Am.  Jour.  Pbarm.) 
March,  1897.  J 
Zanzibar  Copal, 
155 
(c)  Kauri  copal  from  New  Zealand,  the  botanical  origin  of  which 
is  Dammara  australis. 
(d)  Manilla  copal,  obtained  from  Vateria  indica. 
(e)  South  American  copal,  derived  from  Hymenea  coubaril,  H. 
stilbocarpa,  Trachylobium  martianum,  T.  hornemannianum. 
The  first  three  are  fossil  resins,  and  are  dug  up  out  of  the  earth, 
whilst  the  last  two  are  collected  from  the  plants  yielding  them. 
To  the  East  African  copals  belong  the  following  three  varieties : 
(1)  Copal  from  Mozambique. 
(2)  Copal  from  Madagascar. 
(3)  Copal  from  Zanzibar. 
The  purity  and  hardness  of  the  last  variety  render  it  the  most 
valuable,  and  the  principal  object  of  the  author's  work  was  to 
investigate  the  constituents  of  Zanzibar  copal ;  the  details  that 
follow  relate,  therefore,  to  that  variety  only.  This  must  be  empha- 
sized, because  many  statements  are  met  with  without' any  mention 
of  the  variety  of  copal  to  which  they  refer. 
From  Bagamoyo,  in  East  Africa,  the  author  received  raw 
(unwashed)  copal,  pure  copal,  and  specimens  of  the  tree  yielding  it. 
The  resin  is  brought  down  by  the  natives  to  Kiboa  from  districts 
from  the  coast ;  the  botanical  specimens  came  from  Usegna,  which 
lies  inland  westward  from  Bagamoyo.  The  commercial  resin, 
obtained  from  a  German  firm,  agreed  in  its  characters  with  the 
genuine  specimens  sent  from  East  Africa. 
Zanzibar  copal,  finely  powdered,  melts  at  about  1400  C;  it  is 
slowly  but  completely  soluble  in  alcohol ;  benzol,  chloroform  and 
glacial  acetic  acid  dissolve  about  30  per  cent.,  ether  about  34  per 
cent.,  petroleum  spirit  and  carbon  bisulphide  about  10  per  cent. 
When  boiled  with  alcohol  the  resin  caked,  and  only  a  slight  pro- 
portion dissolved,  but  by  repeated  digestion  with  alcohol  it  could  be 
brought  entirely  into  solution  and  precipitated  with  water.  The 
resin  thus  purified  was  more  soluble  in  the  menstrua  previously 
mentioned,  and  dissolved  also  in  boiling  very  dilute  solution  of  pot- 
ash (01).  All  attempts  to  separate  it  into  other  constituents  were 
unsuccessful,  nor  could  it  be  saponified.  It  appeared  to  consist  of 
resin-acids,  the  principal  of  which,  constituting  about  80  per  cent,  of 
the  resin,  was  called  trachylolic  acid.  This  acid  could  be  obtained 
with  difficulty  in  minute  sphaero-crystalline  masses,  melting  at 
1 68°  C.    From  it  the  potassium,  copper  and  iron  salts  were  pre- 
