﻿130 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  carbon 
  1 
  content 
  was 
  a 
  wholly 
  unexpected 
  result. 
  Gaseous 
  

   compounds 
  of 
  carbon 
  are 
  emitted 
  by 
  most 
  cooling 
  lavas, 
  but 
  a 
  con- 
  

   siderable 
  carbon 
  content 
  in 
  the 
  cold 
  lava 
  is 
  most 
  exceptional. 
  

   Inquiry 
  as 
  to 
  its 
  source 
  is 
  naturally 
  suggested. 
  

  

  The 
  knob 
  is 
  surrounded 
  by 
  black 
  shales, 
  which 
  at 
  once 
  suggest 
  

   themselves 
  as 
  a 
  possible 
  source. 
  There 
  are 
  no 
  recognizable 
  shale 
  

   inclusions 
  in 
  the 
  lava, 
  but 
  it 
  might 
  be 
  possible 
  that 
  the 
  explosive 
  

   action 
  of 
  the 
  eruption 
  should 
  have 
  mingled 
  a 
  certain 
  content 
  of 
  

   comminuted 
  shale 
  with 
  it. 
  The 
  thin 
  sections 
  however 
  give 
  no 
  sug- 
  

   gestion 
  of 
  any 
  such 
  admixture, 
  no 
  shale 
  particles 
  being 
  recogni- 
  

   zable 
  in 
  them. 
  And 
  when 
  it 
  is 
  recalled 
  that, 
  in 
  such 
  black 
  shales, 
  

   the 
  entire 
  content 
  of 
  carbonaceous 
  matter 
  does 
  not 
  usually 
  exceed 
  

   5 
  per 
  cent 
  of 
  the 
  rock, 
  it 
  will 
  be 
  seen 
  that 
  the 
  rock 
  at 
  the 
  knob 
  

   would 
  of 
  necessity 
  contain 
  from 
  15 
  to 
  20 
  per 
  cent 
  of 
  shale, 
  in 
  

   order 
  to 
  give 
  the 
  carbon 
  percentage 
  shown 
  on 
  analysis, 
  provided 
  

   it 
  came 
  from 
  this 
  source. 
  But 
  neither 
  the 
  thin 
  section, 
  nor 
  the 
  

   chemical 
  analysis 
  give 
  any 
  suggestion 
  of 
  such 
  an 
  admixture. 
  

  

  A 
  trifling 
  amount 
  of 
  carbon 
  may 
  have 
  been 
  obtained 
  from 
  dis- 
  

   solved 
  limestone, 
  as 
  this 
  contains 
  a 
  small 
  amount 
  of 
  organic 
  matter 
  ; 
  

   and 
  the 
  abundant 
  opaque 
  particles 
  developed 
  in 
  the 
  glass 
  at 
  the 
  

   limestone 
  contacts, 
  definitely 
  suggests 
  something 
  of 
  the 
  sort. 
  But 
  

   there 
  is 
  no 
  evidence 
  of 
  a 
  large 
  amount 
  of 
  limestone 
  corrosion, 
  and 
  

   the 
  rock 
  is 
  low 
  in 
  lime, 
  rather 
  than 
  high. 
  It 
  could 
  not 
  have 
  ob- 
  

   tained 
  much 
  carbon 
  from 
  this 
  source. 
  

  

  There 
  remain 
  apparently 
  two 
  possible 
  sources 
  for 
  the 
  carbon. 
  

   The 
  heat 
  of 
  the 
  intrusion 
  may 
  have 
  liberated 
  hydrocarbons 
  from 
  

   the 
  shales 
  below 
  ground, 
  which 
  were 
  then 
  taken 
  up 
  by 
  the 
  lava, 
  

   or 
  the 
  lava 
  itself 
  may 
  have 
  contained 
  more 
  carbon 
  than 
  usual 
  origi- 
  

   nally, 
  more 
  than 
  could 
  be 
  oxydized 
  by 
  the 
  usual 
  volcanic 
  processes. 
  

   Either 
  process 
  is 
  unusual, 
  but 
  then 
  the 
  occurrence 
  is 
  itself 
  unusual. 
  

   Graphite 
  does 
  occur 
  in 
  igneous 
  rocks, 
  as 
  for 
  example 
  in 
  some 
  of 
  

   the 
  Adirondack 
  pegmatites. 
  Its 
  occurrence 
  in 
  meteorites 
  is 
  well 
  

  

  1 
  Because 
  of 
  the 
  interest 
  attaching 
  to 
  the 
  presence 
  of 
  carbon 
  in 
  an 
  igneous 
  

   rock, 
  Dr 
  H. 
  S. 
  Washington 
  kindly 
  volunteered 
  to 
  look 
  over 
  the 
  thin 
  sections, 
  

   and 
  to 
  examine 
  the 
  insoluble 
  black 
  residues 
  of 
  the 
  rock. 
  In 
  a 
  letter 
  received 
  

   from 
  him 
  too 
  late 
  for 
  incorporation 
  in 
  this 
  report 
  he 
  states 
  that 
  the 
  material 
  

   is 
  carbon, 
  and 
  is 
  not 
  graphite. 
  He 
  also 
  makes 
  the 
  following 
  suggestion 
  to 
  

   account 
  for 
  its 
  presence, 
  that 
  it 
  is 
  not 
  impossible 
  that, 
  under 
  proper 
  condi- 
  

   tions 
  of 
  pressure 
  and 
  temperature, 
  FeO 
  will 
  reduce 
  Co 
  2 
  . 
  He 
  calls 
  attention 
  

   to 
  the 
  limestone 
  inclusions 
  as 
  the 
  source 
  of 
  the 
  CO 
  2 
  , 
  and 
  notes 
  that 
  the 
  

   carbon 
  in 
  the 
  thin 
  sections 
  is 
  in 
  the 
  glass, 
  and 
  not 
  in 
  the 
  feldspars, 
  hence 
  

   associated 
  with 
  the 
  iron-bearing 
  portion 
  of 
  the 
  rock. 
  

  

  