384 
ON  THE  VEGETABLE  ORIGIN  OF  DIAMONDS. 
formation  of  diamonds  to  be  the  result  of  an  uninterrupted  pro- 
cess of  chemical  decomposition.  "  Imagine  this  chemical  decom- 
position taking  place  in  a  fluid  rich  in  carbon  and  hydrogen,  and 
you  have  a  combination  still  richer  in  carbon,  out  of  which  will 
issue,  as  a  final  result  of  its  chemical  decomposition,  pure  carbon, 
and  that  in  a  crystallized  form."  Indeed,  a  high  temperature  is 
adverse  to  the  formation  of  diamonds,  as  diamonds  become  black 
when  subjected  to  a  high  degree  of  temperature,  and,  according 
to  Despretz's  experiments,  they  are  even  converted  into  graphite 
and  coke.  The  black  diamonds,  or  so-called  "  carbonates  of 
Bahia,"  are  in  part  a  mixture  of  uncrystallized  carbon  and  dia- 
monds, as  shown  by  the  process  of  combustion,  to  which,  at  my 
desire,  they  were  submitted  by  Professor  Lowig.  That  diamonds 
originated  under  Neptunian  agency  is  further  proved  by  the  fre- 
quent occurrence  of  crystals  in  them.  I  have  seen  them  in  hun- 
dreds of  different  specimens,  and  even  small  cavities  containing 
them.  In  my  essay  I  have  given  ample  proof  that  at  one  time 
diamonds  were  soft  bodies.  Hitherto  only  one  diamond,  in  the 
possession  of  the  Emperor  of  the  Brazils,  has  been  known,  on 
which  the  impression  of  a  grain  of  sand  was  visible.  I  have 
before  me  a  rhombic  dodecahedron,  on  the  whole  surface  of  which 
impressions  of  grains  of  sand  are  visible,  and  a  similar  crystal  of 
the  black  diamond  on  which  the  same  impressions  exist.  In  a 
third  there  is  a  cavity  with  bent  and  broken  crystals  of  an  un- 
known kind.  Two  others,  an  octahedron  and  a  rhombic  dodeca- 
hedron, have  on  their  surface  deep  impressions  of  crystals  which 
are  not  those  of  diamonds.  The  Neptunian  origin  of  diamonds 
can  therefore  no  longer  be  doubted.  G.  Bischof  also  thinks 
that,  after  the  discovery  of  iron  pyrites  in  the  diamond,  any 
doubt  respecting  the  formation  of  diamonds  in  a  moist  way  has 
been  dispelled.  In  close  connection  with  these  observations  is 
the  question  about  the  vegetable  origin  of  diamonds,  which  in  a 
measure  was  answered  by  Newton,  who  regarded  them,  on  account 
of  their  great  power  of  reflecting  light,  long  before  their  true 
chemical  condition  was  ascertained,  to  be  coagulated  fatty  or  oily 
bodies.  Jameson  and  Wilson  endeavored  to  prove  this  theo- 
retically, Petzholdt  practically,  by  the  vegetable  cells  found  in 
the  ashes  of  diamonds.    The  vegetable  origin  of  coal  and  anthra- 
