jo6 
Resin  of  Gurjun  Balsam. 
Am.  Jour.  Pharm. 
June,  1878. 
crystallized  acid  is  that  mentioned  in  the  said  book.  The  drug 
alluded  to  was  contributed  from  Trinidad  to  the  London  Exhibition  of 
1 85 1.  The  crystals  before  me  are  of  decidedly  acid  reaction  on  litmus 
paper.  I  have  recently  again  examined  several  varieties  of  copaiba,  but 
have  not  been  successful  in  obtaining  copaivic  acid  from  them.  At 
the  same  time  I  prepared  the  essential  oils  from  them  and  was  aston- 
ished to  find  them  all  levogyre,  although  I  had  submitted  to  distillation 
not  only  levogyre  varieties  of  the  balsam,  but  also  strongly  dextrogyre 
ones.  I  must  say  in  fact  (see  "  Pharmacographia,"  p.  204),  that  I  have 
as  yet  not  met  with  an  oil  of  copaiba  deviating  to  the  right. 
Some  time  ago  I  noticed  in  the  price  list  of  Gehe's  and  Co  ,  Dres- 
den, "  crystallized  copaivic  acid."  On  applying  for  it,  and  at  the  same 
time  for  the  very  balsam  from  which  it  had  been  extracted,  I  was  at 
once  informed  that  the  material  by  which  the  acid  had  been  afforded 
was  "  East  Indian  copaiba."  The  balsam  sent,  together  with  the 
crystals,  proved  indeed  to  be  Balsamum  Dipterocarpi,  as  described  by 
Hanbury  and  myself  in  u  Pharmacographia,"  p.  81.  I  therefore  sup- 
posed the  crystals  sent  by  Gehe  and  Co.  to  agree  with  gurjunic  acid, 
but  found  them  to  be  devoid  of  acid  character.  They  were  slightly 
yellowish  and  undoubtedly  crystalline,  and  soluble,  although  not  pre- 
cisely in  abundance,  in  the  usual  solvents  for  resins.  Among  them  I 
found  petroleum  spirit,  boiling  at  about  8o°C,  the  most  suitable  for 
purifying  the  crystals.  If  they  are  dissolved  in  about  twelve  parts  of 
that  liquid,  tolerably  well-formed  crystals,  thin  prisms — sometimes  as 
long  as  two-fifths  of  an  inch — are  obtained  by  exposing  the  solution  to 
cold.  I  have  not  been  able  to  get  finer  crystals,  either  by  evaporation 
of  the  petroleum  spirit  solution  or  by  using  alcohol. 
The  purest,  perfectly  transparent  and  colorless  crystals  of  the  best 
crops  begin  to  melt  at  I26°C.  without  diminishing  their  weight  ;  they 
are  in  fact  anhydrous  \  somewhat  more  considerable  quantities  cannot 
be  perfectly  liquefied  before  reaching  1300.  Gurjunic  acid,1  according 
to  Werner  (Zeitschrift  fur  Chemie,  1862,  588),  melts  at  220°.  The 
resin  under  notice,  as  purified  by  me,  after  it  has  been  melted,  forms 
an  amorphous  mass,  reassuming  immediately  the  crystalline  form  as 
soon  as  it  is  slightly  touched  with  alcohol.     By  heating  the  crystallized 
'It  is  called  "  gurgunic  acid"  in  the  German  books,  owing  no  doubt,  to  a  mis- 
print, for  I  am  not  aware  that  in  India  they  ever  write  "gurgun  balsam  "  but  always 
"  gurjun,"  although  I  am  unable  to  say  what  this  word  signifies. 
