416 
Notes  on  so-called  Wood-oil. 
Am.  Jour.  Pharm. 
Sept.,  1876. 
about  20  parts  carbon  bisulphide,  and  a  drop  of  a  cooled  mixture  of 
equal  parts  of  sulphuric  and  nitric  acids  added,  takes  a  splendid  violet 
color.  A  single  drop  of  the  etherial  oil  is  sufficient  to  produce  the 
reaction,  and  the  color  lasts  several  hours.  It  is  not  prevented  by  the 
presence  of  resin  or  by  copaiva  balsam,  so  that  the  reaction  takes  place 
with  the  crude  Gurgun  balsam,  or  even  when  that  is  mixed  with  eight 
times  its  volume  of  copaiva  balsam.  The  reaction  can,  therefore,  be 
used  to  detect  the  presence  of  Gurgun  balsam  in  copaiva  balsam. 
Under  the  same  conditions  fish  liver  and  oil  of  valerian  are  also  colored 
a  beautiful  violet,  but  only  transiently  so.  In  order  to  exclude  fish  oil 
from  the  test,  it  is  recommended  to  distil  off  the  etherial  oil,  although 
on  account  of  its  high  boiling  point  (2500  to  2600  C.)  this  is  not  an 
agreeable  task.    Only  a  few  drops  are  required,  however,  for  the  test. 
Should  a  wood  oil  not  correspond  to  this  reaction,  the  author  thinks 
it  might  probably  be  due  to  the  fact  that  some  Dipterocarpus  trees 
yield  a  varying  balsam.  The  balsam  is  obtained  in  large  quantities 
from  the  following  species  :  Dipterocarpus  turbinatus,  Gaertn.  (syn.  D. 
laevis,  Ham.,  D.  indicus,  Bedd.\  D.  incanus,  Roxb.,  D.  zeylanicus, 
Thw.,  D.  trinervis,  Blume,  D.  littoralis,  BL,  D.  alatus,  Roxb.,  D.  his- 
pidus,  Thw.,  D.  gracilis,  BL,  D.  retusus,  Bl.  All  these  species  occur 
in  India  and  in  the  Archipelago,  and  the  last  even  in  the  Philippines. 
Their  resinous  juice  is  used  very  generally  as  varnish,  hence  the  name 
"  wood  oil."  It  is  hardly  probable  that  they  all  yield  a  resin  chemi- 
cally and  physically  identical.  The  author  has  found  that  the  oil  dis- 
tilled by  him  from  undoubtedly  true  Dipterocarpus  balsam  is  dextrogyre, 
whilst  Werner,  who  first  examined  Gurgun  balsam,  in  1862,  speaks  of 
it  as  laevogyre.  In  all  the  specimens  examined  by  the  author  to  the 
present  time,  however,  he  has  found  the  color  reaction  constant. 
Another  possible  ground  for  failure  in  obtaining  the  reaction  is  its 
confusion  with  other  liquids  used  for  similar  purposes.  The  balsam 
obtained  from  Hardwickia  pinnata,  Roxb.,  a  leguminaceous  plant,  is 
used  in  Southern  India  in  the  same  medical  cases  as  copaiva  balsam  ; 
but  an  authentic  specimen  in  the  author's  possession  is  not  fluorescent 
like  Dipterocarpus  balsam,  and  dissolved  in  carbon  bisulphide  gives 
only  a  yellow  color  with  the  acid  mixture.  The  author  does  not 
know,  however,  that  it  is  ever  there  called  "  wood  oil." 
A  fat  oil,  used  in  enormous  quantities  in  Eastern  Asia  for  paint  and 
varnish,  and  also  as  a  drastic  medicine,  and  very  generally  called  "  wood 
