﻿HAUGHTON 
  GRANITES 
  OF 
  IRELAND. 
  275 
  

  

  Granite 
  No. 
  V. 
  

  

  This 
  granite 
  fails 
  to 
  satisfy 
  the 
  test-equation 
  derived 
  from 
  iron. 
  

   From 
  Tables 
  II. 
  and 
  VI., 
  it 
  appears 
  that 
  the 
  calculated 
  quantity 
  

   of 
  iron-oxides 
  is 
  — 
  

  

  17-98x0-68 
  55-58 
  x 
  1-22 
  2-69x27-38 
  

  

  100 
  + 
  100 
  H 
  100 
  ~~ 
  33 
  ; 
  

  

  while 
  the 
  quantity 
  actually 
  found 
  by 
  analysis 
  (Table 
  I.) 
  was 
  3-33. 
  

   Granite 
  No. 
  V. 
  fails 
  also 
  to 
  satisfy 
  the 
  lime 
  test-equation. 
  

  

  Granite 
  No. 
  VIII. 
  

  

  fails 
  to 
  satisfy 
  the 
  potash 
  test-equation. 
  The 
  calculated 
  quantity 
  of 
  

   potash 
  is 
  much 
  less 
  than 
  the 
  amount 
  found 
  by 
  analysis. 
  

  

  Granite 
  No. 
  IX. 
  

   fails 
  with 
  respect 
  to 
  lime 
  and 
  iron. 
  The 
  calculated 
  quantity 
  of 
  lime 
  is 
  

  

  25-45 
  x 
  2-75 
  41-5x5-3 
  2-74x0-54 
  

  

  100 
  + 
  100 
  + 
  100 
  "" 
  2 
  ' 
  913 
  ; 
  

  

  but 
  the 
  quantity 
  of 
  lime 
  found 
  on 
  analysis 
  was 
  only 
  1*68. 
  

   It 
  also 
  fails 
  with 
  respect 
  to 
  iron-oxides. 
  

  

  Granite 
  No. 
  X. 
  

   fails 
  with 
  respect 
  to 
  potash, 
  soda, 
  lime, 
  and 
  iron. 
  

  

  Granites 
  Nos. 
  XI. 
  and 
  XII. 
  

   fail 
  to 
  satisfy 
  the 
  soda, 
  iron, 
  and 
  lime 
  test- 
  equations. 
  

  

  Granite 
  No. 
  XV. 
  

   fails 
  with 
  respect 
  to 
  potash 
  and 
  lime. 
  

  

  From 
  the 
  preceding 
  discussion 
  it 
  is 
  plain 
  that 
  not 
  a 
  single 
  granite 
  

   of 
  those 
  analyzed 
  can 
  be 
  composed 
  of 
  quartz, 
  orthoclase, 
  oligoclase, 
  

   and 
  black 
  mica, 
  having 
  the 
  precise 
  composition 
  of 
  those 
  minerals 
  

   given 
  in 
  Table 
  II. 
  

  

  Of 
  the 
  fifteen 
  granites, 
  that 
  which 
  comes 
  nearest 
  to 
  being 
  com- 
  

   posed 
  of 
  these 
  minerals 
  is 
  No. 
  IX., 
  from 
  Doocharry 
  Bridge. 
  

  

  I 
  here 
  give 
  its 
  observed 
  and 
  calculated 
  composition. 
  

  

  Doocharry 
  Bridge 
  Granite. 
  

  

  Observed. 
  Calculated. 
  

  

  Silica 
  72-24 
  .... 
  72-24 
  

  

  Alumina 
  14-92 
  .... 
  15-05 
  

  

  Iron 
  and 
  Manganese 
  oxides 
  2-18 
  .... 
  1-52 
  

  

  Lime 
  1-68 
  .... 
  2-91 
  

  

  Magnesia 
  0-36 
  .... 
  0-48 
  (diff.) 
  

  

  Soda 
  3-51 
  .... 
  2-89 
  

  

  Potash 
  5-10 
  .... 
  4-90 
  

  

  99-99 
  

  

  99-99 
  

  

  