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ON  THE  PREPARATION  OF  COPAL  VARNISH. 
and  possessed  the  usual  basic  characters.  I  did  not  attempt  to 
crystallize  it. 
Extract  of  digitalis  was  tried,  and  readily  yielded  its  alkaloid. 
Extract  of  conium  also,  the  benzole  being  washed  with  weak 
sulphuric  acid,  yielded  the  sulphate  of  conium,  which,  afterwards 
distilled  with  strong  potassa,  yielded  the  coneine  in  a  state  of 
purity. 
Taraxacum,  sarsaparilla,  and  colocynth,  were  tried,  but  no  ac- 
tive principles  could  be  eliminated  from  these  bodies  by  this 
process, 
Nut  galls,  in  fine  powder,  were  treated  with  benzole.  Tannin, 
of  good  color,  was  the  result  of  its  evaporation ;  but  from  the 
impossibility  of  perfectly  freeing  it  from  the  odor  of  the  benzole, 
I  fear  that  this  process  will  not  prove  of  practical  use,  unless  in 
the  production  of  tannin  on  the  large  scale  for  use  in  the  arts, 
when  the  odor  would  be  of  minor  importance. 
I  hope  to  be  able  on  a  future  occasion  to  give  you  a  few  more 
illustrations  on  the  practical  use  of  benzole  in  operative  che- 
mistry.— JV.  Y.  Jour,  of  Pharm.  from  Chemist,  December,  1853. 
ON  THE  PREPARATION  OF  COPAL  VARNISH. 
By  Prof.  Heeren. 
There  is  no  difficulty  in  dissolving  copal  in  fatty  and  volatile 
oils  when  the  resin  has  been  previously  fused ;  by  this  process, 
however,  a  more  or  less  distinct  coloration  is  produced,  and  the 
natural  hardness  of  this  fine  resin  is  injured.  It  has  therefore 
been  often  attempted  to  dissolve  copal  without  previous  fusion ; 
but,  as  is  well  known  to  all  who  have  occupied  themselves  with 
this  question,  great  difficulties  have  been  found  in  effecting  the 
solution.  Directions  have  been  given  to  soak  the  pounded  copal 
in  ether  or  ammonia  until  it  swells  up  into  gelatinous  form,  and 
then  to  dissolve  it  in  strong  alcohol ;  but  this  process  never  suc- 
ceeded with  the  author,  though  he  tried  it  repeatedly.  Others 
recommend  hanging  the  copal  in  a  small  bag  in  a  retort,  in  which 
absolute  alcohol  is  gently  boiling.  This  method  also  failed,  in 
the  author's  hands,  in  producing  even  a  tolerably-concentrated 
varnish. 
I^The  best  prescription  appears  to  the  author  to  be  that  given 
