﻿BISCHOF 
  CHEMICAL 
  AND 
  PHYSICAL 
  GEOLOGY. 
  13 
  

  

  Elements 
  of 
  Chemical 
  and 
  Physical 
  Geology. 
  By 
  Dr. 
  Gustav 
  

   Bischof, 
  For. 
  Mem. 
  G.S., 
  &c. 
  Vol. 
  I. 
  Second 
  Edition. 
  

  

  [Lehrbuch 
  der 
  chernischen 
  und 
  physikalischen 
  Geologie. 
  Von 
  Dr. 
  Gustav 
  Bis- 
  

   chof, 
  Geheimen 
  Bergrath 
  unci 
  Professor 
  der 
  Universitat 
  Bonn, 
  For. 
  Mem. 
  

   G.S., 
  &c. 
  Zweite 
  ganzlich 
  umgearbeitete 
  Auflage, 
  Band 
  I.] 
  

  

  Although 
  a 
  new 
  German 
  edition 
  of 
  the 
  author's 
  ' 
  Elements 
  of 
  Che- 
  

   mical 
  and 
  Physical 
  Geology 
  ' 
  has 
  been 
  required 
  for 
  several 
  years, 
  the 
  

   first 
  being 
  quite 
  out 
  of 
  print, 
  his 
  various 
  engagements 
  (among 
  others 
  

   an 
  English 
  edition 
  of 
  the 
  above 
  work, 
  published 
  by 
  the 
  Cavendish 
  

   Society, 
  London, 
  1854-59) 
  prevented 
  his 
  complying 
  with 
  this 
  want 
  

   until 
  last 
  year. 
  The 
  distinction 
  lately 
  conferred 
  upon 
  him 
  by 
  the 
  

   Council 
  of 
  the 
  Geological 
  Society, 
  namely, 
  the 
  award 
  of 
  the 
  Wol- 
  

   laston 
  gold 
  medal, 
  has 
  induced 
  him 
  to 
  consider 
  it 
  his 
  pleasing 
  duty 
  

   to 
  dedicate 
  to 
  the 
  Society 
  this 
  new 
  German 
  edition, 
  containing 
  the 
  

   results 
  of 
  his 
  continued 
  researches. 
  

  

  The 
  more 
  systematic 
  arrangement 
  of 
  the 
  chapters 
  in 
  the 
  English 
  

   than 
  in 
  the 
  first 
  German 
  edition 
  has 
  been 
  adopted 
  and 
  improved 
  in 
  

   this 
  new 
  German 
  edition, 
  which 
  has 
  also 
  been 
  enriched 
  by 
  many 
  

   new 
  facts. 
  

  

  Amongst 
  the 
  more 
  novel 
  and 
  important 
  contributions 
  to 
  Chemical 
  

   and 
  Physical 
  Geology 
  contained 
  in 
  this 
  volume, 
  are 
  the 
  observations 
  

   on 
  the 
  secular 
  elevations 
  and 
  other 
  dislocations 
  of 
  the 
  earth's 
  crust, 
  

   contained 
  principally 
  in 
  Chapter 
  VI. 
  

  

  Dr. 
  Bischof's 
  argument 
  may 
  be 
  stated 
  as 
  follows 
  : 
  — 
  Exhalations 
  of 
  

   carbonic 
  acid 
  are 
  of 
  universal 
  occurrence, 
  and 
  originate 
  at 
  great 
  

   depths, 
  for 
  the 
  deeper 
  we 
  penetrate, 
  the 
  more 
  abundant 
  they 
  be- 
  

   come. 
  Rocks 
  occurring 
  at 
  such 
  great 
  and 
  inaccessible 
  depths 
  are 
  

   chiefly 
  silicates, 
  like 
  the 
  oldest 
  of 
  the 
  known 
  formations 
  — 
  a 
  fact 
  

   which 
  the 
  volcanic 
  eruptions 
  of 
  lava 
  confirm 
  ; 
  these 
  silicates 
  are 
  

   decomposed 
  by 
  carbonic 
  acid 
  ascending 
  to 
  the 
  surface, 
  the 
  decom- 
  

   position 
  being 
  facilitated 
  by 
  the 
  increase 
  of 
  temperature 
  towards 
  the 
  

   interior 
  of 
  the 
  earth. 
  The 
  products 
  are 
  silicate 
  of 
  alumina 
  and 
  cer- 
  

   tain 
  carbonates, 
  silica 
  being 
  displaced. 
  When 
  minerals 
  or 
  rocks 
  

   combine 
  with 
  other 
  substances, 
  not 
  only 
  an 
  increase 
  of 
  matter, 
  

   but 
  also 
  an 
  increase 
  of 
  volume 
  takes 
  place, 
  provided 
  that 
  such 
  

   combination 
  does 
  not 
  involve 
  an 
  increase 
  of 
  specific 
  gravity. 
  On 
  

   the 
  other 
  hand, 
  if 
  the 
  latter 
  be 
  decreased, 
  the 
  volume 
  must 
  be 
  

   increased 
  in 
  a 
  still 
  greater 
  proportion 
  than 
  the 
  matter. 
  Such 
  is 
  the 
  

   case 
  when 
  silicates 
  are 
  decomposed 
  by 
  carbonic 
  acid: 
  the 
  specific 
  

   gravity 
  of 
  the 
  products 
  of 
  decomposition 
  being 
  below 
  that 
  of 
  the 
  

   undecomposed 
  minerals, 
  their 
  volume 
  must 
  necessarily 
  be 
  greatly 
  

   increased. 
  

  

  If 
  a 
  mountain 
  composed 
  of 
  silicates 
  be 
  supposed 
  to 
  exist, 
  its 
  upper 
  

   parts 
  being 
  exposed 
  to 
  decomposition 
  by 
  carbonic 
  acid 
  and 
  rain, 
  

   then, 
  if 
  there 
  be 
  amorphous 
  silicate 
  of 
  alumina 
  in 
  the 
  lower 
  parts 
  of 
  

   this 
  mountain, 
  and 
  if 
  the 
  soluble 
  products 
  of 
  decomposition 
  (say, 
  

   alkaline 
  silicates) 
  were 
  carried 
  downwards 
  by 
  means 
  of 
  water, 
  crystals 
  

   of 
  felspar 
  may 
  be 
  produced, 
  increasing 
  the 
  bulk 
  of 
  the 
  mountain, 
  and 
  

   thus 
  causing 
  elevation. 
  Not 
  • 
  only 
  will 
  the 
  upper 
  parts 
  be 
  thus 
  

  

  