﻿246 
  Clarke 
  and 
  Steiger 
  — 
  Experiments 
  with 
  Pectolite, 
  etc. 
  

  

  but 
  the 
  analysis 
  shows 
  that 
  it 
  contained 
  some 
  carbonate 
  as 
  an 
  

   impurity. 
  Enough 
  of 
  the 
  material 
  was 
  ground 
  up 
  to 
  furnish 
  

   a 
  uniform 
  sample 
  for 
  the 
  entire 
  series 
  of 
  experiments, 
  and 
  the 
  

   work 
  properly 
  began 
  with 
  a 
  complete 
  analysis. 
  The 
  results 
  

   obtained 
  are 
  as 
  follows 
  : 
  

  

  Analysis. 
  Fractional 
  water. 
  

  

  SiO, 
  > 
  53-34 
  Water 
  at 
  105° 
  027 
  

  

  AIP3 
  -33 
  " 
  "180° 
  0-16 
  

  

  CaO 
  33-23 
  " 
  "300° 
  0-22 
  

  

  MnO 
  -45 
  " 
  "redness... 
  2-32 
  

  

  Na,0 
  9-11 
  

  

  Total 
  H,0 
  ... 
  2-97 
  2-9' 
  

  

  C0„ 
  _-. 
  -67 
  

  

  100-10 
  

  

  All 
  of 
  the 
  water 
  was 
  given 
  off 
  at 
  a 
  barely 
  visible 
  red 
  heat 
  ; 
  

   and 
  the 
  figures 
  show 
  that 
  practically 
  all 
  of 
  it 
  is 
  constitutional 
  ; 
  

   a 
  fact 
  which 
  perhaps 
  hardly 
  needed 
  reverification. 
  The 
  analy- 
  

   sis 
  gives 
  the 
  accepted 
  formula 
  for 
  pectolite, 
  

  

  HNaCa,Si30, 
  . 
  

  

  Does 
  this 
  represent, 
  as 
  is 
  commonly 
  assumed, 
  a 
  true 
  metasili- 
  

   cate 
  ? 
  If 
  it 
  does, 
  we 
  should 
  expect 
  that 
  ignition 
  would 
  split 
  

   off 
  silica 
  proportional 
  to 
  the 
  acid 
  hydrogen, 
  or 
  one-sixth 
  of 
  the 
  

   total 
  amount. 
  To 
  answer 
  this 
  question 
  several 
  portions 
  of 
  the 
  

   pectolite 
  were 
  sharply 
  ignited, 
  to 
  complete 
  dehydration, 
  and 
  

   then 
  boiled 
  each 
  for 
  fifteen 
  minutes 
  with 
  a 
  solution 
  of 
  sodium 
  

   carbonate 
  containing 
  250 
  grams 
  to 
  the 
  liter. 
  In 
  the 
  extract 
  so 
  

   obtained 
  the 
  silica 
  was 
  determined 
  ; 
  and 
  three 
  experiments 
  

   gave 
  the 
  following 
  percentages 
  : 
  

  

  8-96 
  

   8-67 
  

   8-42 
  

  

  Mean, 
  8-68 
  

  

  One-sixth 
  of 
  the 
  total 
  silica 
  is 
  8*89 
  per 
  cent 
  ; 
  and 
  the 
  experi- 
  

   ments, 
  therefore, 
  justify 
  the 
  original 
  expectation. 
  The 
  belief 
  

   that 
  pectolite 
  is 
  a 
  metasilicate 
  is 
  effectively 
  confirmed. 
  

  

  Upon 
  the 
  unignited 
  pectolite 
  the 
  sodium 
  carbonate 
  solution 
  

   has 
  a 
  slow 
  decomposing 
  action, 
  both 
  silica 
  and 
  bases 
  being 
  

   withdrawn. 
  In 
  two 
  experiments 
  fifteen 
  minutes 
  of 
  boiling 
  

   extracted 
  2*07 
  and 
  2-55 
  per 
  cent 
  of 
  silica, 
  and 
  by 
  a 
  treatment 
  

   lasting 
  four 
  days 
  4*80 
  per 
  cent 
  was 
  taken 
  out. 
  With 
  water 
  

   alone 
  similar 
  results 
  were 
  obtained 
  ; 
  the 
  action 
  being 
  so 
  rapid, 
  

   although 
  relatively 
  slight, 
  that 
  pectolite, 
  moistened, 
  gives 
  an 
  

   immediate 
  and 
  deep 
  coloration 
  with 
  phenol 
  phthalein. 
  Qy 
  

  

  