﻿486 
  MESSES. 
  E. 
  T. 
  NEWTON 
  AND 
  J. 
  J. 
  H. 
  TEALL 
  ON 
  [Dec. 
  1 
  89 
  7, 
  

  

  The 
  published 
  analyses 
  of 
  palagonite 
  differ 
  considerably 
  from 
  

   each 
  other, 
  and 
  the 
  one 
  which 
  must 
  now 
  be 
  added 
  to 
  the 
  list 
  does 
  

   not 
  entirely 
  agree 
  with 
  any 
  one 
  of 
  them. 
  It 
  is 
  often 
  stated 
  that 
  

   the 
  iron 
  present 
  is 
  wholly 
  in 
  the 
  condition 
  of 
  ferric 
  oxide. 
  If 
  this 
  

   be 
  taken 
  as 
  an 
  essential 
  character 
  the 
  present 
  substance 
  is 
  certainly 
  

   not 
  palagonite, 
  for 
  most 
  of 
  the 
  iron 
  is 
  in 
  the 
  ferrous 
  condition. 
  

   The 
  discovery 
  of 
  so 
  large 
  an 
  amount 
  of 
  ferrous 
  oxide 
  was 
  quite 
  

   unexpected, 
  and 
  a 
  second 
  determination 
  was 
  made 
  with 
  special 
  care. 
  

   The 
  results 
  in 
  both 
  cases 
  were 
  identical. 
  It 
  may, 
  therefore, 
  be 
  

   taken 
  as 
  certain 
  that 
  the 
  present 
  substance, 
  which 
  so 
  closely 
  

   resembles 
  palagonite 
  in 
  its 
  microscopic 
  character, 
  mode 
  of 
  occur- 
  

   rence, 
  and 
  relation 
  to 
  basic 
  glass, 
  is 
  rich 
  in 
  ferrous 
  oxide. 
  As 
  the 
  

   other 
  analyses 
  differ 
  widely 
  in 
  some 
  respects, 
  no 
  great 
  harm 
  will 
  

   be 
  done 
  by 
  extending 
  the 
  use 
  of 
  the 
  term 
  so 
  as 
  to 
  in 
  elude 
  this 
  

   substance. 
  

  

  The 
  ' 
  hullite 
  ' 
  of 
  Hardman 
  has 
  been 
  shown 
  by 
  Profs. 
  Cole 
  - 
  

   and 
  Sollas 
  2 
  to 
  occur, 
  like 
  the 
  palagonite 
  of 
  Cape 
  Flora, 
  as 
  inter- 
  

   stitial 
  matter, 
  and 
  as 
  the 
  infilling 
  of 
  amygdaloids. 
  Mr. 
  Hardman's 
  

   analysis 
  shows 
  that 
  the 
  two 
  substances 
  have 
  decided 
  chemical 
  

   affinities. 
  Both 
  are 
  remarkable 
  on 
  account 
  of 
  the 
  large 
  amount 
  

   of 
  iron. 
  Under, 
  these 
  circumstances 
  it 
  became 
  important 
  to 
  compare 
  

   them 
  as 
  regards 
  specific 
  gravity. 
  Mr. 
  Hardman 
  gives 
  the 
  specific 
  

   gravity 
  of 
  hullite 
  as 
  1*7(5, 
  and 
  Prof. 
  Sollas 
  confirms 
  this 
  somewhat 
  

   extraordinary 
  result. 
  Five 
  small 
  pieces 
  of 
  palagonite 
  were 
  taken 
  

   from 
  two 
  amygdules 
  occurring 
  in 
  a 
  specimen 
  collected 
  from 
  the 
  

   talus 
  near 
  Cape 
  Flora, 
  and 
  placed 
  in 
  a 
  solution 
  of 
  methylene 
  iodide. 
  

   After 
  twenty-four 
  hours' 
  immersion 
  it 
  was 
  found 
  that 
  two 
  sank, 
  one 
  

   remained 
  suspended, 
  and 
  two 
  floated 
  in 
  a 
  liquid 
  of 
  specific 
  gravity 
  

   2*433: 
  four 
  sank 
  and 
  one 
  remained 
  suspended 
  when 
  the 
  specific 
  

   gravit)' 
  of 
  the 
  liquid 
  was 
  lowered 
  to 
  2*409. 
  The 
  specific 
  gravity 
  

   is 
  therefore 
  not 
  constant, 
  but 
  it 
  is 
  somewhat 
  greater 
  than 
  2*4. 
  

  

  On 
  comparing 
  the 
  analysis 
  of 
  the 
  Cape 
  Flora 
  palagonite 
  with 
  that 
  

   of 
  Palagonia 
  it 
  will 
  be 
  noted 
  that 
  there 
  is 
  a 
  close 
  agreement 
  so 
  far 
  

   as 
  the 
  total 
  amount 
  of* 
  iron 
  is 
  concerned, 
  but 
  an 
  important 
  difference 
  

   as 
  regards 
  its 
  state 
  of 
  oxidation. 
  There 
  are 
  further 
  important 
  

   differences 
  as 
  regards 
  the 
  total 
  amount 
  of 
  lime 
  and 
  the 
  relative 
  

   proportions 
  of 
  lime 
  and 
  magnesia. 
  

  

  The 
  two 
  analyses 
  quoted 
  from 
  the 
  Challenger 
  Pceport 
  are 
  

   especially 
  interesting. 
  One 
  represents 
  the 
  palagonitic 
  crust, 
  and 
  

   the 
  other 
  the 
  nucleus 
  out 
  of 
  which 
  it 
  has 
  been 
  formed. 
  They 
  

   indicate, 
  as 
  the 
  authors 
  point 
  out, 
  that 
  the 
  change 
  is 
  accompanied 
  

   by 
  hydration, 
  elimination 
  of 
  lime 
  and 
  magnesia, 
  oxidation 
  of 
  the 
  

   ferrous 
  iron, 
  and 
  addition 
  of 
  alkalies. 
  

  

  More 
  interesting 
  results 
  will 
  be 
  obtained 
  if, 
  instead 
  of 
  considering 
  

   the 
  palagonite 
  of 
  Cape 
  Flora 
  in 
  relation 
  to 
  more 
  or 
  less 
  allied 
  

   substances 
  from 
  other 
  localities, 
  we 
  consider 
  it 
  in 
  relation 
  to 
  the 
  

   rock 
  in 
  which 
  it 
  occurs. 
  This 
  is 
  a 
  basalt 
  with 
  a 
  specific 
  gravity 
  

  

  1 
  ' 
  On 
  Hullite,' 
  Rep. 
  Belfast 
  Nat. 
  Field 
  Club 
  1894-95, 
  p. 
  1. 
  

  

  2 
  ' 
  On 
  a 
  Volcanic 
  Neck 
  of 
  Tertiary 
  Age 
  in 
  Co. 
  Galway,' 
  Sollas 
  & 
  McHenry, 
  

   Trans. 
  Roy. 
  Irish 
  Acad. 
  vol. 
  xxx. 
  (189(3) 
  p. 
  739. 
  

  

  