﻿348 
  Clarice 
  and 
  Steiger 
  — 
  Action 
  of 
  Ammonium 
  Chloride 
  

  

  species 
  is 
  perfectly 
  clear. 
  This 
  fact 
  is 
  further 
  emphasized 
  by 
  

   an 
  experiment 
  upon 
  the 
  solubility 
  of 
  silica. 
  The 
  fresh 
  scole- 
  

   cite 
  gave 
  up 
  0'36 
  per 
  cent 
  of 
  silica 
  to 
  sodium 
  carbonate 
  solu- 
  

   tion, 
  and 
  the 
  ignited 
  mineral 
  yielded 
  only 
  0*50 
  per 
  cent. 
  

   Again, 
  natrolite 
  and 
  scolecite 
  behave 
  in 
  the 
  same 
  way. 
  

  

  Upon 
  both 
  minerals 
  fractional 
  determinations 
  of 
  the 
  water 
  

   were 
  made, 
  and 
  the 
  amount 
  lost 
  at 
  each 
  temperature 
  was 
  noted. 
  

   The 
  results, 
  expressed 
  in 
  percentages 
  of 
  the 
  original 
  minerals, 
  

   were 
  as 
  follows 
  : 
  

  

  

  

  Water 
  lost. 
  

  

  

  Temperature. 
  

  

  Natrolite. 
  

  

  

  Scolecite. 
  

  

  100° 
  

  

  .. 
  -39 
  

  

  

  •40 
  

  

  180 
  p 
  

  

  ... 
  '40 
  

  

  

  •52 
  

  

  250° 
  

  

  ... 
  -37 
  

  

  4'76 
  

  

  350° 
  

  

  ... 
  8-51 
  

  

  

  •55 
  

  

  Incipient 
  redness. 
  

  

  ... 
  -72 
  

  

  

  7-72 
  

  

  Full 
  redness 
  

  

  ... 
  -12 
  

  

  

  •04 
  

  

  Over 
  blast 
  

  

  _. 
  -06 
  

  

  

  •06 
  

  

  10-57 
  14-05 
  

  

  Scolecite 
  contains 
  one 
  more 
  molecule 
  of 
  water 
  than 
  natrolite, 
  

   and 
  that 
  amount, 
  one-third 
  of 
  its 
  total, 
  seems 
  to 
  go 
  off 
  at 
  a 
  

   lower 
  temperature 
  than 
  the 
  other 
  two 
  molecules. 
  Otherwise 
  

   the 
  two 
  series 
  of 
  experiments 
  are 
  probably 
  not 
  far 
  apart, 
  and 
  

   they 
  indicate 
  that 
  the 
  water 
  is 
  in 
  neither 
  case 
  constitutional. 
  

   The 
  same 
  conclusion 
  is 
  suggested 
  by 
  the 
  existence 
  of 
  the 
  

   anhydrous 
  ammonium 
  compound, 
  the 
  three 
  formulae 
  being 
  as 
  

   follows 
  : 
  

  

  Scolecite 
  CaAl 
  2 
  Si 
  3 
  O 
  10 
  . 
  3ll 
  2 
  

  

  Natrolite 
  Na 
  2 
  Al 
  2 
  Si 
  3 
  O 
  10 
  . 
  2H 
  2 
  

  

  Ammonium 
  natrolite 
  . 
  , 
  (NH 
  4 
  ) 
  2 
  Al 
  2 
  Si 
  3 
  O 
  10 
  . 
  

  

  The 
  parallelism 
  is 
  complete; 
  and 
  all 
  three 
  compounds 
  are 
  

   evidently 
  salts 
  of 
  an 
  acid 
  H 
  8 
  Si 
  3 
  O 
  10 
  , 
  which 
  is 
  probably 
  ortho- 
  

   trisilicic 
  acid, 
  Si 
  3 
  2 
  (OH) 
  8 
  . 
  The 
  second 
  anhydride 
  of 
  this 
  acid, 
  

   H 
  4 
  Si 
  3 
  8 
  , 
  would 
  be 
  the 
  ordinary 
  trisilicic 
  acid 
  of 
  orthoclase 
  and 
  

   albite 
  ; 
  a 
  relation 
  which 
  is 
  certainly 
  suggestive. 
  We 
  do 
  not, 
  

   however, 
  care 
  to 
  enter 
  upon 
  the 
  question 
  of 
  chemical 
  structure 
  

   in 
  this 
  paper, 
  and 
  we 
  therefore 
  leave 
  the 
  subject 
  for 
  fuller 
  con- 
  

   sideration 
  at 
  some 
  future 
  time. 
  It 
  is 
  clear, 
  however, 
  that 
  

   orthosilicate 
  formulae 
  for 
  natrolite 
  and 
  scolecite 
  must 
  be 
  dis- 
  

   carded. 
  

  

  Prehnite. 
  

  

  The 
  prehnite 
  taken 
  for 
  examination 
  was 
  an 
  old 
  specimen 
  

   from 
  Paterson, 
  New 
  Jersey. 
  The 
  analysis, 
  with 
  fractional 
  

   water 
  determinations, 
  is 
  given 
  below. 
  

  

  