﻿366 
  ME. 
  A. 
  JOHNSTONE 
  ON 
  THE 
  ACTION 
  OF 
  WATER 
  ON 
  

  

  toughness. 
  In 
  fact 
  their 
  physical 
  characters 
  were 
  now 
  seen 
  to 
  he 
  

   identical 
  with 
  those 
  of 
  some 
  of 
  the 
  natural 
  less 
  hydrated 
  varieties 
  

   of 
  hydromuscovite. 
  The 
  vessels 
  in 
  which 
  the 
  two 
  specimens 
  had 
  

   been 
  suspended 
  were 
  found 
  to 
  have 
  on 
  their 
  bottoms 
  a 
  little 
  fine 
  

   mica-dust, 
  which, 
  by 
  the 
  action 
  of 
  the 
  water, 
  aided 
  very 
  likely 
  by 
  

   the 
  atmospheric 
  air, 
  had 
  been 
  detached 
  from 
  the 
  original 
  solid 
  masses 
  

   during 
  their 
  twelve 
  months' 
  exposure 
  to 
  those 
  fluids. 
  

  

  There 
  was 
  about 
  the 
  same 
  quantity 
  of 
  this 
  muscovite 
  dust 
  in 
  the 
  

   vessel 
  which 
  contained 
  the 
  pure 
  distilled 
  water 
  as 
  there 
  was 
  in 
  the 
  

   vessel 
  which 
  held 
  the 
  carbonated 
  water. 
  Besides 
  the 
  dust 
  which 
  

   had 
  gathered 
  on 
  the 
  bottoms 
  of 
  the 
  vessels, 
  numerous 
  and 
  very 
  

   much 
  finer 
  mica-spangles 
  were 
  observed 
  by 
  means 
  of 
  the 
  microscope 
  

   to 
  be 
  suspended 
  throughout 
  the 
  body 
  of 
  the 
  fluids. 
  Doubtless 
  they 
  

   were 
  in 
  the 
  act 
  of 
  very 
  slowly 
  descending 
  to 
  the 
  bottoms 
  of 
  the 
  jars. 
  

  

  The 
  waters 
  in 
  which 
  the 
  muscovites 
  had 
  lain 
  were 
  then 
  separately 
  

   and 
  very 
  carefully 
  filtered 
  again 
  and 
  again 
  through 
  several 
  folds 
  of 
  

   the 
  finest 
  filter-paper, 
  until 
  no 
  undissolved 
  or 
  suspended 
  solid 
  

   matter 
  whatever 
  remained 
  in 
  the 
  liquids. 
  Both 
  the 
  waters 
  were 
  

   then 
  evaporated 
  to 
  dryness 
  in 
  different 
  basins, 
  and 
  not 
  a 
  grain 
  of 
  

   solid 
  residue 
  was 
  observed 
  to 
  be 
  left 
  behind 
  in 
  either 
  case, 
  showing 
  

   that 
  nothing 
  had 
  been 
  removed 
  from 
  the 
  muscovites 
  in 
  a 
  state 
  of 
  

   solution, 
  either 
  by 
  the 
  pure 
  water 
  or 
  by 
  the 
  water 
  saturated 
  with 
  

   carbonic 
  acid 
  gas. 
  

  

  The 
  two 
  specimens 
  of 
  muscovite 
  which 
  had 
  been 
  thus 
  experi- 
  

   mented 
  with 
  were 
  afterwards 
  analyzed 
  and 
  their 
  analyses 
  compared 
  

   with 
  that 
  of 
  the 
  mass 
  to 
  which 
  they 
  had 
  originally 
  belonged. 
  These 
  

   three 
  analyses 
  are 
  given 
  below 
  : 
  I. 
  of 
  fresh 
  Muscovite, 
  II. 
  of 
  Mus- 
  

   covite 
  after 
  lying 
  in 
  distilled 
  water 
  for 
  a 
  year, 
  III. 
  after 
  a 
  year's 
  

   immersion 
  in 
  carbonic-acid 
  water. 
  

  

  

  I. 
  

  

  II. 
  

  

  III. 
  

  

  Silica 
  

  

  . 
  . 
  47-76 
  

  

  46-95 
  

  

  46-33 
  

  

  Alumina 
  

  

  . 
  . 
  35-13 
  

  

  34-45 
  

  

  34-86 
  

  

  Potash 
  

  

  9-91 
  

  

  9-62 
  

  

  9-85 
  

  

  Ferric 
  Oxide 
  . 
  . 
  

  

  3-95 
  

  

  3-84 
  

  

  3-69 
  

  

  Magnesia 
  

  

  0-80 
  

  

  0-77 
  

  

  0-83 
  

  

  Soda 
  

  

  . 
  . 
  trace. 
  

  

  trace. 
  

   4-19 
  

  

  trace 
  

  

  Water 
  

  

  2-43 
  

  

  4-42 
  

  

  99-98 
  99-82 
  99-98 
  

  

  It 
  will 
  be 
  seen 
  from 
  the 
  above 
  analyses 
  that 
  all 
  the 
  chemical 
  

   change 
  effected 
  in 
  the 
  muscovites 
  by 
  their 
  twelvemonth's 
  immersion 
  

   was 
  hydration, 
  and 
  that 
  the 
  hydrating 
  process 
  went 
  on 
  as 
  readily 
  

   in 
  the 
  pure 
  water 
  as 
  in 
  the 
  water-solution 
  of 
  carbonic 
  acid 
  gas. 
  In 
  

   fact 
  in 
  both 
  cases 
  the 
  specimens 
  were 
  equally 
  rapidly 
  converted 
  

   into 
  hydromuscovites. 
  

  

  Compare 
  the 
  analysis 
  which 
  is 
  now 
  given 
  of 
  one 
  of 
  the 
  lower 
  

   natural 
  hydromuscovites 
  with 
  the 
  analyses 
  II. 
  and 
  III. 
  above. 
  

  

  