﻿250 
  Clarice 
  and 
  Steiger 
  — 
  Experiments 
  with 
  Pectolite, 
  etc. 
  

  

  L 
  IL 
  

  

  Gain 
  in 
  weight 
  27*60 
  25-78 
  

  

  Soluble 
  in 
  water 
  53-23 
  67*13 
  

  

  A 
  conversion 
  of 
  calamine 
  into 
  the 
  chlorhydrin, 
  Si03(ZnCl), 
  

   would 
  involve 
  a 
  gain 
  in 
  weight 
  of 
  15-34 
  per 
  cent. 
  Complete 
  

   conversion 
  into 
  2ZnCla 
  + 
  Si02 
  implies 
  an 
  increase 
  of 
  38*14 
  per 
  

   cent. 
  The 
  figures 
  given 
  lie 
  between 
  these 
  two; 
  and 
  are 
  

   indefinite 
  also 
  for 
  the 
  reason 
  that 
  there 
  was 
  volatilization 
  of 
  

   zinc 
  chloride. 
  

  

  In 
  two 
  more 
  experiments 
  the 
  calamine, 
  mingled 
  with 
  

   three 
  times 
  and 
  four 
  times 
  its 
  weight 
  of 
  ammonium 
  

   chloride 
  respectively, 
  was 
  heated 
  for 
  an 
  hour 
  and 
  a 
  half 
  to 
  

   bright 
  redness 
  in 
  a 
  combustion 
  tube. 
  The 
  zinc 
  chloride 
  which 
  

   was 
  formed, 
  volatilized, 
  and 
  was 
  collected 
  by 
  suitable 
  means 
  

   for 
  determination. 
  It 
  corresponded 
  to 
  59*6 
  and 
  59*0 
  per 
  cent 
  

   of 
  the 
  original 
  mineral, 
  calculated 
  as 
  zinc 
  oxide 
  ; 
  which 
  indi- 
  

   cates 
  a 
  nearly 
  complete 
  decomposition 
  of 
  the 
  calamine 
  into 
  

   2ZnCl2 
  + 
  Si02. 
  The 
  residue 
  was 
  mainly 
  silica, 
  with 
  a 
  small 
  

   part 
  of 
  the 
  zinc, 
  about 
  half 
  of 
  the 
  silica 
  being 
  soluble 
  in 
  sodium 
  

   carbonate 
  solution. 
  Here 
  again 
  no 
  definite 
  fractionation 
  of 
  the 
  

   mineral 
  could 
  be 
  observed. 
  

  

  Finally 
  the 
  action 
  of 
  dry 
  hydrogen 
  sulphide 
  upon 
  calamine 
  

   was 
  investigated. 
  The 
  mineral 
  was 
  heated 
  to 
  redness 
  in 
  a 
  cur- 
  

   rent 
  of 
  the 
  gas, 
  and 
  gained 
  perceptibly 
  in 
  weight. 
  The 
  per- 
  

   centage 
  data, 
  reckoned 
  on 
  the 
  original 
  calamine, 
  were 
  as 
  

   follows, 
  in 
  two 
  experiments 
  : 
  

  

  I. 
  II. 
  

  

  Gain 
  in 
  weight 
  6*00 
  6*43 
  

  

  SiO^ 
  soluble 
  in 
  Na.COg-. 
  16-45 
  20*95 
  

  

  Sulphur 
  in 
  residue 
  24-12 
  

  

  Complete 
  conversion 
  of 
  calamine 
  into 
  2ZnS-f 
  SiO, 
  implies 
  a 
  

   gain 
  in 
  weight 
  of 
  5*80 
  per 
  cent 
  ; 
  and 
  it 
  is 
  therefore 
  evident 
  

   from 
  the 
  figures 
  of 
  the 
  second 
  experiment 
  that 
  the 
  limit 
  of 
  

   change 
  was 
  approached 
  very 
  nearly. 
  The 
  24*12 
  of 
  sulphur 
  

   taken 
  up 
  is 
  quite 
  close 
  to 
  the 
  26*53 
  per 
  cent 
  which 
  is 
  required 
  

   by 
  theory. 
  About 
  eight-ninths 
  of 
  the 
  calamine 
  had 
  undergone 
  

   complete 
  transformation. 
  Again, 
  no 
  definite 
  fractionation 
  was 
  

   detected. 
  

  

  ,1 
  The 
  hydrogen 
  sulphide 
  reaction 
  was 
  examined 
  still 
  further 
  

   with 
  reference 
  to 
  the 
  temperature 
  at 
  which 
  it 
  becomes 
  effective. 
  

   Even 
  in 
  the 
  cold, 
  calamine 
  is 
  slightly 
  attacked 
  by 
  the 
  gas, 
  but 
  

   its 
  action 
  is 
  unimportant 
  until 
  the 
  temperature 
  of 
  400° 
  is 
  

   approximated. 
  Then 
  it 
  becomes 
  vigorous 
  and 
  the 
  reaction 
  

   goes 
  on 
  rapidly. 
  A 
  few 
  experiments 
  with 
  willemite 
  showed 
  

   that 
  it 
  also 
  was 
  attacked 
  by 
  hydrogen 
  sulphide, 
  but 
  less 
  vigor- 
  

   ously 
  than 
  calamine. 
  

  

  