440 
GUM  COPAL  IN  ANGOLA. 
\ 
or  1,600,000  lbs.  per  annum.  This  resin  is  dug  out  of  the 
loose  strata  of  sand,  marl,  or  clay,  or  else  is  found  in  isolated 
pieces  washed  to  the  surface  by  heavy  rains,  or  exposed 
by  earth-falls,  such  isolated  pieces  inducing  the  negroes  to  dig 
for  larger  quantities  in  adjacent  spots.  The  search  is  sometimes 
carried  to  a  depth  of  eight  or  ten  feet ;  and  is  in  certain  cases 
combined  with  the  gathering  of  the  Urzella,  that  is,  the  different 
varieties  of  Roccella  fuciformis ;  and  also  with  the  collection 
of  several  other  gums,  including  gum  arabic,  which  is  found  on 
the  Acacias  of  these  countries.  The  cop£l;  being  of  unequal 
value,  has  to  be  sorted  when  brought  to  market ;  it  is  mostly 
classed  according  to  color,  the  deeper-colored  being  generally 
worth  double  as  much  as  the  lighter  sort,  and  the  price  is  de- 
termined by  weight.  The  lumps  of  copal  vary  in  size,  but  are 
rarely  found  larger  than  a  hen's  egg,  though  occasionally  they 
weigh  3  or  4  lbs.  The  pieces  are  all  covered  with  a  whitish 
earthy  crust,  which  sometimes  exhibits  veins  or  network.  The 
occurrence  of  this  crust  was  regarded  by  the  author  as  proving 
that  after  falling  from  the  mother  tree  they  were  forcibly  trans- 
ported by  floods  or  earth-falls,  and  imbedded  in  the  soil  in  which 
they  are  now  found.  The  total  annual  export  of  gum  copal  from 
all  the  districts  of  Angola  was  estimated  at  2,000,000  lbs.  As 
to  the  origin  of  this  West  African  copal,  the  author  concluded 
that  it  was  the  exudation  of  some  tree,  though  now  found  in  a 
fossilized  state,  many  of  the  pieces  showing  distinctly  the  remains 
of  bark  to  which  they  had  adhered.  Whether  all  the  varieties 
come  from  the  same  tree  he  regarded  as  a  question  remaining  to 
be  solved,  but  his  observation  had  tended  to  establish  the  con- 
viction that  the  differences  were  attributable  to  the  age  of  the 
tree,  or  the  nature  of  the  soil  on  which  it  grew.  According  to 
Dr.  Daniel,  the  Sierra  Leone  copal  comes,  in  part,  from  a  tree 
described  by  Mr,  Bennett  as  Gfuihortia  copalifera,  and  which 
Mr.  Benthaui  has  since  named  Copaifera  guibourtiana  ;  though 
he  also  states  that  a  considerable  portion  of  it  is  washed  to  the 
surface  of  the  earth,  and  is  therefore  of  a  fossilized  character. 
The  author  concluded  a  lengthy  review  of  the  supposed  sources 
of  copal  by  observing,  "  that  West  African  copal,  and  probably 
all  gum  resins  exported  under  this  name  from  tropical  Africa, 
