612  Examination  of  Balsam  of  Peru.  {^'"i?"'!^?'"- 
only  a  small  quantity  has  been  taken  for  the  experiments,  so  that  no 
reduction  of  sulphuric  acid  has  taken  place  (1  gram  of  balsam  and  1 
gram  concentrated  sulphuric  acid),  a  sample  containing  storax  or 
benzoin  yields  a  mass  that  when  washed  and  superficially  dried  is  only 
partially  soluble  in  ether.  U])on  mixing  1  gram  of  substance  with  1 
gram  of  concentrated  sulphuric  acid,  and  subsequently  washing  with 
hot  and  afterwards  with  cokl  water,  there  was  obtained  with  Peru 
balsam,  copaiba  balsam,  or  colophony,  a  solid  brittle  mass  completely 
soluble  in  ether ;  with  purified  storax  or  benzoin  a  solid  brittle  mass, 
only  partially  soluble  in  ether;  and  with  castor  oil  a  smeary  greasy 
mass  completely  soluble  in  ether. 
The  smeary  property  which  castor  oil  imparts  to  the  sulphuric  resin- 
ous mass  indicates  with  certainty  the  presence  of  this  oil.  In  the  case 
of  all  the  other  substances  the  washed  residue  possessed  a  plastic  or 
even  crumbling  character,  and  became  quite  hard  on  cooling. 
If  the  insoluble  residue  be  well  washed  on  a  filter  with  ether  and 
then  treated  with  alcohol  any  portion  of  it  derived  from  benzoin 
dissolves  completely.  If  it  owes  its  origin  to  storax  a  small  white 
residue  is  left,  consisting  of  a  substance  first  observed  by  the  author  in 
1881  and  which  E.  Mylius  has  named  styrogenin,  and  represented  by 
the  formula  CggH^oOg.  Styrogenin  is  still  better  isolated  by  treating 
the  residue  left  by  ether  with  acetone,  which  dissolves  any  portion  of 
the  residue  derived  from  benzoin  completely  and  that  from  storax  all 
except  the  styrogenin.  Styrogenin  is  insoluble  in  water,  alcohol, 
acetone  and  alkalies,  but  is  easily  soluble  in  chloroform.  It  can  there- 
fore be  readily  got  pure  by  treating  with  a  little  chloroform  the  white 
powder  left  after  washing  the  ether  residue  with  acetone  or  spirit,  and 
allowing  the  chloroformic  solution  to  evaporate  in  a  watch  glass.  The 
styrogenin  is  thus  obtained  in  microscopic  crystals  partly  tabular  and 
partly  more  pointed,  but  always  prismatic. 
If  larger  quantities  of  storax  be  used  no  styrogenin  is  obtained,  since 
the  reduction  of  the  sulphuric  acid  thus  set  up  involves  the  decompo- 
sition of  the  storax  in  other  ways.  But  with  quantities  not  exceeding 
1  to  2  grams  storax  always  yielded  the  author  styrogenin.  It  is  also 
requisite  that  the  quantity  of  sulphuric  acid  used  should  not  be  less 
than  that  of  the  balsam.  Storax  yields  from  6  to  7  per  cent,  of 
styrogenin. 
If  therefore  a  sample  of  Peru  balsam  treated  with  sulphuric  acid  is 
not  entirely  soluble  in  ether,  the  residue  if  completely  soluble  in 
