, 
  a 
  rede- 
  

   scription 
  of 
  which 
  is 
  in 
  process 
  of 
  

   preparation, 
  reveal 
  the 
  presence 
  of 
  

   the 
  phosphate 
  even 
  where 
  it 
  can 
  not 
  

   be 
  determined 
  microscopically. 
  It 
  

  

  was 
  found 
  that 
  when 
  the 
  surface 
  of 
  an 
  uncovered 
  slide 
  was 
  

   treated 
  for 
  but 
  a 
  few 
  minutes 
  with 
  a 
  dilute 
  acid 
  the 
  solution 
  

   obtained 
  would 
  react 
  for 
  both 
  calcium 
  and 
  phosphorus, 
  and 
  

   the 
  slide 
  when 
  again 
  placed 
  under 
  the 
  microscope 
  be 
  found 
  to 
  

   contain 
  numerous 
  minute 
  and 
  irregular 
  cavities 
  left 
  by 
  the 
  

   dissolving 
  away 
  of 
  the 
  mineral. 
  A 
  quantitative 
  analysis 
  shows 
  

   the 
  presence 
  of 
  0*26^ 
  P 
  2 
  5 
  in 
  the 
  stony 
  portion, 
  or 
  0*23^ 
  in 
  the 
  

   bulk 
  or 
  mass 
  analysis. 
  

  

  Unmistakable 
  evidences 
  of 
  the 
  presence 
  of 
  the 
  phosphate 
  I 
  

   have 
  thus 
  far 
  found 
  in 
  the 
  stones 
  of 
  Alfianello, 
  Bath 
  (South 
  

   Dakota), 
  Bluff, 
  Dhurmsala, 
  Estherville, 
  Farmington, 
  Felix, 
  

   Homestead, 
  Indarch, 
  Knyahinya, 
  Mocs, 
  Plainview, 
  Pnltusk, 
  

   Quenggouk, 
  Rich 
  Mountain, 
  and 
  Waconda. 
  

  

  