386  Examination  of  Commercial  Copaiba.  {AmA^87h7arm' 
The  Para  copaiba  was  then,  adulterated  with,  first,  30  per  cent,  of 
castor  oil ;  second,  the  same  amount  of  linseed  oil,  and,  third,  20  to 
50  per  cent,  of  Venice  turpentine.  With  these  mixtures  the  following 
behavior  was  observed  : 
Tests.  Behavior  of  first.  Second.  Third  mixture. 
Alcohol,  absolute,       Clear  solution.  Clear  solution.  CfloccJlent  """^  ak°h01 
Alcohol,  sp.  gr.  "817,  Slightly  cloudy.  fellow0"  ''  Very  s]i§ht  separation. 
Alcohol,  sp,  gr.  "835,  Separation  when  cold.  Separation,  hot  or  cold.  Separation,  hot  or  cold. 
A  bulk,™  WatCr'  haIf  MHky  Wkh  5  PSr  CCnt-  °iL     ^elKsh.5      C£nt* 0il''  Clear  solution 
Dropped  on  paper,     Greasy  margin.  Yellow  greasy  margin.       Well  defined  resin  stain. 
Boiled  with  water,     Soft;  with  little  oil,  plastic    Resi(jUe  soft  or  plastic.       Hard  resin. 
'        residue.  r 
Tjr    .  Odor  of  copaiba,  then  of   Odor  of  copaiba  and  of    Tx-  ..  , 
Heat>  burning  fat.  burning  fat.  Distmct  turpentine  odor. 
Petroleum  benzin,  i  Clear  solution,  even  in  pres-  pjear  Dense    floccules    with  4 
to  4  parts,  ence  of  2  o:l  to  1  copaiba            '  parts  of  turpentine. 
Petroleum  benzin,  Separation,   even  with  10  Dense    floccules    with  4 
10  to  12  parts,  per  cent.  oil.  parts  of  turpentine. 
The  oil  separated  from  the  first  mixture  indicates  pretty  nearly  the 
exact  amount  of  castor  oil  present,  but  little  remaining  dissolved  in 
the  benzin.  The  solution  of  Para  copaiba  in  petroleum  benzin  was 
clear  until  about  8  parts  of  the  solvent  had  been  added,  when  some 
floccules  separated  ;  the  Maracaibo  balsams  gave  clear  solutions. 
Experiments  were  also  made  with  acids,  oxidizing  agents,  various 
chemicals  and  solvents,  without  observing  any  distinguishing  character- 
istic reactions  ;  and  though  I  have  failed,  as  others  have  before  me,  to 
find  a  reliable  test  for  the  purity  of  the  different  varieties  of  copaiba, 
by  which  the  presence  of  all  adulterations  could  be  detected,  yet  I  may 
state  that  petroleum  benzin,  properly  applied,  will  detect  the  presence 
of  Venice  turpentine,  and  not  only  the  presence,  but  also  very  nearly 
the  percentage,  of  castor  oil.   (See  also  paper  in  March  number,  p.  131). 
ANALYSIS  OF  COTTON  ROOT  BARK. 
By  Charles  C.  Drueding,  Ph.G. 
From  an  Inaugural  Essay. 
The  analysis  was  partly  made  at  the  laboratory  of  the  Philadelphia 
College  of  Pharmacy,  and  after  a  series  of  preliminary  experiments  the 
following  course  was  adopted  : 
Five  pounds  of  the  bark  were  exhausted  with  strong  alcohol.  About 
24  pints  of  a  beautiful  dark-red  colored  tincture  was  obtained,  which 
was  reduced  by  distillation  to  16  pints,  and  precipitated  with  an  alcoholic 
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