﻿32 
  

  

  W. 
  P. 
  White 
  — 
  Silicate 
  Specific 
  Heats. 
  

  

  has 
  been 
  connected 
  with 
  the 
  inversion 
  phenomena 
  of 
  

   silica 
  by 
  Fenner 
  and 
  by 
  Smits, 
  42 
  and 
  seems 
  to 
  deserve 
  

   further 
  mention 
  here. 
  The 
  European 
  writers 
  who 
  have 
  

   presented 
  the 
  theory 
  have 
  differed 
  quite 
  warmly 
  among 
  

   themselves, 
  but 
  seem 
  to 
  be 
  in 
  agreement 
  upon 
  as 
  much 
  of 
  

   the 
  theory 
  as 
  is 
  of 
  importance 
  in 
  this 
  paper. 
  Its 
  essen- 
  

   tials 
  will 
  probably 
  be 
  clear 
  in 
  the 
  light 
  of 
  figs. 
  2, 
  3, 
  4. 
  

   Fig. 
  2 
  is 
  the 
  common 
  melting 
  diagram 
  of 
  a 
  2-component 
  

   system, 
  where 
  the 
  two 
  components 
  dissolve 
  each 
  other 
  in 
  

  

  Fig. 
  2. 
  

  

  

  v, 
  

  

  V 
  

  

  / 
  > 
  

  

  1 
  1 
  

  

  

  w 
  

  

  J 
  

  

  f 
  

  

  

  ' 
  /• 
  

  

  Z 
  

  

  P 
  Q 
  

  

  ■*- 
  

   O 
  

   L. 
  

   W 
  

   Q. 
  

  

  E 
  

  

  A 
  Concentration 
  B 
  

  

  the 
  liquid 
  state, 
  but 
  not 
  completely 
  in 
  the 
  solid. 
  Motion 
  

   from 
  left 
  to 
  right 
  in 
  this 
  diagram 
  corresponds 
  to 
  a 
  change 
  

   of 
  composition. 
  The 
  mixture 
  of 
  composition 
  V, 
  if 
  cooled 
  

   in 
  the 
  liquid 
  state, 
  does 
  not 
  at 
  first 
  change 
  its 
  composi- 
  

   tion 
  and 
  thus 
  its 
  representative 
  point 
  on 
  the 
  diagram 
  

   travels 
  vertically 
  down 
  VW. 
  It 
  will 
  usually 
  reach 
  some 
  

   temperature, 
  as 
  at 
  W, 
  at 
  which 
  one 
  of 
  the 
  components 
  

   begins 
  to 
  crystallize 
  out, 
  forming 
  a 
  solid 
  which 
  may 
  be 
  

   represented 
  in 
  composition 
  and 
  temperature 
  by 
  the 
  point 
  

   Y. 
  If 
  the 
  solid 
  component 
  B 
  can 
  take 
  A 
  up 
  into 
  its 
  

  

  "Fenner, 
  op. 
  cit., 
  p. 
  364; 
  Smits, 
  "Nouvelle 
  Theorie," 
  etc., 
  p. 
  31. 
  

  

  