﻿248 
  Clarke 
  and 
  Steiger 
  — 
  Experiments 
  vnth 
  Pectolite, 
  etc. 
  

  

  If 
  now, 
  pyrophyllite 
  is 
  an 
  acid 
  metasilicate 
  it 
  should 
  break 
  up 
  

   on 
  ignition 
  in 
  accordance 
  with 
  the 
  equation 
  

  

  2 
  AlHSi.O, 
  = 
  Al,Si30, 
  + 
  SiO, 
  + 
  H,0. 
  

  

  That 
  is, 
  one-fourth 
  of 
  the 
  sib'ca, 
  or 
  16-18 
  per 
  cent, 
  should 
  be 
  

   liberated. 
  The 
  mineral 
  itself 
  is 
  very 
  slightly 
  attacked 
  by 
  boil- 
  

   ing 
  with 
  the 
  sodium 
  carbonate 
  solution, 
  and 
  in 
  an 
  experiment 
  

   of 
  this 
  kind 
  only 
  0*72 
  per 
  cent 
  of 
  silica 
  was 
  dissolved. 
  Upon 
  

   ignition 
  under 
  varying 
  circumstances 
  the 
  following 
  data 
  were 
  

   obtained 
  : 
  

  

  Ignited 
  ten 
  minutes 
  over 
  a 
  Bunsen 
  burner, 
  and 
  then 
  extracted 
  

   with 
  sodium 
  carbonate 
  solution, 
  Tol 
  per 
  cent 
  of 
  SiO^ 
  dis- 
  

   solved. 
  

  

  Ignited 
  fifteen 
  minutes 
  over 
  a 
  Bunsen 
  burner, 
  1*89 
  per 
  cent 
  be- 
  

   came 
  soluble. 
  

  

  Ignited 
  ten 
  minutes 
  over 
  a 
  Bunsen 
  burner 
  and 
  then 
  fifteen 
  min- 
  

   utes 
  over 
  the 
  blast, 
  2-84 
  per 
  cent 
  of 
  silica 
  was 
  liberated. 
  

  

  These 
  results 
  are 
  of 
  . 
  a 
  different 
  order 
  from 
  those 
  given 
  by 
  

   pectolite 
  and 
  talc, 
  and 
  raise 
  the 
  question 
  whether 
  pyrophyl- 
  

   lite, 
  despite 
  its 
  ratios, 
  is 
  a 
  metasilicate 
  at 
  all. 
  So 
  far 
  as 
  the 
  

   evidence 
  goes, 
  it 
  may 
  with 
  propriety 
  be 
  regarded 
  as 
  a 
  basic 
  

   salt 
  of 
  the 
  acid 
  H,Si„0^, 
  and 
  its 
  formula 
  then 
  becomes 
  

  

  Si,0, 
  = 
  Al-OH. 
  

  

  This 
  formula 
  is 
  at 
  least 
  as 
  probable 
  as 
  the 
  metasilicate 
  ex- 
  

   pression, 
  which 
  latter 
  rests 
  upon 
  assumption 
  alone. 
  Still 
  other 
  

   formulse, 
  but 
  of 
  greater 
  complexit}^, 
  are 
  possible; 
  but 
  until 
  we 
  

   know 
  more 
  of 
  the 
  genesis 
  and 
  chemical 
  relationships 
  of 
  pyro- 
  

   phyllite, 
  speculation 
  concerning 
  them 
  would 
  be 
  unprofitable. 
  

  

  Bj 
  heating 
  with 
  dry 
  ammonium 
  chloride, 
  pyrophyllite 
  is 
  

   very 
  slightly 
  attacked. 
  In 
  two 
  experiments 
  it 
  lost 
  in 
  weight 
  

   6-17 
  and 
  6*30 
  per 
  cent 
  respectively. 
  The 
  excess 
  of 
  loss 
  over 
  

   water 
  is 
  due, 
  as 
  we 
  have 
  proved, 
  to 
  the 
  volatilization 
  of 
  a 
  little 
  

   ferric 
  and 
  aluminic 
  chloride. 
  The 
  residue 
  of 
  the 
  mineral 
  after 
  

   this 
  treatment 
  contained 
  no 
  chlorine, 
  so 
  that 
  no 
  chlorhydrin- 
  

   like 
  body 
  had 
  been 
  formed. 
  The 
  formation 
  of 
  such 
  a 
  com- 
  

   pound, 
  the 
  replacement 
  of 
  hydroxyl 
  by 
  chlorine, 
  would, 
  if 
  it 
  

   could 
  be 
  effected, 
  be 
  a 
  valuable 
  datum 
  towards 
  determining 
  

   the 
  actual 
  constitution 
  of 
  the 
  species. 
  

  

  Calamine. 
  

  

  The 
  simplest 
  constitutional 
  formula 
  for 
  calamine, 
  the 
  one 
  

   which 
  is 
  generally 
  accepted, 
  represents 
  it 
  as 
  a 
  basic 
  metasilicate, 
  

   Si03=(ZnOH)2. 
  In 
  this 
  the 
  hydrogen 
  is 
  all 
  combined 
  in 
  one 
  

   way, 
  and 
  so, 
  too, 
  is 
  the 
  zinc. 
  In 
  all 
  other 
  possible 
  formulae, 
  

  

  