﻿548 
  Mr. 
  L 
  L. 
  Bell 
  on 
  some 
  [June 
  17, 
  

  

  It 
  will 
  be 
  observed 
  that, 
  in 
  the 
  first 
  three 
  instances 
  quoted 
  of 
  the 
  compo- 
  

   nent 
  parts 
  of 
  whinstone, 
  carbonic 
  acid 
  is 
  named 
  as 
  a 
  constituent 
  varying 
  

   in 
  amount 
  from 
  1*02 
  to 
  2*57 
  per 
  cent, 
  of 
  the 
  whole. 
  This 
  is 
  a 
  little 
  remark- 
  

   able, 
  because 
  I 
  confirmed 
  by 
  actual 
  experiment 
  that 
  when 
  protoxide 
  of 
  iron, 
  

   lime, 
  magnesia, 
  potash, 
  and 
  soda, 
  in 
  the 
  form 
  of 
  carbonates, 
  are 
  fused 
  with 
  

   silica 
  and 
  alumina- 
  in 
  the 
  proportions 
  in 
  which 
  these 
  substances 
  are 
  

   found 
  to 
  exist 
  in 
  the 
  whin, 
  the 
  resulting 
  mass 
  does 
  not 
  contain, 
  as 
  might 
  

   be 
  expected, 
  a 
  trace 
  of 
  carbonic 
  acid. 
  Whether 
  the 
  small 
  quantities 
  

   just 
  mentioned 
  of 
  this 
  acid 
  represent 
  portions 
  which 
  under 
  immense 
  

   pressure 
  could 
  not 
  escape 
  from 
  the 
  lime 
  with 
  which 
  it 
  was 
  perhaps 
  

   originally 
  combined, 
  is 
  a 
  question 
  to 
  which 
  no 
  satisfactory 
  answer 
  can 
  be 
  

   given. 
  

  

  On 
  the 
  other 
  hand, 
  it 
  is 
  not 
  improbable 
  that 
  basalt 
  may, 
  after 
  or 
  

   possibly 
  during 
  the 
  act 
  of 
  cooling, 
  be 
  placed 
  in 
  circumstances 
  where 
  

   carbonic 
  acid 
  may 
  be 
  absorbed 
  by 
  such 
  of 
  its 
  constituents 
  as 
  are 
  known 
  

   to 
  form 
  carbonates. 
  

  

  The 
  following 
  experiments 
  were 
  tried 
  on 
  a 
  sample 
  of 
  the 
  pounded 
  

   whin-rock 
  previously 
  ascertained 
  to 
  contain 
  1*97 
  per 
  cent, 
  of 
  carbonic 
  

   acid 
  : 
  — 
  

  

  per 
  cent. 
  CO.,. 
  

  

  a. 
  2' 
  5 
  grammes 
  having 
  been 
  exposed 
  during 
  four 
  days 
  to 
  dry 
  

  

  carbonic 
  acid, 
  then 
  contained 
  (being 
  practically 
  un- 
  

   changed) 
  . 
  , 
  1*94 
  

  

  b. 
  2*5 
  grammes, 
  after 
  exposure 
  during 
  four 
  clays 
  to 
  moist 
  

  

  carbonic 
  acid, 
  contained 
  2*04 
  

  

  c. 
  2*5 
  grammes 
  had 
  passed 
  over 
  it 
  during 
  five 
  hours, 
  at 
  a 
  

  

  temperature 
  of 
  about 
  500° 
  C, 
  a 
  current 
  of 
  carbonic 
  acid. 
  

  

  It 
  gave 
  1-10 
  

  

  d. 
  2'5 
  grammes 
  treated 
  as 
  in 
  c, 
  the 
  carbonic 
  acid 
  being 
  

  

  moist, 
  gave 
  1*70 
  

  

  e. 
  2-5 
  grammes, 
  exposed 
  at 
  a 
  low-red 
  heat 
  for 
  five 
  hours 
  

  

  to 
  a 
  current 
  of 
  dry 
  carbonic 
  acid, 
  contained 
  *29 
  

  

  /. 
  2*5 
  grammes 
  treated 
  as 
  in 
  e, 
  but 
  moisture 
  was 
  present, 
  

  

  gave 
  *49 
  

  

  The 
  experiment 
  b 
  in 
  the 
  series 
  would 
  indicate 
  that 
  when 
  moisture 
  is 
  

   present 
  a 
  small 
  quantity 
  of 
  carbonic 
  acid 
  is 
  absorbed 
  at 
  ordinary 
  tem- 
  

   peratures. 
  "When 
  the 
  temperature 
  was 
  raised, 
  as 
  in 
  c, 
  d, 
  e, 
  and/, 
  there 
  

   was 
  a 
  perceptible 
  loss 
  of 
  acid 
  ; 
  but 
  in 
  d 
  and 
  / 
  this 
  loss 
  was 
  materially 
  

   retarded 
  by 
  the 
  presence 
  of 
  vapour 
  of 
  water. 
  It 
  is 
  therefore 
  conceiv- 
  

   able 
  that 
  carbonic 
  acid, 
  if 
  at 
  one 
  time 
  entirely 
  expelled 
  from 
  the 
  fluid 
  

   basalt, 
  may 
  have 
  been 
  reabsorbed, 
  when 
  aided 
  by 
  the 
  presence 
  of 
  mois- 
  

   ture 
  and 
  probably 
  under 
  enormous 
  pressure, 
  during 
  the 
  countless 
  ages 
  

   which 
  have 
  elapsed 
  since 
  it 
  first 
  occupied 
  its 
  present 
  position. 
  

  

  This 
  idea 
  is 
  confirmed 
  to 
  some 
  extent 
  by 
  an 
  examination 
  of 
  the 
  com- 
  

  

  