﻿upon 
  JVatrolite, 
  Scolecite, 
  Prehnite 
  and 
  Pectolite. 
  351 
  

  

  the 
  analysis 
  of 
  the 
  pectolite 
  itself. 
  Secondly, 
  we 
  give 
  the 
  

   analysis 
  of 
  the 
  insoluble 
  residue 
  obtained 
  in 
  experiment 
  C. 
  

   The 
  third 
  column 
  of 
  figures 
  is 
  obtained 
  by 
  subtracting 
  from 
  

   the 
  second 
  column 
  61*79 
  of 
  soluble 
  silica 
  and 
  1*18 
  of 
  hygro- 
  

   scopic 
  water, 
  and 
  recalculating 
  the 
  remainder 
  to 
  100 
  per 
  cent. 
  

   The 
  fourth 
  column 
  contains 
  the 
  molecular 
  ratios 
  calculated 
  

   from 
  the 
  third. 
  

  

  Residue 
  Residue 
  

  

  Pectolite. 
  found. 
  reduced. 
  Ratios. 
  

  

  Si0 
  2 
  - 
  53-34 
  75-98 
  37*74 
  -629 
  

  

  A1 
  3 
  -33 
  -08 
  -19 
  -002 
  

  

  CaO 
  33-23 
  9-56 
  25'43 
  '454 
  

  

  MnO 
  -45 
  -24 
  *63 
  '009 
  

  

  Na„0 
  9-11 
  1*84 
  4*89 
  '079 
  

  

  NH 
  3 
  2-23 
  5-93 
  -349 
  

  

  BLO 
  at 
  100° 
  -27 
  

  

  H;0 
  above 
  100° 
  ... 
  2'70 
  9'47 
  25*19 
  

  

  CO„ 
  _ 
  -67 
  

  

  75*98 
  

  

  37-74 
  

  

  •08 
  

  

  •19 
  

  

  9-56 
  

  

  25-43 
  

  

  •24 
  

  

  •63 
  

  

  1-84 
  

  

  4-89 
  

  

  2-23 
  

  

  5-93 
  

  

  1'18 
  

  

  _ 
  

  

  9-47 
  

  

  25-19 
  

  

  

  

  

  

  100-10 
  100-58 
  100-00 
  

  

  These 
  ratios 
  roughly 
  suggest 
  the 
  formation 
  of 
  a 
  salt 
  approxi- 
  

   mating 
  in 
  composition 
  to 
  the 
  formula 
  R/ 
  2 
  Ca 
  2 
  Si 
  3 
  9 
  .6H 
  2 
  0, 
  in 
  

   which 
  B/ 
  is 
  about 
  two-thirds 
  ammonium 
  and 
  one-third 
  

   sodium. 
  Pectolite 
  itself 
  has 
  the 
  formula 
  N"aHCa 
  2 
  Si 
  3 
  9 
  ; 
  so 
  

   that 
  the 
  existence 
  of 
  a 
  hydrous 
  ammonium 
  pectolite 
  is 
  indi- 
  

   cated 
  ; 
  a 
  conclusion 
  which 
  is 
  probable, 
  but 
  not 
  proved. 
  The 
  

   reaction 
  between 
  pectolite 
  and 
  ammonium 
  chloride 
  is 
  possibly 
  

   simple 
  at 
  first, 
  but 
  followed 
  by 
  or 
  entangled 
  with 
  secondary 
  

   changes 
  which 
  obscure 
  the 
  results. 
  The 
  experiments 
  are 
  

   interesting, 
  however, 
  as 
  showing 
  how 
  widely 
  pectolite 
  differs 
  

   from 
  the 
  other 
  minerals 
  which 
  we 
  have 
  studied, 
  as 
  regards 
  the 
  

   ammonium 
  chloride 
  reaction. 
  The 
  general 
  investigation 
  is 
  to 
  

   be 
  continued, 
  and 
  we 
  hope 
  to 
  take 
  up 
  next 
  the 
  more 
  important 
  

   lime-soda 
  zeolites. 
  

  

  Laboratory 
  U. 
  S. 
  Geological 
  Survey, 
  

  

  Washington, 
  March 
  1, 
  1900. 
  

  

  