﻿BARREN 
  ISLAND. 
  29 
  

  

  It 
  will 
  be 
  seen 
  that, 
  with 
  one 
  exception, 
  the 
  proportion 
  of 
  sulphur 
  is 
  

   quite 
  trifling*, 
  and 
  decreases 
  with 
  increased 
  depth, 
  Considering 
  that 
  the 
  

   rich 
  sulphur 
  occurs 
  in 
  superficial 
  crusts, 
  apparently 
  indicating 
  that 
  it 
  is 
  

   only 
  freely 
  deposited 
  where 
  there 
  is 
  unrestricted 
  access 
  to 
  the 
  atmo- 
  

   sphere/ 
  a 
  diminution 
  in 
  the 
  proportion 
  contained 
  in 
  the 
  ash 
  might 
  be 
  

   expected 
  as 
  the 
  depth 
  increases. 
  The 
  exceptional 
  case 
  is, 
  therefore, 
  pro- 
  

   bably 
  due 
  to 
  some 
  local 
  and 
  special 
  cause, 
  and 
  the 
  figures 
  given 
  are 
  

   sufficient 
  to 
  show 
  that 
  a 
  large 
  proportion, 
  at 
  least, 
  of 
  the 
  ash 
  contains 
  too 
  

   low 
  a 
  percentage 
  of 
  sulphur 
  to 
  be 
  worth 
  treatment. 
  Including 
  the 
  

   stones, 
  which 
  contain 
  scarcely 
  any 
  sulphur, 
  even 
  the 
  ash 
  second 
  on 
  the 
  

   list 
  would 
  not 
  yield 
  more 
  than 
  7 
  or 
  8 
  per 
  cent. 
  

  

  I 
  have 
  previously 
  stated 
  2 
  that 
  there 
  appears 
  to 
  have 
  been 
  no 
  eruption 
  

   from 
  the 
  crater 
  since 
  1857-58, 
  when 
  it 
  was 
  examined 
  by 
  Playfair 
  and 
  

   Liebig, 
  who 
  described 
  the 
  deposits 
  of 
  sulphur 
  in 
  their 
  time. 
  As, 
  beyond 
  

   the 
  taking 
  of 
  mere 
  hand 
  specimens, 
  these 
  were 
  never 
  disturbed 
  until 
  our 
  

   visit, 
  it 
  is 
  clear 
  that 
  the 
  crusts 
  of 
  a 
  few 
  inches 
  in 
  thickness, 
  described 
  

   above, 
  have 
  taken 
  at 
  least 
  a 
  quarter 
  of 
  a 
  century 
  to 
  form, 
  from 
  which 
  

   it 
  may 
  be 
  inferred 
  that, 
  if 
  the 
  sulphur 
  were 
  worked 
  out 
  now, 
  a 
  fresh 
  crop 
  

   could 
  not 
  be 
  expected 
  until 
  after 
  many 
  years, 
  unless 
  the 
  volcano 
  should 
  * 
  

   become 
  more 
  active 
  than 
  it 
  has 
  been 
  during 
  the 
  last 
  few 
  decades. 
  

  

  That, 
  besides 
  the 
  deposits 
  of 
  sulphur 
  now 
  visible, 
  there 
  are 
  other, 
  and 
  

   older 
  ones, 
  which 
  have 
  been 
  buried 
  beneafch 
  the 
  later 
  showers 
  of 
  ash, 
  is 
  

   very 
  likely. 
  But 
  any 
  search 
  for 
  such 
  by 
  digging 
  must 
  be 
  purely 
  hap- 
  

   hazard, 
  and, 
  unless 
  perhaps 
  in 
  the 
  immediate 
  neighbourhood 
  of 
  the 
  crater, 
  

   the 
  chance 
  of 
  success 
  would 
  be 
  very 
  small. 
  

  

  It 
  is, 
  then, 
  I 
  think, 
  clear 
  that 
  the 
  sulphur 
  is 
  not 
  sufficiently 
  abund- 
  

   ant 
  to 
  allow 
  of 
  its 
  being 
  profitably 
  worked 
  by 
  convict 
  labour, 
  with 
  the 
  

   attendant 
  expenses 
  for 
  police 
  and 
  communications, 
  &c. 
  3 
  But 
  if 
  taken 
  

   up 
  in 
  a 
  small 
  way 
  by 
  a 
  native 
  contractor 
  or 
  lessee, 
  who 
  was 
  acquainted 
  

  

  1 
  Volcanic 
  sulphur 
  is 
  generally 
  considered 
  due, 
  either 
  to 
  the 
  reaction 
  of 
  sulphurous 
  

   anhydride 
  and 
  sulphuretted 
  hydrogen 
  on 
  each 
  other, 
  or 
  to 
  the 
  decomposition 
  of 
  the 
  latter 
  

   by 
  the 
  oxygen 
  of 
  the 
  air. 
  

  

  2 
  Foot-note, 
  p. 
  18. 
  

  

  8 
  A 
  similar 
  opinion 
  was 
  arrived 
  at 
  by 
  Mr. 
  Ball 
  (Records, 
  G. 
  S. 
  I., 
  Vol. 
  VI, 
  p. 
  88). 
  

  

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