AmAug^'i89iarm'}  hocinnamic  Acid  in  Cocaine  Alkaloids.  423 
cinnamic  acid  by  repeatedly  extracting  it  with  small  quantities  of 
light  petroleum,  in  which  cinnamic  acid  is  only  very  sparingly 
(0  095  in  100),  isocinnamic  acid,  on  the  other  hand,  readily  (17  in 
100)  soluble.  It  is  then  converted  into  the  calcium  salt,  and  the 
latter  extracted  with  water,  in  which  calcium  cinnamate  is  only  very 
sparingly  (1  in  430),  but  calcium  isocinnamate  readily  (1  in  8)  solu- 
ble. These  two  processes  are  repeated  many  times  until  the  cal- 
cium salt  obtained  is  completely  soluble  in  a  small  quantity  of  cold 
water.  The  salt  is  then  decomposed  with  hydrochloric  acid,  and 
the  acid,  which  is  precipitated  as  an  oil,  extracted  with  ether,  and 
recrystallized  from  light  petroleum. 
Isocinnamic  acid,  C9H302,  separates  from  cold  light  petroleum  in 
transparent  crystals  melting  at  45-470  ;  if  the  acid  be  coarsely 
powdered  and  treated  with  a  small  quantity  of  cold  light  petroleum 
in  such  a  way  that  the  more  compact  crystals  remain  undissolved, 
the  latter  melt  at  570,  which  is  the  true  melting  point  of  the  acid. 
It  is  very  readily  soluble  in  light  petroleum,  carbon  bisulphide, 
alcohol  and  all  ordinary  solvents,  except  water,  whereas  cinnamic 
acid  and  atropic  acid  are  only  sparingly  soluble  in  light  petroleum 
and  carbon  bisulphide.  Molecular  weight  determinations  by 
Raoult's  method,  in  glacial  acetic  acid  solution,  gave  results  in 
accordance  with  the  molecular  formula  given  above  ;  on  evaporat- 
ing the  acetic  acid  solution  on  the  water-bath,  the  isocinnamic  acid 
was  deposited  unchanged.  It  is  immediately  oxidized  by  potassium 
permanganate  in  cold  sodium  carbonate  solution,  with  formation  of 
benzaldehyde,  but  it  does  not  reduce  Fehling's  solution,  and  it  is 
not  changed  by  boiling  alcoholic  potash.  Crystalline  measurements 
showed  that  this  acid  is  not  identical  either  with  cinnamic  acid  or 
with  atropic  acid. 
The  calcium  salt  (C9H702)2Ca  -\-  3H20,  separates  from  cold  water 
in  crystals  which  effloresce  on  exposure  to  the  air  ;  the  salt  then 
contains  3  mols.  H20,  which  are  expelled  at  1250.  The  barium  salt 
is  not  quite  so  readily  soluble  in  water  as  the  calcium  salt.  The 
silver  salt,  C9H702Ag,  is  colorless,  and  undergoes  no  change  on 
exposure  to  light.  In  aqueous  solutions  of  the  ammonium  salt, 
cobalt,  manganese  and  zinc  acetate  produce  no  precipitation,  but 
copper  acetate  gives  a  green,  and  mercuric  nitrate  a  colorless  pre- 
cipitate.   The  methyl  salt  is  a  colorless  liquid. 
Isocinnamic  acid  begins  to  boil  at  265 °,  but  the  boiling  point 
