﻿W. 
  P. 
  White— 
  Silicate 
  Specific 
  Heats. 
  29 
  

  

  and 
  Kolb, 
  35 
  and 
  Wright 
  36 
  have 
  shown 
  that 
  the 
  volume 
  

   increases, 
  and 
  most 
  of 
  the 
  optical 
  properties 
  of 
  qnartz 
  

   also 
  change, 
  at 
  a 
  continually 
  increasing 
  rate 
  through 
  an 
  

   interval 
  of 
  400° 
  or 
  more 
  up 
  to 
  the 
  inversion, 
  after 
  which 
  

   the 
  volume 
  diminishes 
  slowly 
  for 
  an 
  interval 
  of 
  probably 
  

   500° 
  more. 
  The 
  specific 
  heat, 
  as 
  Table 
  VII 
  shows, 
  fol- 
  

   lows, 
  in 
  the 
  main, 
  these 
  other 
  changes. 
  But 
  if 
  the 
  effect 
  

   of 
  the 
  expansion 
  on 
  the 
  specific 
  heat 
  is 
  calculated 
  by 
  

   formula 
  6, 
  taking 
  for 
  the 
  compressibility 
  0-00000265, 
  the 
  

   value 
  at 
  room 
  temperatures, 
  a 
  remarkable 
  discrepancy 
  

   appears 
  as 
  is 
  shown 
  in 
  Table 
  IX. 
  The 
  increase 
  in 
  

   specific 
  heat, 
  great 
  as 
  it 
  is, 
  is, 
  even 
  at 
  25° 
  below 
  the 
  

  

  Table 
  IX. 
  

  

  Components 
  of 
  Atomic 
  Heat 
  of 
  Quartz 
  due 
  to 
  Expansion, 
  etc. 
  

  

  Q 
  p 
  -C 
  v 
  = 
  3340a 
  2 
  # 
  by 
  (6), 
  if 
  K 
  is 
  O'OOO 
  002 
  65 
  

  

  

  Ap 
  - 
  A 
  v 
  = 
  (C 
  ; 
  , 
  - 
  a) 
  x 
  

  

  20.1 
  = 
  

  

  = 
  67000a 
  2 
  #. 
  

  

  A 
  p 
  — 
  A, 
  taken 
  as 
  

  

  

  Expansion* 
  per 
  degree 
  

  

  A, 
  

  

  — 
  A 
  v 
  calc. 
  

  

  quartz 
  minus 
  

  

  

  in 
  parts 
  of 
  Vol. 
  at 
  0° 
  

  

  from 
  expansion 
  

  

  glass 
  

  

  100° 
  

  

  •000 
  043 
  36 
  

  

  

  0-0463 
  

  

  0060 
  

  

  300° 
  

  

  058 
  47 
  

  

  

  0-1313 
  

  

  0-170 
  

  

  500° 
  

  

  1290 
  

  

  

  •862 
  

  

  0-563 
  

  

  550° 
  

  

  2631 
  

  

  

  3-832 
  

  

  0-868 
  

  

  * 
  Taken 
  from 
  the 
  original 
  (not 
  fully 
  published) 
  data 
  of 
  Day, 
  Sosman, 
  

   and 
  Hostetter. 
  

  

  inversion 
  point, 
  over 
  4 
  times 
  too 
  small 
  to 
  acconnt 
  for 
  the 
  

   work 
  demanded 
  by 
  the 
  expansion. 
  This 
  result 
  is 
  dis- 
  

   cussed 
  later. 
  

  

  Cristobalite 
  undergoes 
  an 
  inversion 
  from 
  a-cristo- 
  

   balite 
  to 
  /^-cristobalite 
  at 
  from 
  198° 
  to 
  277 
  °, 
  37 
  which 
  it 
  was 
  

   not 
  convenient 
  to 
  investigate 
  in 
  detail 
  during 
  the 
  present 
  

   work. 
  There 
  is 
  little 
  doubt, 
  however, 
  from 
  the 
  relatively 
  

   high 
  specific 
  heat 
  of 
  cristobalite 
  at 
  100°, 
  that 
  the 
  cristo- 
  

   balite 
  inversion 
  is 
  of 
  the 
  same 
  type 
  as 
  that 
  of 
  quartz. 
  

   Moreover, 
  above 
  its 
  inversion 
  cristobalite 
  is 
  like 
  quartz 
  

   in 
  having 
  a 
  specific 
  heat 
  lower 
  than 
  that 
  of 
  silica 
  glass, 
  

   which 
  has 
  practically 
  no 
  expansion. 
  The 
  resulting 
  

   probability 
  of 
  a 
  negative 
  expansion 
  has 
  already 
  been 
  

   pointed 
  out. 
  

  

  85 
  F. 
  Einne 
  und 
  E. 
  Kolb, 
  Optisches 
  zur 
  Modifikationsanderung 
  von 
  a- 
  in 
  

   /3-Quarz 
  sowie 
  von 
  a- 
  in 
  ^-Leucit, 
  Neues 
  Jahrb., 
  1910, 
  2, 
  pp. 
  138-158 
  ; 
  

   Geometrisches 
  zur 
  Modifikationsanderung 
  von 
  a- 
  in 
  /3-Quarz, 
  Neues 
  Jahrb. 
  

   Centrbl. 
  1911, 
  pp. 
  65-74. 
  

  

  36 
  F. 
  E. 
  Wright, 
  The 
  Change 
  in 
  the 
  Crystal 
  Angles 
  of 
  Quartz 
  with 
  Bise 
  

   in 
  Temperature, 
  J. 
  Wash. 
  Acad. 
  Sci., 
  3, 
  485, 
  1913. 
  

  

  37 
  C. 
  N. 
  Fenner, 
  Stability 
  Eelations 
  of 
  Silica 
  Minerals, 
  this 
  Journal, 
  36, 
  

   369, 
  1913. 
  

  

  