﻿HAT7GHT0N 
  GRANITES 
  OF 
  IRELAND. 
  

  

  273 
  

  

  From 
  the 
  preceding 
  Table 
  the 
  following 
  is 
  deduced 
  : 
  — 
  

  

  Table 
  V. 
  — 
  Oxygen 
  contained 
  in 
  Silica, 
  Peroxides, 
  and 
  Protoxides 
  in 
  

  

  the 
  Donegal 
  Granites. 
  

  

  

  Oxygen 
  

  

  Oxygen 
  

  

  Oxygen 
  

  

  

  No. 
  

  

  contained 
  

  

  contained 
  in 
  

  

  contained 
  in 
  

  

  51-92-A 
  x 
  

  

  

  in 
  Silica. 
  

  

  Peroxides. 
  

  

  Protoxides. 
  

  

  

  

  K 
  

  

  B 
  

  

  C 
  

  

  A 
  

  

  I. 
  

  

  36-35 
  

  

  8-48 
  

  

  2-69 
  

  

  15-57 
  

  

  II. 
  

  

  3416 
  

  

  7-97 
  

  

  3-52 
  

  

  17-76 
  

  

  III. 
  

  

  35-80 
  

  

  8-88 
  

  

  2-62 
  

  

  1612 
  

  

  IV. 
  

  

  30-34 
  

  

  11-27 
  

  

  3-87 
  

  

  21-58 
  

  

  V. 
  

  

  3603 
  

  

  8-38 
  

  

  2-75 
  

  

  15-89 
  

  

  VI. 
  

  

  35-31 
  

  

  8-95 
  

  

  3-12 
  

  

  16-61 
  

  

  VII. 
  

  

  35-41 
  

  

  8-56 
  

  

  3-02 
  

  

  16-51 
  

  

  VIII. 
  

  

  36-68 
  

  

  8-10 
  

  

  2-50 
  

  

  1524 
  

  

  IX. 
  

  

  37-51 
  

  

  745 
  

  

  251 
  

  

  14-41 
  

  

  X. 
  

  

  38-21 
  

  

  7-22 
  

  

  2-38 
  

  

  13-71 
  

  

  XI. 
  

  

  35-72 
  

  

  8-26 
  

  

  2-72 
  

  

  16-20 
  

  

  XII. 
  

  

  35-93 
  

  

  8-29 
  

  

  2-81 
  

  

  15-99 
  

  

  XIII. 
  

  

  28-66 
  

  

  10-83 
  

  

  4-94 
  

  

  23-26 
  

  

  XIV. 
  

  

  3906 
  

  

  7-42 
  

  

  2-49 
  

  

  12-86 
  

  

  XV. 
  

  

  37-92 
  

  

  7-10 
  

  

  2-46 
  

  

  1400 
  

  

  If 
  we 
  now 
  introduce 
  the 
  values 
  of 
  A, 
  B, 
  C, 
  contained 
  in 
  Table 
  V., 
  

   into 
  equations 
  (4), 
  we 
  obtain, 
  finally, 
  

  

  Table 
  VI. 
  — 
  Calculated 
  Mineralogical 
  Composition 
  of 
  the 
  Granites 
  

  

  of 
  Donegal. 
  

  

  No. 
  

  

  Orthoclase, 
  

  

  Oligoclase, 
  

  

  Mica, 
  

  

  Quartz, 
  

  

  

  =x. 
  

  

  =y- 
  

  

  == 
  z» 
  

  

  =u. 
  

  

  I.* 
  

  

  2-51 
  

  

  7103 
  

  

  093 
  

  

  25-39 
  

  

  n. 
  

  

  122-87 
  

  

  -1415 
  

  

  - 
  8-33 
  

  

  - 
  0-51 
  

  

  in. 
  

  

  - 
  12-45 
  

  

  75-95 
  

  

  8-13 
  

  

  28-74 
  

  

  IV. 
  

  

  38-28 
  

  

  71-75 
  

  

  - 
  201 
  

  

  - 
  8-17 
  

  

  v.* 
  

  

  17-98 
  

  

  55-58 
  

  

  2-69 
  

  

  23-91 
  

  

  VI. 
  

  

  22-41 
  

  

  75-60 
  

  

  -10-28 
  

  

  12-76 
  

  

  VII. 
  

  

  3613 
  

  

  52-38 
  

  

  - 
  3-92 
  

  

  15-85 
  

  

  VIII.* 
  

  

  5-83 
  

  

  5402 
  

  

  8-70 
  

  

  31-33 
  

  

  IX.* 
  

  

  25-45 
  

  

  41-50 
  

  

  2-74 
  

  

  30-30 
  

  

  X.* 
  

  

  16-48 
  

  

  46-31 
  

  

  205 
  

  

  35-36 
  

  

  XI.* 
  

  

  29-12 
  

  

  3702 
  

  

  8-77 
  

  

  25-08 
  

  

  XIL* 
  

  

  29-45 
  

  

  48-07 
  

  

  1-69 
  

  

  20-78 
  

  

  XIII. 
  

  

  158-22 
  

  

  12-83 
  

  

  -29-48 
  

  

  -42-41 
  

  

  XIV. 
  

  

  - 
  5-41 
  

  

  90-69 
  

  

  -1502 
  

  

  29-46 
  

  

  XV.* 
  

  

  33-58 
  

  

  32-25 
  

  

  2-63 
  

  

  31-65 
  

  

  Of 
  the 
  fifteen 
  granites 
  examined, 
  eight, 
  which 
  are 
  thus 
  marked 
  (*), 
  

   give 
  positive 
  values 
  for 
  u, 
  x,y,z; 
  and 
  seven 
  have 
  some 
  one 
  or 
  more 
  

   of 
  these 
  quantities 
  negative 
  ; 
  hence 
  it 
  follows 
  that 
  seven 
  -fifteenths 
  of 
  

   the 
  granites, 
  or 
  46f 
  per 
  cent., 
  are 
  certainly 
  not 
  composed 
  of 
  quartz, 
  

   orthoclase, 
  oligoclase, 
  and 
  black 
  mica. 
  

  

  