﻿F. 
  A. 
  Perret 
  — 
  Volcanic 
  Research 
  at 
  Kilauea. 
  485 
  

  

  I 
  have 
  explained 
  elsewhere 
  the 
  presence 
  of 
  CO. 
  The 
  examina- 
  

   tion 
  of 
  the 
  composition 
  of 
  these 
  gases, 
  as 
  well 
  as 
  of 
  the 
  

   substances 
  volatilized 
  and 
  easily 
  condensed 
  at 
  the 
  ordinary 
  tem- 
  

   perature, 
  shows 
  immediate^ 
  that 
  a 
  great 
  part 
  is 
  combustible. 
  

   On 
  coming 
  into 
  contact 
  with 
  the 
  atmosphere 
  these 
  substances 
  

   will 
  burn, 
  owing 
  to 
  the 
  high 
  temperature 
  which 
  they 
  possess 
  on 
  

   leaving 
  the 
  magma 
  in 
  fusion. 
  Therefore 
  there 
  will 
  also 
  be 
  

   formed 
  C0 
  2 
  , 
  and 
  water 
  of 
  extra 
  magmatic 
  origin. 
  

  

  This, 
  therefore, 
  easily 
  explains 
  the 
  flames, 
  giving 
  more 
  or 
  less 
  

   light, 
  which 
  observers 
  have 
  seen 
  rising 
  from 
  Lake 
  Halemaumau. 
  

   It 
  is 
  also 
  advisable 
  to 
  note 
  that 
  these 
  gases 
  contain 
  very 
  little 
  N 
  2 
  . 
  

   The 
  percentage 
  of 
  N~ 
  2 
  will 
  always 
  be 
  a 
  criterium 
  of 
  great 
  general 
  

   importance, 
  which 
  will 
  denote 
  the 
  purity 
  of 
  the 
  gaseous 
  products 
  

   collected 
  on 
  the 
  spot, 
  either 
  from 
  a 
  f 
  umarole 
  or 
  from 
  the 
  liquid 
  

   lava. 
  

  

  Oxidization 
  of 
  the 
  Lava 
  (by 
  water). 
  — 
  The 
  lava 
  collected 
  by 
  Mr." 
  

   F. 
  A. 
  Perret 
  from 
  "Old 
  Faithful" 
  is 
  not 
  complete! 
  y 
  oxidized. 
  

   After 
  having 
  extracted 
  all 
  the 
  gases 
  from 
  it, 
  there 
  remains 
  a 
  

   melted 
  mass 
  of 
  black 
  silicates, 
  opaque 
  even 
  in 
  thin 
  splinters 
  ; 
  this 
  

   mass 
  is 
  rich 
  in 
  C. 
  Therefore 
  the 
  silicate 
  does 
  not 
  contain 
  enough 
  

   peroxides 
  in 
  order 
  to 
  oxidize 
  all 
  its 
  C 
  at 
  the 
  temperature 
  of 
  the 
  

   lake. 
  But 
  if 
  we 
  supply 
  the 
  necessary 
  2 
  , 
  either 
  in 
  the 
  form 
  of 
  

   water 
  or 
  air, 
  we 
  shall 
  be 
  able, 
  at 
  the 
  temperature 
  of 
  the 
  lake, 
  to 
  

   oxidize 
  all 
  the 
  C 
  easily, 
  and 
  to 
  obtain 
  a 
  great 
  quantity 
  of 
  C0 
  2 
  

   and 
  H 
  2 
  ; 
  therefore 
  this 
  experiment 
  proves 
  that 
  the 
  magma 
  did 
  not 
  

   contain 
  enough 
  water 
  to 
  oxidize 
  all 
  its 
  C. 
  

  

  This 
  demonstration 
  may 
  be 
  made, 
  in 
  a 
  very 
  elegant 
  way, 
  as 
  

   follows 
  : 
  Let 
  us 
  take 
  the 
  black 
  silicate 
  residue 
  which 
  during 
  the 
  

   first 
  heating 
  gives 
  off 
  all 
  its 
  gases, 
  and 
  its 
  volatile 
  substances, 
  and 
  

   which 
  only 
  contained 
  a 
  residue 
  of 
  carbon. 
  This 
  residuum 
  must 
  

   be 
  heated 
  in 
  a 
  closed 
  apparatus 
  in 
  the 
  presence 
  of 
  steam 
  and 
  noth- 
  

   ing 
  else, 
  and 
  without 
  any 
  traces 
  of 
  atmospheric 
  air. 
  A 
  manom- 
  

   eter 
  shows 
  the 
  pressure, 
  at 
  every 
  moment, 
  of 
  the 
  gases 
  formed 
  at 
  

   the 
  given 
  temperature. 
  In 
  the 
  course 
  of 
  the 
  heating 
  a 
  reaction 
  

   is 
  developed. 
  The 
  water 
  attacks 
  the 
  lava 
  and 
  its 
  carbon. 
  The 
  

   pressure 
  in 
  the 
  apparatus 
  which 
  I 
  used 
  reached 
  500 
  millimeters 
  of 
  

   mercury 
  at 
  1000°. 
  

  

  Under 
  the 
  same 
  conditions 
  the 
  gases 
  of 
  lava 
  alone, 
  without 
  the 
  

   action 
  of 
  the 
  water, 
  only 
  give 
  a 
  pressure 
  of 
  8-10 
  millimeters 
  of 
  

   mercury. 
  The 
  gases 
  collected 
  during 
  this 
  intense 
  reaction 
  have 
  

   the 
  following 
  composition; 
  B, 
  first 
  exp't 
  ; 
  C, 
  second 
  exp't 
  : 
  

  

  Composition 
  of 
  the 
  gases. 
  

  

  

  B 
  

  

  C 
  

  

  so, 
  

  

  co 
  2 
  __. 
  

  

  | 
  26-2 
  

  

  0-25 
  

   19'4 
  

  

  CO 
  

  

  5-0 
  

  

  6-4 
  

  

  H 
  3 
  

  

  68*0 
  

  

  74-0 
  

  

  N 
  

  

  0-4 
  

  

  traces 
  

  

  

  

  

  99-6 
  100-05 
  

  

  