﻿20 
  W. 
  P. 
  White 
  — 
  Silicate 
  Specific 
  Heats. 
  

  

  The 
  mean 
  atomic 
  interval 
  heats 
  in 
  Table 
  VI 
  are 
  

   obtained 
  by 
  multiplying 
  the 
  interval 
  specific 
  heats 
  by 
  

   the 
  mean 
  atomic 
  weights 
  of 
  Table 
  V. 
  They 
  are 
  liable 
  to 
  

   slight, 
  quite 
  constant 
  errors 
  due 
  to 
  possible 
  error 
  in 
  the 
  

   value 
  taken 
  for 
  the 
  mean 
  atomic 
  weight, 
  especially 
  in 
  the 
  

   natural 
  minerals 
  and 
  their 
  glasses. 
  

  

  The 
  "true" 
  or 
  "instantaneous" 
  mean 
  atomic 
  heats, 
  or 
  

   atomic 
  heats 
  at 
  definite 
  temperatures, 
  obtained 
  by 
  the 
  

   procedures 
  already 
  described, 
  are 
  given 
  in 
  Table 
  VII. 
  

   The 
  true 
  specific 
  heats 
  can 
  of 
  course 
  be 
  obtained 
  from 
  

   them 
  by 
  dividing 
  by 
  the 
  numbers 
  in 
  Table 
  V. 
  

  

  Comparison 
  with 
  Previous 
  Work. 
  

  

  The 
  present 
  results 
  indicate 
  that 
  my 
  results 
  published 
  

   in 
  1909 
  were 
  correct 
  to 
  the 
  degree 
  there 
  estimated, 
  5 
  per 
  

   mille. 
  On 
  the 
  whole, 
  the 
  differences 
  are 
  not 
  systematic. 
  

   K. 
  Schulz 
  19 
  has 
  given 
  a 
  list 
  of 
  published 
  specific 
  heat 
  

   determinations 
  made 
  on 
  minerals 
  and 
  other 
  solids 
  from 
  

   1831 
  to 
  1912. 
  In 
  this 
  list, 
  microcline 
  and 
  quartz 
  and 
  the 
  

   corresponding 
  glasses 
  are 
  the 
  only 
  substances 
  which 
  also 
  

   appear 
  in 
  the 
  present 
  paper. 
  

  

  For 
  both 
  quartz 
  and 
  orthoclase 
  or 
  microcline 
  the 
  

   observers 
  frequently 
  differ 
  from 
  themselves 
  by 
  1 
  per 
  cent 
  

   or 
  more, 
  and 
  for 
  quartz, 
  where 
  the 
  results 
  of 
  different 
  

   observers 
  were 
  compared, 
  20 
  the 
  differences 
  between 
  them 
  

   were 
  somewhat 
  larger. 
  This 
  applies 
  to 
  results 
  between 
  

   0° 
  and 
  100°. 
  At 
  higher 
  temperatures 
  the 
  discrepancies 
  

   were 
  larger 
  still. 
  Bartoli 
  (1891) 
  was 
  30 
  per 
  cent 
  above 
  

   the 
  present 
  paper 
  for 
  quartz 
  from 
  30° 
  to 
  530°, 
  though 
  he 
  

   agreed 
  at 
  100° 
  to 
  1/2 
  per 
  cent, 
  or 
  best 
  of 
  all 
  in 
  the 
  list. 
  

   For 
  silica 
  glass 
  Dieterici 
  (1905) 
  agrees 
  to 
  0-5 
  per 
  mille, 
  

   that 
  is, 
  practically 
  perfectly, 
  at 
  100°. 
  At 
  300° 
  he 
  comes 
  

   5 
  per 
  mille 
  lower. 
  Our 
  result 
  at 
  300° 
  is 
  a 
  preliminary 
  

   determination, 
  and 
  should 
  be 
  too 
  low 
  if 
  anything, 
  so 
  there 
  

   is 
  a 
  real 
  discrepancy 
  here. 
  Heinrichs 
  (1906) 
  is 
  1/2 
  

   per 
  cent 
  higher 
  at 
  100° 
  and 
  at 
  300°. 
  Stierlin 
  (1907) 
  is 
  

   over 
  2 
  per 
  cent 
  higher, 
  and 
  Schulz 
  (1912) 
  nearly 
  one 
  per 
  

   cent 
  higher, 
  at 
  100°. 
  (Schulz 
  was 
  nearly 
  2 
  per 
  cent 
  

  

  10 
  K. 
  Schulz, 
  Die 
  spezifisehe 
  Warme 
  der 
  Mineralien 
  und 
  der 
  kunstlich 
  

   hergestellten 
  Stoffe 
  von 
  entsprechender 
  Zusammensetzung, 
  Fortschr. 
  der 
  

   Mineralogie, 
  2, 
  259, 
  1912, 
  3, 
  273, 
  1913. 
  

  

  20 
  By 
  comparing 
  each 
  of 
  them 
  with 
  the 
  corresponding 
  value 
  from 
  equation 
  

   4, 
  which 
  could 
  be 
  applied 
  to 
  the 
  very 
  various 
  temperature 
  intervals 
  involved. 
  

  

  